joides journal 23(1) - ocean drilling program...joides journal volume 23 number 1 in this issue:...

JOIDES JournalVolume 23 Number 1

In this Issue:

SCIENCE SECTIONCritical Boundaries in Earth’s History andthe K-T Boundary ......................... Cover

Leg 169 Drills a Major Massive SulfideDeposit on a Sediment-BuriedSpreading Center ............................... 4

Hydrogeology of the Upper OceanicCrust ................................................ 6

Neogene Evolution of the CaliforniaCurrent System ................................. 8

The Cause and Effect of Sea LevelChange ........................................... 11

Drilling Tectonic Windows into the LowerCrust and Upper Mantle .................... 14

TECHNOLOGY NEWSDetection of in-situ Physical PropertiesUsing Logging-While-Drilling .............. 16

Technological Innovations at ODP ....... 19

PLANNING SECTIONMessage from the Chair .................... 21An Overview of the New JOIDES ScienceAdvisory Structure ........................... 22

The ODP Science Plan ....................... 24Janus in January ............................... 27Ocean Drilling in the 21st Century ...... 28ODP Contractors ............................... 30ODP National Offices ......................... 30Continued on page 2

Critical Boundaries in Earth’s History - and the K-T BoundaryContributed by the ODP Leg 171B Shipboard Scientific Party

to document climate variability when the Earth’sclimate switched from a greenhouse to an icehousestate.

Leg 171B recovered a suite of critical events inEarth’s history that includes the late Eoceneradiolarian extinction, late Paleocene benthicextinction, the K-T boundary, the midMaastrichtian event, and several episodes oforganic-rich sediments in the Albian warm period.The upper Paleocene benthic foraminifer extinctionoccurs within an expanded interval of calcareoussediments unlike most regions of the Atlanticwhere calcareous fossils have been severely dis-solved just above the extinction horizon.

The recovery of spectacular records of theK-T boundary attracted the attention andinagination of both the public and theinternational news media. The K-Tboundary was recovered at threesites, each with a biostratigraphi-cally and magnetostratigraphicallycomplete sequence that includesthe earliest part of the aftermath ofthe Late Cretaceous extinctions.Three copies of the boundaryinterval at one site were collectedin a section that includes a 10-17cm thick graded bed of greenspherules capped by a fine-grained,rusty brown limonitic layer that isoverlain by dark gray clay of theearliest Danian (Figure 2). Thissuccession is interpreted as falloutfrom the Chicxulub impactstructure on the Yucatan Peninsulaand the succeeding deposition oflowermost Danian sedimentfollowing the K-T extinction event.Notably, neither of the two K-Tboundary sections drilled updipfrom this site have well developedejecta beds between earliest Danianand latest Maastrichtian deposits.The spherules at these sites wereeither slumped into deeper water

Ocean Drilling Program Leg 171B wasdesigned to recover a series of ‘critical

boundaries’ in Earth history in which abruptchanges in climate and oceanography coincide withoften drastic changes in the Earth’s biota. Some ofthese events such as the Cretaceous-Paleogene(K-T) extinction and the late Eocene tektite layersare associated with the impacts of extraterrestrialobjects, like asteroids or comets, whereas otherevents, including the benthic foraminifer extinctionin the late Paleocene and the mid Maastrichtianextinction events, are probably related to intrinsicfeatures of the Earth’s climate system. Two of thecritical boundaries, the early Eocene and the lateAlbian, are intervals of unusually warm climaticconditions when the Earth is thought to haveexperienced such extreme warmth that the epi-sodes are sometimes described as ‘super-green-house’ periods. The major objectives of Leg 171Bwere to recover records of these critical boundariesat shallow burial depth where microfossil andlithological information would be well preserved,and to drill cores along a depth transect where thevertical structure of the oceans during the bound-ary events could be studied.

Five sites were drilled down the spine of BlakeNose, a salient on the margin of the Blake Plateauwhere Paleogene and Cretaceous sediments havenever been deeply buried by younger deposits(Figure 1). The Blake Nose is a gentle rampextending from about 1000 m water depth toabout 2700 m depth, and is covered by a drape ofPaleogene and Cretaceous strata that are largelyprotected from erosion by a thin veneer ofmanganiferous sand and nodules. A continuous,expanded, and almost complete, record of theEocene period was recovered that showsMilankovitch-related cyclicity. In combination withthe excellent magnetostratigraphic record and thepresence of both calcareous and siliceous microfos-sils, the Milankovitch-controlled cycles will be usedto recalibrate the late-middle Eocene and lateEocene timescale. Radiometric dates on ash layers,and dating by astronomical tuning, will produce anintegrated timescale to recalibrate magneto- andbiostratigraphy. In addition, the chemistry of thewell-preserved calcareous microfossils will be used

Joint Oceanographic Institutions for Deep Earth Sampling

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very shortly after deposition or turbidites carryingthe ejecta debris bypassed the upper slope anddeposited at least part of their load near the tip ofBlake Nose. The recovered sections of the K-Tboundary are complete at several sites, and thusexcellent for studying the response of marine biota

to theextraterres-trial event.For instance,the plank-tonicforaminiferaare extremelywell preserved, and hence are ideal for stableisotope studies that hopefully will reveal the chainof climate events caused by the impact.

Based on the results from drilling, the ship-board scientific party has derived a preliminarygeologic history of Blake Nose. The Blake Nose iscomposed largely of Jurassic to mid Cretaceouscarbonate platform deposits. The platform rests onbasement rocks formed by intrusion and volcanismthrough attenuated continental crust during therifting stage of the Atlantic. As much as 10 km ofcarbonates accumulated in this area. By about 110Ma, the reef tract stepped back 40-50 km from thelower Cretaceous margin and formed a long tract

of coral-rudist reefs. These reefs ceased growth afew Ma later, and the deposition of green and redvariegated clays began. Black shales of latest Aptianage (about 105 Ma) found at Site 1049 suggestthat the disaerobic conditions associated with theorganic rich sediments extended to a water depth

of at least 1500 m. Black shaledeposition returned in the lateAlbian-Cenomanian in a series ofcycles that are age-correlativewith Oceanic Anoxic Event 1dknown from Europe andelsewhere.

There is a widespread, majorunconformity above the Cen-omanian (100 Ma) on BlakeNose from which upper Cen-omanian to lower Campanian(95-75 Ma) strata were largelyremoved. In addition, theMaastrichtian sequence (65-70Ma) contains numerous slumps,including one at theMaastrichtian-Cenomanian

contact at Site1052, so it ispossible thatCampaniansediments wereremoved fromthe area of Site1052 by downslope transport.Despite theslumping, muchof theMaastrichtianappears to bepresent as a drapeof nannofossilchalk and ooze.The preservedrecord has a well-

developed color banding that may record orbitalcycles.

The end of the Cretaceous and earliest eventsof the Cenozoic (K-T boundary) are well preservedon Blake Nose. Deposition of a nearly uniformdrape of pelagic sediment continued into thePaleocene. Paleocene strata are the first to preservegeochemical and lithological evidence for abundantvolcanic ash on Blake Nose – a trend that contin-ued throughout the Eocene.

By the latest Paleocene, deposition wasconcentrated into a major clinoform stack thatreached its greatest thickness near the center of theBlake Nose transect. At least two hiatuses are

Figure 1. Location of ODPLeg 171B Blake Nosepaleoceanographic drilling,Western North Atlantic.

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present in this sequence. One is within the upper-most Paleocene, and occurs close to the upperPaleocene ‘Thermal Maximum’ when the deepoceans appear to have abruptly warmed for a fewhundred thousand years. However, the hiatus iseither absent or very short near the center of theclinoform stack where the Paleocene-Eocenetransition is biostratigraphically complete. A secondhiatus is present near the lower-middle Eocenetransition where about two million years of theEocene are absent across the whole of Blake Nose.The locus of sedimentation apparently backsteppedup the slope of Blake Nose during the middle andlate Eocene. Sediments are mostly green siliceousnannofossil chalks and ooze with well-preservedcalcareous and siliceous microfossils. Volcanic ashbeds are common throughout the sequence andprobably record major eruptions in the LesserAntilles. The combination of goodmagnetostratigraphy, biostratigraphy,and color cycles should result in greatimprovements in the chronology forthis part of the Eocene. In addition,sediments correlative with the UpperEocene meteorite impact event in theChesapeake Bay were recovered.

It is probably no coincidence thatthe youngest Eocene sediments are oflatest Eocene age. The Oligocene isassociated with widespread hiatuses inthe North Atlantic. The Gulf Streamassumed its present course for themost part in the Oligocene and cutinto the surface of the Florida Straitsand the Blake Plateau. A highstand ofsea level in the late Oligocene shiftedsedimentation from the shelf to thecoastal plain starving the outer shelfand slope landward of the BlakeEscarpment. In the Blake Basin,Oligocene cooling at high latitudesintensified the southward flow ofdeep water along the Blake Escarp-ment and formed the widespreadseismic reflector that represents aunconformity distributed over mostof the western North Atlantic.

Shore-based research will focuson studies of the sequence of eventssurrounding both the K-T andUpper Eocene impact events and thepaleoceanographic history of thePaleogene and Cretaceous se-quences. The excellentmagnetostratigraphy record fromBlake Nose will be used to deter-mine the polar-wander path of

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Figure 2: Compilation ofthe three K/T boundary sec-tions recovered at Site 1049.

North America from the Aptian to the Eocene.Major research effort will be devoted to analysis ofhistory of orbital forcing of both Cretaceous andCenozoic climate and the dynamics of both theCenomanian and lower Eocene warm periods.Finally, the depth transect of cores will be used toreconstruct the vertical structure ofthe oceans in the distant pastwhen patterns of ocean circula-tion were much different fromtoday.

Continued on page 10

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Figure 1. Location mapshowing tectonic setting ofthe sediment-coveredspreading centers atMiddle Valley andEscanaba Trough on theJuan de Fuca-GordaRidge spreading system.

Leg 169 Drills a Major Massive Sulfide Deposit on a Sediment-Buried Spreading Center

by Yves Fouquet, Robert Zierenberg, Jay Miller and Leg 169 Scientific Party

able sedimentary horizon during stages of thedevelopment of the deposit when the pathways tothe seafloor, represented by the feeder zonemineralization, were sealed. This zone is cappedand isolated by an impermeable silicification frontthat may have formed in response to in situ coolingof the hydrothermal fluid. Pore fluid derived frombelow this horizon is distinct from that sampledabove and has the low chlorinity signal typical ofthe only vent known in the area prior to Leg 169indicating that the hydrothermal system underlyingthe Bent Hill area is separated from the hydrother-mal system that delivers higher salinity fluids to theDead Dog vent field, which is located 3 km to thenorthwest. Hole 1035F penetrated this horizonand was vigorously venting hydrothermal fluid afterthe drilling.

The metal zonation observed in ancientmassive sulfide deposits is also present in theBHMS. Continued hydrothermal circulationthrough the massive sulfide after its initial deposi-tion converted much of the primary pyrrhotite topyrite ± magnetite. In addition, remobilized metals,such as zinc, have been reprecipitated at the topand on the sides of the mound at lower tempera-tures. Much of the copper transported in thehydrothermal fluid was deposited below theseafloor in the stockwork zone and in the DeepCopper Zone.

A second mound, the Ore Drilling Program(ODP) mound, occurs 350 m south of the BHMS(Figure 2). A single hole was drilled near the top ofthe mound, 50 meters south of the only knownnatural active vent. The results were spectacular!Hole 1035H penetrated three stacked zones ofmassive and semi-massive sulfide along with theirfeeder zones. Metal grades are much higher thanthose encountered at BHMS with some samplesexceeding 40% Zn and 15% Cu. Most mininggeologists will never have the experience of drillinga hole that intersects as much high grade ore as1038H. However, the true value of this deposit isin the complex record of deposition, recrystalliza-tion, and remobilization of metal recorded throughthe multiple hydrothermal stages that remainedfocused beneath this mound throughout its history.Although the continuity of mineralization betweenthe ODP mound and BHMS could not be tested, azone of high-grade stratiform copper mineraliza-tion was intersected at approximately the samestratigraphic horizon as the zone under BHMS.Hole 1038H is also now the third known hydro-

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OPD Leg169 was the second ODP leg de-signed to investigate the genesis and evolu-

tion of Fe-Cu-Zn deposits formed at sediment-covered spreading centers, with the ultimate goalof quantifying the transfer of mass and energyduring hydrothermal circulation. This Leg built onresults from drilling at Middle Valley on the Juande Fuca Ridge during Leg 139 (Davis et al., 1992)with additional drilling in this area, and also inves-tigated hydrothermal sites at Escanaba Trough on

the SouthernEscanaba Ridge(Figure 1).

The Bent HillMassive Sulfide(BHMS) inMiddle Valleycomprises threemajor mineral-ized parts(Figure 2). Theuppermost zoneconsists of a 100m thick conicalmound ofmassive sulfideformed at theseafloor andsubsequentlyburied bysediment.Underlyingthis is a 100 mthick feederzone consist-ing ofsubverticalcrosscuttingveins filledwith Cu-Fesulfide and

pyrrhotite. The intensity of veining decreases withdepth and the style of mineralization changes topredominantly subhorizontal impregnation andreplacement of sediment. At the base of the feederzone there is a 4 m thick strongly silicified horizonunderlain by a 13 m thick zone of intense alter-ation and replacement of the host sandstones byCu-Fe sulfides and chlorite (Deep Copper Zone).This zone of high grade (up to 16% Cu) stratiformcopper mineralization may represent a zone wherehydrothermal fluid flowed laterally into a perme-

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across the Dead Dog active hydrothermal mounddemonstrated that the mound is young and wasformed by build-up and collapse of anhydritechimneys, rather than by subsurface deposition andinternal inflation.

