Sediment transport processesand lateral facies gradientsacross a muddy shelf Examplesfrom the Geneseo Formation ofcentral New York United StatesRyan D Wilson and Juergen Schieber

ABSTRACT

Studying fine-grained siliciclastic deposits of late Middle Devo-nian in the northern Appalachian Basin provides an exquisitenatural laboratory to observe the complex environments inwhich mud can accumulate More detailed correlation andfacies characterization of this succession provide a wealth ofinformation and insight into the diverse transport mechanismsresponsible for distributing clastics hundreds of kilometersaway from a tectonically active source area Commencementof the third tectophase of the Acadian orogeny and a concur-rent transgression is expressed throughout the region throughthe development of a basin-scale unconformity (the TaghanicOnlap) above a shelf collapse (ie Tully Limestone) and wide-spread deposition of organic-matterndashrich mudstones Deposi-tion of the lower Genesee Group is believed to reflect thecoupling of this local expression of a global eustatic highstandevent and contemporaneous cratonic downwarping as a flexuralresponse of the craton to a continentndashmicrocontinent collisionHigh-resolution stratigraphy has allowed differentiation of ge-netically related packages composed of distinct lithofacies withcharacteristic physical biological and chemical attributesThe present paper advances an overview of this detailed in-vestigation based on detailed core measurement and surfacecorrelation to assess the controlling factors on the mid-Devonian stratigraphic fill of the northern Appalachian Basinand demonstrate the distribution in mudstone facies and theirrelation to changing environmental conditions

AUTHORS

Ryan D Wilson ~ Department ofGeological Sciences Indiana University107 South Indiana Ave Bloomington Indiana47405 present address Chevron EnergyTechnology Company 1500 Louisiana StreetHouston Texas 77002 ryanwilsonchevroncom

Ryan D Wilson is a geologist with Chevron(Energy Technology Company) in HoustonTexas His research interests focus onunderstanding the fundamental causes ofvariability in mudstone-dominated systemsthrough the application of sequencestratigraphy subsurface characterizationpetrography and scanning electronmicroscopy and process sedimentology This isconducted through the quantitativereconstruction of depositional environments offine-grained sediments and sedimentary rocksin all settings from deep-sea to swamps andlakes in order to assess hydrocarbon playelement presence quality and distribution Hereceived his PhD and MSc in mudstonesedimentologystratigraphy from IndianaUniversity and his BSc in geology from theUniversity of Cincinnati

Juergen Schieber ~ Department ofGeological Sciences Indiana University107 South Indiana Ave BloomingtonIndiana 47405 jschiebeindianaedu

Juergen Schieber is a specialist on shales He ispublished extensively (117 papers 20guidebook chapters 2 books 251 conferenceabstracts) and is an invited lecturer atuniversities in the United States CanadaEurope and Asia as well as at researchorganizations industry short courses andsymposia His research interests include basinanalysis and sedimentology sedimentology ofshales the genesis of black shales and sedimenthosted mineral deposits evolution of the BeltBasin and the Devonian basins of the easternUnited States geochemistry of sediments andplanetary and sedimentary geologyofMars Heis a member of the science team that currentlyexplores the geology of Gale Crater on Marswith NASArsquos Curiosity rover Juergen SchieberreceivedhisBSc in geology from theUniversityof Tubingen Germany in 1978 and his PhDfrom the University of Oregon in 1985

Copyright copy2017 The American Association of Petroleum Geologists All rights reserved

Manuscript received January 16 2017 final acceptance January 18 2017DOI101306021417DIG17093

AAPG Bulletin v 101 no 4 (April 2017) pp 423ndash431 423

INTRODUCTION

A long history of geological study exists for the Devonianforeland strata of the northern Appalachian Basin representinga global reference section because of the nearly completestratigraphic record with significant continuous sections ex-posed throughout the state Units observed on this trip reflectthe weathering and denudation of a renewed orogen sup-plying fine-grained detritus to a rapidly subsiding fore-land basin At that time an oblique convergence betweenLaurentia and Avalon terranes fostered magmatic arc volca-nism and formation of a retroarc fold and thrust belt(ie Hudson Valley Fold and Thrust Belt) that loaded theeastern edge of the North American craton (Ettensohn 19851987 Faill 1985 Figure 1) This event drastically reshapedthe depositional and biological character of the basin which isexemplified in a transition from platform carbonate depositioninto distal offshore organic-rich facies (ie Tully FormationndashGeneseo Formation) Tectonically induced subsidence wascompounded with a eustatic sea-level rise further supportingregional flooding of the craton and dysoxic to intermittentlyanoxic conditions across the basin Moreover the north-ern Appalachian Basin was situated 30degndash35deg south of theequator (Figure 2) As illustrated in Figure 2 some parts ofLaurentia were emergent whereas other parts were cov-ered by a shallow sea Globally the MiddlendashLate Devonianhas been characterized as being dominated by greenhouseconditions with 4ndash12 times present-day pCO2 (Berner1990)

Changing basinal conditions along with potential globalwarming may have caused what is referred to as the globalTaghanic Bioevent which resulted in the demise of MiddleDevonian taxa worldwide and impactful shifts in trophic andcommunity structure (Johnson 1970 Aboussalam 2003Baird and Brett 2008) As the hinterland was carved anddenuded enhanced delivery of fine-grained detritus andterrestrial-derived nutrients fostered high surface-water algalproductivity and widespread burial of organic carbon (Algeoet al 1995) Drainage of the Acadian terrain fueled deltagrowth and offshore-directed sediment dispersal which isexpressed at aggradational to progradational stacking patternsobserved in the Geneseo Formation The peak of organic-carbon preservation is recognized in basal parts of the Gene-seo Formation which constitute themost distal facies depositedsubsequent to this phase of tectonism Following active thrustloading sediment input eventually outcompetes the rate ofbasin subsidence and the foreland basin fills with clastic sed-iments As a result coarser-grained facies belts migratebasinward

ACKNOWLEDGMENTS

We thank Rene Jonk and Joe MacQuakerfor inviting us to present this researchwhich is ongoing as part of a regionalcharacterization of the Genesee Group inthe northern Appalachian Basin We alsoare thankful to the Indiana University ShaleResearch Consortium (Anadarko ChevronConocoPhillips ExxonMobil Shell andMarathon) Field work and analyticalsupplies were supported through studentresearch grants awarded to Ryan D Wilsonby the Geological Society of AmericaIndiana University Department ofGeological Sciences and AAPG (PittsburghAssociation of Petroleum GeologistsNamed Grant Richard W BeardsleyNamed Grant)

424 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

Stratigraphic Framework

Because of the historic attention awarded to the De-vonian strata of the easternUnitedStates a largenumberof lithostratigraphic chemostratigraphic and bio-stratigraphic studies enabled the development of a fullyintegrated stratigraphic hierarchy (Johnson et al 1985Baird and Brett 1986 2008 House and Kirchgasser1993 Ver Straeten 2004 Brett et al 2011) Inasmuchas extensive surface correlation has resulted in a high-resolution fully integrated stratigraphic framework anissue that persists is the abundance of unit andmember names adopted by various workers

For the purpose of this paper the Geneseo For-mation herein is subdivided into three members (ieLower Geneseo Member Fir Tree Member UpperGeneseo Member Figures 3 4) Locally the LowerGeneseo Member overlies the Tully Formation andwhere the latter is absent its basal contact is markedby a pyritic-phosphatic lag (the Leicester Pyrite Bed)The Fir Tree Member unconformably overlies the

Lower Geneseo and consists of silt-rich calcareousmudstones rich in auloporid tabulate corals ostracodsand small brachiopods The Upper Geneseo displaysdark-gray silty mudstones and muddy siltstones withabundant wavecurrent ripples graded beds and ev-idence of extensive reworking and erosion

Detailed Facies Characterization

Detailing the small-scale variability observed in fine-grained strata is a critical aspect for inferring pastenvironments of deposition There have been sig-nificant advances over the last decade in recognizingpertinent information in terms of physical bedformsand biologic attributes in a stratigraphic context (Lazaret al 2015) Despite these efforts to define amethodicframework to characterize mudstone-rich successionsit can be quite cumbersome and difficult particularlyin outcrop exposures For the lower Genesee succes-sion samples were collected from the field for thin-section preparation as well as polishing hand sam-ples to assist unveiling the small-scale features andlinking with the outcrop expression Throughoutthis succession in central New York nine mudstonefacies were identified and were used to establisha stratigraphic depositional framework (Figure 4)

Mudstone Facies of the Lower GeneseoMember

The Lower Geneseo Member stratigraphically restsabove the Tully Limestone and beneath the Fir TreeMember and represents the initial phases of thrust

