CALIFORNIA

GEOLOGY

A PUBUCATlON OF ntED£PAATlIENT OF CONSERVATIONDMSION OF -.lES AND GEOlOGY

SUM 01~ PETE WILSON""_The~~ DOUGLAS P WHEELER

Socterary lOt' RftSO/Jrcef/

o.p.ton_ (II CooseNal_ EDWARD G HEIDIGl>,_JAMES F DAVIS

SI818 Geologisl

CALIFORNIA GEOLOGY Slat!

In This Issue IMINERALS EDUCATION CONFERENCE 74DIATOMS-THE FORAGE OF THE SEA 75MEMORIAL, G DALLAS HANNA, 1887-1970 81MEMORIAL, CHARLES W. CHESTERMAN, 1913-1991 83WHEN THE BAY AREA QUAKES 84MAGMA ENERGY EXPLORATORY WELL, LONG VALLEY CALDERA 85INLAND GEOLOGICAL SOCIETY CALL FOR PAPERS 93MAIL ORDER FORM 93DMG RELEASE 94

SPECIAL PUBLICATION 105.............................. . 94CALIFORNIA GEOLOGY SUBSCRIPTION FORM 94NEW DIRECTOR-DEPARTMENT OF CONSERVATION 96

Tedlnocal Edotor:AsIIs"n, EcMOf;GraphICS am ~n.Pubbca!1(ln$ 5upeMsof'

Don DupraslenaTabllio

'-'"-""'"Jeff Tamber1 Cover Photo: The diatom As/erotampra tnsl{Jnls rendered about1000 limes actual SIZe, Photo courtesy of Grefco CorporatlOfl.

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C,t,LIFOflNIA GEOLOGV IISSN 0026 4555) ..~monlhly b'f'~~ 01 CooseNlt>on. O!v>-.on 01 MMs.,.., Geology The R8co«ls OIIoce " II 17111 20th SlrM!Slcrarnenlo. CA 9581' Se<:an::l elDll& ~.. IS ~Ill IIS;>ct.....nl0. CA Postma51'" S&nd Ilddr..... ch-.'IgM toCALIFORNIA GEOlOGY (USPS 350 8'10) 80. 2910, sacra·"*"0, C"'ll5812-2!lIlO

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THE CONCl..USlOP'lS AND OP"'~ EJlPflESSEO II.NlTJCUS AIlE SCl.ElV THOSE OF TME AlJT1oIORS NttJAAE NOT PECESSARIl.Y ENDClf'SEl) BY T)ff DEPART·IotENT OF CONSER\tATIOH

Co<.up.o<>denQ should be' .odd'''"'' to Edlt~t:CAllFOI'WIAGEOLOGY.6IlO&.raller- s.-- CA15811-'0'31

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April 1991Nolume 44JNumber 4

CGEOA 44 (4) 73-96 (1991)

Minerals EducationConference

A Minerals Education Conference. cosponsored by California StateUniversity, Sacramento (CSUS) and the California Mining Association(CMAl. will be held August 14, 15. and 16, 1991 on the CSUS cam­pus, The conference. which is designed for teachers. will present infor­mation, ideas, and activities concerning minerals and mining to be usedin various earth science classes. Comprehensive material on geologyand minerals, the environment, economics. and consumer products,and ways to use the material in classroom applications will be pre­sented.

All teachers are invited to attend. Registration is limited to the first100 applkations received. A $10.00 registration fee is required toguarantee altendance: the fee will be refunded at check-in. Universitycredit is available to all teachers who complete the course under univer­sity requirements. 1he cost of the credit course is $30.00

1he CMA will give a $50.00 stipend to each teacher who completesthe course. For information contact:

Barbara BennettCalifornia Mining Association1121 L Street. Suite 909Sacramento, California 95814(916l447-1977X

" CALIFORNIA GEOLOGY APRIL 1991

DIATOMS-The Forage of the SeaBy

JOHN L BURNETT, GeologistDivision of Mines and Geology

INTRODUCTION

D iatoms. a type of algae. are tiny plant-like organismsthat produce food through photosynthesis. Through the

action of sunlight, diatoms strip carbon from carbon dioxideand combine it with nitrogen. phosphorus. and essentialcompounds to creale food. Although they appear plant-like.scientists have detennined that these single-celled organismsare neither plant nor animal. Diatoms aTe classified with thesingle-celled protozoans, molds. and fungi into a separategroup called the Kingdom Protista. The living diatom forms asilica skeleton called a fruslule that is mineralogically identicalto opal.

appearance of a highly diverse and specialized population inthe fossil record is usually characteristic of an organism thathas had a long time to evolve.

Diatoms will grow in almost any environment that com­bines water and sunlight. Diatoms are abundant in both freshand salt water. Biologists refer to them as "the forage of thesea"- that is, they form one of the most important groups ofbasic organisms upon which all other aquatic life to some de­gree depends (Hanna, 1951).

REPRODUCTION

Diatoms can producesexually or asexually. Inasexual reproduction,which is the more fre­quent method of repro-­duction in diatoms. eachhalf of the pillbox-likefrustle forms a similar butslightly smaller valve. Theresult is two completefrustules. Diatoms divideabout once every 24hours. With additionalasexual (or Mvegetative")divisions, smaller individu­als are formed, althoughornamentation of thevalves is similar to the"parent" valves. A conse­quence of vegetative celldivision is that the cell linebecomes progressivelysmaller.

Through asexual repro-­duction. and the resultingdiminution. a critical cellsize is reached where.

when environmental conditions are favorable. sexual repro-­duction is initiated. Sexual reproduction in diatoms is complexand several different types of non-siliceous germ cells, calledgametes, may form. Each gamete germ cell contains half ofthe necessary genetic code to produce a diatom. When twogametes fuse they combine the necessary genetic informationto form a complete cell (called a zygote) which becomes en­larged and forms a frustule. This first frustule produced in the

The diatom Cyc/o/ella asiatica rendered about 1000 times actualsize. Photos courtesy of Grefco Corporation excepf as noted.

Diatoms first appear in the geologic record about onehundred million years ago during the Cretaceous Period. Thefamed diatom specialist G Dallas Hanna speculated that dia­toms must have originated prior to the Upper Cretaceous(see page 81). By that time diatoms were already abundant.highly organized and of many diverse forms; apparently aplace favorable for their preselVation simply had not beenfound (Hanna, 1951). Throughout geologic time. the first

Each frustule encloses thecytoplasm (a jelly-like colloid),a nucleus containing the ge­netic material. oil globulesand one to several chloro­plasts (microscopic structurescontaining chlorophyll). Thebrown or golden color typicalof living diatoms is caused byphotosynthetic pigments inthe chloroplasts. The oil glob­ules are food reselVes. Afterthe organism dies, the or­ganic portions decomposeleaving only the intricatewhite frustule. Each diatomfrustule is constructed like aminiature pillbox; that is, it ismade of two halves, thesmaller half fitting inside thelarger half. The entire frustuleis ornamented with sieve-likeperforations and intricate ribsthat hold the framework to­gether. These delicate andelaborate frustules have fasci­nated microscopists for over150 years.

CALIFORNIA GEOLOGY APRil 1991 75

The diatom TnceratJum f1Jtescens rendered about1.000 times actual SIze.

sexual reproductive life cycle is the largest. Subsequent divi­sions are asexual. Sexual reproouclion provides diatoms withbenefits of recombining genetic material; each parent contrib­utes to toe genetic makeup of toe resulting offspring. Sexualreproouction allows the diatomite cell line to become ~big~

again.

When conditions are favorable, such as an abundance ofnutrients due to upwellings. diatom reproouctlon forms a"'bloom.

M

The diatom profusion in these blooms results fromrapid asexual reproouction. The diatom bloom ends whensome nutrient or combination of nutrients becomes limited.For example. when diatoms assimilate and deplete the avail­able silica. the diatom populations plummet while other algaepopulations. that do not require silica. expand.

THE ENVIRONMENT OF THE DIATOM

As with all living things, diatoms need food and a compat­ible environment to survive. The nutritional requirements ofdiatoms include nitrogen. phosphorus. and carbon dioxide.Although these necessities are similar to those of land plants.they differ in lhat diatoms need silicon to form lheir opalinefrustule. Minor elements. such as iron. also playa part intheir nUlritional requirements. These minerals and elementsseem to act in the same way they do in humans; a smallamount is essential but a much larger amount can be toxic.

Diatoms also have environmental requirements. Sunlightis needed for photosynthesis. However. there are diatomspecies that have no chloroplasts to photosynthesize sunlightand these species must absorb their nutrients from the envi­ronment. A defined temperature range is another require­ment; diatoms do quite well in cold waters and thrtve in theoceans at both poles.

As a group. diatoms have evolved and adapted to manyaqueous environments. including salty inland seas. oceans.bays, and freshwater systems. Individual diatom species aresensitive to alterations in their physical. chemical. and biOlogi­cal surroundings. Because of this sensitivity, diatoms are usedto monitor changes in aquatic systems throughout geologictime; diatom frustules deposited in aquatic sediments reflectthe water conditions at the time they lived. Therefore. fresh­water diatoms are not found in the ocean. nor are salt waterdiatoms found in freshwater systems.