A high priority scientific objective was toestablish the differences between the maturehydrothermal system developed at Bent Hill inMiddle Valley and the young hydrothermal systemin Escanaba Trough. These systems differ in morethan their state of evolution. Metals in the MiddleValley sulfide deposits seem to be dominantlyderived from basaltic rocks, whereas in EscanabaTrough, the composition of the deposits showsextensive contribution of metals from the sediment.Massive sulfide recovered from the Central Hill at

thermal vent in the Bent Hill area. An NSFsponsored “event response” cruise using the R/VThompson and the Canadian ROPOS ROVsampled 272°C hydrothermal fluids from this ventjust weeks after its creation (D.S. Kelley and M.D.Lilley, personal communication).

Although creating new vents in the Bent Hillarea was not a goal of this Leg, conducting activehydrological experiments in the Dead Dog ventfield, which is located 4 km to the northwest, was ahigh priority objective. The existing CORK fromHole 858G was successfully removed and recov-ered the first CORK-hosted hydrothermal chimneydeposits in the process, and 272°C hydrothermalfluids were sampled from the borehole. Theborehole was then reinstrumented with a newtemperature string and pressure transducer and anew CORK was installed. The damaged CORK inHole 857D wasrecovered andreplaced with an 898m long thermistorstring and a newCORK in a techno-logically difficultoperation that wasefficiently executed bythe ODP engineeringgroup and theSEDCO staff. Therecovered CORK datalogger contains animportant record ofthe initial recovery ofthis drill hole fromdrilling induceddisturbance (E. Davis,personal communica-tion). Rapiddownflow of coldbottom water in thishole was confirmed,and this may lead toboth a pressure pulsethat is potentiallydetectable in Hole858G, 1.6 km to thenorth, and to inducedseismicity, which maybe detected by anarray of OBSsdeployed prior todrilling by SpahrWebb and colleaguesat Scripps Institutionof Oceanography. Atransect of short holes

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Figure 2. Map of Bent Hill(Middle Valley area) show-ing the location of BentHill and the two mounds(Bent Hill and Ore Drill-ing Program massive sul-fide) to the south. The posi-tions of holes drilled duringLeg 139 (black circles) andLeg 169 (white circles) areshown. Modified fromGoodfellow and Peter(1994).


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Hydrogeology of the Upper Oceanic Crust

by Earl Davis, Andy Fisher, John Firth and the ODP Leg 168 ShipboardScientific Party

distance from outcropping basement and ap-proached that believed to be representative of thetotal lithospheric heat flow (Davis et al., 1992),and seismic velocities in the upper crust were foundto increase from values of less than 3 to over5 km/s over this same distance (Rohr, 1994).Major changes in the hydrothermal regime overthis 20 km scale were confirmed by drilling at thesethree sites, but they were seen as only part of amuch larger scale regional pattern.

This large-scale pattern is illustrated in Figure1, where upper basement temperatures and pore-fluid compositions are plotted against distancefrom the ridge crest, or more importantly from ahydrologic perspective, against the distance fromthe last point of basement outcrop and potentialseawater recharge. Upper basement temperaturevariations (Fig. 1B) are the result of several factors.The general increase in the thickness of theinsulating sediment cover with crustal age tends toincrease the basement temperature, although thiseffect is partly offset by the decrease with age ofthe background heat flow from the coolinglithosphere. The magnitude of these effects hasbeen estimated, and it leads to the conclusion thatbasement temperatures are anomalously low alongthe entire transect, but most noticeably so at thewestern end. Advective heat loss to lateral hydro-thermal flow in the upper basement is the mostplausible mechanism for removal of heat, resultingin the anomalously low basement temperatures.

Variations in magnesium concentration arecontrolled by temperature-sensitive rock-waterreactions, and are much less influenced by re-charge. The correlation between Mg concentrationand temperature along the transect (compare Fig.1B and 1C) provides an excellent “calibration” forthe temperature dependence of Mg concentrationthat can be applied to any ocean basin settingwhere the thermal regime is known but fluidsampling is not possible. At Site 1030/31, the Mgconcentration is anomalously low relative to thesimple Mg-temperature relationship defined byother sites. This, together with the anomalous highchlorinity at these sites (Fig. 1D) suggest aninfluence of deeper, higher temperature water-rockinteractions.

The chlorinity of basement water (Fig. 1D),determined from pore waters squeezed from basalsediment, shows clear signs of “contamination” byfresh post-glacial seawater recharge and lateral fluidflow. The variation in cholrinity along the transectsuggests flow rates on the order of meters per year.

Hydrothermal circulation through the oceaniccrust is known to carry a significant portion

of the heat from cooling lithospheric plates, toexert a strong influence on the chemistry of theoceans, and to modify the composition of oceaniccrust before it is recycled by subduction. Amongthe primary objectives of Ocean Drilling ProgramLeg 168 were 1) to determine just how thiscirculation takes place, and 2) to establish howrapidly fluids move through the sediments andupper igneous crust of mid-ocean ridge flanks. Thiswas accomplished with a transect of drill sites onthe eastern flank of the northern Juan de FucaRidge on crust ranging in age from 0.6 to 3.6 Ma(Fig. 1).

In most oceans, burial and the resultanthydrologic isolation of the permeable upperigneous crust takes place over a time spanning tensof millions of years; on the eastern Juan de FucaRidge flank, burial is accelerated as a consequenceof the proximity of the ridge to the abundantsupply of turbidite sediments shed from theadjacent North American continental marginduring the Pleistocene. Drilling sites were placed incontext of distance from the position of sediment/igneous-basement onlap, and of the local hydro-thermal regime that had been defined previouslyby seismic reflection profiles and by heat-flow andsediment pore-fluid geochemical variations (e.g.,Davis et al., 1992; 1997; Wheat and Mottl, 1994).Clues concerning Long-Distance Transport inthe Upper Igneous Crust

This article focuses on those observations thatdocument the extreme efficiency with whichbuoyancy-driven fluid circulation moves heat andsolutes laterally in the uppermost igneous crust.Perhaps the most surprising result of Leg 168 wasthe distance over which the influence of locallyventilated circulation in the igneous crust appearsto extend beneath the relatively continuoussediment cover on the eastern ridge flank. Thethree youngest Sites 1023, 1024, and 1025 weredrilled to characterize the local transition fromigneous crust that is exposed in outcrop on theseafloor,where generally unrestricted fluid dis-charge and recharge can occur, to crust buried by acontinuous sediment layer that is sufficiently thickto provide a hydrologically resistive barrier to localfluid exchange across the seafloor. Previousobservations along this transect had suggested thatthe effects of ventilated circulation were felt over adistance of about 20 km. Seafloor heat flowmeasurements increased systematically with

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The systematic variation in basement-watersulfate (Fig. 1E) tells a similar story; valuesdecrease systematically with distance from the mostlikely source of sulfate (i.e., recharging seawater inthe region of basement outcrop). This source,perhaps together with the dissolution of relicanhydrite precipitated by high-temperaturehydrothermal circulation at the time of crustal

formation, is required to balance the strong sinkfor sulfate present in the sediments that bury thecrust.What Drives the Regional Fluid Flow?

There are two possible mechanisms for thetransport of heat and solutes that may cause theregional variations in composition and tempera-tures observed along the Leg 168 drilling transect.

Recharge of cool, densewater in sediment-freeareas close to the ridgecrest could result inpersistent lateral fluidflow to the east in theuppermost crust. Thehead of cool water in theregion of recharge wouldforce distributed seepageupwards through thesediment section on theridge flank. A secondmethod of producing nettransport of heat andsolutes may be efficientmixing by local butvigorous hydrothermalconvection. We antici-pate that long-termobservations of basementfluid temperature andpressure, to be providedby borehole observatoryinstruments at Sites 1024and 1025, will providecritical informationabout the relativeimportance of these twomodes of transport.The Nature of LocalConvection

Drilling at the oldesttwo Sites 1026 and 1027targeted a buriedbasement ridge-troughpair, an environmentwhere buoyancy-drivenfluid circulation in theuppermost crust ismodified and enhancedby basement relief (e.g.,Fisher and Becker, 1995;Davis et al., 1997; Wanget al., 1997). The siteswere drilled to investi-gate quantitatively the

Figure 1. Section through ODP Leg 168 drilling sites showing seafloor and basementtopography and crustal age. The profile, derived from seismic reflection data, crosses theridge at 48°N and is oriented at N 107°E, perpendicular to the strike of the ridgecrest(A). Systematic variations of temperature (B), magnesium concentration (C), chlo-rinity (D), and sulfate concentration (E) in upper basement pore waters along thedrilling transect are shown above the section.


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Neogene Evolution of the California Current System:Preliminary Results from ODP Leg 167by the ODP Leg 167 Shipboard Scientific Party

Figure 1.Locations of sitesdrilled along theCalifornia marginduring ODP Leg167.

ODP Leg 167 drilled thirteen sites along theCalifornia margin in a series of depth and latitudi-nal transects (Figure 1) to reconstruct the Neogenehistory of deep, intermediate, and surface oceancirculation, and to understand the paleoclimaticand geochemical history of this region. Previouspiston coring and drilling along the Californiamargin had recovered continuous records only asfar as isotope stage 6 or about 150 ka. The goals ofLeg 167 were to collect sedimentary recordssufficiently long to study the response of theCalifornia Current system to orbital forcing, as wellas to recover high resolution, continuous recordsfrom the late Pliocene to Holocene in areas withhigh sedimentation rates that would permit studiesat submillenial time scales.High Resolution Studies for the Period 3-0 Ma

All of the Leg 167 sites (except Site 1015 inthe Santa Monica Basin) were triple-cored toensure collection of a long, continuous sedimentsequence. The shipboard measurements andanalytical program, and the wireline loggingprogram were designed to measure a variety ofphysical properties at high resolution both todemonstrate the continuity of the record, and topermit reconstruction of high resolutionpaleoceanographic records for historical andprocess studies. 7.5 km of core were recovered, andseveral properties (e.g., magnetic susceptibility, wetbulk density and natural gamma activity) weremeasured at intervals of <5 cm. Collection of bothcolor digital imagery of all of the cords, as well asultraviolet to near infrared color spectra on muchof the core, helped minimize ambiguous correla-tions between different holes at each site, andimproved the reliability with which a continuoussedimentary sequence could be spliced together.These data will ultimately provide methods toexpand discrete chemical and mineralogical data tomore continuous records (e.g. Hagelberg et al.,1995; Mix et al., 1995).

The paleomagnetic signal at many Leg 167drillsites was surprisingly stable despite a sedimen-tary environment sufficiently reducing to producelarge quantities of biogenic methane. Site 1014, forexample, has a sedimentation rate that averagedmore than 80 m/m.y. since 2.6 Ma and thesediments contain about 5% organic carbon.Nevertheless a stable paleomagnetic signal wasrecorded for the length of the piston-cored section.These paleomagnetic records provide importantage control for the sedimentation models, and will

Understanding the sedimentary record ofpaleoceanographic change within the

California Current system is important for under-standing how the North Pacific Ocean affectsclimate change. On a more regional scale, varia-tions in currents along the climatically-sensitiveCalifornia margin may affect precipitation in thewestern United States and primary productivity offthe coast of California. Climate model simulationsindicate that the NE Pacific surface ocean and landsurface should respond strongly to NorthernHemisphere glaciation. Previous drilling at one sitein the Santa Barbara Basin (Site 893) had demon-strated decadal-to-millenial-scale variations inintermediate and surface water properties linked tochanges in North Atlantic climate during the last150 ka.

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Figure 2. Downhole pro-file of the chlorinity of in-terstitial waters (left) anddownhole logs of resistivityand velocity at Site 1019,ODP Leg 167.

be extremely useful for understanding the pro-cesses which maintain earth’s magnetic field andcause it to switch polarity.Neogene Oceanographic Trends

Shipboard measurements have identifiedgeneral trends in the evolution of Pacific climatefrom the relatively warm latest Miocene to thecooler climate of the Pleistocene. Between 7 and 5Ma, siliceous microfossils decreased sharply inabundance marking a major oceanographic changesimilar in timing to the end of siliceous depositionin the Monterey formation. A mid-Pliocenebiogenic CaCO3 production event occurs,perhaps controlled by strengthened offshoreupwelling beneath a stable surface ocean layer.We hypothesize that this production eventto have been caused by enhanced sub-tropical gyral wind strength from 3.5 to2.5 Ma, immediately prior to the appear-ance of major northern hemisphere icesheets. The productivity events that weobserve along the California margin aredifferent in timing from those in either thesubarctic or equatorial Pacific. Thedifferent regional responses will ultimatelyallow us to better understand climaticprocesses. Because regional oceanographiccirculation patterns within the Pacific lastfor long periods of time (up to millions ofyears), stable oceanographic circulationpatterns must exist even while the climateslowly drifts, or climate must respond in astepwise fashion to the gradual tectonicchanges in boundary conditions.Geochemical Studies of theCalifornia Margin

Geochemical studies were a major partof the Leg 167 scientific program, andwere designed primarily to understanddiagenesis along a highly productive continen-tal margin but also to understand the interactionsbetween climate and the carbon cycle. Theprogram included a high resolution interstitialwater sampling program to model the oxygenisotopic composition of the last glacial maximum(Site 1010), and to study the methane hydratesthat may have caused the development of aprominent bottom simulating reflector (BSR) atSite 1019 in the Eel River Basin. Interstitial waterswere sampled at 9.5 m intervals from the first holeat each site to at least 100 mbsf in order to modelthe diagenetic processes within the sedimentcolumn. In addition, geothermal gradients weremeasured at all sites in order to constrain thethermal environment of diagenesis.

Site 1019, which has a moderate BSR at about190 mbsf, was sampled at 9.5 m intervals to 240

mbsf. Although no hydrates were recovered in thecore, a very strong chlorinity minimum wasdiscovered (Figure 2). The chlorine contentsdecreased to about 60% of sea water, indicatingperhaps 40% of hydrate in the formation, similar toprofiles at Site 888 (Yuan et al, 1996). The loggingrecords (Figure 2) identify high velocity and highresistivity anomalies that may indicate hydratedeposition, although the high resistivity zone atabout 100 mbsf is not matched by a significantvelocity spike.