Figure 2 Middle Devonianpaleogeographic map modifiedafter Blakey (2005) Global mapzooms into the eastern NorthAmerica during the Middle De-vonian Various structural fea-tures and basins are outlined onthe right Note the continentndashmicrocontinent(s) collision pro-ducing a rotational ldquoscissorlikerdquoclosure and uplift of the AvalonTerrane

Figure 1 Idealized cross section of the Appalachian forelandbasin during the Acadian orogeny Note the collision and sub-duction of Avalonia to Laurentia (North America) creating aretroarc fold and thrust belt (modified from Ver Straeten 2004)

WILSON AND SCHIEBER 425

loading and cratonic downwarping during the thirdphase of the Acadian orogeny Consequently oro-genesis was coupled with a eustatic rise in sea levelresulting in an expansive epicontinental seaway thatcoveredmuch of eastern Laurentia As a result exten-sive depositions of organic-matterndashrich sediments werespread throughout the basin and coeval depositscan be traced to the neighboring basins (ie Illinoisand Michigan basins) Continental flooding in asso-ciation with limited water circulation has been a keyfactor for many depositional models for Devonianorganic-rich mudstones in the Appalachian Basin(Murphy et al 2000 Werne et al 2002 Sagemanet al 2003 Algeo et al 2007)

The most prevalent facies throughout the LowerGeneseoMember is a banded grayish-blackmudstone(BBM) and it manifests as the most organic-richfacies of the succession (Figure 5) The BBM faciesshows meioturbational fabrics and is texturally a fineto medium mudstone with erosional contacts andcurrent-ripple cross-lamination with abundant lami-naset normal grading Many sedimentologists would beinclined to describe this facies as ldquofinely laminatedrdquoldquohomogeneousrdquo or perhaps even ldquomonotonousrdquo Thatbeing said careful petrographic and microscopic in-spection demonstrate that deposition occurred inquite an energetic environment because this faciespreserves many features that indicate tractiontransport and reworking of the seabed Upsectionbasal deposits of the BBM facies grade into dark-graymudstones with an increase in erosional contacts

current- andwave-formed features and bioturbationintensity and diversity (Figure 6)

An interesting facies development throughoutthe Geneseo is the presence of intercalated siltymudstones and muddy siltstones with terrestrial phy-todetritus normal and inverse laminaset grading con-volute bedding as well as current- and wave-formedfeatures indicating event deposition through lateraltransport (Figures 7 8) In outcrop this facies is typi-cally expressed as recessive beds that interrupt theorganic-rich facies of the Lower Geneseo and canbe difficult to sample because of textural integrityStratigraphic correlation can be aided by recogniz-ing carbonate concretion and cemented horizons thatoccur atmultiple levels andmanifest as prominent bedsand ridges in outcrop

Depositional Environment of the GeneseoFormation

Key takeaways from the preceding observations dem-onstrate the infilling of a rapidly subsiding forelandbasin subsequent to a major orogenic event Rejuve-nation of the Acadian terrain as a clastic source sup-plied considerable volumes of fine-grained terrigenoussediment to the deltaic system Although expansion ofthe seaway inundated a vast majority of the continentsediment supply began to overwhelm accommodationas sediments were shed from the hinterland for dis-persal to the shelf and offshore setting

Figure 3 Generalizedchronostratigraphic chart forMiddlendashLate Devonian strataof New York (Wilson andSchieber 2014 2015) TheGeneseo Formation marksthe onset of the third tecto-phase of the Acadian orogenyThrust loading and cratonicdownwarping coincidedwith a major transgression(transgressivendashregressive[T-R] cycle IIa) The GeneseeGroup onlaps the Taghanicdisconformity westwardthus the ages of the onlappingGeneseo and Penn YanShales become progressively younger westward BUF = Buffalo CAN = Canandaigua GEN = Geneseo ITH = Ithaca mbr =member SHB = Sherburne

426 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

Throughmany depositional processes basinwardmigration of the shoreline is indicated via prograda-tional parasequence stacking patterns and a system-atic increase in benthic fauna and wave-formedfeatures upsection The abundance of current- andwave-related features displayed throughout the var-ious facies suggests that deposition did not occur asa result of suspension settling in a stagnant seawayinstead episodic storm events and bottom currentswere the primary agents for sedimentation Organic-richness of the succession particularly in the BBMfacies appears to be a function of primary pro-ductivity as well as decreased clastic input (dilution)following the deepening event that occurred

The Lower Geneseo Member is capped by a se-quence boundary that marks a drastic seaward mi-gration of the shoreline and resulted in deposition ofthe auloporid-rich calcareous silty mudstones of theFir Tree Member (Baird et al 1988) Above the FirTree Member the Upper Geneseo Member (alsoknown as Hubbard Quarry Member) is observed andrepresents a landward migration of the paleoshore-line However tectonically driven sediment supplyoutpaced the change in accommodation and coarser-grained facies of the Sherburne Formation interfingerwith the Upper Geneseo Member (including the FirTree and LodiMembers Baird et al 1988) Thus theUpper Geneseo Member consists of gray silty mud-stones and muddy siltstones reflecting progradationof the Catskill delta and a basinward migration ofcoarser-grained facies belts Internally the UpperGeneseo is composed of gray silty mudstones andmuddy siltstones that show hummocky cross-stratification ripple cross-lamination climbing rip-ples scour surfaces and intense bioturbationDepositionally the Upper Geneseo Member recordsrelatively continuous background sedimentation thatis interrupted by major storms

CONCLUDING REMARKS

The Geneseo Formation of New York representsa complex interplay between tectonically drivenaccommodation and sediment supply and eustaticsea-level rise Throughout the deposition of thismudstone-dominated succession the onset of thethird tectophase of the Acadian orogeny put down-ward pressure on eastern Laurentia The resulting

Figure 4 Lithostratigraphic section of the lower Genesee Groupdrafted from the Lansing drill core Note the vertical facies pro-gression from basal organic-rich mudstones of the Lower Geneseoto organic-lean muddy siltstones reflecting progradation of theCatskill delta BBM = banded black mudstone CSM = calcareoussilty mudstone DGM= dark gray mudstone DSM = dark gray siltymudstone GM = graded gray mudstone GMS = gray muddysiltstone GSBC = strongly bioturbated calcareous mudstoneGSM = gray silty mudstone Ls = limestone Ms =mudstone PBM =pyritic black mudstone Zs = siltstone

WILSON AND SCHIEBER 427

rapid subsidence of the Appalachian foreland basinallowed extensive deposition of organic-rich mud-stones (Ettensohn 1985 1987) During active tec-tonism rapid subsidence of the foreland basinfollowed by periods of stagnation have been keyfactors in depositional models for Devonian blackshales of the eastern United States (Ettensohn et al1988 Brett and Baird 1996) The Geneseo Forma-tion represents the basal black shale of the thirdtectophase of the Acadian orogen and diachronouslyoverlies the Tully Limestone in central New York Inwestern New York this unconformity is marked bythe Leicester Pyrite Bed separating the GeneseoFormation from the underlying Windom Shale inareas where the Tully Limestone has been eroded

Figure 6 (A) Hand sample image (contrast enhanced) of thedark-gray mudstones (DGM) facies showing erosional fea-tures (yellow arrows) current ripples wave ripples witharcuate scalloped topography (white arrows) laminasetgrading disrupted lamina and bioturbationbiodeformationalstructures The DGM facies contains biodeformation (Bd)navichnia traces (Na) and a suite of ichnogenera includingPlanolites (Pl) and Phycosiphon (Ph) The increase in bio-turbation intensity (bioturbation index [BI] = 3ndash4) suggeststhat aerobic conditions prevailed and that the redox boundarywas located deeper below the sediment surface (B) Photo-micrograph showing the DGM facies with several graded bedsAt the base we see planar-laminated to low-angle cross-laminated silt-rich beds that fine upward into sparsely tomoderately bioturbated (BI = 2ndash3) DGM These graded bedsprobably represent distal tempestites where storm wavessuspended and transported shelfal muds offshore (C) Pho-tomicrograph showing the DGM facies with current ripplescontinuous planar silt laminae and amalgamation An in-teresting observation is the bundling of silt-laminae upsectionand an overall coarsening-upward trend which probablyreflects a more proximal environment (coarser clastic influx)with extensive current reworking