DIATOMS' INFLUENCE ON OUR ENVIRONMENT

Diatoms in the world's oceans have a profound effect onour environment. both in our oxyogen and food supplies. Dia­toms use carbon dioxide and water in photosynthesis to con­vert the carbon and hydrogen to carbohydrates with energyabsorbed from the sun. Oxygen is proouced as a by-proouetand is released. Because carbon dioxide is the principal gasresponsible for global warming through the ~greenhouseef­feet, ~ its conversion to oxygen by diatoms plays a fundamen·tal role in moderating our future climate. It is estimated thatas much as 60 percent of the oxygen in our atmosphere isderived from the oceans: this oxygen is largely due to the ac­tivity of diatoms. It may not be the rain forests that generatemost of our oxygen but the tiny diatom.

Diatoms are also the foundation of the oceanic food chain:they are the staple food for krill. tiny shrimp-like crustaceans.Krill move in immense schools sometimes several miles acrossand containing millions of individuals. These schools becomethe feeding grounds for a very diverse group of animalsknown as suspension-feeding vertebrates. Whales. tadpoles.sharks. ducks, flamingoes. and many varieties of fish areamong the animals that feed on krill. These animals have de­veloped different but highly specialized mouths that strainlarge quantities of water to remove the tiny animals.

A 30 foot~1ong basking shark can strain 2.000 cubic yardsof water in an hour and remove 130 gallons of marine life.mainly krill (Sanderson and Wassersug. 1970). Krill constitutethe primary food of the baleen whale ....>hieh has evolved theunique whalebone strainer to remove the crustacean fromseawater.

Krill are currently being caught and processed inlo feed forlivestock. poultry. and farmed fish. The potential yield of krillcould exceed the present world harvest of all other marinespecies combined (Hamner. 1984). The potential for usingkrill as a protein source for humans is huge.

" CALIFORNIA GEOlOGY APRil 1991

Although diatoms and krill form the foundation of a vitaloceanic food chain. neither group seems to be in any realdanger of extinction through over-grazing. Both flourish inpolar oceans and probably will continue to do so barring anymassive pollution of these remote regions. The benefits ofthese two tiny organisms have been recognized only in recentyears.

If diatoms are so important. why are they not farmed artifi­cially? This has been proposed and is touted as a simple andeconomical solution to the global warming that results fromthe bUildup of carbon dioxide in the atmosphere. The hy­pothesis is that diatom blooms are held in check only by adeficiency in iron (Martin. Gordon and Fitzwater. 1990), Theso-called "Geritol Solution·· would involve seeding the polaroceans with soluble iron compounds which would allow theproliferation of diatoms. This proliferation. according to thishypothesis. would greatly reduce atmospheric carbon dioxide.lower global temperatures and. if carried to the extreme, leadto an advance of glacial ice. However. the availability of otherdiatomite nutrients such as nitrogen and phosphorus wouldalso be limiting factors in such an experiment.

Some diatom species produce a large proportion of theiroverall weight as oiL Research is ongoing to determine thepotential of farming diatoms in large quantities as an addi­tional source of fuel.

Dark field photomicrograph of the diatom Pinnularia dactylus.Magnificalion is approximately 1.250 limes actual size. Courtesyof Grefco; photo by Richard B. Hoover.

FOSSIL LOCALITIES IN CALIFORNIA

The most massive fossil deposits of diatom remains haveformed in cold parts 01 ocean basins or in cold inland lakes.However. diatoms will also grow in such diverse habitats asthermal springs. roadside ditches, moist top soil. or on moisttree trunks (Hoover 1979). Fossil deposits of diatoms arecommon in California and other states in the far west. butare rare in other parts of the United States.

The largest fossil diatomite deposits in California are theupper Miocene and Pliocene (8 - 2 million years agol marinedeposits found in the Coast Ranges of central California andthe Peninsular Ranges of southern California. These depositsextend discontinuously from Point Reyes. Marin County toSan Onofre in northernmost San Diego County. Large areasof these rocks have been lost to mineral development due tourbanization. especially in Ventura, Los Angeles. and Orangecounties. Another group of potential deposits are the diato­maceous marine shales of the Eocene. Paleocene. and Creta­ceous formations found on the west side of the San JoaquinValley from Stanislaus County to southern Fresno County.

Smaller but important fossil diatom groups are the fresh­water deposits found in many parts of the state. The largestreserves of freshwater diatomite are in California's northeast·ern counties: Shasta, Siskiyou, Modoc, and Lassen. In addi­tion. marine diatomite deposits are present in the eightChannel Islands located in the Peninsular and Transverseranges. The largest deposits are on Santa Catalina, SanClemente. Santa Cruz. and Santa Rosa islands.

In the California Coast Ranges, huge deposits of oceanicsediments containing diatoms are quite common. howeverpure diatomite is rarely found. Most of these materials aremixtures of diatoms and bentonitic clay derived from theweathering of volcanic glass. These diatomaceous shales formstratigraphic units thousands of feet thick stretching for hun­dreds of miles in the central and southern Coast Ranges.Materials of unusual purity near Lompoc in Santa BarbaraCounty form the most important commercial deposits in theworld: the White Hills. These deposits contain strata 3,000feet thick and consist mostly of marine diatom frustules.

This same region is the location of the most importantpetroleum reserves in California. Hanna (1923. 1951) notedthis relationship and suggested that the brown or goldencolored globule of oil is similar to petroleum and that diatomsmay be the source of most of the petroleum in California.Due to the porosity of diatomaceous shale, petroleum couldreadily migrate out of the diatomite and be trapped by someimpermeable unit in a structural geologic trap such as ananticline.

McKittrick

The Getty Oil Diatomite Project near McKittrick in westernKern County was a pilot plant begun in 1972 to investigatethe economic feasibility of recovering petroleum from an oil­saturated diatomaceous shale in the McKittrick oil field. 14miles northwest of Taft. This deposit consists of diatoma­ceous and siliceous mudstones. chert, tuffaceous. and carbon­ate rocks. asphaltites, and breccias. It is an extensive depositof Antelope Shale in the upper Miocene Monterey Formationdiatomite and related siliceous deposits.

This field has been producing oil and gas since 1896.Numerous tar steps are present on the property. There isan estimated 832 million barrels of in-place oil remaining.

CALIFORNIA GEOLOGY APRIL 1991 77

Late Tertiary·Quaternaryfreshwater formationsMiocene-Pliocene fOrmatiOns}

. Marineupper Eocene formatIons

EXPLANATION

DIATOMITE IN CALIFORNIA

o

OREGON~~-._._._._._._._.-

NOATE' •• 1 I) Copeo 't Tablelands, i. Reservoir ,I Lower Klamath lake-,t . .. .." ," """"" I """'" 1rf" ,..t.... (1' g;s;~ --;'-r-"- UssaiI, . Lake 1 •

1 ! Britton 'l I'I /' .~.~. I

~9Ol.DT .. .. --' .. - ............. , '......... .

_ ..i"'."'C'.)' /1 ". ", Ir" \ . • Diatomite localities

,L,T~.~- '''-. :_pt~-H Long Valley

I· "",,', .--1_'~, <-----J""'.1 eun_~~.J' NE~_ADA ' . ..tj Boca( ·l.ca.US.l\~, ....;:iJj/ ~ Reservoir

~",/--\,,'? r'~' )-.""""'\-\~¥\-\-~~",oJ"" \ \ i "":"/1/' >-...~ '". 1.J SOI..ANo - -----1r /WOlUMtIE \ ..

..... .,:/1 ~.' Knights...., ".cg:T"t· ~,,~ FerrY ··1 ........... Long Valley

~~F ~j ../-:J~~,r· ........ -J4'>")" !IICH}"'-',

~IMTEO ~~:l C:m~~ .!/,p-P' \-wo-_":\.Z~v.,ffi~ClAI'J< ~o:-/...-J \... " ()= ~.-L c- .r' \ Pove:rty <,

• SAN\':-{ ''-'.-. ,FRE~. Hills "'-,llE1«TO. Fnan I ---J- ----' -\ .. "'-

.,; r'~ \ "'. . I 1 ".

""'die, "./. , ".. 0 • -J ""'" L ~._._.-."", ",,-.\-.- -'-'-'- T - "~ 1, McKittrick· ".

-'-\, Taft I Piute ".Santa ,~.--_ ~. Maricopa I Valley ,. '.Maria ~~ ......... KERN \

Casmalia 0 SAHI~1WIlAAA1"~\ lOSNiGf:LES"""T \• oc 1 \ I ')

. I /'4 ..........., _._._. ~>.//-_.- I~'< '0

~) )~. _."'~- ----sAN0IEI"iCi-~-- '-,

San Onofre ! White L( Christmas j

-L" _.-'____ - '" {;It"C)''

Map 01 California ShoWl1lQ the generalized distribution 01 diatomlle and diatomaceous lormations (modified from Oakeshofl, 1957).

CALIFORNIA GEOLOGY APRIL 1991

The Airox mine near Casmalia.High quality pozzolan and struc­tural lightweight aggregate wereproduced from this deposit 01petroleum-bearing diatomite.