SummaryLeg 167 represents one end-member drilling

leg in which the prime shipboard concern is therecovery of a continuous sediment section andmeasurement of ephemeral physical propertiesbefore they degrade. The most significant scientificresults will come from careful postcruise studieswhen details in records from different drillsites canbe aligned with a high degree of confidence. Thislevel of control will result from the development ofhigh resolution chronostratigraphy based onradiocarbon and oxygen isotope studies on selectedtime intervals. These records will be used inconjunction with other shipboard and shorebaseddata to reconstruct the variability of the CaliforniaCurrent system and its effects on the changingglobal climate.


SCIENCERecent Leg

Reports


Leg 168 Shipboard Scientific Party:Earl Davis, Geological Survey of Canada, Sidney,B.C., Canada; Andrew Fisher, University ofCalifornia, Santa Cruz; John Firth, Staff Scientist,Ocean Drilling Program; Marc Constantin, ArleneHunter, Pietro Marescotti, David Vanko, KimberlyBrown, Martine Buatier, Atsuyuki Inoue, MichaelUnderwood, Kan Aoike, Jeffrey Martin, DanielPribnow, Joshua Stein, Henry Elderfield, Christo-pher Monnin, Michael Mottl, Geoff Wheat, EvaAndersson, Xin Su, Roisin Lawrence, Keir Becker,Jens Grigel, Carlos Goncalves, and Yue-Feng Sun.ReferencesDavis, E.E., Chapman, D.S., Mottl, M.J., Bentkowski,W.J., Dadey, K., Forster, C., Harris, R., Nagihara, S.,Rohr, K., Wheat, G., and Whiticar, M.; 1992. FlankFlux:an experiment to study the nature of hydrothermalcirculation in young oceanic crust. Can. J. Earth Sci., 29,925-952.

Davis, E.E., Wang, K., He. J., Chapman, D.S., Villinger,H., and Rosenberger, A.; 1997. An unequivocal case forhigh Nusselt-number hydrothermal convection insediment-buried igneous oceanic crust, Earth Plan. Sci.Lett., 146, 137-150.

Fisher, A.T., Becker, K., and Davis, E.E.; in review,1997. The permeability of young oceanic crust east ofthe Juan de Fuca Ridge as determined using boreholethermal measurements, Geophys. Res. Lett.Fisher, A.T., and Becker, K.; 1995. Correlation betweenseafloor heat flow and basement relief: observational andnumerical examples and implications for upper crustalpermeability. J. Geophys. Res., 100, 12641-12657.

Rohr, K.; 1994. Increase of seismic velocities in upperoceanic crust and hydrothermal circulation in the Juande Fuca plate, Geophys. Res. Lett., 21, 2163-2166.

Wang, K., He, J., and Davis, E.E.; 1997. Influence ofbasement topography on hydrothermal circulation insediment-buried igneous oceanic crust, Earth Plan. Sci.Lett., 146, 151-164.

Wheat, C.G., and Mottl, M.J.; 1994. Hydrothermalcirculation, Juan de Fuca Ridge eastern flank: Factorscontrolling basement water composition. J. Geophys. Res.,99, 3067-3080.◆

Leg 168 continued from page 7

vigor of upper basement fluid circulation and theefficiency with which heat and solutes are trans-ported by determining the lateral temperature,pressure, and pore-fluid compositional gradients.Temperature and fluid chemistry gradients werepredicted to be small despite large local sedimentthickness variations of over 3:1 (Davis et al., 1997).

Observations made during drilling attested toan even greater degree of homogenization in upperbasement than anticipated. Basement was encoun-tered by drilling at 240 m below the seafloor at theburied ridge (Site 1026), and at 600 m in theburied valley (Site 1027). Temperatures of circulat-ing fluid, roughly 64°C, appeared to be nearlyidentical at the two sites despite their separationand the contrasting depths of burial. Boreholeobservatories installed at this pair of sites shouldimprove the accuracy to which the lateral upper-basement temperature difference is known, andallow the pressure gradients that drive the flow tobe determined.

A serendipitous outcome of drilling at theburied ridge (Site 1026) was that basement fluidswere sufficiently overpressured to reverse thetendency for the cool water circulated duringdrilling to sink into the formation. During the twoweeks that elapsed between drilling and observa-tory installation operations, the hole began toproduce formation water. This provided a uniqueopportunity to sample basement water directly, andit also provided an unusual hydrologic test. Adetailed temperature log allowed the rate of fluidflow from uppermost basement into and up thehole to be determined (about 100m/hr), therebyallowing the permeability of upper basement to beestimated (about 10-12 m2). This estimate isparticularly valuable in that it is representative of amuch larger volume of the formation than isnormally sampled by relatively short-term packertesting, and suggests that the upper igneous crustat this site is permeable over a scale of severalkilometers or more.

Leg 171B Scientific Party:Dick Kroon, Co-Chief Scientist, University of

Edinburgh, United Kingdom; Richard D. Norris,Co-Chief Scientist, Woods Hole OceanographicInstitution; Adam Klaus, Staff Scientist, OceanDrilling Program; Ian T. Alexander, Leon PaulBardot, Charles E. Barker, Jean-Bierre Bellier,Charles D. Blome, Leon J. Clarke, JochenErbacher, Kristina L. Faul, Mary Anne Holmes,

Leg 171 continued from page 3 Brian T. Huber, Miriam E. Katz, Kenneth G.MacLeod, Sandra Marca, Francisca C. Martinez-Ruiz, Isao Mita, Mutsumi Nakai, James G. Ogg,Dorothy K. Pak, Thomas K. Pletsch, Jean M. Self-Trail, Jan Smit, William Ussler III, David K.Watkins, Joen Widmark, Paul A. Wilson.◆

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Interval of sediment starvation at clinoform toes

The Cause and Effect of Sea Level Change -Unraveling the Stratigraphic Yarn

by Gregory S. Mountain and Kenneth G. Miller

are very difficult to date with precision. Lastly,passive margins provide extensive evidence of theeffects of sea-level change on the stratigraphicrecord, but unwinding the eustatic signal fromthose of local subsidence and sediment supply isespecially challenging.

The continental margin approach requireschoosing a region where subsidence and sedimentsupply histories are well known. A transect ofsample locations across the margin improves thereliability of: 1) ages of depositional sequences andtheir bounding surfaces; 2) inverse subsidence(backstrip) models; and 3) paleobathymetricestimates derived from the recovered sediments.Nonetheless, the uncertainties imposed by localeffects can obscure the eustatic record, andtransects from more than one margin are needed todetermine the global signal with confidence.Furthermore, transect records from times ofcontrasting global climate such as the Oligocene-Recent “Icehouse” and the mid-Cretaceous“Greenhouse” worlds are needed because rates andmagnitudes of the processes driving these twosystems must have been very different. Ironically,the stratigraphic record from these times areremarkably similar, and this inconsistency needsexplanation.

This transect approach was begun along theNE Australia margin during ODP Leg 133, andmost recently continued on Leg 166 in the

Figure 1 - Idealized stratalgeometries prograding sea-ward across a continentalmargin such as New Jersey.Seismic data detect surfacessuch as “SB2” that mark adownward shift in deposi-tion to a position seaward ofa major clinoform, followedby landward onlap ontoand subsequent re-burial ofthe clinoform, and thus de-fine sequence boundariesformed by a rapid fall insea level. The age of this fallis best determined by drill-ing seaward of the fan atthe foot of the clinoform(ODP Leg 150). The samestratal surface far updipprovides added age controland facies to determine theextent of marine floodingduring sea-level highstands(Legs 150X and 174AX.)Shelf drilling to either sideof the SB2 rollover is theonly way to accurately mea-sure the amplitude of sea-level change associated withSB2. This will be doneacross middle Miocene se-quence boundaries duringLeg 174A. Determining theamplitudes of remainingIcehouse sea-level falls willhave to await a supplemen-tary drilling platform, asthese clinoform rollovers arein water too shallow for safeJOIDES Resolution opera-tions.

Gregory Mountain is atLamont-Doherty Earth Ob-servatory and KennethMiller is at Rutgers Uni-versity.

Sea level divides the Earth into two realms, landand ocean. Despite such apparent simplicity,

processes controlling this partition are complexlyintertwined, and include global sea-level change,sediment supply, and subsidence (the sum ofsimple thermal subsidence, active tectonics,isostasy, flexure, and sediment compaction) actingon time scales from tens to tens of millions ofyears. Sea-level fluctuations are a primary influenceon how, where, when, and what type of sediment ispreserved in the geologic record. Consequently,one of five goals spelled out in the ODP LongRange Plan is to learn the history of global sea-level and gain from it an understanding of howthese processes work.

By drilling and logging continuously coredholes almost anywhere in the ocean, ODP has theunique ability to unravel global sea-level historyusing three integrated strategies: 1) deriveglacioeustasy from marine oxygen isotopic records;2) recover direct indicators of sea-level changecontained in the shallow-water sediments ofcarbonate platforms and atolls; and 3) sampledepositional sequences in transects across passivecontinental margins. No one approach stands onits own. While oxygen isotopic studies providereliable ages of ice volume changes, the magni-tudes of eustatic change are less certain. Carbonatesediments can yield excellent measures of theamplitude of sea-level change, but these materials

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Results


Bahamas; more will be done off south Australiaduring Leg 182. All these locations addressed sea-level questions in carbonate environments. Thisarticle reports on work along the New Jerseymargin during Legs 150/150X and soon tocontinue on 174A/174AX (J. Austin and N.Christie-Blick, Co-Chief Scientists; Fig. 2), in asetting where the sedimentary record is exclusivelysiliciclastic. Carbonate and siliciclastic faciesrespond differently to sea-level fluctuations, andfor a full understanding of the effects of sea-levelchange, records from both types of settings arerequired.

A grid of high-quality seismic data wascollected on the New Jersey margin aboard theR/V Ewing in 1990 to prepare for ODP drilling.This grid included long dip lines that for the firsttime made it possible to map “Icehouse” sequenceboundaries from the inner shelf to the slope. In1995, the Ewing data were augmented by higher-resolution profiles collected aboard the R/VOceanus. These latter are of such high quality thatthey make it possible to examine the New Jerseystratal record for evidence of sea-level changes on amuch shorter time scale (at the orbitally-forcedfrequencies of 104-105 years) than previouslythought possible (106 years).

ODP Leg 150 (Mountain, Miller, Blum, et al.,

1994) drilled four locations on the slope (Sites902-904 and 906) at water depths between 445and 1250 m (Fig. 2). These sites documented theage and facies of sediments associated with a totalof 22 lower Eocene to mid-Pleistocene reflectingsurfaces traced to sequence boundaries beneath theshelf and tentatively interpreted to register times ofsea-level lowering (Fig. 1). Integrated bio-,magneto-, and strontium isotopic stratigraphyprovided temporal resolution that in most cases wasbetter than 106 years. Several major surfacesmatched the age of rapid δ18O increases derivedfrom deep-sea records; these increases result fromglobal ice buildup and eustatic lowerings (Fig. 3).In almost all instances, sequence boundariessampled on the slope during Leg 150 wereassociated with little or no temporal hiatus; manywere expressed by a slight coarsening of sedimentthat had been transported to the slope during sea-level lowstands. Others were marked by underlyingintervals of intensified cementation that may havebeen the result of lengthy periods of reduced slopesedimentation when deposition centered on theadjacent shelf, presumably at times of sea-levelhighstand.

Complementing Leg 150 offshore drilling, welaunched an onshore drilling program with supportfrom the ODP, NSF, USGS, and State of New

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Figure 2. Seismic and bore-hole data contributing tothe New Jersey Sea LevelTransect. ODP Legs 150/150X drilled on the slopeand coastal plain, respec-tively, and dated majorOligocene-Recent “Ice-house” sequence bound-aries, and correlated themto glacioeustatic falls. Legs174A/174AX will con-tinue this offshore/onshorepairing at sites MAT-8Band -9B to determine theamplitude of sea-levelchanges in the middle Mi-ocene. Sites MAT-1through -7 have been se-lected to complete thetransect and evaluate simi-lar facies andglacioeustatic amplitudesof older Icehouse sequenceboundaries; because of shal-low water depths (<75 m)these will have to be drilledwith a platform other thanthe JOIDES Resolution.

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Jersey Geological Survey (Miller et al., 1994). Theprimary objectives of these Leg 150X onshoreboreholes were to date Late Cretaceous to Ceno-zoic sequences and evaluate facies architecture inthis updip setting. Four holes close to the modernshoreline have thus far been cored and logged;more are planned (Fig. 2.) As in the offshore slopesites, Oligocene to middle Miocene sequenceboundaries correlate with prominent δ18O in-creases, consistent with the hypothesis that thesesurfaces developed during global lowerings of sealevel (Fig. 3). The ages of these sequence bound-aries also compare well with timing of “global”boundaries interpreted by Haq et al. (1987) on thebasis of proprietary seismic and well-log data plusoutcrop interpretations. Facies successions in thePaleocene through middle Miocene of theseonshore wells are typically a transgressive shell bedor glauconite sand at the base of each sequencefollowed by quartz sand at the top (upper part ofthe highstand systems tract). Thus, onshoredrilling has provided important data for regionalprofiles, although all of the boreholes are landwardof the Oligocene-Miocene clinoforms imaged inseismic reflection data beneath the shelf.

The shelf sites remain as the most importantlocations for estimating amplitudes of sea-levelchange during the “Icehouse” interval. Only sitespaired to either side of clinoform “roll-overs” (Fig.1) can hope to provide accurate estimates of waterdepths at the time of deposition, and as our seismicsurveys correlated to Leg 150 on the slope haveshown, these positions for Icehouse strata arespread across the shelf in steadily progradingpackages. The stratal geometries observed inIcehouse sediments of the New Jersey shelf arecommon in sedimentary basins of all ages, andhave spawned several depositional models thatstrive to explain the spatial and temporal distribu-tion of facies (“systems tracts”) and their boundingunconformities. A major contribution by ODPdrilling on the New Jersey shelf that will beginwith Leg 174A, or on any shelf with similarsequence geometry, will be to evaluate thesevarious models.

Implementing this global ocean-drillingstrategy has been long in coming, and remainsincomplete. Several shortfalls need to be addressedin the science planning and in the technologicaldevelopments required to achieve global sea levelhistory objectives.