Figure 5 (A) Image of polished hand sample (contrast en-hanced) of the banded grayish-black mudstone facies showinga subtle erosional scour infilled with darker muds (arrows) (B)Photomicrograph showing predominant horizontal banding withalternating light and dark layers with subtle erosional scours andcontinuous to discontinuous silt laminae caused by bottom-currentsorting and transport The alternating light and dark layers areinterpreted to reflect fluctuating intensity of bioturbation pro-duced by very shallow burrowing meiofauna and surface-grazingorganisms such as polychaetes and nematodes (C) Overview imageof thin section with continuous to discontinuous planar-parallelsilt laminalaminasets with scoured bases (arrows)

428 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

(Baird et al 1988 Baird and Brett 1991 Brett andBaird 1996)

Water depths were probably greatest during thedeposition of the Lower Geneseo Formation Afterthe major marine transgression that is marked by theLower Geneseo fine-grained sediments were trans-portedwestward via rapid deposition ofmud blanketsfrom density-minimal clastic dilution and high pri-mary productivity possibly aided by minor seaso-nal stratification (Sageman et al 2003) The redox

boundary at the time of deposition was probably justbeneath the sedimentndashwater interface only allowingorganisms to penetrate a few millimeters into thesediment Poorly defined layer boundaries and laminadisruption are suggestive of disturbance of surficial sed-iments by small meiofaunal organisms such as nema-todes polychaete worms and benthic foraminifera Theadditional presence of agglutinated foraminifera andfecal pellets of benthic sediment feeders further con-firms this assessment What emerges is a picture of an

Figure 7 Photograph and detailed measured section of closely stacked hyperpycnal layers consisting of interbedded moderatelybioturbated (BI = 3) silty mudstone and unbioturbated (BI = 0ndash1) muddy siltstones with erosional scours soft-sediment deformationnormal and inverse laminaset grading and current- wave- and combined-flow ripples (see legend) Various trace fossils are presentincluding fugichnia traces (Fu) navichnia traces (Na) Planolites (Pl) and Phycosiphon (Ph) The BI is from Taylor and Goldring (1993) it isshown as a vertical bar graph Ms = mudstone Zs = siltstone

WILSON AND SCHIEBER 429

oxygen-restricted (but generally not anoxic) sea floorthat was intermittently swept by currents that trans-ported mud across the sea floor The general absenceof larger trace fossils suggests that the bottom waterswere generally too low in oxygen to allow colonizationby larger soft-bodied metazoans but had just enoughoxygen to allow small low-oxygenndashtolerant specialiststo thrive

Upsection the Lower Geneseo Member is char-acterized by dark-gray shales with abundant wave andcurrent ripples graded beds and increased abun-dance of macroscopically visible bioturbation Thusthe Lower Geneseo displays an aggradation to pro-gradational succession reflecting increased sedimentsupply upsection and closer proximity to the shorelineupsection Judging from sedimentary features thesediments of the Fir Tree Limestone Member prob-ably reflect initial deposition on a shallower-watermud-dominated shelf Accelerated deepening proba-bly drowned these strata and sediment starvationled to formation of an ldquooverprintedrdquo diagenetic con-cretionary carbonate bed Newly generated accom-modation allowed renewed deposition of organic-richfine-grained clastics represented by the UpperGeneseoMember In central New York dark-gray

silty mudstones grade vertically into dark muddysiltstones as the Sherburne Formation interfingersthe Geneseo Formation This expression representsanother shallowing-upward succession as a result ofprogradation and increasing sediment supply

REFERENCES CITED

Aboussalam Z S 2003 Das ldquoTaghanic-Eventrdquo im hoherenMittel-DevonvonWest-EuropaundMarokkoMunsterscheForschungen zur Geologie und Palaontologie 97 330 p

Algeo T J R A Berner J B Maynard and S E Scheckler1995LateDevonianoceanic anoxic events andbiotic crisesldquoRootedrdquo in the evolution of vascular land plants Geo-logical Society of America Today v 5 no 3 p 45 64ndash66

Algeo T J T W Lyons R C Blakey and D J Over 2007Hydrographic conditions of the Devono-CarboniferousNorth American seaway inferred from sedimentary Mo-TOC relationships Palaeogeography PalaeoclimatologyPalaeoecology v 256 p 204ndash230 doi101016jpalaeo200702035

Baird G C and C E Brett 1986 Erosion on an anaerobicseafloor Significance of reworked pyrite deposits fromthe Devonian of New York state Palaeogeography Pa-laeoclimatology Palaeoecology v 57 no 2ndash4 p 157ndash193doi1010160031-0182(86)90012-X

Figure 8 (A) Photomicro-graphs showing enrichment ofterrestrial phytodetritus in clay-rich laminae of wave-aided hy-perpycnal flows (yellow arrows)(B) Zoom to larger phytodetritus(gt1 mm in diameter) (C) Back-scatter image detailing the cellularstructure of terrestrial phytode-tritus (D) Zoom to other region ofbackscatter image with terrestrialorganic-material detailing cellularstructure as well as enhanceddiagenetic overprint (white pyriteframboids) Det = detector HV =high voltage Mag = magnifica-tion SSD-BSD = solid statebackscattered detector WD =working distance

430 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

Stratigraphic Framework

Because of the historic attention awarded to the De-vonian strata of the easternUnitedStates a largenumberof lithostratigraphic chemostratigraphic and bio-stratigraphic studies enabled the development of a fullyintegrated stratigraphic hierarchy (Johnson et al 1985Baird and Brett 1986 2008 House and Kirchgasser1993 Ver Straeten 2004 Brett et al 2011) Inasmuchas extensive surface correlation has resulted in a high-resolution fully integrated stratigraphic framework anissue that persists is the abundance of unit andmember names adopted by various workers

For the purpose of this paper the Geneseo For-mation herein is subdivided into three members (ieLower Geneseo Member Fir Tree Member UpperGeneseo Member Figures 3 4) Locally the LowerGeneseo Member overlies the Tully Formation andwhere the latter is absent its basal contact is markedby a pyritic-phosphatic lag (the Leicester Pyrite Bed)The Fir Tree Member unconformably overlies the

Lower Geneseo and consists of silt-rich calcareousmudstones rich in auloporid tabulate corals ostracodsand small brachiopods The Upper Geneseo displaysdark-gray silty mudstones and muddy siltstones withabundant wavecurrent ripples graded beds and ev-idence of extensive reworking and erosion

Detailed Facies Characterization

Detailing the small-scale variability observed in fine-grained strata is a critical aspect for inferring pastenvironments of deposition There have been sig-nificant advances over the last decade in recognizingpertinent information in terms of physical bedformsand biologic attributes in a stratigraphic context (Lazaret al 2015) Despite these efforts to define amethodicframework to characterize mudstone-rich successionsit can be quite cumbersome and difficult particularlyin outcrop exposures For the lower Genesee succes-sion samples were collected from the field for thin-section preparation as well as polishing hand sam-ples to assist unveiling the small-scale features andlinking with the outcrop expression Throughoutthis succession in central New York nine mudstonefacies were identified and were used to establisha stratigraphic depositional framework (Figure 4)

Mudstone Facies of the Lower GeneseoMember

The Lower Geneseo Member stratigraphically restsabove the Tully Limestone and beneath the Fir TreeMember and represents the initial phases of thrust

Figure 2 Middle Devonianpaleogeographic map modifiedafter Blakey (2005) Global mapzooms into the eastern NorthAmerica during the Middle De-vonian Various structural fea-tures and basins are outlined onthe right Note the continentndashmicrocontinent(s) collision pro-ducing a rotational ldquoscissorlikerdquoclosure and uplift of the AvalonTerrane

Figure 1 Idealized cross section of the Appalachian forelandbasin during the Acadian orogeny Note the collision and sub-duction of Avalonia to Laurentia (North America) creating aretroarc fold and thrust belt (modified from Ver Straeten 2004)

WILSON AND SCHIEBER 425

loading and cratonic downwarping during the thirdphase of the Acadian orogeny Consequently oro-genesis was coupled with a eustatic rise in sea levelresulting in an expansive epicontinental seaway thatcoveredmuch of eastern Laurentia As a result exten-sive depositions of organic-matterndashrich sediments werespread throughout the basin and coeval depositscan be traced to the neighboring basins (ie Illinoisand Michigan basins) Continental flooding in asso-ciation with limited water circulation has been a keyfactor for many depositional models for Devonianorganic-rich mudstones in the Appalachian Basin(Murphy et al 2000 Werne et al 2002 Sagemanet al 2003 Algeo et al 2007)