Because much of this oil cannot be extracted by conventionalmethods. two experimental pilot plants were built side-by-sideto test the feasibility of extracting petroleum through eitherretorting or by chemically extracting it by a solvent process(Mulhern. Eacmen and Lester, 1983). The plants closed inthe mid-1980s when oil prices became unstable and therewas a general slowdown in the petroleum industry. The sol­vent extraction pilot plant has been removed and all opera­tions have ceased (1990).

RESERVES

Diatomite resources are difficult to describe because diato­maceous rocks underlie large areas and include strata of vari­ous qualities. The diatomite resources and reserves of Califor­nia. where most of the world's diatomite is produced. havenever been computed and classified according to grade.

However. abundance of the material is evident. For ex­ample, diatomaceous reserves controlled by one actively pro­ducing company at Lompoc. California cover an area of 4square miles and is minable to a depth of 700 feel (Anony­mous, 1969. p. 14). Allha current rate of consumption thisdeposit could supply the world's demand for diatomite for sev­eral hundred years. Therefore. we can assume that diatomiteresources of the United States are adequate to allow for asteady increase in diatomite production. Although there areabundant quantities 01 diatomite available for future use. thelocation and quality appear to be more important factors inthe economics of diatomite production (Durham. t 973).

CALIFORNIA PRODUCTION

The commercial value of diatomite was not recognized un­til the late 1880s when a small amount was mined for build­ing stone from the deposits at Lompoc. In 1889 productionrecords show that 39 tons of diatomite were mined from de­posits near Calistoga. Napa County. During the 1900s. only

a few hundred tons were mined annually in California, but thematerial was being tested for use in insulation, filtering, and inrelining beet sugar. Beel sugar refining became the foundationof the modem diatomite industry. SUitability for filter applica­tion has been a prime consideration in the evaluation of anydiatomaceous deposit planned for large scale exploitatlon.

The Lompoc deposits were being actively developed at thetum of the century and. beginning in 1904. the deposits inMonterey County were developed. During World War I, Cali­fornia's annual production had reached about 13,000 tons.

The working face of the Dicalite quarry near Lake Brilton,Shasta County. The man is pointing to a 2·inch layer of sandydetritus which wHi be selectively removed during mining.

CALIFORNIA GEOLOGY APRIL 1991 79

After World War I the diatomite industry developed rapidlyfrom an important statewide industry to one of national andinternational significance. The Johns-Manville Corporationacquired a large part of the Lompoc deposits in 1928. andin 1930 the Dicalite Company opened the extensive depos·its in the Palos Verdes Hills in Los Angeles County.

The California dialOmite industry was consolidated by afew large corporations during the 1940s and with the stimu­lus of World War Il and the industrial expansion since then.a steady rise in both tonnage and average price has been re­corded. The Dicalite Company acquired deposits near Lom­poc in 1942 and in 1944 the company was purchased bythe Great Lakes Carbon Corporation. Mining of diatomitenear Bradley, in Monterey County, ceased in 1942 afternearly $500,000 worth of material had been produced bythe Pacatome Company, The Palos Verdes Hills depositsnear Walteria, Los Angeles County were abandoned in1958 due to encroaching urbanization and depletion of orereserves.

Although some effort was made toward the commercialproduction of diatomite in California counties other thanMonterey and Los Angeles from 1947-1955 (Oakeshott,1957), by 1955 the only major deposits being operatedwere those at Lompoc. Between 1955-1980 diatomite pro­duction increased appreciably in the Lompoc area and mi­nor production was contributed by operators in Napa. Kern.and Lassen counties (Taylor. 1981).

UTILIZATION AND PRODUCTION

Because diatomite consists of billions of minute silicaframeworks, the material has many unusual properties. Thefrustules are strong and support intricate internal frame­works with maximum void space resulting in bulk densitiesas low as 0.1 or 0.2. The siliceous framework is chemicallyinert and resistant to high temperatures. The small size ofthe open pores gives diatomite excellent capillary allractionmaking it a good absorbent. The material has an extremelyhigh surface area per unit of volume, commonly on the or­der of thousands of square yards per ounce of diatomite.

Diatomite has hundreds of specific uses that can beplaced into ten general categories:

1. filters 6. reactive-silica sources

2. fillers 7. structural materials(lightweight aggregate)

3. insulating materials 8. additives for concrete(pozzolan)

4. mild abrasives 9. conditioners or anti-cakingagents

5. absorbents 10. silica components inportland cement

Most uses of diatomite benefit from the aggregate effectof the microscopically complex and chemically inert diatom

frustules. Aside from its light weight and porosity. other char·acterlstics of diatomite make it suitable for industrial uses. Di·atomite has a low thermal conductivity and a melting pointthat ranges between 1,400"C and 1,750"C. although certainimpurities can result in a considerably lower melting point.The opaline silica of diatomite is nearly chemically inert andis soluble only in hydrofluoric acid and strongly alkaline solu·tions. Its inert chemistry makes diatomite especially useful asa filler (Durham, 1973).

Most of the California production comes from the Lom­poc area of Santa Barbara County although substantial pro­duction comes from the Lake Britton deposits in ShastaCounty. Competing diatomaceous prcx:lucts are prcx:lucedat Mina. Sparks, Fernley and Lovelock. Nevada; Vale andChristmas Valley, Oregon; Quincy. Washington; andMammoth, Arizona (Davis. 1990).

ACKNOWLEDGMENTS

J. Patrick Kociolek, who holds the G Dallas Hanna Chairof the Diatom Collection. California Academy of Sciences.reviewed the manuscript and significantly contributed towardits accuracy and completeness.

scanmng electron micrograph of Lompoc marine diatomite.Magnification is 250 times actual size. Photo courtesy ofManville Products Company.

80 CALIFORNIA GEOlOOY APRil 1991

REFERENCES

Anon~mous, 1969, Diatomite-its production. uses and potential:Industrial Minerals. no. 18, p. 9·17,19,21. 23·27. 37.

Davis, L.L., 1990, Diatomite in 1989. Mineral industry surve~s:

U.S. Bureau of Mines.

Durham. D.L., 1973. Diatomite in Brobst. D.A. and Pratl. W.P..editors. United States Mineral Resources. U.S. GeologicalSurve~ Bulletin 820. p. 191·195.

Hamner, W.M.. 1984. Krill-untapped bounty from the sea:National Geographic, May, v. 165, no. 5, p. 626-643.

Hanna. G D.. 1923, Genera of diatoms characteristic of marineand fresh waters: Eighteenth Report of the State Mineralogist,p. 59-76.

Hanna, G D.. 1951. Diatom deposits: California Division of MinesBulletin 154, p. 281-290.

Hoover. R.B.. 1979. Those marvelous myriad diatoms. NationalGeographic, June, v. 156. no. 6. p. 870·878.

MEMORIALG Dallas Hanna

1887-1970

T he diatomite deposits of northeastern California wereknown for decades but their extent and content were

poorly defined prior to field work by G Dallas Hanna andCharles W. Chesterman from 1949 to 1955. Hanna de·scribed many vertebrate fossils as well as individual diatomspecies and Chesterman made some of the first obselVationson the lateral extent and thickness of the diatomaceous de­posits. This work was later augmented by Quintin A. Aunewhen he conducted reconnaissance mapping in the late1950s for the geologic map of California. Descriptive workwas also done on diatoms in the mid-1980s by Platt Bradburyof the U.S. Geological SUlVey. The pioneering work of Dr.Hanna came toward the end of a long career in biology, pale­ontology. zoology. geology, optics. and mechanics. From1919 until his death. he was curator of geology at the Cali­fornia Academy of Sciences in San Francisco.

Hanna was born in Arkansas and educated at the Univer­sity of Kansas where he earned the A.B. and M.A. degrees inzoology. In 1918 he received a Ph.D. in zoology at GeorgeWashington University in Washington. D.C.

His first job after graduating from the University of Kansasin 1909 was with the U.S. Bureau of Fisheries where he wasassigned to the Bristol Bay area of Alaska. While in Alaska hehelped manage fur seal herds on the Pribilof Islands in theBering Sea. Hanna first began studying diatoms when hecollected specimens from a freshwater lake while on SI. Paul

Martin, J.H., Gordon A.M., and Fitzwater, S.E., 1990. Iron in Ant­arctic waters: Nature. v. 345. no. 6271, May. p. 156·158.

Mulhern. M.E., Eacmen J.C., and Lester, G.K.. 1983, Geology andoil occurrence ot displaced diatomite member. Monterey Forma·tion-McKillrick oil field in C.M. Isaacs, and R,E. Garrison, edi­tors, Petroleum generation and occurrence in the Miocene Mon­terey Formation, California: Pacific Section. Society of EconomicPaleontologists and Mineralogists, Los Angeles.

Oakesholl. G.B.. 1957. Diatomite in Mineral Commodities of Cali­'ornia: California Division of Mines Bulletin 176, p. 183-193.

Sanderson, S.L. and Wassersug. R.. 1990. Suspension-feedingvertebrates: SCientific American. v. 262. no. 3. March, p. 96.