(1) ODP drilling for sea-level objectives hasthus far focused on Icehouse sequences datingfrom the last 35 Ma. However, the geologic recordfrom earlier times shows stratal patterns that areindistinguishable from those of the Icehouse; tounderstand their significance, and to understand

fully the Earth’s response to global sea-levelchange, it is necessary that we investigate timeswhen there were no known ice buildups.

(2) The response of the underlying crust tochanging loads of water and sediment, controlledby the age and character of that crust and by localprocesses, can be very large compared to themagnitude of sea level changes and is different forevery margin. Consequently, it is crucial thatidentical intervals of sea-level change be examinedin sedimentary packages from margins of widelycontrasting tectonic histories so that we canuntangle the true eustatic signal that is woven intothe observed sedimentary architecture.

"Eustatic" CurveHaq et al. (1987)

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Figure 3. The timing of Oligocene to middle Miocene reflectors on the New Jersey slope vs. δ18O,onshore sequences, and the inferred eustatic record of Haq et al. (1987). The δ18O is a stackedrecord of Cibicidoides spp. from several sites, smoothed to remove periods longer than ~1 m.y.Oi1 to Mi6 are δ8O maxima; dashed lines mark inflections in the δ18O records. o1 to m1 are re-flectors dated on the New Jersey slope; horizontal lines mark best age estimates; ver tical lines in-dicate uncertainties. Onshore sequences are shown in black; white areas in between are hiatuses.O1 to O6 are Oligocene and Kw0 to Kw-Coh. are Miocene onshore sequences; gray areas indicteuncertain ages. TA4.4 to TB3.1 are sequence boundaries of Haq et al. (1987), drawn at theinflection points of their inferred eustatic record. Time scale is that of Berggren et al. (1985).(From Miller et al., 1996a)


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Drilling Tectonic Windows into the Lower Crust and Upper Mantle:ODP Leg 153

by J.A. Karson, M. Cannat, J. Miller and ODP Leg 153 Shipboard Scientific Party

about 40 m apart to depths of 126 m and 200 m,with recovery of 38% and 47%, respectively. Therecovered material (144.5 m of core) is dominantlypyroxene-poor serpentinized harzburgite to dunitewith pyroxene-rich (up to 35% orthopyroxene)layers a few meters to centimeters thick. Mineralchemistry of the primary phases indicate moderatepartial melting of a depleted mantle source. Widelypreserved relict coarse-grained porphyroclastictextures define a high-temperature foliation with avariable orientation. Also present are numerouselongate segregations of clinopyroxene and lesserspinel interpreted as the crystallization products ofinterstitial melt channels in the ultramafic rocks.

Intercalated with the serpentinites are minorintervals of mafic rocks with textures ranging frommagmatic to mylonitic; they have granulite toamphibolite metamorphic assemblages. A fewdiabase dikes with chilled margins also cut theserpentinized harzburgites in both holes. Collec-tively the mafic rocks are compositionally similar tothose drilled to the north (see below) and representa wide range of magmatic differentiates.

The primary minerals in the ultramafic rocksare pervasively serpentinized or altered to am-phibolite to greenschist facies assemblages. Mul-tiple generations of serpentine veins are one of themost obvious features of the cores. Moderately togently east-dipping anastomosing serpentine veinsare nearly ubiquitous. Both the groundmass andvein serpentines have low oxygen isotope valuesindicating serpentinization at temperatures greaterthan 300°C.

Paleomagnetic studies document significantanisotropy of susceptibility and show that no post-serpentinization rotation has affected the massif orthe dikes. Thus, despite a complex alteration anddeformation history near the MAR axis, uplift andexhumation of the serpentinites appears to havebeen accomplished primarily by displacement onsteeply dipping normal faults of the median valleywall.Variably Deformed Gabbroic Plutonsat Sites 921-924

Sites 921-924 are located in extensive expo-sures of gabbroic rocks, in a 2 km x 2 km area ofthe western wall of the MAR median valley. Atthese sites, a total of 120 m of gabbroic rocks wasrecovered from coring 447 m (26.8% recovery).The material recovered spans a wide range ofigneous compositions, from relatively primitive

Figure 1. Generalized geo-logical map of the MARKArea. Sites 920 and 921-924 are located 5 and 35km south of the KaneTransform, respectively inextensive tectonic windowsinto lower crustal gabbroicrocks (dark blue) andserpentinized upper mantleperidotites (light blue).

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A major, long-term goal of the Ocean DrillingProgram (ODP) is to investigate the composi-

tion and structure of deep crustal and uppermantle rocks of the oceanic lithosphere. As a short-cut, ODP drilling has exploited tectonic exposuresof deep-level plutonic rocks, in an approachreferred to as “offset drilling”. Leg 153 was thefirst attempt at offset drilling in slow-spreading(~30 mm/yr) oceanic crust of the Mid-AtlanticRidge (MAR).

Five drill sites were located on the western wallof the MARK Area (Figure 1) where previoussubmersible studies suggested that mafic andultramafic plutonic rocks are exposed in the

footwall of majordetachment faults(Karson et al., 1987;Mével et al., 1991).Site 920 is located inan exposure ofserpentinized uppermantle peridotiteswithin a narrow beltof serpentiniteoutcrops extendingfor ~20 km alongthe edge of the riftvalley. This area isinterpreted as adominantlyserpentinite crustthat has beenstripped of itsbasaltic cap by majornormal faults. Sites921-924 are locatedto the north inmiddle to lowercrustal gabbroicrocks where adetachment fault hasunroofed a thick(few km) magmaticcrustal assemblage.SerpentinizedMantle Peridotitesat Site 920

At Site 920,serpentinizedperidotites weredrilled at 2 holes

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troctolite and olivine gabbro to lesser volumes ofleucogabbro to trondhjemite. The dominant rocktypes are gabbro and olivine gabbro. Primarymagmatic layering defined by changes in grain sizeand modal mineralogy, is present on the scale of 1cm up to a few meters. The attitude of this layeringvaries significantly within the cores, locally chang-ing from subhorizontal to subvertical over a fewdecimeters. In some cores, cycles of relativelyprimitive to somewhat more evolved rock typesmay indicate recurrent evolutionary magmaticsequences on the scale of a few meters. The cyclesmay record, to varying degrees, a transition fromcrystallization of relatively primitive olivine gabbro,or troctolite to gabbro. Igneous textures are highlyvariable and heterogeneous, and several intervals ofolivine gabbro display cumulus textures.

Many of the gabbroic rocks recovered containessentially igneous textures. Weak foliations and/orlineations suggest magmatic deformation in someplaces. A remarkably wide range of crystal-plasticto cataclastic deformation fabrics are concentratedin shear zones. The shear zones are mostly moder-ately dipping and commonly have down-dipstretching lineations and normal-slip kinematicindicators, possibly correlating with fault surfacesmapped by submersible studies.

Alteration in the gabbroic rocks is typically notextensive, but pervasive greenschist facies alterationoccurs in areas of concentrated fracturing orveining. Locally amphibolite and less commongranulite facies assemblages also occur.

The most striking characteristic common to allthe gabbroic rocks drilled during Leg 153 is thewide range of compositions and textures developedover length scales of a few centimeters to a few tensof meters. This variability may result from closed-system fractionation in relatively small plutons withsharp temperature gradients that produce acomplex interplay between magmatism anddeformation. Although clear contacts betweendifferent rock types were only rarely recovered,variations in geochemical trends, deformation,metamorphism, and magnetic characteristicsindicate that in nearly all the holes, multipledistinct plutonic bodies were penetrated. Inaddition, the cores have complex remanentmagnetizations, including components of bothnormal and reversed polarity, suggesting thepossibility of intimately mixed intervals of differentpolarities.Fine-Scale and Large-Scale Heterogeneity inOceanic Lithosphere

Despite the limited depths of penetration,drilling on Leg 153 has substantially improved theunderstanding of the processes that create andmodify the lower crust and upper mantle at slow-

spreading ridges. This study documents thatsignificant heterogeneity in both gabbroic andultramafic rocks is present on scales of less than acentimeter to several kilometers. This variability islikely to be a reflection of the complex interplaybetween tectonic extension, magmatism, andhydrothermal metamorphism that occurs alongmany parts of slow-spreading ridges.

The array of holes drilled into the gabbroicmassif reveals a bewildering level of compositionaland textural heterogeneity, inconsistent withcrystallization of these gabbros in a long-lived sub-axial magma chamber. Instead, this heterogeneitysuggests that the gabbros crystallized in a collage ofsmall plutons that intruded one other as well asproximal upper mantle rocks during tectonicextension. A similar interpretation was proposed forgabbros drilled at Site 735 in the SW IndianOcean, suggesting that this process is typical ofcrustal accretion at slow-spreading ridges.Leg 153 Scientific Party:

Mathilde Cannat, Co-chief Scientist,Université Pierre et Marie Curie, France; JeffreyKarson, Co-chief Scientist, Duke University; JayMiller, Staff Scientist, Ocean Drilling Program; SueAgar, Jane Barling, John Casey, Georges Ceuleneer,Yildirim Dilek, John Fletcher, Norie Fujibayashi,Laura Gaggero, Jeffrey Gee, Stephen Hurst,Deborah Kelley, Pamela Kempton, RoisinLawrence, Vesna Marchig, Carolyn Mutter, KiyoakiNiida, Katherine Rodway, Kent Ross, ChristopherStephens, Carl-Dietrich Werner, HubertWhitechurch.ReferencesKarson, J.A., Thompson, G., Humphris, S.E., Edmond,J.M., Bryan, W.B., Brown, J.R., Winters, A.T., Pockalny,R.A., Casey, J.F., Campbell, A.C., Klinkhammer, G.,Palmer, M.R., Kinzler, R.J. and Sulanowska, M.M.,1987. Along-Axis Variations in Seafloor Spreading in theMARK Area, Nature, v. 328, p. 681-685.

Mével, C., Cannat, M., Gente, P., Marion, E., Auzende,J.-M. and Karson, J.A., 1991. Emplacement of DeepCrustal and Mantle Rocks on the West Median ValleyWall of the MARK Area (MAR 23°N), Tectonophysics,v. 190, p. 31-53.

Cannat, M., Karson, J.A., Miller, D.J. et al., 1995.Proceedings of the Ocean Drilling Program, InitialReports, v. 153, Ocean Drilling Program, Texas A&MUniversity, College Station, TX, 798 pp.Karson, J.A., Cannat, M., Miller, D.J., and Elthon, D.,eds., 1997; Proceedings of the Ocean Drilling Program,Scientific Results, v. 153, Ocean Drilling Program, TexasA&M University, College Station, TX, in press.◆

TECHNOLOGY


Detection of in situ Physical Properties using Logging-While-Drilling

by Dave Goldberg

These data were used to address critical questionssuch as the physical properties at the plate bound-ary fault, its role as a conduit for fluid movement,and the deformation of sediment accreted in theprism (Shipley et al., 1995). Porosity computedfrom the LWD density and resistivity logs wereused to identify zones of high porosity and lowresistivity within the fault zone, which are too thin(0.5-1.5 m) to be resolved seismically. Moore et al.(1995) suggest that these zones may be tectonicallysignificant because the pore pressure inferred fromthe porosity surpasses 90% of the overburdenpressure, which leads to dilation and fracturing inthe formation. The ability to acquire and resolve insitu data in such environments is critical becausephysical properties change immediately after thehole is drilled.

Previous wireline logging results on anotheraccretionary prism off the Cascadia margin(MacKay et al., 1994) provide an excellent oppor-tunity to compare wireline records with continuousLWD profiles as a function of depth. Two LWDporosity logs (calculated with density and resistivitymeasurements) from Barbados compared with aconventional wireline porosity log from theCascadia accretionary prism illustrates the advan-tage of LWD in these notoriously difficult drillingenvironments (Figure 2). In the Cascadia example,

the wireline log shows a gapin a zone of high watercontent associated withfaulting, and the measure-ments of porosity from bothlaboratory core tests and thewireline log are sparse andless representative of theporosity structure in theupper 150 m of the hole. Theporosity profiles fromBarbados, in contrast, coverthe entire depth rangeincluding the top 100 metersand correspond well with thelaboratory data. Whencalibrated, LWD profiles andcore data can be used jointlyto compute pore pressure andeffective stress versus depth(e.g. Moore et al, 1995; Saitoand Goldberg, 1997).

It is clear that “triplecombo” logs using LWD canidentify the porous structure

Figure 1. Schematic dia-gram of LWD tools locatedimmediately above the drillbit that enable measure-ments within minutes afterthe hole is made (afterShipley, et al., 1995).

Neutron measurement-to-bit 13.28m

Density measurement-to-bit 11.38m

Gamma-ray measurement-to-bit 6.29m

Resistivity measurement-to-bit 2.91m

Tot

al le

ngth

: 17.

44m

Dave Goldberg is Directorof the Borehole Research

Group, Lamont-DohertyEarth Observatory.

Over the last 5-10 years, new technology hasbeen developed to measure in situ properties

in oil industry holes where conventional loggingwith a flexible wireline is not feasible. This innova-tive technology is called “logging-while-drilling”(LWD; Fig. 1) and uses sensors placed just abovethe drill bit to measure porosity, resistivity, anddensity (referred to as a “triple combo”), andnatural gamma radiation (e.g. Allen et al., 1989;Bonner et al., 1992; Murphy, 1993). Conse-quently, data are recorded 4-30 minutes after thedrill bit cuts through the formation and ephemeralin situ physical properties can be measured withprecision. In many industry and ODP environ-ments, LWD is the only type of open hole loggingpossible. More detailed descriptions of LWD andwireline tools can be found via the URL sitehttp://www.ldeo.columbia.edu/BRG.

LWD has several advantages over conventionalwireline logging. The primary advantage is thatdata can be acquired continuously with depth evenin unstable holes. In situ physical properties can bemeasured over the entire drilled interval, particu-larly in the critical shallow section where wirelinelogging is compromised by the need to leave thedrillpipe 80-100 m below the seafloor and at thebottom of the hole which is often filled bysloughed material from the borehole walls. LWDmeasurements also donot require interruptionduring drilling as occursduring normal coringoperations, hence, thechances of borehole wallcollapse are reduced andunstable intervals can belogged more easily.Another advantage ofLWD is that transientphysical properties suchas porosity can bemeasured before in situconditions deteriorate.