The most prevalent facies throughout the LowerGeneseoMember is a banded grayish-blackmudstone(BBM) and it manifests as the most organic-richfacies of the succession (Figure 5) The BBM faciesshows meioturbational fabrics and is texturally a fineto medium mudstone with erosional contacts andcurrent-ripple cross-lamination with abundant lami-naset normal grading Many sedimentologists would beinclined to describe this facies as ldquofinely laminatedrdquoldquohomogeneousrdquo or perhaps even ldquomonotonousrdquo Thatbeing said careful petrographic and microscopic in-spection demonstrate that deposition occurred inquite an energetic environment because this faciespreserves many features that indicate tractiontransport and reworking of the seabed Upsectionbasal deposits of the BBM facies grade into dark-graymudstones with an increase in erosional contacts

current- andwave-formed features and bioturbationintensity and diversity (Figure 6)

An interesting facies development throughoutthe Geneseo is the presence of intercalated siltymudstones and muddy siltstones with terrestrial phy-todetritus normal and inverse laminaset grading con-volute bedding as well as current- and wave-formedfeatures indicating event deposition through lateraltransport (Figures 7 8) In outcrop this facies is typi-cally expressed as recessive beds that interrupt theorganic-rich facies of the Lower Geneseo and canbe difficult to sample because of textural integrityStratigraphic correlation can be aided by recogniz-ing carbonate concretion and cemented horizons thatoccur atmultiple levels andmanifest as prominent bedsand ridges in outcrop

Depositional Environment of the GeneseoFormation

Key takeaways from the preceding observations dem-onstrate the infilling of a rapidly subsiding forelandbasin subsequent to a major orogenic event Rejuve-nation of the Acadian terrain as a clastic source sup-plied considerable volumes of fine-grained terrigenoussediment to the deltaic system Although expansion ofthe seaway inundated a vast majority of the continentsediment supply began to overwhelm accommodationas sediments were shed from the hinterland for dis-persal to the shelf and offshore setting

Figure 3 Generalizedchronostratigraphic chart forMiddlendashLate Devonian strataof New York (Wilson andSchieber 2014 2015) TheGeneseo Formation marksthe onset of the third tecto-phase of the Acadian orogenyThrust loading and cratonicdownwarping coincidedwith a major transgression(transgressivendashregressive[T-R] cycle IIa) The GeneseeGroup onlaps the Taghanicdisconformity westwardthus the ages of the onlappingGeneseo and Penn YanShales become progressively younger westward BUF = Buffalo CAN = Canandaigua GEN = Geneseo ITH = Ithaca mbr =member SHB = Sherburne

426 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

Throughmany depositional processes basinwardmigration of the shoreline is indicated via prograda-tional parasequence stacking patterns and a system-atic increase in benthic fauna and wave-formedfeatures upsection The abundance of current- andwave-related features displayed throughout the var-ious facies suggests that deposition did not occur asa result of suspension settling in a stagnant seawayinstead episodic storm events and bottom currentswere the primary agents for sedimentation Organic-richness of the succession particularly in the BBMfacies appears to be a function of primary pro-ductivity as well as decreased clastic input (dilution)following the deepening event that occurred

The Lower Geneseo Member is capped by a se-quence boundary that marks a drastic seaward mi-gration of the shoreline and resulted in deposition ofthe auloporid-rich calcareous silty mudstones of theFir Tree Member (Baird et al 1988) Above the FirTree Member the Upper Geneseo Member (alsoknown as Hubbard Quarry Member) is observed andrepresents a landward migration of the paleoshore-line However tectonically driven sediment supplyoutpaced the change in accommodation and coarser-grained facies of the Sherburne Formation interfingerwith the Upper Geneseo Member (including the FirTree and LodiMembers Baird et al 1988) Thus theUpper Geneseo Member consists of gray silty mud-stones and muddy siltstones reflecting progradationof the Catskill delta and a basinward migration ofcoarser-grained facies belts Internally the UpperGeneseo is composed of gray silty mudstones andmuddy siltstones that show hummocky cross-stratification ripple cross-lamination climbing rip-ples scour surfaces and intense bioturbationDepositionally the Upper Geneseo Member recordsrelatively continuous background sedimentation thatis interrupted by major storms

CONCLUDING REMARKS

The Geneseo Formation of New York representsa complex interplay between tectonically drivenaccommodation and sediment supply and eustaticsea-level rise Throughout the deposition of thismudstone-dominated succession the onset of thethird tectophase of the Acadian orogeny put down-ward pressure on eastern Laurentia The resulting

Figure 4 Lithostratigraphic section of the lower Genesee Groupdrafted from the Lansing drill core Note the vertical facies pro-gression from basal organic-rich mudstones of the Lower Geneseoto organic-lean muddy siltstones reflecting progradation of theCatskill delta BBM = banded black mudstone CSM = calcareoussilty mudstone DGM= dark gray mudstone DSM = dark gray siltymudstone GM = graded gray mudstone GMS = gray muddysiltstone GSBC = strongly bioturbated calcareous mudstoneGSM = gray silty mudstone Ls = limestone Ms =mudstone PBM =pyritic black mudstone Zs = siltstone

WILSON AND SCHIEBER 427

rapid subsidence of the Appalachian foreland basinallowed extensive deposition of organic-rich mud-stones (Ettensohn 1985 1987) During active tec-tonism rapid subsidence of the foreland basinfollowed by periods of stagnation have been keyfactors in depositional models for Devonian blackshales of the eastern United States (Ettensohn et al1988 Brett and Baird 1996) The Geneseo Forma-tion represents the basal black shale of the thirdtectophase of the Acadian orogen and diachronouslyoverlies the Tully Limestone in central New York Inwestern New York this unconformity is marked bythe Leicester Pyrite Bed separating the GeneseoFormation from the underlying Windom Shale inareas where the Tully Limestone has been eroded

Figure 6 (A) Hand sample image (contrast enhanced) of thedark-gray mudstones (DGM) facies showing erosional fea-tures (yellow arrows) current ripples wave ripples witharcuate scalloped topography (white arrows) laminasetgrading disrupted lamina and bioturbationbiodeformationalstructures The DGM facies contains biodeformation (Bd)navichnia traces (Na) and a suite of ichnogenera includingPlanolites (Pl) and Phycosiphon (Ph) The increase in bio-turbation intensity (bioturbation index [BI] = 3ndash4) suggeststhat aerobic conditions prevailed and that the redox boundarywas located deeper below the sediment surface (B) Photo-micrograph showing the DGM facies with several graded bedsAt the base we see planar-laminated to low-angle cross-laminated silt-rich beds that fine upward into sparsely tomoderately bioturbated (BI = 2ndash3) DGM These graded bedsprobably represent distal tempestites where storm wavessuspended and transported shelfal muds offshore (C) Pho-tomicrograph showing the DGM facies with current ripplescontinuous planar silt laminae and amalgamation An in-teresting observation is the bundling of silt-laminae upsectionand an overall coarsening-upward trend which probablyreflects a more proximal environment (coarser clastic influx)with extensive current reworking

Figure 5 (A) Image of polished hand sample (contrast en-hanced) of the banded grayish-black mudstone facies showinga subtle erosional scour infilled with darker muds (arrows) (B)Photomicrograph showing predominant horizontal banding withalternating light and dark layers with subtle erosional scours andcontinuous to discontinuous silt laminae caused by bottom-currentsorting and transport The alternating light and dark layers areinterpreted to reflect fluctuating intensity of bioturbation pro-duced by very shallow burrowing meiofauna and surface-grazingorganisms such as polychaetes and nematodes (C) Overview imageof thin section with continuous to discontinuous planar-parallelsilt laminalaminasets with scoured bases (arrows)

428 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

(Baird et al 1988 Baird and Brett 1991 Brett andBaird 1996)

Water depths were probably greatest during thedeposition of the Lower Geneseo Formation Afterthe major marine transgression that is marked by theLower Geneseo fine-grained sediments were trans-portedwestward via rapid deposition ofmud blanketsfrom density-minimal clastic dilution and high pri-mary productivity possibly aided by minor seaso-nal stratification (Sageman et al 2003) The redox

boundary at the time of deposition was probably justbeneath the sedimentndashwater interface only allowingorganisms to penetrate a few millimeters into thesediment Poorly defined layer boundaries and laminadisruption are suggestive of disturbance of surficial sed-iments by small meiofaunal organisms such as nema-todes polychaete worms and benthic foraminifera Theadditional presence of agglutinated foraminifera andfecal pellets of benthic sediment feeders further con-firms this assessment What emerges is a picture of an

Figure 7 Photograph and detailed measured section of closely stacked hyperpycnal layers consisting of interbedded moderatelybioturbated (BI = 3) silty mudstone and unbioturbated (BI = 0ndash1) muddy siltstones with erosional scours soft-sediment deformationnormal and inverse laminaset grading and current- wave- and combined-flow ripples (see legend) Various trace fossils are presentincluding fugichnia traces (Fu) navichnia traces (Na) Planolites (Pl) and Phycosiphon (Ph) The BI is from Taylor and Goldring (1993) it isshown as a vertical bar graph Ms = mudstone Zs = siltstone