Taylor. G.C.. 1981, California's diatomite industry: CALIFORNIAGEOLOGY, v. 34, no. 9, September. p. 183·192.><

THE MINERAL COMMODITY REPORTDIATOMITE 1991 WILL BE AVAILABLE SOON.

G Dallas Hanna

CALIFORNIA GEOLOGY APRIL 1991 "

Island (one of the Pribilof Islands). [n 1916, while studyingthese diatoms. he developed a "mechanical finger~ for moreefficient handling of individual diatom specimens.

Hanna later developed an improved method of mountingdiatoms by using a medium that facilitated studying diatoms.His new medium. called "hyrax." has a higher index of re­fraction than the previous mounting medium and helps inves­tigators see diatoms in greater detail. Hanna also developeda method of coating diatom specimens with a thin film of re­algar (arsenic sulfide) to photograph them in sharper focus atvery high magnifications. His contributions to microscopyled to his appointment as a Fellow of the British Royal Mi­croscopy Society.

Improving diatom visibility by microscope inspired Hannato study optics. During World War II he worked with a groupof amateur telescope makers. glass grinders and polishers.and instrument repair people at the Califomia Academy ofSciences to make optical parts and repairs for the armedservices. Following World War ll. the Academy became inter­ested in building a planetarium. However. because most starprojectors were constructed by the destroyed Zeiss opticalworks in Germany. Hanna and a group of optical workers.machinists. and technicians developed and constructed thestar projector for the Academy's Morrison Planetarium.

Hanna's interest in diatoms continued throughout his lifeand eventually led to the use of these and other microfossilsby the oil industry as an index for the correlation of strata inoil exploration. In 1924 Hanna was placed in charge of thefirst laboratory for micropaleontology on the Pacific Coast.The project was funded by the Associated Oil Company(now ARCO).

During his 51 years at the California Academy of Sciences.Dr. Hanna built one of the finest diatom reference librariesin the world. This library includes many photographs andan extensive slide collection of originally described diatomspecimens.

Research on diatoms continues at the California Academy01 Sciences and in 1987 the Academy established a G DallasHanna Chair in diatom studies. During his distinguished ca­reer. Hanna produced many publications relating to diatomsand their uses. Hanna's contributions were both practicaland theoretical. He is credited with developing more than430 recognized advances in mammology, ornithology,optics. malacology. geology. paleontology. and especially mi­cropaleontology. for which he is world renowned. One of hismost significant works is a 208 page index to 'Schmidt'sAlias of Diatoms."

Many honors were given to Dr. Hanna during his career.In 1959 his alma mater, the University of Kansas. conferredupon him the Erasmus Haworth Distinguished Alumni Honorsin geology. In 1962 volume 32 of the Proceedings of theCalifornia Academy of Sciences was dedicated to him on his75th birthday. In 1967 he was awarded the Fellows Medal.the highest award of the California Academy of Sciences. andin 1970 he received the Honorary Degree of Doctor of Sci­ences from the University of Alaska.

The reader may have noticed the "improper" spelling ofHanna's name-"G Dallas Hanna." When questioned aboutthe spelling of his name. Hanna gently but firmly instructedthe author that his parents gave him the leiter G as his firstname. [t stood only for G and was not an abbreviation foranything else. He said that he had spent a lifetime correctingeditors who were, in his view. trying to rename him. "Afterall." he said. "I should know how to spell my own name!"However. all too often he lost the battle and his name isnearly always cited as "G. Dallas Hanna." By John L.Burnell with the assistance of Charles W. Chestermanand Mrs. Margaret M. HannaY

Arachno/discus orantus, Asingle disc­shaped diatom found in the Lompocdeposits. Photo courtesy of ManvilleProducts Company.

52 CALIFORNIA GEOLOGY APRIL 1991

MEMORIALCharles W. Chesterman

1913-1991

Charles W. "Charlie" Chesterman. along-time Senior Scientist with the

Division of Mines and Geology passedaway on March 25 at Queen of the Val­ley Hospital in Napa. He was 78. Char­lie was a valuable member of the Divi­sion and an outstanding mineralogist.petrographer. and field geologist. Heworked in the Division's San Franciscooffice from 1947 until his retirement in1978. AI the time of his death he was aFellow and Honorary Curator of Miner­als al the California Academy of Sci­ences in San Francisco. For many yearshe had been responsible for the Acad­emy's fine mineral display.

Charlie was the author of numerouspublications on various mineral com­modities, nephrite jade and jadeite. vol­canic hazards, volcanic rocks, SierraNevada metamorphic rocks, the geol­ogy and gold deposits of the Bodie min­ing district. and geologic maps of theShoshone, Bodie and Matterhorn Peakquadrangles. He was also the author ofthe 'The Audubon Society Field Guideto North American Rocks and Miner­als." Earlier in his career he was incharge of the Division's Public Services

Laboratory and was responsible formodernizing the staff GeochemicalLaboratory. Many of the young geolo­gists started their careers with the Divi­sion in that laboratory. Charlie was agreat help to all of them.

Charlie was born in Larned. Kansas.and moved to Bakersfield with his fam­ily al age 7. He received a Bachelor ofArts degree in geology from FresnoState College and a Master of Arts de­gree in geology from the University of

California at Berkeley. Prior to his ca­reer with the Division of Mines and Ge­ology, he taught at San Francisco CityCollege and worked for the U.S. Geo­logical Survey. He was also a geologistfor the U.S. government in Japan afterthe Second World War, Those of uswho had the privilege of working withCharlie always found him to be verycongenial and helpful. He is survived byhis Wife. Norma. a son. two daughters.a stepson, a stepdaughter. and ninegrandchildren.

In recognition of his distinguishedcareer over many years as a profes­sional geologist and mineralogist. Char­les W. Chesterman was honored byhaving a new mineral named after himin 1988. Chestermanite is a magne­sium-iron-aluminum-antimony-boratefrom the Twin Lakes region of north­ern Fresno County. Charlie began hisstudies of the mineralogy and petrologyof the Twin Lakes region in 1939 andhis interest in this area continuedthroughout his life. The contact meta­morphic rocks of the Twin Lakes re­gion was the subject of his Master ofArts thesis)'::

CALIFORNIA GEOLOGY APRIL 1991 83

A Page For Teachers

Collapse of porch in downtownWatsonville. Photo by John K.Nakara, U.S. Geological Survey.

When the Bay Area

Quakes

This nontechnical video documentary shows what happenswhen a large earthquake strikes the San Francisco Bay

area. Television news (ootage of the Loma Prieta earthquakeis used throughout the program to illustrate the four main geo­logic effects of Bay area quakes: groundshaking. liquefaction.landslides, and ground ruptures. It can be seen that the localgeology is very important in determining how a given area willbe affected. Damage to manmade structures is also illustratedand explained. A graphic computer animation shows the proc­ess of liquefaction in a neighborhood built on artificially filledground, such as San Francisco's Marina district.

After introducing the effects of earthquakes, the many dif­ferent earthquake-monitoring efforts taking place throughoutthe Bay area are shown and described. The program thenlooks to the future-when and where large earthquakes arelikely to occur in the Bay area in the next 30 years and why.The consequences of a major quake on the Hayward fault areexamined.

The program ends with a look at the world's largest earth­quake-prediction effort: the Parkfield earthquake-predictionexperiment. Near a small town in central California, hundredsof monitoring instruments stand ready to capture the geologicevents that should happen before the next earthquake strikesthe area.

IntelViews with U.S. Geological SUlVey scientists and otherearthquake officials appear throughout the video. The pro­gram is narrated by San Francisco newswoman WendyTokuda. and it contains an original stereo soundtrack. Newsfootage of the Loma Prieta earthquake was acquired fromthree Bay area stations: KPIX-TV, KGO-lV, and KlVU-TV.

WHEN THE BAY AREA QUAKES is available fromGLOBALVISION, 3790 EJ Camino Real. Suite 221, PaloAlto. California 94306. VHS. stereo, 20 minutes. $19.95.includes shipping and handling. Allow 3-4 weeks for delivery.By Doug Prose. X'

" CALIFORNIA GEOLOGY APRIL 1991

Magma Energy Exploratory WellLong Valley Caldera

Mono County, California

By

SYLVIA BENDER-LAMB, LibrarianDivision of Mines and Geology

INTRODUCTION

9

STUDYAREA

o-Z

"

LONGVALLEY

MIles

The degree of violence with which avolcano erupts relates closely to the vis­cosity and gas content of the magma.

hydrogen chloride (Van Rose andMercer. 1986). The manner in whichgases separate from the magma deter­mines the character and violence of aneruption.

o

caldera rim G1as( s MOUI],--_J!"-.... .... 'q/., ., ,

MONOCRATERS

o

N

I1

June IlLakeC/ :z

~ ()

MONO LAKE

Figure I. Location map 01 the Long Valley caldera in eastern Californiashowing the magma energy e~ploratory well.