LWD data wererecorded on theBarbados accretionaryprism during ODP Leg156 and produced anew understanding ofthis active tectonicregime, its physicalproperties, and themigration of pore fluids.

TECHNOLOGY


within accretionary prisms and that these measure-ments are more robust than standard wirelinetechniques. However, differences in measurementtechnologies must be considered when directlycomparing results from wireline and LWD tools(e.g. Evans, 1991). The resolution of LWD sensorsis similar to that of wireline logging tools (approx.15-30 cm), but depends on rotation and drillingrates. With adequate drilling rates, LWD porositymeasurements have a vertical resolution of about30 cm; resistivity, density, and gamma-ray measure-ments have resolution of 15 cm or less. Thereliability and comparison of LWD to wireline logshas been under considerable study by industrygroups for typical oil and gas drilling environments(Brami et al., 1996). Both core and wireline logmeasurements should be acquired in ODP envi-ronments, which often differ substantially fromthose in industry, to enable comparisons and theevaluation of LWD measurement reliability on aleg-by-leg basis.

So far this year, LWD data have been acquiredduring two ODP legs and another is scheduled thissummer. Five holes were logged using the LWD“triple combo” on the Costa Rica accretionaryprism (Leg 170), one of which penetrated thedécollement fault zone. Wireline logs wereacquired over a short interval in one other hole,allowing a comparison with the LWD data. Areturn to the Barbados accretionary prism (Leg171A) successfully recorded LWD “triple combo”data across the décollement fault zone at a total offive additional sites, generating ODP’s mostcomprehensive data set across an oceanic plateboundary. Leg 174A on the New Jersey continen-tal shelf/slope will use LWD through potentiallyunstable prograding sand/clay sequences at twosites and compare the results with wireline logs atleast at one. Determining in situ properties usingLWD during Leg 174A will quantify shallowsequence boundaries, thought to result from rapidsea level fluctuations, and estimate profiles in theshallow sea floor.Future LWD Measurements and Applications

Penetrating young crustal sections andhydrothermal environments have proven to be adifficult task throughout the history of oceandrilling. Hole instability while coring has been amajor cause of low recovery (often 20-30%) andpoor logging success in the recent past. NewLWD tools measuring resistivity-at-the-bit (e.g.RAB™) and sonic-while-drilling (e.g. ISONIC™)may be critical in such environments whichcharacteristically recover only limited lithologicaland structural information. The RAB tool recordsoriented electrical images with 5-cm resolutionusing sensors that scan a full 360 degrees around

the drill bit, as well as natural gamma ray, bitinclination, and drill string information (Lovell etal., 1995). These images resemble wireline resistiv-ity imaging data (e.g. FMS™) tool with somewhatpoorer resolution, but unlike the FMS, boreholewall coverage is complete and the data are recordedbefore borehole conditions deteriorate (Figure 3).The structural fabric and formation anisotropy areimportant parameters in shallow crustal environ-ments, as are fractures and bedding in competentsedimentary sequences. In both of these environ-ments, poor core recovery and low-quality logsmay no longer limit interpretations of the subsur-face lithostratigraphy and the orientation ofstructures and anisotropy.

Sonic-while-drilling presents unique chal-lenges. LWD sonic tools must be strong enough towithstand drilling stresses, yet must sufficientlyattenuate noise generated by the drill bit todistinguish formation signals. LWD sonic tools canmeasure formation velocities reliably above 2,000m/s (e.g. Aron et al., 1994), which limits theirapplication in marine sediments to depths greaterthan about 500 m. The potential for improving

Barbados(LWD)

Porosity (decimal)

Figure 2. Porosity logsthrough accretionary prismsin ODP Hole 948A (Bar-bados) and 889C(Cascadia) recorded usingLWD and wireline loggingtools, respectively. The LWDlogs indicate continuous po-rosity profiles derived fromdensity and resistivity mea-surements from the seafloorto 350 m depth. Thewireline logs are limited todepths greater than 80-100m below the seafloor andare of lesser quality due topoor borehole conditions af-ter drilling. Measurementsof porosity from laboratorycore tests are shown fromboth holes for comparison.

Cascadia(Neutron log)

Porosity (decimal)

TECHNOLOGY


shallow seismic-log correlation, detection ofnatural fractures, and estimation of shallowmechanical properties are clear applications ofsonic LWD. Neither resistivity imaging, nor sonic-while-drilling measurements, have yet been used inODP environments.

LWD may be used with little additional timeto address scientific questions in new ways. Simplyemploying a new strategy that uses LWD to drillclosely spaced holes could produce three-dimen-sional maps of the in situ properties where coringmultiple holes would be too time consuming.Using such a strategy, the five holes drilled during

Leg 171A logged nearly 3,000 m depth in lessthan 12 operating days. With a full leg ‘pogo-stick’drilling program, ~10-20 km of logs could beacquired over an array of shallow-penetration(100-500 m) LWD holes, providing dense spatialcharacterization of an area. Alternatively, usingLWD in conjunction with a riser, drilling inhorizontal and highly deviated holes, somethingthat has routinely been accomplished for industrydrilling objectives , would be possible for scientificocean drilling. Directional drilling using a riser willrequire LWD with real-time data monitoring forthe control of drilling parameters. Such experi-ments may reveal unique information in closelateral proximity to a structure, such as along afault zone or around a mineral deposit.

ConclusionsLWD technology can now measure in situ

properties like porosity across fault zones, inaccretionary prisms, and in unconsolidated shallowsequences. This technology will become increas-ingly important as ODP attempts to drill in morechallenging environments and core recoverybecomes more difficult, such as in ultra-deep anddeviated holes, when real-time hydrocarbonmonitoring is required, or when coring timeconstraints limit the spatial distribution of holesdrilled. The acquisition of downhole data are mostrepresentative of in situ conditions and most validas a proxy for geologic interpretation when they aremade immediately after drilling. Using LWD, itwill be possible to observe high-resolution forma-tion properties and transient variations in new,unexplored environments will be possible toobserve.

™RAB, ISONIC, FMS , and FMI are marks ofSchlumbergerReferences Allen, D., D. Bergt, D. Best, B. Clark, I. Falconer, J.-M.Hache, C. Kienitz, M. Lesage, J. Rasmus, C. Roulet, andP. Wraight; 1989. Logging While Drilling,OilfieldReview, 1, 4-17.

Bonner, S., B. Clark, J. Holenka, B. Voisin, J. Dusang,R. Hansen, J. White, and T. Walsgrove; 1992. Loggingwhile drilling—a three-year perspective,Oilfield Review,4, 4-21.Brami, J., K. Weeks, T. Burgess, G. Heemink, L.Robinson, and W. Hendricks; 1996. SPWLA TopicalConference on MWD, The Pulser (International MWDSoc.), 1-1.

Evans, H.B.; 1991. Evaluating differences betweenwireline and MWD systems, World Oil, 212, 51-61.

Lovell, J.R., R.A. Young, R.A. Rosthal, L. Buffington,and C.L. Arceneaux, Jr.; 1995. Structural Interpretationof Resistivity-at-the-Bit Images, Trans. of the SPWLA36th Annual Logging Symposium, June 26-29, Paris,France, paper TT.

MacKay, M.E., R.D. Jarrard, G.K. Westbrook, and R.D.Hyndman; 1994. Origin of bottom-simulating reflec-tors—geophysical evidence from the Cascadia accretion-ary prism, Geology, 22, 459-462.Moore, J.C., T. H. Shipley, D. Goldberg, et al.; 1995.Abnormal fluid pressures and fault-zone dilation in theBarbados accretionary prism: Evidence from loggingwhile drilling, Geology, 23, 605-608.

Murphy, D.P.; 1993. What’s new in MWD and forma-tion evaluation, World Oil, 214, 47-52.

Saito, S., and D. Goldberg; in press 1997. Evolution oftectonic strain in the Barbados Accretionary Prism:Estimates from logging-while-drilling, Earth and Plan.Sci. Lett.Shipley, T., Ogawa, Y., Blum, P., et al.; 1995. Proc.ODP, Init. Repts., 156: College Station, TX (OceanDrilling Program).◆

RAB Image FMI ImageTOPTOP TOP TOP TOPBOTTOM BOTTOM

Dep

th 4

ft

Figure 3. Comparison ofLWD resistivity-at-bitRAB™ tool (left) andwireline electrical imagingFMI™ tool (right) of densefracturing in consolidatedsediments (after Lovell etal., 1995). Both images ofthe interior of the boreholewall are oriented to top andbottom of a deviated hole.Although the LWD tool hasinferior bed resolution (by afactor of 30), it offers theadvantage of data coveragearound the entire circum-ference of the borehole andmeasurements within min-utes after the hole is made.

TECHNOLOGY


Technological Innovations for ODP: The Hard Rock Coring System(HRCS) and the Hard Rock Re-Entry System (HRRS)

by C. A. Buddy Bollfrass, P.E., Michael W. Friedrichs, G. Leon Holloway, P.E.,Thomas L. Pettigrew, P.E., Mark Robinson

heave into air compression. Its capacity for com-pensating ship heave is related to responsiveness(seal friction and compression rate) and mechanicallimits (length of stroke). Seal friction creates athreshold (lower limit) operational value, wherevery small sea swells (heave forces) cannot over-come the compensator seal friction, and therefore,lift and drop the drill string a small amount. Thisvariation of drill collar WOB is only an inconve-nience for roller-cone bits, but the consequence fordiamond bits is potential damage from bumpingthe bottom of the hole.

The normal operating mode of the existingHeave Compensator is the range of sea swellswhere heave forces exceed the threshold frictionand can be mostly compensated by air compres-sion. The consequence of partial compensation isdrill string stretch and relaxation due to shipmomentum. Additionally, when the heave period isless than the compensator response to ship mo-mentum, the compensator cannot react to theshorter period and additional motion is transmittedto the drill string.

The maximum operating condition (upperlimit) of the Heave Compensator occurs when shipheave exceeds the compensator stroke limit (about6 meters). Sea swell greater than this would alsohave to be added directly to the drill string motion.However, personnel safety would normally limit seafloor activities to about 3 meters stroke for 5-6meter seas.

In summary, the existing Heave Compensatorimposes a threshold movement (stretches the drillstring) for low sea states, absorbs up to 4 meters ofheave for normal operational sea states and isinadequate for high sea states, with total heavegreater than 6 meters. Nevertheless, without theshock protection provided by the passive HeaveCompensator for rotary drilling or landing bits,CORKS and Hard Rock Bases, current operationsin sea swells would be quite limited.Diamond Coring System Platform

Coring in several hundred meters of water hasbeen conducted from geotechnical vessels over theyears with a secondary platform that is suspendedin the derrick and senses heave related to a tautwire fixed to the sea floor. ODP built a secondaryplatform and tested it on Legs 124E (1989), 132(1990) and 142 (1992). Its purpose was to adaptmining coring technology to obtain hard rock

Buddy Bollfrass, P.E., TeamLeader, ODP Development,Engineering, Michael W.Friedrichs, EngineeringAdvisor, G. Leon Holloway,P.E., Senior DevelopmentEngineer, Thomas L.Pettigrew, P.E., Engineer-ing Advisor; MarkRobinson, Senior Develop-ment Technician, all atODP– Texas A&M Uni-versity.

Achievement of a large number of the scientificobjectives within the ODP Long Range Plan

requires improved core recovery, the ability to drillin young, fractured oceanic crust and the alternat-ing sequences of very different lithologies, and theinitiation of drilling and re-entering holes onsloping, hard-rock surfaces. The DevelopmentEngineering Team at ODP–TAMU is addressingthese issues through two challenging technologicaldevelopments programs. The first of these is todevelop a Hard Rock Coring System (HRCS)–aninitiative that began several years ago and wasknown to many as the Diamond Coring System(DCS) development–which is now taking anexciting new direction. The second innovativeprogram is the development of a Hard-Rock Re-entry System (HRRS) that has been referred to inthe past as the Hammer Drill-in Systems (HDS),but that consists of considerably more than ahydraulic hammer.The Hard Rock Coring System (HRCS)

The Hard Rock Coring System (HRCS) isintended to provide a stable platform on theJOIDES Resolution from which to employ highspeed diamond bits to improve coring in hardrock. A key requirement for high-speed diamonddrilling is the ability to maintain a uniform weight-on-bit (WOB) under sea conditions that causesignificant ship heave. Diamond bits are consider-ably less tolerant of impact than the roller cone bitsnow in use, that are designed to withstand bounc-ing against hard rock. For example, the desirableWOB variation for diamond drilling is 250 Kgcompared with 3000 Kg for roller core bits. Asecond requirement for diamond drilling coring isrotational speeds that are currently limited by thecapacity of the JOIDES Resolution. Thus, higherspeed requirements for diamond bits can be met bydownhole motors. Both of these problems must bemanaged if high-speed diamond drilling is to beimplemented from the JOIDES Resolution.Heave Compensation on the JOIDESResolution

The JOIDES Resolution’s existing passiveHeave Compensator is used to reduce the effect ofship heave on drilling and coring tools, as well toprovide soft landings for Hard Rock Guide Basesor CORKS. This passive Heave Compensator is alarge shock absorber, or pneumatic spring, thattranslates the increase in string weight due to ship

TECHNOLOGY


cores with recovery near 100%. This entailedprovision for a high speed top drive for diamondbits, drilling inside the drill string (small riser) toprovide structural stability for the small coringstring and provision for active heave compensationfrom this platform to maintain uniform WOB.