WILSON AND SCHIEBER 429

oxygen-restricted (but generally not anoxic) sea floorthat was intermittently swept by currents that trans-ported mud across the sea floor The general absenceof larger trace fossils suggests that the bottom waterswere generally too low in oxygen to allow colonizationby larger soft-bodied metazoans but had just enoughoxygen to allow small low-oxygenndashtolerant specialiststo thrive

Upsection the Lower Geneseo Member is char-acterized by dark-gray shales with abundant wave andcurrent ripples graded beds and increased abun-dance of macroscopically visible bioturbation Thusthe Lower Geneseo displays an aggradation to pro-gradational succession reflecting increased sedimentsupply upsection and closer proximity to the shorelineupsection Judging from sedimentary features thesediments of the Fir Tree Limestone Member prob-ably reflect initial deposition on a shallower-watermud-dominated shelf Accelerated deepening proba-bly drowned these strata and sediment starvationled to formation of an ldquooverprintedrdquo diagenetic con-cretionary carbonate bed Newly generated accom-modation allowed renewed deposition of organic-richfine-grained clastics represented by the UpperGeneseoMember In central New York dark-gray

silty mudstones grade vertically into dark muddysiltstones as the Sherburne Formation interfingersthe Geneseo Formation This expression representsanother shallowing-upward succession as a result ofprogradation and increasing sediment supply

REFERENCES CITED

Aboussalam Z S 2003 Das ldquoTaghanic-Eventrdquo im hoherenMittel-DevonvonWest-EuropaundMarokkoMunsterscheForschungen zur Geologie und Palaontologie 97 330 p

Algeo T J R A Berner J B Maynard and S E Scheckler1995LateDevonianoceanic anoxic events andbiotic crisesldquoRootedrdquo in the evolution of vascular land plants Geo-logical Society of America Today v 5 no 3 p 45 64ndash66

Algeo T J T W Lyons R C Blakey and D J Over 2007Hydrographic conditions of the Devono-CarboniferousNorth American seaway inferred from sedimentary Mo-TOC relationships Palaeogeography PalaeoclimatologyPalaeoecology v 256 p 204ndash230 doi101016jpalaeo200702035

Baird G C and C E Brett 1986 Erosion on an anaerobicseafloor Significance of reworked pyrite deposits fromthe Devonian of New York state Palaeogeography Pa-laeoclimatology Palaeoecology v 57 no 2ndash4 p 157ndash193doi1010160031-0182(86)90012-X

Figure 8 (A) Photomicro-graphs showing enrichment ofterrestrial phytodetritus in clay-rich laminae of wave-aided hy-perpycnal flows (yellow arrows)(B) Zoom to larger phytodetritus(gt1 mm in diameter) (C) Back-scatter image detailing the cellularstructure of terrestrial phytode-tritus (D) Zoom to other region ofbackscatter image with terrestrialorganic-material detailing cellularstructure as well as enhanceddiagenetic overprint (white pyriteframboids) Det = detector HV =high voltage Mag = magnifica-tion SSD-BSD = solid statebackscattered detector WD =working distance

430 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

loading and cratonic downwarping during the thirdphase of the Acadian orogeny Consequently oro-genesis was coupled with a eustatic rise in sea levelresulting in an expansive epicontinental seaway thatcoveredmuch of eastern Laurentia As a result exten-sive depositions of organic-matterndashrich sediments werespread throughout the basin and coeval depositscan be traced to the neighboring basins (ie Illinoisand Michigan basins) Continental flooding in asso-ciation with limited water circulation has been a keyfactor for many depositional models for Devonianorganic-rich mudstones in the Appalachian Basin(Murphy et al 2000 Werne et al 2002 Sagemanet al 2003 Algeo et al 2007)

The most prevalent facies throughout the LowerGeneseoMember is a banded grayish-blackmudstone(BBM) and it manifests as the most organic-richfacies of the succession (Figure 5) The BBM faciesshows meioturbational fabrics and is texturally a fineto medium mudstone with erosional contacts andcurrent-ripple cross-lamination with abundant lami-naset normal grading Many sedimentologists would beinclined to describe this facies as ldquofinely laminatedrdquoldquohomogeneousrdquo or perhaps even ldquomonotonousrdquo Thatbeing said careful petrographic and microscopic in-spection demonstrate that deposition occurred inquite an energetic environment because this faciespreserves many features that indicate tractiontransport and reworking of the seabed Upsectionbasal deposits of the BBM facies grade into dark-graymudstones with an increase in erosional contacts

current- andwave-formed features and bioturbationintensity and diversity (Figure 6)

An interesting facies development throughoutthe Geneseo is the presence of intercalated siltymudstones and muddy siltstones with terrestrial phy-todetritus normal and inverse laminaset grading con-volute bedding as well as current- and wave-formedfeatures indicating event deposition through lateraltransport (Figures 7 8) In outcrop this facies is typi-cally expressed as recessive beds that interrupt theorganic-rich facies of the Lower Geneseo and canbe difficult to sample because of textural integrityStratigraphic correlation can be aided by recogniz-ing carbonate concretion and cemented horizons thatoccur atmultiple levels andmanifest as prominent bedsand ridges in outcrop

Depositional Environment of the GeneseoFormation

Key takeaways from the preceding observations dem-onstrate the infilling of a rapidly subsiding forelandbasin subsequent to a major orogenic event Rejuve-nation of the Acadian terrain as a clastic source sup-plied considerable volumes of fine-grained terrigenoussediment to the deltaic system Although expansion ofthe seaway inundated a vast majority of the continentsediment supply began to overwhelm accommodationas sediments were shed from the hinterland for dis-persal to the shelf and offshore setting

Figure 3 Generalizedchronostratigraphic chart forMiddlendashLate Devonian strataof New York (Wilson andSchieber 2014 2015) TheGeneseo Formation marksthe onset of the third tecto-phase of the Acadian orogenyThrust loading and cratonicdownwarping coincidedwith a major transgression(transgressivendashregressive[T-R] cycle IIa) The GeneseeGroup onlaps the Taghanicdisconformity westwardthus the ages of the onlappingGeneseo and Penn YanShales become progressively younger westward BUF = Buffalo CAN = Canandaigua GEN = Geneseo ITH = Ithaca mbr =member SHB = Sherburne

426 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

Throughmany depositional processes basinwardmigration of the shoreline is indicated via prograda-tional parasequence stacking patterns and a system-atic increase in benthic fauna and wave-formedfeatures upsection The abundance of current- andwave-related features displayed throughout the var-ious facies suggests that deposition did not occur asa result of suspension settling in a stagnant seawayinstead episodic storm events and bottom currentswere the primary agents for sedimentation Organic-richness of the succession particularly in the BBMfacies appears to be a function of primary pro-ductivity as well as decreased clastic input (dilution)following the deepening event that occurred

The Lower Geneseo Member is capped by a se-quence boundary that marks a drastic seaward mi-gration of the shoreline and resulted in deposition ofthe auloporid-rich calcareous silty mudstones of theFir Tree Member (Baird et al 1988) Above the FirTree Member the Upper Geneseo Member (alsoknown as Hubbard Quarry Member) is observed andrepresents a landward migration of the paleoshore-line However tectonically driven sediment supplyoutpaced the change in accommodation and coarser-grained facies of the Sherburne Formation interfingerwith the Upper Geneseo Member (including the FirTree and LodiMembers Baird et al 1988) Thus theUpper Geneseo Member consists of gray silty mud-stones and muddy siltstones reflecting progradationof the Catskill delta and a basinward migration ofcoarser-grained facies belts Internally the UpperGeneseo is composed of gray silty mudstones andmuddy siltstones that show hummocky cross-stratification ripple cross-lamination climbing rip-ples scour surfaces and intense bioturbationDepositionally the Upper Geneseo Member recordsrelatively continuous background sedimentation thatis interrupted by major storms

CONCLUDING REMARKS

The Geneseo Formation of New York representsa complex interplay between tectonically drivenaccommodation and sediment supply and eustaticsea-level rise Throughout the deposition of thismudstone-dominated succession the onset of thethird tectophase of the Acadian orogeny put down-ward pressure on eastern Laurentia The resulting