Grant

""0 39

extrusive igneous rocks. The gases areheld within the magma by the confiningpressure of the magma chamber oroverburden. At the slart of an eruption.the magma effervesces and the gasesseparate out. The gaseous mixturecommonly includes water vapor. hydro­gen. hydrogen sulfide. sulfur diOXide,carbon monoxide, carbon dioxide, and

A caldera is a large circular or semi­circular shaped volcanic craler that maybe many times larger than the volcanicvenl system that produced it. Mostcalderas form when the crater floor col­lapses into a vacated magma chamberbeneath the volcano (as occurred whenMount Mazama collapsed to form CraterLake. Oregon). or when a volcano'ssummit is blown off by exploding gases(as occurred at Mount St. Helens.Washington in May 1980).

Calderas

The molten rock-or magma-thatfeeds such volcanic eruptions is a combi­nation of lava and volcanic gases. Whenthe lava is ejected. it crystallizes to form

V iolent volcanic eruptions such asthe one that formed Long Valley

caldera in eastern California are amongthe most catastrophic geologic events onEarth (Figure 1, Photo 1). Magma,which is responsible for volcanic activity.is potentially the ultimate geothennalresource. The key to magma utilizationas an energy resource, however. is theexistence of magma reservoirs at rela­tively shallow depths in the Earth's crust.

Intensive study of Long Valley overthe past 15 years indicates evidence formagma al depths accessible to drilling.The Department of Energy's MagmaEnergy Extraction Program is currentlydrilling a 20.000 foot exploratory wellinto the Long Valley caldera. The pur­pose of this program is to determine thefeasibility of producing electrical powerfrom magma. If the magma energy ex­periment is successful. the Long Valleycaldera could hypothetically supply theelectrical power needs of California for100 years at present power consump­tion rates (Crewsdon and others, 1991).

CALIFORNIA GEOLOGY APRIL 1991 65

Photo 1. View 01 the Long Valley caldera from the south caldera rim. The low hills in themiddle of the photo are pan of the resurgent dome. The nonh rim 0' the caldera is visiblein the upper right. The lown of Mammoth Lakes is just off the photo to the lett (west).Photo by Steve McNutt.

Magma viscosity in tum is influencedby two factors: (1) the temperature atwhich a magma solidifies. and (2) thesilica content of the magma. Silica- andgas-rich magmas. such as rhyolite. aresignificant in the formation of largecalderas because they tend to producelarger and more explosive eruptionsthan mafic magmas. such as basalt.

Because mafic magmas are low insilica content. they tend to lose theirgas and flow easily. For example. theoften-photographed flowing rivers ofred-hot basaltic lava in Hawaii are ofmafic composition. [n contrast. silica­rich magmas are very viscous and donot flow freely. The high viscosity in­hibits gas separation and escape. SiI­ica'rich magma eruptions can be ex­tremely violent. and the ejecta and lavaflows look much different than the Ha­waiian-type runny-lava flows. Eruptionsthat are dominated by magma high insilica and dissolved gases seldom formliquid lava: more commonly they sendpumice and fine ash explosively into thesky as the magma leaves the confiningpressure of the magma chamber.

The largest known calderas are thoseassociated with silicic pyroclastic erup­tions and are more than 40 miles indiameter (Francis. 1983: Lipman and

Bolded terms are in Glossary on page 93.

others. 1984). Catastrophic eruptionsand subsequent collapse are followed bya gradual raising of the floor as magmaintrudes upward once again into thechamber that originally formed thecaldera. A ~resurgent dome" formswithin the caldera over the next severalhundreds to thousands of years. Thebasic structure of a resurgent calderais a broad depression with a centraldomed uplift (Francis. 1983).

Geologically recent calderas are ofinterest to scientists. The threat of re~

newed violent volcanism and accompa­nying earthquake activity could devas­tate large regions. For example. theexplosive 1883 Krakatau event in Indo­nesia that killed over 30.000 peopleerupted from a pre-existing caldera(Francis and Self. 1983).

Caldera investigations provide insightinto the origin. evolution. and move­ment of magma bodies. Caldera studiesalso aid in understanding how are miweralization is associated with volcanism.Remnant magmatic heat beneathcalderas may provide vast future geo­thermal energy resources (Lipman andothers. 1984).

Within the past few years scientistshave initiated investigations to deter·mine the feasibility of extracting geo­thermal energy from residual magma,

Large magma bodies insulated withinthe Earth's crust, such as the one be­neath the Long Valley caldera. have avery slow cooling rate and can retainsignificant amounts of heat for hun·dreds of thousands of years.

Several calderas in the western conti­nental United States are known to belarge enough and young enough to con­tain residual magma (Figure 2): the Yel­lowstone caldera. Wyoming (formedabout 600.000 years ago). the Vallescaldera. New Mexico (formed about1.100.000 years ago). and the LongValley caldera. California (formed about730.000 years ago) (Francis. 1983).

GEOTHERMAL ENERGY

Estimates of potential energy fromnear-surface magma bodies in theUnited States exceed the total annualU.S. energy consumption by about6.500 times (Eichelberger and Dunn.1990). Magma bodies within theUnited States at depths of less than 6miles of the Earth's surface contain upto 500.000 quads (Lyster. 1989), IAquad is a unit of energy that equals aquadrillion (lxl015) British ThennalUnits (BTUs) and is equivalent to 172million barrels of oil. I Total U.S. annualenergy usage is 75-80 quads. Califor­nia contains five of the most promisingmagma resource sites in the UnitedSlates (Crewsdon and others. 1991).

Drilling is one of the most directways of verifying the existence of anactive magma chamber and determiningthe feasibility of extracting energy re­sources from it. To investigate the via­bility of extracting energy from magma.in 1975 the U.S, Continental ScientificDrilling Program initiated the MagmaEnergy Extraction Program under theGeothermal Technology Division of theDepartment of Energy. While commer­cial power generation from magma is20 to 30 years away. data from thisexperiment will help determine the fea·sibility of extracting energy from crustalmagma sources (Dunn. 1988).

The current focus of the federal pro­gram is to increase understanding ofmagma physics and to develop the spe­cific technology needed to producepower from magma (Chu and others.

CALIFORNIA GEOLOOY APRIL 1991

~-~-------r----T--Mounl i

51. Helens

,~

~1I0WSlone

....... ...4ttCaldera

--VallesCald9ra

N

I • '. ... •• .. -.,,,

.... Figure 2. Mapped occurrences of the Bishop Tull ash bed,Maximum thicknesses 01 this unit range 'rom nearly 10 feet insome areas of California, Nevada, and Utah to over 2 feet inNebraska (Izen and others. 1988). When the Bishop Tufferupted it sent an estimated 140 cubic miles of volcanic ashinto the atmosphere. Its explosive 'orce sent a ground·huggingcloud 0' super-heated gases mixed with a froth of pumice andash that obliterated the surrounding landscape. In comparison.the devastating Mount SI. Helens' eruption in May 1980ejected only about 0.6 cubic mile of debris.

Figure 3. SChematic northwest·southeast cross section throughthe Long Valley caldera as inferred from geophysical measure·ments. Four layers of material are expected to lie above thepartially molten magma predicted at a depth 01 4-5 miles: thecompacted ash and fine-grained pumice ot post-caldera till(2.000 feet): the volcanic ash of the caldera·forming eruption.now solidified into the Bishop Tuff (2,000·5,000 feet): the meta­morphosed shale of the Sierran basement rock (5,000-9.000feet): and crystallized magma (9.500 feet to 4 miles). Courtesyof Sandia National Laborafories.

NNW SSE!"'I----LONG VALLEY CALDERA----~

,...- RESURGENT ZONE-~ SierraNevada

Exploratory well

rocks of the Sierra Nevada batholith.and Paleozoic and Mesozoic metamor­phic rocks of the Mount Morrison andMount Ritter roof pendants. Thicksequences of late Tertiary pre'calderavolcanic rocks overlie the basement

rocks.

no verticalexaggeration

Evidence of the earliest volcanismassociated with the Long Valley calderamagma chamber originated fromupwelling deep-crustal magma culminat­ing in eruptions starting 3.2 millionyears ago. These older basaltic andandesitie lava flows are scattered over

SIERRAN BASEMENT

3

PARTIALLY MOLTENMAGMATIC ZONE

OSIcald6fu

2,Miles

o,

precalderavolcaniCS

The pre-Tertiary basement rocks inthe vicinity of the Long Valley calderainclude Jurassic and Cretaceous granite

Long Valley caldera is an ellipticaldepression in eastern California thatformed about 730,000 years ago fromthe catastrophic eruption and collapseof a large rhyolite magma chamber(Bailey. 1987). The caldera is about170 square miles in area and has anextensive history of volcanism (Figurell. The eastem half of the caldera.

Long Valley proper, is a broad grassand sage-covered valley of low relief(Photo 1). The western half of thecaldera near the town of MammothLakes is a forested area of higherrelief (Bailey and others, 1976).

LONG VALLEY GEOLOGY

1990). Seismic. geological. and geo­physical data indicate that a major shal­low magma body may exist beneath theLong Valley caldera (Figure 3). TheLong Valley caldera also contains anextensive and very active hydrothennalsystem (Bailey, 1987; Lamkin. 1990).Consequently. Long Valley was selectedas the site for a scientific deep drillingproject 10 verify the existence of themagma chamber and-more impor­tantly-to evaluate the feasibility ofextracting energy from it (Goldstein,1988).