Active heave compensation is the adaptation ofcomputer technology to ship movement sensors inorder to hydraulically move the active heave com-pensator in cycle with ship heave, rather than toallow the passive heave compensator to react toheave forces. The significant difference is that thesystem is responsive enough to reduce ship heaveto some small threshold amount due to systemicfriction. The negative aspect is that coring tools atthe sea floor are affected by the activity below theship, as well as ship heave. This includes drill stringreaction to dynamic positioning, ocean currents,heave friction, WOB drill-off end hole friction.New Development Direction

Three recent advances have now altered thedirection of development of a secondary platformfor diamond coring. The first has been the recent(since 1990) successful application of activecontrollers to large heave compensators for lowstring weight (coring) and shallow water depth(<700 meters). This “activation” modificationwould now be more cost effective to apply to theJOIDES Resolution than completing (testing andinstalling) the secondary platform with its atten-dant logistics (17 truck loads) and the greatamount of ship time required to rig-up and rigdown.The second advance was the recognition thatsignificant variables exist below the ship thatrequire additional controls, irrespective of heavecompensation on the ship. This means that theprudent course for the present is to “activate” theexisting heave compensator aboard the JOIDESResolution to remove at least 90% of ship heave,and then to resolve the remaining variables with“smart” tools at the sea floor. The third advancehas been the creation of “smart” tools, that can beadapted to isolate the bottom-hole-assembly(BHA) from the remaining ship heave and drillstring dynamics and to provide the necessarydrilling operations at the sea floor. Such toolsshould require far less logistical support or opera-tional time aboard ship than would a secondaryplatform.

Hence, ODP is now planning to activate theexisting Heave Compensator onboard the JOIDESResolution instead of developing a SecondaryPlatform Compensator. Mike Fredrichs is planningon making these changes during the Capetownport call in mid October 1997. The improvedcompensator responsiveness should improve all

drilling, landing and coring activities—not justdiamond coring.

At the Halifax port call in July 1997, thecompensator cylinder will be evaluated by MarkRobinson and the existing heave compensator rodand piston seals will be replaced with more currentfluorocarbon materials. This will greatly reduce sealbreak-away friction which will lower the thresholdheave value, allowing the existing heave compensa-tor to be more responsive to lower sea swells andwith lower hanging loads, i.e., improved corerecovery and quality.

The effect of variables such as drillstringreaction to heave friction, ship dynamic positioningor ocean currents, as well as WOB drill-off andhole friction as on scientific coring tools, will alsohave to be addressed. Sea floor solutions mayinvolve the adaptation of an Isolation Sub and“Smart” Tools, such as a WOB Sub and VerticalThruster to provide downward force-on-bit (FOB),much like the existing Motor Driven Core Barrel(MDCB) tool. The MCB utilizes a high speedmotor to achieve diamond coring speeds. Theeffectiveness of such tools depends on the capabil-ity of minimizing the effects of ship heave in orderto be able to focus the efforts on the drilling tools.With structural stability available at the sea floor,the possible use of existing diamond coring toolsshould be revisited.Hard Rock Re-Entry System (HRRS)

The Hard Rock Re-entry System consists of aunique set of drilling tools that are designed tocreate a re-entry hole in a sloping, hard rock seafloor. Tom Pettigrew and G. Leon Holloway arecollaborating to develop a hard rock drill-in casingre-entry system, designed around a water hammerand compatible with ODP’s casing program, thatwill:

• spud-in on bare, sloped hard rock,• drill into rock with an improved rate of

penetration,• carry casing into the hole along with the

drilling tools, and• achieve a setting depth adequate to structur-

ally support re-entry.Since the heart of the system is a hydraulic

hammer, actuated by sea water, this project hasbeen referred to in the past as the Hammer Drill-InSystem (HDS). However, much more innovation isrequired by this system than by a drill hammer. Theother components being developed are retractableand eccentric bits, a hydraulically actuated casingrunning tool, a casing hanger latch system, latchtype free-fall re-entry cone, and a hardened casingshoe.


PLANNING


A Message from the Chair—This is the first JOIDES Journal produced from the JOIDES Office in Woods Hole. It has been

completely redesigned to consist of articles on ODP-related scientific research and technological develop-ments; contributions of articles or suggestions of topics you would like to hear about are always welcome.We have retained an extensive Planning Section that will continue to provide news from ODP and theJOIDES Advisory Structure, and announcements and updates from all ODP-partner countries andconsortia. This new JOIDES Journal will be issued twice a year, with an Annual JOIDES ODP PanelDirectory accompanying the Fall issue. If you have any comments about the new format, or any sugges-tions as to how to make it more useful to the ODP community, we would like to hear from you.

As many of you are aware, this is a time of important changes for the Ocean Drilling Program. TheLong Range Plan published a year ago identified a range of scientific problems for the next five years andbeyond that are broadly focused under two major themes: Dynamics of Earth’s Environment and Dynam-ics of Earth’s Interior. In order to better align the flow of scientific and operational advice within theprogram to the goals of the Long Range Plan, the JOIDES Planning Committee has developed a plan ofreorganization for the JOIDES Advisory Structure. At its February 1997 meeting, the Executive Commit-tee gave final approval to the new structure that is discussed in the Planning section. As I write this, thenational ODP committees are in the process of nominating members to panels that will convene for thefirst time in the next few months.

In response to community input, there will also be some changes to the proposal submission andevaluation process. EXCOM has approved a change in the ODP proposal deadline, which will be 15March and 15 September of each year. Hence, the next deadline will be 15 September 1997. Newguidelines for proposal preparation and submission are being developed that will better facilitate thenurturing of exciting scientific ideas, and will eventually lead to a new evaluation process for fully-devel-oped drilling proposals. We hope to have the new guidelines approved by EXCOM in June 1997 to comeinto effect for the 15 September deadline. Hence, if you are considering submitting a new or revisedproposal at that time, check with our web site, or the JOIDES Office for new requirements.

During the fall of 1996, JOI organized a workshop to revise ODP’s Sampling and Curation Policy toprovide the greater flexibility in sampling of ODP cores that will be needed to achieve new scientificobjectives (e.g., very high-resolution studies of climate change). The new policy has now been approved,and ODP-TAMU will begin implementation for upcoming legs.

All of these changes mean that the current Guide to the Ocean Drilling Program is outdated. We planto publish a new version in the summer, when the changes have been approved and new policies are ineffect.

The next few months will be challenging for us all as we attempt to implement these changes. We willdo our best to make the transition as smooth as possible, and ensure we have an efficient, fair, and effectiveadvisory and evaluation process in place. However, throughout this reorganization, it is important to keepin mind that the science conducted by the Ocean Drilling Program is ultimately driven by the quality ofproposals submitted by members of the geoscience community. We can accomplish these scientific goals ofthe ODP Long Range Plan, and hopefully move beyond them, with your continued input and support.

Susan Humphris, the head of the JOIDES Office in Woods Hole and Chair of the newJOIDES SCICOM, has had a long association with deep sea drilling. She sailed on twoof the first legs which attempted to drill into “zero-age” crust at an oceanic spreadingcenter (DSDP Leg 54 to the East Pacific Rise and Galapagos Spreading Center in1977, and ODP Leg 106 to the Mid-Atlantic Ridge MARK area in 1985), and wasCo-Chief Scientist on ODP Leg 158 which successfully drilled the TAG hydrothermalmound. She also served on the Lithosphere Panel from 1988 to 1993, and as its Chairbetween 1990 and 1993. Susan has published extensively on the alteration history of

oceanic basalts, volcanic processes on slow spreading ridges, and the distribution and mineralogy of sulfides fromboth the TAG and Lucky Strike hydrothermal areas on the Mid-Atlantic Ridge. She is also a widely respectedmarine educator and lecturer, and the former Dean of the Sea Education Association in Woods Hole. When notat sea, or flying off to attend yet another ODP meeting, Susan can be found at home with her husband Pattending their chickens and vegetable garden.

PLANNING


EXCOM

OPCOM

SCIENTIFICMEASUREMENTS

PANELSSP PPSP

TEDCOM

JOI

SCICOM

SCIENCESTEERING &

EVALUATIONPANEL

ENVIRONMENT

SCIENCESTEERING &

EVALUATIONPANEL

INTERIOR

PROGRAM PLANNING &DETAILED PLANNING

GROUPS

An Overview of the New JOIDES Science Advisory Structureby Maria Mutti

by the ODP committee for each member country/consortium, rather than by direct recommenda-tions from the JOIDES Panels and Committees.Although this has been the case for most non-USmembers in the past, the US Science AdvisoryCommittee (USSAC) will be playing more of a rolein the US in determining JOIDES Panel member-ship. Another important change is a strongeremphasis on collaboration with other internationalgeoscience programs. More information about thenew structure is now available under the JOIDESOffice web page (http://www.whoi.edu/joides),and a new Guides to the Ocean Drilling Programwill be issued later this year.New JOIDES Science Advisory Structure

JOIDES provides scientific direction for ODPthrough an advisory structure of panels andcommittees (Figure 1). The primary governingbody of the JOIDES organization is, and willcontinue to be, the Executive Committee(EXCOM), which consists of representatives oforganizations that are partners in the OceanDrilling Program. A Science Committee(SCICOM) replaces the previous Planning Com-mittee (PCOM) as head of the new JOIDESScience Advisory Structure. However, the mandateof SCICOM is now more narrowly focused on thelong-term science planning activities necessary tomeet, and go beyond, the goals of the ODP LongRange Plan. In this capacity, SCICOM will

prioritize scientific and technologicalobjectives, based on input and advice fromthe rest of the Advisory Structure, in orderto optimize the scientific returns from ODPdrilling. In addition, it will take a moreproactive role in soliciting drilling proposalsto address the scientific themes andinitiatives of the ODP Long Range Plan. Asubcommittee of SCICOM, the OperationsSubcommittee (OPCOM), will deal with

Figure 1. The newJOIDES Scientific

Advisory Structure.

Providing scientific and technological advice toa program as complex as the Ocean Drilling

Program, while satisfying the diverse scientificcommunities as well as the funding agencies of theODP partners, is a challenging task. The ODPMid-Term Review Committee in late 1995recognized that the structure that had evolved toprovide this advice had been “outstandinglysuccessful” in maintaining a proposal-drivenprogram while delivering high-quality science.However, with the development of the ODP LongRange Plan, with an emphasis on new directionsfor ocean drilling, reorganization of the advisorystructure to be better aligned with the themes andscientific objectives of the ODP Long Range Planwas recommended.

The process of redesigning the JOIDESAdvisory Structure began in early 1996 throughthe efforts of the Planning Committee and theJOIDES Office (which was then in Cardiff, UK).Taking advice from all the panels and committeeswithin the structure, a simplified JOIDES AdvisoryStructure was developed that closely reflects thegoals of the Long Range Plan but maintains theemphasis on a proposal-driven program. Afterseveral iterations and refinements of the newcommittee and panel structure, their mandates, andterms of reference over the course of a year, thenew JOIDES Science Advisory Structure wasformally approved at the most recent EXCOMmeeting, which took placeFebruary 10-12 in WashingtonDC.

This article is intended togive a brief overview of the newstructure and the mandates ofthe different committees andpanels. One important change isthat membership for JOIDESPanels and Committees will nowbe determined

PLANNING


many of the logistical and technological implemen-tation issues that previously occupied much ofPCOM’s time. For the first year, OPCOM will bechaired by the SCICOM Chair and will consist oftwo other SCICOM members, plus three othermembers from the international marine geosciencecommunity. OPCOM’s responsibilities will includedetermining drilling schedules (for SCICOMapproval) based on the SCICOM ranking ofproposals, and advising SCICOM on short-termlogistical and technological implementations ofhighly ranked scientific programs, as well as longerterm technological requirements for implementingthe ODP Long Range Plan.

SCICOM will receive advice on drillingproposals from two Science Steering and Evalua-tion Panels (SSEPs) — the Dynamics of Earth’sEnvironment SSEP and the Dynamics of Earth’sInterior SSEP — which replace the previousthematic panels. They will provide SCICOM withevaluations of high priority drilling proposals, aswell as advice on longer-term thematic develop-ment. In order to allow evaluation of inter-disciplinary proposals, the SSEP’s meetings will bescheduled to overlap by at least one day for jointdeliberations. A new aspect of the proposal reviewprocess will be the inclusion of external evaluationssolicited from members of the geoscience commu-nity. External evaluation of ODP proposals hasbeen introduced to broaden the participation ofthe community in the program, and to ensure thatODP drilling focuses on high priority problemswith the potential to yield exciting results andcontribute to fundamental advances in understand-ing earth’s history and/or earth’s processes. Theexternal evaluation process is still under prepara-tion, but will include changes to the proposalsubmission process; these will be made available assoon as they are approved.

Program Planning Groups (PPGs) andDetailed Planning Groups (DPGs) are smallfocused groups that may be created by SCICOM.PPGs will be formed when there is a need to

develop drilling programs of technological strate-gies to achieve the goals of the ODP Long Rangeplan. They can be appointed for up to three years.DPGs are short-lived groups that may meet onlyonce or twice for more intensive study of certainaspects of planning. For example, as in the previousAdvisory Structure, a DPG may be asked to createa viable drilling plan from a series of drillingproposals for a specific scientific objective.

JOIDES Service Panels include the Site SurveyPanel (SSP), the Pollution, Prevention and SafetyPanel (PPSP), and the new Scientific Measure-ments Panel (SciMP). The latter replaces theShipboard and Downhole Measurements Panels,and the Information Handling Panel, and willprovide information and advice on the handling ofODP data, samples and information, and onmethods and techniques of all ODP measurements,including shipboard and downhole measurements,and experiments. The Service Panels are notdirectly involved with selection of drilling targets ordefinition of cruise objectives. The Service Panelswill report to OPCOM, although recommenda-tions involving major fiscal decisions or majorprogrammatic changes will be channeled throughOPCOM to SCICOM.

The Technology and Engineering Develop-ment Committee (TEDCOM) will continue to becharged with recommending the proper drillingtools and techniques to meet the objectives ofODP Long Range Plan, and monitoring theprogress of their development.

The new JOIDES Science Advisory Structurewill be fully in place by November 1997, after aperiod of transition that is already underway. Theschedule of meetings for this year (See the JOIDESWeb site) reflects the timing required to implementthe transition, and to ensure that information canbe passed from the different panels in a timelymanner. This transition towards the new AdvisoryStructure will be difficult, but its smooth andefficient implementation is in the interest of theentire ODP community.◆

The Drill-In Casing concept was tested byODP and the hammer manufacturer in Australia inmid-1996. In quarry tests, a small hammer wasused to drill-in 7" casing. A larger hammer hasnow been produced and is currently undergoingperformance testing by the manufacturer. ODPplans to test this hammer with a 14-3/4" bit todrill-in 13-3/8" casing in early 1997 in order toevaluate a more typical environment prior to seatrials of these systems on Leg 179 in April 1998.