Figure 4 Lithostratigraphic section of the lower Genesee Groupdrafted from the Lansing drill core Note the vertical facies pro-gression from basal organic-rich mudstones of the Lower Geneseoto organic-lean muddy siltstones reflecting progradation of theCatskill delta BBM = banded black mudstone CSM = calcareoussilty mudstone DGM= dark gray mudstone DSM = dark gray siltymudstone GM = graded gray mudstone GMS = gray muddysiltstone GSBC = strongly bioturbated calcareous mudstoneGSM = gray silty mudstone Ls = limestone Ms =mudstone PBM =pyritic black mudstone Zs = siltstone

WILSON AND SCHIEBER 427

rapid subsidence of the Appalachian foreland basinallowed extensive deposition of organic-rich mud-stones (Ettensohn 1985 1987) During active tec-tonism rapid subsidence of the foreland basinfollowed by periods of stagnation have been keyfactors in depositional models for Devonian blackshales of the eastern United States (Ettensohn et al1988 Brett and Baird 1996) The Geneseo Forma-tion represents the basal black shale of the thirdtectophase of the Acadian orogen and diachronouslyoverlies the Tully Limestone in central New York Inwestern New York this unconformity is marked bythe Leicester Pyrite Bed separating the GeneseoFormation from the underlying Windom Shale inareas where the Tully Limestone has been eroded

Figure 6 (A) Hand sample image (contrast enhanced) of thedark-gray mudstones (DGM) facies showing erosional fea-tures (yellow arrows) current ripples wave ripples witharcuate scalloped topography (white arrows) laminasetgrading disrupted lamina and bioturbationbiodeformationalstructures The DGM facies contains biodeformation (Bd)navichnia traces (Na) and a suite of ichnogenera includingPlanolites (Pl) and Phycosiphon (Ph) The increase in bio-turbation intensity (bioturbation index [BI] = 3ndash4) suggeststhat aerobic conditions prevailed and that the redox boundarywas located deeper below the sediment surface (B) Photo-micrograph showing the DGM facies with several graded bedsAt the base we see planar-laminated to low-angle cross-laminated silt-rich beds that fine upward into sparsely tomoderately bioturbated (BI = 2ndash3) DGM These graded bedsprobably represent distal tempestites where storm wavessuspended and transported shelfal muds offshore (C) Pho-tomicrograph showing the DGM facies with current ripplescontinuous planar silt laminae and amalgamation An in-teresting observation is the bundling of silt-laminae upsectionand an overall coarsening-upward trend which probablyreflects a more proximal environment (coarser clastic influx)with extensive current reworking

Figure 5 (A) Image of polished hand sample (contrast en-hanced) of the banded grayish-black mudstone facies showinga subtle erosional scour infilled with darker muds (arrows) (B)Photomicrograph showing predominant horizontal banding withalternating light and dark layers with subtle erosional scours andcontinuous to discontinuous silt laminae caused by bottom-currentsorting and transport The alternating light and dark layers areinterpreted to reflect fluctuating intensity of bioturbation pro-duced by very shallow burrowing meiofauna and surface-grazingorganisms such as polychaetes and nematodes (C) Overview imageof thin section with continuous to discontinuous planar-parallelsilt laminalaminasets with scoured bases (arrows)

428 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

(Baird et al 1988 Baird and Brett 1991 Brett andBaird 1996)

Water depths were probably greatest during thedeposition of the Lower Geneseo Formation Afterthe major marine transgression that is marked by theLower Geneseo fine-grained sediments were trans-portedwestward via rapid deposition ofmud blanketsfrom density-minimal clastic dilution and high pri-mary productivity possibly aided by minor seaso-nal stratification (Sageman et al 2003) The redox

boundary at the time of deposition was probably justbeneath the sedimentndashwater interface only allowingorganisms to penetrate a few millimeters into thesediment Poorly defined layer boundaries and laminadisruption are suggestive of disturbance of surficial sed-iments by small meiofaunal organisms such as nema-todes polychaete worms and benthic foraminifera Theadditional presence of agglutinated foraminifera andfecal pellets of benthic sediment feeders further con-firms this assessment What emerges is a picture of an

Figure 7 Photograph and detailed measured section of closely stacked hyperpycnal layers consisting of interbedded moderatelybioturbated (BI = 3) silty mudstone and unbioturbated (BI = 0ndash1) muddy siltstones with erosional scours soft-sediment deformationnormal and inverse laminaset grading and current- wave- and combined-flow ripples (see legend) Various trace fossils are presentincluding fugichnia traces (Fu) navichnia traces (Na) Planolites (Pl) and Phycosiphon (Ph) The BI is from Taylor and Goldring (1993) it isshown as a vertical bar graph Ms = mudstone Zs = siltstone

WILSON AND SCHIEBER 429

oxygen-restricted (but generally not anoxic) sea floorthat was intermittently swept by currents that trans-ported mud across the sea floor The general absenceof larger trace fossils suggests that the bottom waterswere generally too low in oxygen to allow colonizationby larger soft-bodied metazoans but had just enoughoxygen to allow small low-oxygenndashtolerant specialiststo thrive

Upsection the Lower Geneseo Member is char-acterized by dark-gray shales with abundant wave andcurrent ripples graded beds and increased abun-dance of macroscopically visible bioturbation Thusthe Lower Geneseo displays an aggradation to pro-gradational succession reflecting increased sedimentsupply upsection and closer proximity to the shorelineupsection Judging from sedimentary features thesediments of the Fir Tree Limestone Member prob-ably reflect initial deposition on a shallower-watermud-dominated shelf Accelerated deepening proba-bly drowned these strata and sediment starvationled to formation of an ldquooverprintedrdquo diagenetic con-cretionary carbonate bed Newly generated accom-modation allowed renewed deposition of organic-richfine-grained clastics represented by the UpperGeneseoMember In central New York dark-gray

silty mudstones grade vertically into dark muddysiltstones as the Sherburne Formation interfingersthe Geneseo Formation This expression representsanother shallowing-upward succession as a result ofprogradation and increasing sediment supply

REFERENCES CITED

Aboussalam Z S 2003 Das ldquoTaghanic-Eventrdquo im hoherenMittel-DevonvonWest-EuropaundMarokkoMunsterscheForschungen zur Geologie und Palaontologie 97 330 p

Algeo T J R A Berner J B Maynard and S E Scheckler1995LateDevonianoceanic anoxic events andbiotic crisesldquoRootedrdquo in the evolution of vascular land plants Geo-logical Society of America Today v 5 no 3 p 45 64ndash66

Algeo T J T W Lyons R C Blakey and D J Over 2007Hydrographic conditions of the Devono-CarboniferousNorth American seaway inferred from sedimentary Mo-TOC relationships Palaeogeography PalaeoclimatologyPalaeoecology v 256 p 204ndash230 doi101016jpalaeo200702035

Baird G C and C E Brett 1986 Erosion on an anaerobicseafloor Significance of reworked pyrite deposits fromthe Devonian of New York state Palaeogeography Pa-laeoclimatology Palaeoecology v 57 no 2ndash4 p 157ndash193doi1010160031-0182(86)90012-X

Figure 8 (A) Photomicro-graphs showing enrichment ofterrestrial phytodetritus in clay-rich laminae of wave-aided hy-perpycnal flows (yellow arrows)(B) Zoom to larger phytodetritus(gt1 mm in diameter) (C) Back-scatter image detailing the cellularstructure of terrestrial phytode-tritus (D) Zoom to other region ofbackscatter image with terrestrialorganic-material detailing cellularstructure as well as enhanceddiagenetic overprint (white pyriteframboids) Det = detector HV =high voltage Mag = magnifica-tion SSD-BSD = solid statebackscattered detector WD =working distance

430 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

Throughmany depositional processes basinwardmigration of the shoreline is indicated via prograda-tional parasequence stacking patterns and a system-atic increase in benthic fauna and wave-formedfeatures upsection The abundance of current- andwave-related features displayed throughout the var-ious facies suggests that deposition did not occur asa result of suspension settling in a stagnant seawayinstead episodic storm events and bottom currentswere the primary agents for sedimentation Organic-richness of the succession particularly in the BBMfacies appears to be a function of primary pro-ductivity as well as decreased clastic input (dilution)following the deepening event that occurred

The Lower Geneseo Member is capped by a se-quence boundary that marks a drastic seaward mi-gration of the shoreline and resulted in deposition ofthe auloporid-rich calcareous silty mudstones of theFir Tree Member (Baird et al 1988) Above the FirTree Member the Upper Geneseo Member (alsoknown as Hubbard Quarry Member) is observed andrepresents a landward migration of the paleoshore-line However tectonically driven sediment supplyoutpaced the change in accommodation and coarser-grained facies of the Sherburne Formation interfingerwith the Upper Geneseo Member (including the FirTree and LodiMembers Baird et al 1988) Thus theUpper Geneseo Member consists of gray silty mud-stones and muddy siltstones reflecting progradationof the Catskill delta and a basinward migration ofcoarser-grained facies belts Internally the UpperGeneseo is composed of gray silty mudstones andmuddy siltstones that show hummocky cross-stratification ripple cross-lamination climbing rip-ples scour surfaces and intense bioturbationDepositionally the Upper Geneseo Member recordsrelatively continuous background sedimentation thatis interrupted by major storms