CALIFORNIA GEOLOGY APRIL 1991

Photo 2. Road cut in the Bishop Tuff along California State Highway 395 near Toms Place.The basal 15 feet 01 the tull consists 01 air·fall ash and pumice. whereas the overlying ma­terial is ash flow that was presumably deposited as a nuea ardente (Belden and Haus­back. 1990). A series of three clastic dikes cut the Bishop Tull at a steep angle.Phoro by Don Dupras.

a 1.500 square mile area around thecaldera. Intermittent associated volcan­ism continued from 3.2 million yearsago to 800,000 years ago. During thisperiod, a large shallow magma chamberformed beneath Long Valley (Bailey.19871.

Bishop Tuff

About 730.000 years ago a cataclys­mic pyroclastic eruption from the pre­caldera volcano spewed a voluminousrhyolite ash flow sheet and buried anarea greater than 570 square miles (Fig­ure 2). Massive clouds of superheatedgas and pumice swept over surroundingridges that were hundreds of feet higherin elevation than the pre-caldera vol­cano at speeds in excess of 100 milesper hour. Local accumulations of pum­ice and ash reached depths of 4,500feet (Bailey. 1987: Hill and others,1985: Norris and Webb. 1990).

This explosive eruption sent an esti­mated 140 cubic miles of ash into theatmosphere. Remnants of this ash oc­cur as far south as San Diego and as fareast as Washington, D.C (Bailey,1987; Simon. 1983). Following theeruption. the ground surface collapsedalong a series of ring-shaped faults to

form the 2-mile-deep oval depressionof the Long Valley caldera. 11 was anevent of incredible intensity that has notoccurred elsewhere on Earth during his­toric time. Remains of this widespread

pyroclastic unit, known as the BishopTuff. form bold escarpments and otherprominent landscape features in easternCalifornia (Photo 2) (Izelt and others.1988).

Photo 3. Aerial view 01 a porlion 01 the resurgent dome in the long Valley caldera and therig that is currenlly being used to drill the magma energy exploratory well. This drill sitewas chosen on the basis of extensive geophysical. geological. hydrothermal. and seismicinvestigations that indicate a large, shallow magma chamber may exist beneath this resur­gent dome. Apparently driven by shilting magma, the ground level at this drill site rose 2feet in the last eight years. All photos are by John Finger. courtesy of Sandia NarionalLaboratories. unless noted.

Postcaldera Volcanism

Following the eruption of the BishopTuff. residual volcanic activity resumedand fresh magma migrated into the col­lapsed magma chamber. This renewedvolcanism raised a resurgent dome in thecenter of the caldera about 1.500 feetabove the adjacent caldera floor (Photo3). Episodes of eruptive volcanism con'Unued sporadically and the last majoreruption was about 100.000 years ago.The most recent episode of volcanismin the caldera originated from the Mono­lnyo Craters about 500 to 600 yearsago. Since 1980 numerous earthquakesin this area have been accompanied by arise in elevation of the resurgent domeand by spasmodic increases in the activ­ity of boiling hot springs (Bailey. 1982:Norris and Webb. 1990).

Abundant evidence gathered by manyscientists indicates that a major magmabody may exist between 3 to 4.5 milesbeneath the central part of the caldera

88 CALIFORNIA GEOLOGY APRil 1991

Photo 4. The 177-'oot-high Lotlland drilling rig being leasedby Sandia National Laboratories at the exploratory well drillsite. This rig is capable of drilling to 30.000 feet and is one ofthe largest in the world. The rig floor is at the top of lhe stairsto the left. This immense derrick was assembled on site andis made of high-quality steel so that it can lift the 20,000 feetof drill string (the attached drilling pipe that transmits mud androtary power 10 the bottom drill bit).

(Figure 3) (Bailey and others, 1976; Norris and Webb. 1990;Rundle and Hill, 1988). These data are from several sources:(lj there is profuse geothermal activity. such as hot springs.within the Long Valley caldera: (Z) extensive geophysical. seis­mic, and geophysical investigations conducted over the past10 years indicate that an active magma chamber is within afew miles of the surface; (3) measurable vertical uplift of theresurgent dome and seismic activity indicate possible mag­matic migration (Savage and Clark. 1982: Rundle and others.1985; 1986b).

Photo 5. A new 26-inch tungsten carbide drill bit resting on the rigfloor. This roller bit has three cones and sealed bearings. Thecones are studded with numerous teeth that gouge out rock asthe drill pipe turns. Like all drill bits. it contains passages thatpermit drilling fluid 10 exit.

Hot springs, £umaroles, and areas of active hydrothermalalteration are prevalent in many areas within the Long Valleycaldera. The heat source for these features is presumablyfrom a residual magma chamber beneath the resurgent dome.With few exceptions. however. drill holes show that hot wateris confined to relatively shallow aquifers that are less than2.300 feet deep and does not substantially increase in tem­perature with depth (Bailey. 1987: Lamkin. 1990).

LONG VALLEY MAGMA ENERGY EXPLORATORY WELL

Seven years of study by the Department of Energy (DOE)of the near-surface magma body at Kilauea lki lava lake on theIsland of Hawaii indicate that energy extraction from activemagma bodies is feasible (Dunn, 198B). The Magma EnergyExtraction Program of DOE's Geothermal Technology Divi­sion contracted with Sandia National Laboratories to drill a20,000 loot-deep hole very close to the magma chamber.

CALIFORNIA GEOLOGY APRIL 1991

"..

89

Photo 6. Floor crew unscrewing a section of drill pipe to change the drill bit Well drillingis rigorous dirty work requiring good teamwork to avoid serious injury. Dnlling lIuid is com­ing out 01 the pipe. This lIuid, also called "drill mud," is a mixture of clay. water. a weight·ing material (such as barite), and chemical additives. It has three fundamental purposes:(1) to force drill cunings from the bottom or the hole to the surface where they are reomoved. (2) to keep underground formation pressures in check so the hole does not im­plode. and (3) to cool and lubricate the drill bit. Giant pumps circulate cleansed mudthrough the drill string, out the drill bit, and up the outside 01 the drill string to the surface.

natural gas well in Oklahoma, the deep­est well in the United States and one ofthe deepest in the world (Carroll,1989). At intervals throughout thedrilling process, samples will be takenof rock cores and formation flUids;measurements will be made of the vari­ous seismic. electromagnetic, and ther­mal parameters of the country rock(Photos 5-7) (Rundle and others,1986a; 1986b).

After the hole is drilled. boreholegeophysical measurements will providea means to infer deep-seated geologicstructures and rock properties at depthsgreater than those reached by the wellitself.

Project Goals

Plans call for a four-phase drillingprogram to reach 20.000 feet or 932degrees Fahrenheit. whichever comesfirst (Figure 4). The exploratory well isnot attempting to drill into the magma.The primary purpose of this explora­tory drilling program is to determinewhether a magma chamber exists.

The $8 million Long Valley exploratorydrilling project will evaluate the use ofmagma as a high-quality. dean energyalternative to fossil fuels. When com­pleted it will be the deepest well everdrilled into an active caldera system(Lyster. 1989).

The magma exploratory well is lo­cated in the south-central portion of thecaldera directly on top of the active re­surgent dome. a large rounded hill thatis the blistered-up floor of the caldera(Figure 1. Photo 3). Due to recent up­lift of the resurgent dome. the drill siteis 2 leet higher than it was 8 years ago(Lyster. 1989). This uplift may indicatemagma chamber upwelling. A crosssection of Long Valley caldera showingthe underlying magma chamber as in­ferred from numerous geophysical datais shown in FIgure 3 (Rundle and Hill.1988; Rundle and others. 1985).

The deep bore hole project is beingdrilled by a 1n-foot-high rig (Photo 4)that was used to drill a 30.000 foot

Photo 7. Steel 20·inch·diameter casing being hoisted into the derrick. Once a section ofthe hole is drilled and the pipe is removed, casing is lowered into the hote to prevent thehole from caving in. Like drilling pipe. casing is screwed together as the casing string istowered into the hole. The well design at the deep exploratory magma well calls for a se­ries of tive different sized lengths of casing to be cemented into the hole (Figure 4).

90 CALIFORNIA GEOLOGY APRIL t991

FIoure 4 Proposed wei deslQn tor lhe deep magma ellpioralOf)' well The hole WII becased 10 14.000 leet and the last 6.000 leet of hole wil be lett open, Courtesy 01 SandiaNalKXla/laboratones.

Core samples from the first 2.500feet Indicate that the Bishop Tuff isthkker than was expected. The subsur­face roof of this unit displays considerableirregularity, Because this undulated sur­face is too deep to have resulted fromeTosKx'l. it is asswned thaI this featureformed by post-eruplive collapse and re­surgence In contrast to lhe surface lavasthat dominate the sides of the resurgentdome. core samples from Phase I indicatethat an exceptionally tephra-rich eru~

lion occurred after the caldera fonned(Bnger and Eichelberger. 1990: McCon­nel and Eichelberger. 1990).

Phase I Results

Phases III and IV

..

caklera eruptions. Phase I drilling endedin the caldera-forming Bishop Tuff. Thebase of the rhyolite and the top of theBishop Tuff was found at 1.989 feet(Finger and Bc:hefberger. 1990).