Technological Innovations (Continued from page 20) InnovationBoth the Hard Rock Coring System and the

Hard Rock Re-Entry System are broad develop-ment programs that will each provide incrementaladvances in our ability to improve core recoveryand quality, to diamond core in deep oceans, andto initiate drilling on sloping, hard rock andprovide a re-entry hole therein.

These are important and challenging projectsthat are crucial to technological innovation withinthe Ocean Drilling Program, and to the accom-plishment of the scientific goals of the Long RangePlan.◆

PLANNING


The ODP Science PlanLegs 176 to 181 (FY 1998) & Legs 182 to 183 (FY 1999)

by Kathy Ellins

timing, extent, and variability of the Antarctic icesheet in order to better understand its effect onglobal sea level, and its influence on the surround-ing ocean. Drilling will recover a direct record ofAntarctic Cenozoic glacial history by samplingsediments that have been transported at the base ofgrounded ice sheets to the Antarctic continentalmargin, and deposited on the shelf and slope asprogradational wedges and on the continental risein drifts. A single site within the Palmer Deep, asmall depression on the western side of theAntarctic Peninsula, will also be drilled to obtain ahigh resolution Holocene record ofpaleoproductivity which can be compared with theresults of ODP drilling in Saanich Inlet, theCariaco Basin, and the Santa Barbara Basin. Leg178 holds the promise of significantly advancingour understanding of the vital role of the Antarcticice sheet in global climate dynamics by providingan unprecedented high-resolution record ofAntarctic continental climate over the past 6-10Ma.

During the long transit (Leg 179) from theWestern Antarctic Peninsula to the Woodlark Basin,ODP will drill a borehole into basement on theNinety East Ridge in the Indian Ocean to provide asite for the installation of a broadband oceanseismometer and instrument package for theInternational Ocean Network (ION) program. TheNinety East Ridge Observatory (NERO) will filla gap in the Global Seismic Network and permitstudy of the dynamics of the Indian Plate. Drillingplans entail the reoccupation of either ODP Leg121 Site 756 or Site 757 and penetration ofbasement to 100 m to allow the subsequentinstallation of the instrument package by submers-ible. Setting the stage for NERO underscoresODP’s commitment to provide boreholes forconducting long-term experiments.

The Hammer Drill-In Casing System,currently under development, will be tested on Leg179 at a site yet to be determined. This systemuses a 14 3/4 inch bit to establish holes on theseafloor in terrain that is difficult to penetrate withcurrent ODP drilling technology. Initial landtesting carried out in Australia and Iceland in 1996have yielded promising results. Additional landtests of the Hammer Drill-In Casing System areplanned for 1997.

The role of low-angle normal faulting incontinental break-up is a fundamental unansweredquestion relating to the physical processes and

The ODP Science Plan for Legs 176 to 183was developed by the JOIDES Planning

Committee (PCOM) in December of 1996 andcomprises a series of legs that address importantscientific objectives in the ODP Long Range Plan(Table 1). The schedule takes the JOIDES Resolu-tion from the Indian Ocean (Leg 176) through theAtlantic sector of the Southern Ocean (Leg 177)to the Pacific margin of the Antarctic Peninsula(Leg 178). From there, the JOIDES Resolution willsail eastwards (Leg 179) to the south westernPacific for three Legs around Australia and NewZealand (Legs 180, 182, and 181), and then backto the Indian Ocean (Leg 183) (Figure 1).

Leg 176 will deepen ODP Hole 735B,located on a wave cut terrace east of the Atlantis IItransform fault in the Indian Ocean. The goal ofLeg 176 is drill to a nominal depth of 2 km sub-basement to directly determine the nature of themagmatic, metamorphic, tectonic and hydrother-mal processes in the lower ocean crust at a slowspreading ocean ridge. While it is hypothesizedthat deepening Hole 735B may reach the petro-logic Moho, the recovery of a truly representativesection of plutonic crust, will, by itself, be a majorbreakthrough in understanding the geologicprocesses occurring beneath ocean ridges.

The primary goal of Leg 177, SouthernOcean Paleocanography, is to recover a latitudinaland depth transect across the Antarctic Circumpo-lar Current to document the paleoceanographicand climatic history of the southern high latitudesin the Atlantic sector of the Southern Ocean. Thisperiod was marked by major changes in SouthernHemisphere paleogeography, including the gradualisolation of the Antarctic continent and theopening of the Drake Passage. A second majorobjective of Leg 177 is to obtain expanded sectionsof late Neogene sediments in order to resolve thetiming of Southern Hemisphere climatic eventsrelative to those previously documented in icecores and sediment records from the NorthernHemisphere. Leg 177 will contribute significantlyto understanding the Earth’s climatic system bypermitting paleoclimatic and paleoceanographicstudies on both the long (Cenozoic) and short(orbital and sub-orbital) time scales of the historyof the Southern Ocean, a key component ofEarth’s climate system.

Leg 178 to the margin of the WesternAntarctic Peninsula is the first in a series ofproposed ODP Antarctic drilling legs to study the

PLANNING


mechanics of lithospheric extension. Leg 180drilling will address the nature of low-anglefaulting, continental break-up, and the evolution ofconjugate rifted margins in the western WoodlarkBasin, where lateral variation from active continen-tal rifting to seafloor spreading occurswithin a small region. To achievethis goal, ODP will drill atransect of sites acrossthe asymmetricconjugate marginto characterizethe in situproperties ofthe activelow-anglefault zonein theregion ofcontinentalseparation,and todeterminethe verticalmotionhistory of theupper and lowerplates in order toestimate the timingand amount of extensionprior to spreading.

Leg 181 is another in the seriesof ODP Legs to examine the Global Conveyor BeltModel of ocean circulation in key “gateway” areas.An essential feature of the Global Conveyor BeltModel is the circulation of cold, deep AntarcticBottom Water (AABW), which is believed to beparticularly important in controlling Earth’sclimate. Today, forty percent of AABW enters theworld ocean through the Southwest PacificGateway as a thermohaline-driven Deep WesternBoundary Current (DWBC). Leg 181 will drill onthe eastern New Zealand Plateau to reconstructthe stratigraphy, paleohydrography and dynamicsof the DWBC and related water masses since theearly Miocene when plate movements created thefirst deep-water oceanic gaps south of Australia andSouth America. This program will provide impor-tant information fundamental to understandingworld oceanic and climatic histories, and yield thesedimentary sequences needed to address otherhigh-priority problems in Southern Ocean Neo-gene palaeohydrography, sedimentology, paleocli-matology and micropaleontology.

Leg 182 will drill an array of holes across theCenozoic carbonate shelf in the Great Austra-lian Bight to determine how this platform, the

largest cool-water carbonate shelf on Earth today,evolved throughout the past 65 Ma. in response tooceanographic and biotic change, and to documentglobal sea level fluctuations. The results of Leg 182will complement the findings of the New Jersey

(ODP Legs 150 and 174A) and Bahamas(ODP Leg 166) sea level transects.

In addition, Leg 182 drilling willprovide a more detailed

understanding of thehistory of southern

hemisphere climatesand global deepwater circulationpatterns through-out the Cenozoicevolution of theSouthern Ocean.Finally, because ofarchitectural andcompositionalsimilarities of theGreat Australian

Bight carbonateswith many older

Phanerozoic carbon-ate platforms, the

findings of leg 182 will beimportant for modeling

ancient open platforms andramps.Leg 183 represents the first leg in a

proposed two-leg program to investigate theorigin, growth, compositional variation, andsubsidence history of the Large Igneous Province(LIP) formed by the Kerguelen Plateau andBroken Ridge in the southeastern Indian Ocean.A suite of holes of approximately 200 m basementpenetration will be drilled into the plateau and anoffset drilling program carried out in the vicinity ofmajor fault scarps. The chief goals of this drillingstrategy are to determine the length of timerequired to form the Broken Ridge-KerguelenPlateau System and to establish the volume ofmagmatic products as a function of time, toexamine the mechanism of plateau growth, tounderstand the role of the Kerguelen Plume, andto document the vertical tectonic history of theplateau. The study of LIPs is a high priority in theODP LRP because they represent the products ofthe largest volcanic events in Earth history and areindicative of major episodic transfers of heat andmass from the mantle to the lithosphere. Evidencesuggests that the intense episodic nature offormation of LIPs resulted in the rapid release oflarge quantities of volatiles, such as CO2, whichmay have had an impact on past climate. ◆

LEG 182GAB Carbonates

LEG 180 Woodlark Basin

LEG 181 SW Pacific Gateway

LEG 178 - ADPG 1 Western Antarctic

Peninsula

LEG 177 Southern Ocean

Paleoceanography

LEG 179Transit, NERO, and

Hammer DrillingSystem Test

LEG 176 Return to 735B

LEG 183Kerguelen LIP

See JOIDES ResolutionOperations Schedule onpage 26.

PLANNING


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PLANNING


Janus in Januaryby Kate Moran

interpretation of hole and site age models.MST data, including GRAPE, P-wave

velocity, magnetic susceptibility and naturalgamma, were uploaded to Janus and madeavailable to the shipboard party from anycomputer station. During Leg 171B, reportingsoftware was written to download MST datainto Splicer, the custom software used forconstruction of composite stratigraphic sectionsat multiple-hole sites. During the Leg 172portcall, this reporting utility was improved inorder to simplify access to Janus from Splicer.

Discrete physical property measurementshave seen vast improvements over the past yearwith upgrades to the Labview interfaces for thisdiverse mix of instruments. With the new Janusdatabase, the text files generated from theseinstruments are now uploaded using a simplewindows environment. Given the diversity ofmeasurements made in this lab, utilities will bedeveloped for the physical properties specialiststo upload and overwrite any data set.

Providing consistent and unified softwaresystems for the chemistry lab has been a chal-lenge during Janus development. Janus inter-faces for chemistry are modeled after spread-sheets commonly used in this lab. The interfacesfor interstitial waters, gas, and carbonate werecompleted and successfully tested during Leg171B. Sample ID’s are scanned into the systemusing a hand-held bar code scanner. The cou-lometer has recently been interfaced to aLabview application that automatically capturesthese data into spreadsheet form, reducingtedious data entry. The chemistry softwaresystems will be completed during Leg 172 withthe addition of wet rock chemistry and XRDdata input and reporting utilities.

Drilling data are now captured to Janus.The drillers used Janus in real-time to trackthese operations and have suggested someimprovements to their Janus data reports thatwill further assist them.

The highest priority for the next stage ofJanus development is visual core description forhard rock and structures. Other developmentswill include the data capture for paleomagnetics,color reflectance, thermal conductivity and theroutine downhole tools.◆

Editor’s Note: Kate Moran is Chair of JOI’s JanusSteering Committee.

Janus, the new ODP computer databasesystem, was successfully deployed this Jan-

uary on Leg 171B. In addition to drilling andcore/sample information, the system nowcaptures paleontological, MST (multi-sensortrack), physical property, chemistry and X-raydata directly into the Oracle relational data-base.The Janus system enables data acquisitionand retrieval through both manual and instru-mented interfaces which significantly reduceserrors, data collection time, and entry of redun-dant data. Other features include:

• a bar code system for sample stickers;• use of the computer system at novice and

expert levels so that it may be customizedfor personal preferences;

• a consistent and user-friendly connectionto the system through a graphical userinterface; and

• database output that can easily be im-ported into commercial software packagessuch as Excel and Kaleidagraph.Thescience party on Leg 171B were able toaccess and share much data using develop-mental software to “query” the databaseand receive the desired information in auseful format.

Visual description of the cores is now beingaccomplished with a software package calledApplecore. This was first used on Leg 169 in its“off the shelf” mode, but was customized forODP conventions for Leg 171B. This package isstill under development, and additional modifi-cations were incorporated into the version usedon Leg 172. Applecore forms the basis of a newunified core description system for Janus. In thenear future, Applecore will be modified toincorporate structural and hard rock data. Thetarget for completion of these modifications isLeg 176 when Hole 735B will be deepened.

A software package named Paleo now linkspaleontological data captured directly to theJanus database. Data are entered as paleonto-logical species are identified and species abun-dances determined. The data can be easilyedited at any time so that scientists can beflexible with data entry. Reports are generatedby direct queries to the database using thecustomized paleo software. For example, markerspecies, age, depth, and depth range can bedownloaded from Janus into spreadsheets for

Kate Moran is at the Geo-logical Survey of CanadaAtlantic, Dartmouth.

PLANNING


OD-21 - Ocean Drilling in the 21st Century

by Hans Christian Larsen and Ikuo Kushiro

program of scientific ocean drilling beyond 2003that will have a scientific advisory structure and aproposal process similar to the present JOIDESstructure.

The OD-21 drill ship is expected to beconstructed by the year 2003, and will be able todeploy as much as 11 km of drill string and tosupport large casing programs. It is also plannedthat it will carry a riser system that allows circula-tion of density-controlled muds into the boreholeand back to the ship. These features will enabledeep drilling, drilling through difficult and unstableformations, or a combination hereof. However,direct application of current industrial type risers todeep sea drilling (4000 m+) as required by thescientific community involves extremely large andheavy systems. Hence, construction of a risersystem for deep sea drilling is a major engineeringchallenge that might involve completely newdesigns and/or materials.

In October, 1996, an International Workshopon Riser Technology was held in Yokohama, Japanjointly organized by JAMSTEC, the OceanResearch Institute of the University of Tokyo(ORI), and the JOIDES Technology and Engineer-ing Development Committee. Representatives fromthe international science community presented asuite of highly challenging model holes in order toillustrate the types of environments in which deepdrilling and use of a mud circulation system isenvisaged. Engineers presented tentative thoughtson small diameter systems, riserless systems, etc.which could be developed to meet the scientificand environmental requirements, and demon-strated strong industry interest in pursuing alterna-tive approaches to riser drilling in deep water.