CONCLUDING REMARKS

The Geneseo Formation of New York representsa complex interplay between tectonically drivenaccommodation and sediment supply and eustaticsea-level rise Throughout the deposition of thismudstone-dominated succession the onset of thethird tectophase of the Acadian orogeny put down-ward pressure on eastern Laurentia The resulting

Figure 4 Lithostratigraphic section of the lower Genesee Groupdrafted from the Lansing drill core Note the vertical facies pro-gression from basal organic-rich mudstones of the Lower Geneseoto organic-lean muddy siltstones reflecting progradation of theCatskill delta BBM = banded black mudstone CSM = calcareoussilty mudstone DGM= dark gray mudstone DSM = dark gray siltymudstone GM = graded gray mudstone GMS = gray muddysiltstone GSBC = strongly bioturbated calcareous mudstoneGSM = gray silty mudstone Ls = limestone Ms =mudstone PBM =pyritic black mudstone Zs = siltstone

WILSON AND SCHIEBER 427

rapid subsidence of the Appalachian foreland basinallowed extensive deposition of organic-rich mud-stones (Ettensohn 1985 1987) During active tec-tonism rapid subsidence of the foreland basinfollowed by periods of stagnation have been keyfactors in depositional models for Devonian blackshales of the eastern United States (Ettensohn et al1988 Brett and Baird 1996) The Geneseo Forma-tion represents the basal black shale of the thirdtectophase of the Acadian orogen and diachronouslyoverlies the Tully Limestone in central New York Inwestern New York this unconformity is marked bythe Leicester Pyrite Bed separating the GeneseoFormation from the underlying Windom Shale inareas where the Tully Limestone has been eroded

Figure 6 (A) Hand sample image (contrast enhanced) of thedark-gray mudstones (DGM) facies showing erosional fea-tures (yellow arrows) current ripples wave ripples witharcuate scalloped topography (white arrows) laminasetgrading disrupted lamina and bioturbationbiodeformationalstructures The DGM facies contains biodeformation (Bd)navichnia traces (Na) and a suite of ichnogenera includingPlanolites (Pl) and Phycosiphon (Ph) The increase in bio-turbation intensity (bioturbation index [BI] = 3ndash4) suggeststhat aerobic conditions prevailed and that the redox boundarywas located deeper below the sediment surface (B) Photo-micrograph showing the DGM facies with several graded bedsAt the base we see planar-laminated to low-angle cross-laminated silt-rich beds that fine upward into sparsely tomoderately bioturbated (BI = 2ndash3) DGM These graded bedsprobably represent distal tempestites where storm wavessuspended and transported shelfal muds offshore (C) Pho-tomicrograph showing the DGM facies with current ripplescontinuous planar silt laminae and amalgamation An in-teresting observation is the bundling of silt-laminae upsectionand an overall coarsening-upward trend which probablyreflects a more proximal environment (coarser clastic influx)with extensive current reworking

Figure 5 (A) Image of polished hand sample (contrast en-hanced) of the banded grayish-black mudstone facies showinga subtle erosional scour infilled with darker muds (arrows) (B)Photomicrograph showing predominant horizontal banding withalternating light and dark layers with subtle erosional scours andcontinuous to discontinuous silt laminae caused by bottom-currentsorting and transport The alternating light and dark layers areinterpreted to reflect fluctuating intensity of bioturbation pro-duced by very shallow burrowing meiofauna and surface-grazingorganisms such as polychaetes and nematodes (C) Overview imageof thin section with continuous to discontinuous planar-parallelsilt laminalaminasets with scoured bases (arrows)

428 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

(Baird et al 1988 Baird and Brett 1991 Brett andBaird 1996)

Water depths were probably greatest during thedeposition of the Lower Geneseo Formation Afterthe major marine transgression that is marked by theLower Geneseo fine-grained sediments were trans-portedwestward via rapid deposition ofmud blanketsfrom density-minimal clastic dilution and high pri-mary productivity possibly aided by minor seaso-nal stratification (Sageman et al 2003) The redox

boundary at the time of deposition was probably justbeneath the sedimentndashwater interface only allowingorganisms to penetrate a few millimeters into thesediment Poorly defined layer boundaries and laminadisruption are suggestive of disturbance of surficial sed-iments by small meiofaunal organisms such as nema-todes polychaete worms and benthic foraminifera Theadditional presence of agglutinated foraminifera andfecal pellets of benthic sediment feeders further con-firms this assessment What emerges is a picture of an

Figure 7 Photograph and detailed measured section of closely stacked hyperpycnal layers consisting of interbedded moderatelybioturbated (BI = 3) silty mudstone and unbioturbated (BI = 0ndash1) muddy siltstones with erosional scours soft-sediment deformationnormal and inverse laminaset grading and current- wave- and combined-flow ripples (see legend) Various trace fossils are presentincluding fugichnia traces (Fu) navichnia traces (Na) Planolites (Pl) and Phycosiphon (Ph) The BI is from Taylor and Goldring (1993) it isshown as a vertical bar graph Ms = mudstone Zs = siltstone

WILSON AND SCHIEBER 429

oxygen-restricted (but generally not anoxic) sea floorthat was intermittently swept by currents that trans-ported mud across the sea floor The general absenceof larger trace fossils suggests that the bottom waterswere generally too low in oxygen to allow colonizationby larger soft-bodied metazoans but had just enoughoxygen to allow small low-oxygenndashtolerant specialiststo thrive

Upsection the Lower Geneseo Member is char-acterized by dark-gray shales with abundant wave andcurrent ripples graded beds and increased abun-dance of macroscopically visible bioturbation Thusthe Lower Geneseo displays an aggradation to pro-gradational succession reflecting increased sedimentsupply upsection and closer proximity to the shorelineupsection Judging from sedimentary features thesediments of the Fir Tree Limestone Member prob-ably reflect initial deposition on a shallower-watermud-dominated shelf Accelerated deepening proba-bly drowned these strata and sediment starvationled to formation of an ldquooverprintedrdquo diagenetic con-cretionary carbonate bed Newly generated accom-modation allowed renewed deposition of organic-richfine-grained clastics represented by the UpperGeneseoMember In central New York dark-gray

silty mudstones grade vertically into dark muddysiltstones as the Sherburne Formation interfingersthe Geneseo Formation This expression representsanother shallowing-upward succession as a result ofprogradation and increasing sediment supply

REFERENCES CITED

Aboussalam Z S 2003 Das ldquoTaghanic-Eventrdquo im hoherenMittel-DevonvonWest-EuropaundMarokkoMunsterscheForschungen zur Geologie und Palaontologie 97 330 p

Algeo T J R A Berner J B Maynard and S E Scheckler1995LateDevonianoceanic anoxic events andbiotic crisesldquoRootedrdquo in the evolution of vascular land plants Geo-logical Society of America Today v 5 no 3 p 45 64ndash66

Algeo T J T W Lyons R C Blakey and D J Over 2007Hydrographic conditions of the Devono-CarboniferousNorth American seaway inferred from sedimentary Mo-TOC relationships Palaeogeography PalaeoclimatologyPalaeoecology v 256 p 204ndash230 doi101016jpalaeo200702035

Baird G C and C E Brett 1986 Erosion on an anaerobicseafloor Significance of reworked pyrite deposits fromthe Devonian of New York state Palaeogeography Pa-laeoclimatology Palaeoecology v 57 no 2ndash4 p 157ndash193doi1010160031-0182(86)90012-X

Figure 8 (A) Photomicro-graphs showing enrichment ofterrestrial phytodetritus in clay-rich laminae of wave-aided hy-perpycnal flows (yellow arrows)(B) Zoom to larger phytodetritus(gt1 mm in diameter) (C) Back-scatter image detailing the cellularstructure of terrestrial phytode-tritus (D) Zoom to other region ofbackscatter image with terrestrialorganic-material detailing cellularstructure as well as enhanceddiagenetic overprint (white pyriteframboids) Det = detector HV =high voltage Mag = magnifica-tion SSD-BSD = solid statebackscattered detector WD =working distance