Phases III and IV are expected to takemuch longer lhan Phases I and II Atsuch depths the drilling rale Is sIa.wd be­cause of the much increased rock densi­ties Drilling operations are also morelaborious al depths exceeding 1 mileHigh temperature accelerates bit wear.degrades drilling fluids. corrodes the drillstring. and Increases wellbore instability(Boger and Eichelberger. 1990). Chang­ing drill bits and running downhole ge0­

physical studies at 20.000 feet is exhaus­tive work and may take most of a day(Photos 5·7).

Phase II

Phase II is pro,ected to begin in thesummer of 1991 and plans can for drill·ing to 7.500 feet (F19ure 4). In a OO5t­sharing grant. the California EnergyCommission and Mono County will grantSandia National laboratories $12 millionto continue with Phase II; another$300,000 will be granted to initiatePhase IJ1 (lamkin. 1990)

Phase III drilling is designed 10 reacha depth of 14.000 feet. Phase IV planscall for drilling to 20.000 feet or until abottom-hole temperature of 932 degreesFahrenheit is reached. It is hoped thatthis exploratory well will be completedin late 1992 (FIgUre 4).

APRIL 1991CALIFORNIA GEOlOGY

EXPLORATORY WELL DRILLING

The four-phase approach of theMagma Energy Expk>ratory Well drillingproject will allow for ongoing hypothe­Sis testing and flexibility in designing ex­periments (Bgure 4), Data collected ateach stage will be extenslwly evaluated.

Phase I

Phase 1was started in August 1989and was completed in Seplember 1989(F"lgure 4). A drill hole depth of 2.568feet was reached The lNel was coredan additional 118 feet to 2.686 feet.The dnll hole began In a fine-grainedcompacted volcanic ash of rhyoliticcomposition that formed from post-

within the magma or adjacent to it forlong-term experiments A heat ex­changer is a sort of reverse radiator thatuses magma to heat a nuid The super­heated fluid VJOUId be circulated througha secondary system where water VJOUIdtum to steam and drive Industrial tur­bines. The turbines would. in tum. beused to produce electrical power (Chuand others. 1990; Dunn. 1988).

. ~I

ILc or or:e- ~ ll· U-

C- OO ,,-C- PHASE' (tlU'

e-e- lIPHASE II {IOIU'

'C- lJ 1 ,- 11 I ,-

.----- /PHASE 11/ (fo/gO

- I 15,. ' 12 II. ~

-- ·C- · /PHASE IV;'I2'·e- • •I, .

DEPTH CASING SIZE HOLE SlZE

"30t2,0002.500

7.500

WELL DESIGN

5.000

1,500

14,000

20.000'

UTHOlOGY

LAVA, ASH,PIIOIlCe

..."""nH"

lilT. MORR!SOHNElAMORPHOSED

SHALE

SIfRRAHGRANITE

Do.AmhoIe geophysical invesdgalions.which will pr<Mde higher resolutiondata than presently available. will beconducted between each stage of theproject (Dunn. 1988). Evidence thatthe magma chamber exists VJOUId vali­date current geophysical subsurface im­aging techniques.

The k>ng~range plan. once themagma exploratory well is completed.will be to build a nearby power plant toextract energy. A spedally engineeredheal exchanger win be inserted either

Once the exploratory well is drilled.scientists will analyze the data and. de­pending on the results. may drill directlyinto the magma chamber and performenergy extraclion experiments (Chu andothers. 1990; Eichelberger and Dunn.1990) Specially cooled bits \AliI! beused that are similar 10 those used todrill into molten lava in Hawaii wheretemperatures exceeded 1.832 degreesFahrenheit (Lamkin. 1990). When theexistence of the magma body is venfied.$dentists will then eI.'aJuate the magmaresource.

REFERENCESFive separate intrusive episodeswithin the Bishop Tuff were identifiedduring Phase I drilling. The stronglyintrusive nature of the central portion ofthe caldera leads scientists to speculatethat accepted models of the caldera'sstructure may be inaccurate. A muchclearer idea of the caldera's structurewill be resolved with future drilling andsubsequent geophysical measurements(Finger and Eichelberger, 1990;McConnel and Eichelberger, 1990).

CONCLUSIONS

Progress in understanding magmaticprocesses comes not from finding de­finitive answers, but through a processof limiting the range of plausible an­swers and learning to ask more incisivequestions. The fundamental questionthat scientists ask about the Long Valleycaldera is; What is the character of thismagma body? Deep drilling is the onlycurrent direct means of understandingmagma temperature, size, depth. vis­cosity, and compoSition (Eichelbergerand Dunn, 1990). Once the characterof this geologic phenomenon is known.extracting geothermal energy may thenbecome viable.

If the existence and nature of magmaunderlying the caldera are verified bythis drilling program, scientists then in­tend to drill into the magma and em~

place and operate a heat exchangerthere. It will be the first time anyonehas drilled into a major magma body ofthis kind.

Should magma at drillable depths bediscovered beneath the Long Valleycaldera. it could represent an enormousenergy source. Tapping this magmaenergy is technically possible. but theengineering needed to make it a realitypresents an audaCiOUS, but worthwhilechallenge.

ACKNOWLEDGMENTS

Appreciation is extended to DonDupras, DMG geologist, for encourage­ment in researching and writing this ar­ticle; to Steve McNutt. DMG seismolo­gist. for his technical assistance: andJohn Finger, Sandia National laborato­ries. for providing figures and photo­graphs.

Bailey,R.A., 1982, Other potential eruptioncenters in California-long Valley-MonoLake, Coso, and Clear lake volcanofields, in Martin. A.C., and Davis. J.F.,editors, Status of volcanic prediction andemergency response capabilities in Vol­canic hazard zones of California: Cali·fornia Department of Conservation, Divi­sion of Mines and Geology Special Pub·lications 63, p. 17-28.

Bailey, R.A. 1987. long Valley caldera,eastern California in Geological Societyof America centennial field guide-Cor·dilleran section: Decade of North Ameri­can Geology Project, v.l, p. 163-168.

Bailey, A.A., Dalrymple, G.B.• andLanphere. M.A., 1976. Volcanism, struc­ture, and geochronology of Long Valleycaldera, Mono County, California: Jour­nal 01 Geophysical Research. v. 81,p. B725-B744.

Belden K., and Hausback, B.P., 1990. Fieldtrip guidebook. Geology Alumni Asso·ciation. California State University, Sac­ramento, 4th annual field trip, Long Val­ley, California, September 7·9.1990,41 p.

Carroll, G.. 1989. The furnace beneath us:Newsweek, August 28, p. 55.

Chu, T.Y.. Dunn. J.C.• Finger. J.T.. Rundle,J.B., and Wesfrich, H.A., 1990, Themagma energy program: GeothermalResources Council Bulletin. v. 19,February issue, p. 42-52.

Crewsdon. P.A., Martin W.F. Jr,. Taylor.D.L.. and Bakhtar, K., 1991, Magma en­ergy: an evaluation of extracting energyfrom magma resources for electricpower generation: Mine Developmentand Engineering Corporation,Bakersfield. CA. 98 p.

Dunn. J.C., 1988, Status of the magmaenergy project Geothermal ResourcesCouncil Bulletin, v. 17, July issue.p.3·9.

Eichelberger, J.C.. and Dunn. J.C., 1990,Magma energy-what is the potential?:Geothermal Resources Council Bulletin,v. 19. February issue. p. 53-56.

Finger, J.T., and Eichelberger, J.C., 1990.The magma energy exploratory well:Geothermal Resources Council Bulletin,v. 19. February issue, p. 36·41.

Francis, P., 1983, Giant volcanic calderas:Scientific American. v. 248. no. 6,p.60-70.

Francis, p .. and Self. S., 1983, The erup­tion of Krakatau: Scientific American.v. 249, no. 5, p. 172·186.

Goldstein, N.E., 1988, Pre·drilling data re­view and synthesis for the Long Valleycaldera. California: EOS. v. 69. p. 43-45.

Hill, D.P., Bailey. R.A.. and Ryall. A.S.,1985. Active tectonic and magmatic

processes beneath long Valley caldera.eastern California-an overview: Journalof Geophysical Research, v. 90,p. Bl1,111-B11,120.

Izett, GA. Obradovich. J.D., and Mehnert,H. H., 1988, The Bishop ash bed(middle Pleistocene) and some older(Pliocene and Pleistocene) chemicallyand mineralogically similar ash beds inCalifornia. Nevada, and Utah: U.S.Geological Survey Bulletin 1675,38 p.

Lamkin, B., 1990, The hydrogeology andgeothermal resources of Long Valley.Mono County, California in Belden, KK..and Hausback, B.P., editors, Field tripgUidebook, Geology Alumni Association,California State University. Sacramento.4th annuallield trip, Long Valley, Cali·fornia, September 7,9, 1990, p. B1·B15.

Lipman, P.W., Self, S.. and Heiken, G..1984, Introduction to calderas: Journal01 Geophysical Research. v, 89,p. B8219·B8221.

Lyster, D.. 1989. The deep magma well:Geothermal Hot Line. December issue,p.39-41.