The Workshop also emphasized the need forclose linkages between science planning beyond2003, and the specifications of the new OD-21

CONCORD: CONference on Cooperative Ocean Riser Drilling

22-24 July 1997

National Olympics Memorial Youth Center, Tokyo, JapanExpressions of interest should be sent by 30 May 1997 to one of the two Co-Chairs: Hans

Christian Larsen, Director, Danish Lithosphere Centre, Oester Voldgade 10, 1350 Copenhagen K,Denmark ([email protected]) or Ikuo Kushiro, Director, Institute for Study of the Earth’s Interior,Okayama University, Japan ([email protected]).

Please, provide brief statement of research interest and Working Group preference, fax andphone number when you register at [email protected]

Additional information regarding the meeting can be found at the Web site:http://www.dlc.ku.dk.

APPLY NOW!

The current Ocean Drilling Program isscheduled to end in 2003, after 35 years and

several programs of scientific ocean drilling. Thus,all earth scientists must consider the possibility thatthis exceptional program may not exist beyond2003. The function of scientific ocean drilling isnot a given, but something the geoscience commu-nity must constantly develop and justify. However,planning for the next era of ocean drilling that willbuild on the Program’s remarkable scientificachievements to date is already well underway.New scientific problems, as well as some outstand-ing, but as yet unattained, scientific objectives havebeen defined for drilling post-2003 and arepresented in the ODP Long Range Plan. Several ofthe future scientific goals can be achieved withcurrent drilling and logging technology. However,the demands for drilling time, the specializationand the technical requirements of many futuredrilling experiments will require a new level ofdrilling capacity and and new capabilities; thesemust be planned for now, if we are to be ready tocontinue and develop scientific ocean drilling inthe 21st century.

“Ocean Drilling in the 21st Century” (OD-21), the program proposed by JAMSTEC (JapanMarine Science and Technology Center), iswelcomed by the international scientific commu-nity organized in JOIDES. It envisions scientificocean drilling that will be further advancedthrough the construction of a large, deep drillingvessel with riser capabilities that will focus onscientific objectives beyond the current capabilityof the present ODP and its drilling vessel JOIDESResolution. This initiative provides realistic hopefor two, globally operating ships offering comple-mentary drilling capabilities — as envisioned forpost-2003 in the ODP Long Range Plan. OD-21will form part of an integrated, international

PLANNING


drilling vessel and its drilling system. To do this, animportant international meeting will be convenedin order to identify the science that will be targetedfor the OD-21 vessel, to manifest the internationalnature of OD-21, and to lay out the specificationsthat will need careful consideration during theinitial planning phase (1998-1999). This meeting,CONCORD (CONference on Cooperative OceanRiser Drilling), is to be held in Tokyo, Japan onJuly 22-24, 1997. Planned Working Groups for themeeting are:

• Climate and sea-level change• Architecture of the oceanic lithosphere• Continental rifting and LIPs• Subduction and earthquake processes• Drilling and tool technology developments• Borehole and seafloor observatories.

It is critical for the continued development ofocean drilling to secure funding for this importantproject. The construction phase is budgeted atUS$500 million. In order to get funding from theJapanese government for the planning and con-struction phase, and hence, for the OD-21 pro-gram to become reality, the international earthscience community must demonstrate its strongsupport for continued ocean drilling and, inparticular, for a vessel capable of deep penetrationand hole stabilization. The CONCORD meetingprovides that opportunity and the conferencereport will be part of the final proposal to besubmitted by JAMSTEC and ORI later in 1997 tothe Japanese government. We hope that you willdemonstrate your support by applying for partici-pation in the CONCORD meeting!◆


(3) Until Leg 174A is successfully completed,no continental shelves will have been continuouslycored because of concern for drilling withoutadequate safety and platform stability technologyaboard the JOIDES Resolution. We stress thatdespite this obstacle, samples from this setting areabsolutely essential because they provide thespectrum of sediment types that best record theeffects and the magnitudes of past sea-levelchanges.

(4) The shelf sites in carbonate platforms andatolls are generally intensively lithified and it isdifficult to recover continuos records necessary tounravel sea level records. Good core recovery incarbonate rocks is a technological challenge thatmust be overcome before these valuable recordscan be properly used.

REFERENCESHaq, B.U., Hardenbol, J. and Vail, P.R.; 1987. Chronol-ogy of fluctuating sea levels since the Triassic (250million years ago to Present). Science, 235: 1156-1167.Miller, K.G., et al.; 1994. Proc.ODP, Initial Reports, Leg150X, 59 pp.Miller, K.G., Mountain, G.S., the Leg 150 ShipboardParty, and Members of the New Jersey Coastal PlainDrilling Project, 1996. Drilling and dating New JerseyOligocene-Miocene sequences: ice volume, global sealevel, and Exxon records, Science, 271: 1092-1094.Mountain, G.S., K.G. Miller, and P. Blum; 1994. Proc.ODP, Initial Reports, Leg 150, 885 pp.◆

Cause and Effect continued from page 13

Leg 167 Scientific Party:Mitch Lyle, Co-Chief Scientist, Boise State

University, Idaho; Itaru Koizumi , Co-ChiefScientist, Hokkaido University, Japan; Carl Richter,Staff Scientist, Ocean Drilling Program; Richard J.Behl, Per Boden, Jean-Pierre Caulet, Margaret L.Delaney, Peter deMenocal , Marc Desmet, ElianaFornaciari, Akira Hayashida, Franz Heider, JulieHood, Steven A. Hovan, Thomas R. Janecek,Aleksandra G. Janik, James Kennett, David Lund,Maria L. Machain Castillo, Toshiaki Maruyama,Russell Merrill, David J. Mossman, Jennifer Pike,A. Christina Ravelo, Gloria A. Rozo Vera, RainerStax, Ryuji Tada, Jürgen Thurow, MasanobuYamamoto.

REFERENCESHagelberg, T. K., N. G. Pisias, L. A. Mayer, N. J.Shackleton, and A. C. Mix; 1995. Spatial and temporalvariability of late Neogene equatorial Pacific carbonate:Leg 138. In Pisias, N. G., L. A. Mayer, T. R. Janecek, A.Palmer-Julson, and T. H. van Andel (eds.) Proc. ODP,Sci. Results, 138: College Station, TX (Ocean DrillingProgram), 321-337.

Mix, A. C., S. E. Harris, and T. R. Janecek; 1995.Estimating lithology from nonintrusive reflectancespectra: Leg 138. In Pisias, N. G., L. A. Mayer, T. R.Janecek, A. Palmer-Julson, and T. H. van Andel (eds.)Proc. ODP, Sci. Results, 138: College Station, TX (OceanDrilling Program), 413-429.Yuan, T., R. D. Hyndman, G. D. Spence, and B.Desmons; 1996. Seismic velocity increase and deep-seagas hydrate concentration above a bottom-simulatingreflector on the northern Cascadia continental slope. J.Geophys. Res., 101, 13655-13671.◆

PLANNING


ODP ContractorsJoint Oceanographic Institutions

Prime ContractorProgram ManagementPublic AffairsJOIDES Journal distribution1755 Massachusetts Ave., N.W., Suite 800Washington DC 20036-2102, USATel. 202/232-3900Fax 202/[email protected]

JOIDES OfficeScience Planning and PolicyProposal SubmissionJOIDES Journal articlesMarine Geology & Geophysics DepartmentWoods Hole Oceanographic Institution, MS #22Woods Hole, MA 02543, USATel. 508/289-3481Fax. 508/ [email protected]

ODP Site Survey data bankSubmission of Site Survey DataSite Survey Data RequestsLamont-Doherty Earth ObservatoryP.O. Box 1000, Rt. 9WPalisades, NY 10964, USATel. 914/365-8542Fax 914/[email protected]

ODP-TAMUScience OperationsODP/DSDP Sample requestsLeg StaffingODP PublicationsOcean Drilling ProgramTexas A&M University1000 Discovery DriveCollege Station, TX 77845-9547, USATel. 409/845-2673Fax 409/845-4857

ODP-LDEOWireline Logging ServicesLogging InformationLogging SchoolsLog-Data RequestsBorehole Research GroupLamont-Doherty Earth ObservatoryP.O. Box 1000, Rt. 9WPalisades, NY 10964, USATel. 914/365-8672Fax 914//[email protected]

Bremen Core RepositorySample InformationAvailability of Residues and Thin Sections(from ODP Leg 151 onward)Bremen UniversityOcean Drilling ProgramBremen Core RepositoryKonsul-Smidt Str. 30Schuppen 328217 Bremen, GermanyTel. 49/421/3966336Fax 49/421/[email protected]

Member Country/ConsortiaAdministrative Offices

Australia-Canada-Chinese Taipei-KoreaConsortium

Dr. Steve Scott, DirectorCanadian ODP SecretariatDepartment of GeologyUniversity of Toronto22 Russell StreetToronto, Ontario M5S 3B1, Canada.Phone: (416) 978-6554Fax: (416) 978-4820E-Mail: [email protected]

JapanDr. Tetsuya Hirano, DirectorODP Japan OfficeOcean Research Institute,University of Tokyo1-15-1 Minamidai, Nakano-ku,Tokyo 164, JapanPhone: 81-3-5351-6438Fax: 81-3-5351-6439E-Mail: [email protected]

GermanyDr. Helmut Beiersdorf, DirectorGerman ODP OfficeBundesanstalt f. Geowiss und RohstoffeStilleweg 2, Postfach 510153D-30631 Hannover, GermanyPhone: 49(511) 643-2413 or 2782Fax: 49(511) 643-2304E-Mail: [email protected]

ESF Consortium for Ocean Drilling (ECOD)Dr. Judith McKenzie, ChairESCO Secretariat,ETH-Zentrum,Sonneggstrasse 5CH-8092 Zurich, SwitzerlandPhone: 41-1-632-5697Fax: 41-1-632-1080E-Mail: [email protected]

PLANNING


United KingdomDr . Roger Padgham, Programme ManagerUK ODP Office,N.E.R.C.,Polaris House,North Star Avenue,Swindon SN2 1EU, United KingdomPhone: 44(0) 1793 411573Fax: 44(0) 1793 411502E-Mail: [email protected]

FranceDr. John Ludden, Président du Comité ScientifiqueODP-FranceCRPGB.P. 2054501 Vandoeuvre-les-NancyFrancePhone: 33 3 83 51 22 13Fax: 33 3 83 51 17 98E-Mail: [email protected]

United StatesDr. Ellen S. KappelProgram Director/JOI/USSSPJoint Oceanographic Inst., Inc.1755 Massachusetts Ave. NW, Suite 800Washington, DC 20036-2101Phone: (202) 232-3900 x216Fax: (202) [email protected]

Escanaba Trough suggests that the thickness ofmassive sulfide is little different from the amountexposed above the seafloor (5-15m). The absenceof a well-developed, veined feeder zone indicatespervasive diffuse venting of hot fluid over a shortperiod of time rather than long-lived, focused hightemperature discharge, as was the case at Bent Hill.

A hydrothermal component in the pore fluidsfrom Escanaba Trough indicates that hydrothermalfluid flow was relatively recent. Both low and highsalinity fluids are present indicating phase separa-tion, followed by segregation of most of the lowsalinity fluids in an unconsolidated sand unit in theinterval from 70-120 mbsf. Concentrations ofalkalis and other elements indicate that thehydrothermal fluids have interacted extensivelywith sediment, even though most of the recoveredsediment is not extensively altered. Organic mattermaturation confirms that the sediments have seenat least a brief pulse of high temperature thatlocally resulted in generation of minor amounts ofhydrothermal petroleum.


Documentation of the contrast between therecurrent, highly focused, long-lived hydrothermalactivity that formed large massive sulfide deposits atODP Mound and Bent Hill and the high tempera-ture, pervasive diffuse flow system that resulted inextensive surface mineralization in EscanabaTrough provides important insight into the oreforming process. Discovery of the unexpected highgrade copper replacement mineralization (DeepCopper Zone) below the vein controlled feederzone mineralization may provide new explorationtargets for the minerals industry. While this leg wasfocused on the genesis of metallic mineral deposits,the Leg had considerable success in unraveling thetectonic and sedimentary history of these sedimentcover spreading centers. Post cruise researchpromises to add greatly to our understanding ofthese systems. The success of Leg 169 is related inlarge part to the detailed planning and hard workof the group at ODP/TAMU, especially theengineering group, and is yet another example ofhow the scientific accomplishments of the OceanDrilling Program are directly relevant to societallyimportant problems such as natural resourceavailability.Leg 169 Scientific Party:Yves Fouquet, Co-Chief Scientist, IFREMER,France; Robert A. Zierenberg, CoChief Scientist,U.S. Geological Survey and University of Califor-nia, Davis; Jay Miller, Staff Scientist, OceanDrilling Program; Jean M. Bahr, Paul A. Baker,Terje Bjerkgårdn, Charlotte A. Brunner, RowenaC. Duckworth, Robert Gable, Joris Gieskes, WayneD. Goodfellow, Henrike M. Gröschel Becker, GillesGuérin, Junichiro Ishibashi, Gerardo Iturrino,Rachael H. James, Klas S. Lackschewitz, L. LynnMarquez, Pierre Nehlig, Jan M. Peter, CatherineA. Rigsby, Peter Schultheiss, Wayne C. (Pat)Shanks, III, Bernd R.T. Simoneit, Melanie Summit,Damon A.H. Teagle, Michael Urbat, Gian G.Zuffa.REFERENCES:Davis, E.E., Mottl, M.J., Fisher, A.T., et al.; 1992. Proc.ODP, Init. Repts., 139: College Station, TX (OceanDrilling Program).

Goodfellow, W.D., and Peter, J.M., 1994. Geochemistryof hydrothermally altered sediment, Middle Valley,northern Juan de Fuca Ridge. In Mottl, M.J., Davis,E.E., Fisher, A.T., and Slack, J.F., (Eds.), Proc. ODP, Sci.Results, 139: College Station, TX (Ocean DrillingProgram), 207-290.◆

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