McConnel. V.S.. and Eichelberger, J.C.,1990. Initial stratigraphic results fromthe Magma Energy Exploratory Well,long Valley caldera, California: EOS(abstract). v. 71. p. 260.

Norris. R.M, and Webb, A.W.. 1990, Geol·ogy 01 California, second edition: JohnWiley & Sons, 542 p.

Rundle. J.B. and others, 1985, Seismic im­aging in Long Valley. California by sur­face and borehole techniques: an inves­tigation of active tectonics: EOS. v. 66,p.194-201.

Rundle. J.B., Carrigan, C.A., Hardee, H.C.,and Luth. W.C.• 1986a. Deep drilling tothe magmatic environment in LongValley Caldera: EOS, v. 67, p. 490·491.

Rundle, J.B., Carrigan, C.R .. Hardee, H.C.,and luth, W.C.. 1986b. Assessment ofLong Valley as a site for drilling themagmatic environment: Sandia NationalLaboratories Report SAND 85-2356.47 p.

Rundle. J.B.. and Hill, D.P., 1988, The geo­physics of a restless caldera; Long Val­ley, California in Annual review of earthand planetary sciences, v. 16, p. 251­271.

Savage, J.C.. and Clark. M.M., 1982. Mag­matic resurgence in long Valleycaldera. California-possible cause ofthe 1980 Mammoth Lakes earthquakes:Science, v. 217, August 6. p. 531-533.

Simon, C.. 1983, A gianrs troubled sleep:SCience News. v. 124. p. 40·43.

Van Rose, S., and Mercer, Ian. 1986.Volcanoes: Cambridge University Press.38 p.

92 CALIFORNIA GEOLOGY APRIL 1991

Glossary

andesitic: Refers to a volcanic rock intermediate between basalt and rhyolite with achemical composition containing 57-63 percent silica.

clastic dike: An intrusion composed of broken fragments of pre-exisiting rock whichcuts across the structure of the host rock.

fumarole: A vent. usually volcanic. from which gases and vapors are emitted.

nuee ardente: A dense. incandescent "glowing cloud" of hot volcanic ash and gaswhich moves al great speed down the sides of a volcano during an eruption.

pyroclastic: Refers to volcanic rock fragments thai aTe ejected during volcanic erup­tions; pyroclastics may range in size from ash 10 fragments as large as a house.

roof pendant: Remnants of older rock projecting downward inlo an igneous intrusion.

tephra: A general lem lor all pyroclastic rocks ejected from a volcano; sometimesused synonymously with pryroclastics.X

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INDUSTRIAL MINERALS IN CALIFORNIA: EconomicImportance. Present Availability. and Future Development.Reprinted from u.s. Geological Survey Bulletin 1958. Com­piled and edited by Edwin W. Tooker and David J. Beeby.1990. 127 p. $6.00

A basic requirement for meeting the challenge 10 sustaineconomic growth for the expanding population in Californiais to lind and produce essential rock and mineral-resourcematerials (industrial minerals) that will. in part. provide andmaintain the housing. food, transportation. societal infrastruc­tures, and related jobs for an increasingly urbanized Califor­nia. To confront the problem of resource adequacy, the U.S.Geological Survey (USGS) and the Division of Mines and Ge­ology (DMG) jointly sponsored a resources workshop in Ma­rina Del Rey. California on February 15 and 16. 1989. toexplore the industrial-mineral-resource-supply problems

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CALMAT Company's Bissel magnesite mine, Kern County,California. Magnesite was used in the past for refractorybricks. but is now a source of magnesium oxide. Photosfrom DMG Photo File.

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Though relatively unheralded, indus­trial-mineral commodities form the back­bone of our industrialized society, andalthough they lack the glamour of theprecious metals, they are used daily inhugh quantities worth millions of dollars.Of the $2.9 billion worth of nonfuelminerals produced in California in1988. more than 88 percent ($2.5 bil­lion) resulted from the production ofindustrial minerals.

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A

Informal workshop sessions included presentations of in­dustrial-mineraI-resource issues followed by discussion amongthe workshop participants. The participants represent abroad spectrum of interests in California's induslrial-mineralresources and include producers and consultants, Stale andfederal land managers and resource specialists. the CaliforniaLegislature. the Governor's Office of Planning and Research,regional land-use planners. transportation specialists. univer­sity scientific experts. mineral economists and marketing ex­perts, environmental specialists. and the user community.

The workshop sessions were tape-recorded and subse­quently transcribed and edited by the compiler-editors intotheir present form. To preserve the atmosphere and excite­ment of the sessions. editing was minimized. The six infor­mational workshop sessions highlighted (1) the variety ofuses and demand for industrial-mineral resources in Califor­nia; (2) problems of access to lands and permitting for indus­trial-mineral exploration and development; (3) environmentalimpacts of mining and mine reclamation; (4) economic is­sues. such as transportation; (5) information that is availablefrom government agencies. universities. and other organiza­tions to assist both the public and private sectors. and (6)education of the public about the need for critical industrialminerals and for improving the public's image of mining.Recommendations were made for improving the sponsors'program focus and for further collaboration and sharing ofexpertise in solving industrial-mineral-resource problems.

The initial workshop subject was the impact of industrialminerals on the average citizen and how much of these min­erals are required presently. The next questions were wherethe large. but unknown. quantities of these required materialswill come from-whether from domestic or foreign sources­and how they will be produced. Underlying these queries

Zeolite deposit. A. Steelhead Specialty Mineral's Ash Meadowszeolite (clinoptilolite) mine. B. Parent rock is a thick ash-fall tuffthat was altered to zeolite in an alkaline lake. Photos from DMGPhoto File.

Ptizer's Marble Canyon marble deposit. While marbleis used in various fillers and extenders.

were how the sponsors might beller focus their programs ofoutreach to the resource-user constituency; how to bettershare the responsibility for providing various types of infor·mation required by public and private decisionmakers; andhow data users in government agencies. universities, and thepublic at large can increase public awareness about the needfor industrial-mineral resources and. ultimately. help improvethe public's image of the resource industry.

A long-term objective of the workshop was to develop aclear idea of the nature of industrial-mineral'resource prob­lems in California. to identify the USGS and DMG program'matic directions that will help ameliorate these problems. andto fonn a broad coalition of concerned organizations and in­dividuals that will reduce California's anticipated resourcestresses....From the Introduction.X

CALIFORNIA GEOLOGY APRIL 1991 95

SlA'IT OF CAUFORN1AlHE RESOURCES AGENCY

OEPARlMENT OF CONSERVATION

CALIFORNIA GEOLOGYOI'IlSION OF

MINfS AND GfOlOGYP.O. BOX 2980

SACRAMENTO, CAUFORNIA 95812,2980

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ADDRESS CORREOION RfOUESTED

New DirectorDepartment of Conservation

SECOND ClASS POSTAGE PAIDAT SACRAMfNTO, CAUfOll:N1A

Governor Pete Wilson has appointedEdward G, Heidig as Director of

the Department of Conservation. sig­naling a renewed commitment to pro­tect and conservie California's naturalresources. Heidig. 38. most recentlyserved as Legislative Assistant onenvironmental and energy issues inWilson's Washington, D,C. office. Heplayed a leading role in Wilson's effortsto strengthen the Clean Air Act andpromote the use of alternate fuels.

Heidig graduated cum laude with aBachelor of Arts degree from Clare­mont Mens College and earned a JurisDoctorate degree from the PepperdineUniversity School of Law. He began hiscareer as a private land-use attorneyand then became Staff Counsel andChief Administrative officer for theSanta Monica Mountains Conservancy.He also has been a land-use consultant.

The Department of Conservation.which has about 500 employees. con­sists of four Divisions concerned withresource management:

• Division of Mines and Geology(DMG). which develops and dissemi­nates information on mineral resourcesand geologic hazards.

Edward G. Heidig. Director

• Division of Recycling, which en­courages the recycling of beverage con·tainers sold in California.

• Division of Oil and Gas. whichregulates the production of oil. gas. andgeothermal resources-both onshoreand offshore.

• Division of Administration, whichprovides support services and whichencourages the conservation of agricul­tural lands.

Heidig believes that DMG's programsare particularly relevant to GovernorWilson's central theme of encouragingpreventive measures such as those posi­tive actions that society can undertaketo avoid or reduce potential problems.For example. DMG helps balance theneed for preserving important mineraldeposits through classification of min­eral lands while ensuring the sound rec­lamation of mined lands by providingtechnical advice to local governments.

Beginning in July, DMG will signifi­cantly expand its contributions to publicsafety through implementation of thenew Seismic Hazards Mapping Act.Special Studies Zone maps will identifyareas where significant hazards of earth­quake ground failure or ground shakingexist. According to Heidig. the Depart­ment plans to institute a GeographiCInformation System (GIS) so that thisimportant information can be presentedto users in easily updated, computerizedmap formats.

A strong. responsive Department ofConservation serving the resource infor­mation needs of local governments, in­dustry and the public is the new Direc­tor's chief goal. He would welcomecomments concerning the programs ofthe Department:x:

96 CALIFORNIA GEOlOGY APRIL 1991