430 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

rapid subsidence of the Appalachian foreland basinallowed extensive deposition of organic-rich mud-stones (Ettensohn 1985 1987) During active tec-tonism rapid subsidence of the foreland basinfollowed by periods of stagnation have been keyfactors in depositional models for Devonian blackshales of the eastern United States (Ettensohn et al1988 Brett and Baird 1996) The Geneseo Forma-tion represents the basal black shale of the thirdtectophase of the Acadian orogen and diachronouslyoverlies the Tully Limestone in central New York Inwestern New York this unconformity is marked bythe Leicester Pyrite Bed separating the GeneseoFormation from the underlying Windom Shale inareas where the Tully Limestone has been eroded

Figure 6 (A) Hand sample image (contrast enhanced) of thedark-gray mudstones (DGM) facies showing erosional fea-tures (yellow arrows) current ripples wave ripples witharcuate scalloped topography (white arrows) laminasetgrading disrupted lamina and bioturbationbiodeformationalstructures The DGM facies contains biodeformation (Bd)navichnia traces (Na) and a suite of ichnogenera includingPlanolites (Pl) and Phycosiphon (Ph) The increase in bio-turbation intensity (bioturbation index [BI] = 3ndash4) suggeststhat aerobic conditions prevailed and that the redox boundarywas located deeper below the sediment surface (B) Photo-micrograph showing the DGM facies with several graded bedsAt the base we see planar-laminated to low-angle cross-laminated silt-rich beds that fine upward into sparsely tomoderately bioturbated (BI = 2ndash3) DGM These graded bedsprobably represent distal tempestites where storm wavessuspended and transported shelfal muds offshore (C) Pho-tomicrograph showing the DGM facies with current ripplescontinuous planar silt laminae and amalgamation An in-teresting observation is the bundling of silt-laminae upsectionand an overall coarsening-upward trend which probablyreflects a more proximal environment (coarser clastic influx)with extensive current reworking

Figure 5 (A) Image of polished hand sample (contrast en-hanced) of the banded grayish-black mudstone facies showinga subtle erosional scour infilled with darker muds (arrows) (B)Photomicrograph showing predominant horizontal banding withalternating light and dark layers with subtle erosional scours andcontinuous to discontinuous silt laminae caused by bottom-currentsorting and transport The alternating light and dark layers areinterpreted to reflect fluctuating intensity of bioturbation pro-duced by very shallow burrowing meiofauna and surface-grazingorganisms such as polychaetes and nematodes (C) Overview imageof thin section with continuous to discontinuous planar-parallelsilt laminalaminasets with scoured bases (arrows)

428 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

(Baird et al 1988 Baird and Brett 1991 Brett andBaird 1996)

Water depths were probably greatest during thedeposition of the Lower Geneseo Formation Afterthe major marine transgression that is marked by theLower Geneseo fine-grained sediments were trans-portedwestward via rapid deposition ofmud blanketsfrom density-minimal clastic dilution and high pri-mary productivity possibly aided by minor seaso-nal stratification (Sageman et al 2003) The redox

boundary at the time of deposition was probably justbeneath the sedimentndashwater interface only allowingorganisms to penetrate a few millimeters into thesediment Poorly defined layer boundaries and laminadisruption are suggestive of disturbance of surficial sed-iments by small meiofaunal organisms such as nema-todes polychaete worms and benthic foraminifera Theadditional presence of agglutinated foraminifera andfecal pellets of benthic sediment feeders further con-firms this assessment What emerges is a picture of an

Figure 7 Photograph and detailed measured section of closely stacked hyperpycnal layers consisting of interbedded moderatelybioturbated (BI = 3) silty mudstone and unbioturbated (BI = 0ndash1) muddy siltstones with erosional scours soft-sediment deformationnormal and inverse laminaset grading and current- wave- and combined-flow ripples (see legend) Various trace fossils are presentincluding fugichnia traces (Fu) navichnia traces (Na) Planolites (Pl) and Phycosiphon (Ph) The BI is from Taylor and Goldring (1993) it isshown as a vertical bar graph Ms = mudstone Zs = siltstone

WILSON AND SCHIEBER 429

oxygen-restricted (but generally not anoxic) sea floorthat was intermittently swept by currents that trans-ported mud across the sea floor The general absenceof larger trace fossils suggests that the bottom waterswere generally too low in oxygen to allow colonizationby larger soft-bodied metazoans but had just enoughoxygen to allow small low-oxygenndashtolerant specialiststo thrive

Upsection the Lower Geneseo Member is char-acterized by dark-gray shales with abundant wave andcurrent ripples graded beds and increased abun-dance of macroscopically visible bioturbation Thusthe Lower Geneseo displays an aggradation to pro-gradational succession reflecting increased sedimentsupply upsection and closer proximity to the shorelineupsection Judging from sedimentary features thesediments of the Fir Tree Limestone Member prob-ably reflect initial deposition on a shallower-watermud-dominated shelf Accelerated deepening proba-bly drowned these strata and sediment starvationled to formation of an ldquooverprintedrdquo diagenetic con-cretionary carbonate bed Newly generated accom-modation allowed renewed deposition of organic-richfine-grained clastics represented by the UpperGeneseoMember In central New York dark-gray

silty mudstones grade vertically into dark muddysiltstones as the Sherburne Formation interfingersthe Geneseo Formation This expression representsanother shallowing-upward succession as a result ofprogradation and increasing sediment supply

REFERENCES CITED

Aboussalam Z S 2003 Das ldquoTaghanic-Eventrdquo im hoherenMittel-DevonvonWest-EuropaundMarokkoMunsterscheForschungen zur Geologie und Palaontologie 97 330 p

Algeo T J R A Berner J B Maynard and S E Scheckler1995LateDevonianoceanic anoxic events andbiotic crisesldquoRootedrdquo in the evolution of vascular land plants Geo-logical Society of America Today v 5 no 3 p 45 64ndash66

Algeo T J T W Lyons R C Blakey and D J Over 2007Hydrographic conditions of the Devono-CarboniferousNorth American seaway inferred from sedimentary Mo-TOC relationships Palaeogeography PalaeoclimatologyPalaeoecology v 256 p 204ndash230 doi101016jpalaeo200702035

Baird G C and C E Brett 1986 Erosion on an anaerobicseafloor Significance of reworked pyrite deposits fromthe Devonian of New York state Palaeogeography Pa-laeoclimatology Palaeoecology v 57 no 2ndash4 p 157ndash193doi1010160031-0182(86)90012-X

Figure 8 (A) Photomicro-graphs showing enrichment ofterrestrial phytodetritus in clay-rich laminae of wave-aided hy-perpycnal flows (yellow arrows)(B) Zoom to larger phytodetritus(gt1 mm in diameter) (C) Back-scatter image detailing the cellularstructure of terrestrial phytode-tritus (D) Zoom to other region ofbackscatter image with terrestrialorganic-material detailing cellularstructure as well as enhanceddiagenetic overprint (white pyriteframboids) Det = detector HV =high voltage Mag = magnifica-tion SSD-BSD = solid statebackscattered detector WD =working distance

430 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

(Baird et al 1988 Baird and Brett 1991 Brett andBaird 1996)

Water depths were probably greatest during thedeposition of the Lower Geneseo Formation Afterthe major marine transgression that is marked by theLower Geneseo fine-grained sediments were trans-portedwestward via rapid deposition ofmud blanketsfrom density-minimal clastic dilution and high pri-mary productivity possibly aided by minor seaso-nal stratification (Sageman et al 2003) The redox

boundary at the time of deposition was probably justbeneath the sedimentndashwater interface only allowingorganisms to penetrate a few millimeters into thesediment Poorly defined layer boundaries and laminadisruption are suggestive of disturbance of surficial sed-iments by small meiofaunal organisms such as nema-todes polychaete worms and benthic foraminifera Theadditional presence of agglutinated foraminifera andfecal pellets of benthic sediment feeders further con-firms this assessment What emerges is a picture of an

Figure 7 Photograph and detailed measured section of closely stacked hyperpycnal layers consisting of interbedded moderatelybioturbated (BI = 3) silty mudstone and unbioturbated (BI = 0ndash1) muddy siltstones with erosional scours soft-sediment deformationnormal and inverse laminaset grading and current- wave- and combined-flow ripples (see legend) Various trace fossils are presentincluding fugichnia traces (Fu) navichnia traces (Na) Planolites (Pl) and Phycosiphon (Ph) The BI is from Taylor and Goldring (1993) it isshown as a vertical bar graph Ms = mudstone Zs = siltstone

WILSON AND SCHIEBER 429

oxygen-restricted (but generally not anoxic) sea floorthat was intermittently swept by currents that trans-ported mud across the sea floor The general absenceof larger trace fossils suggests that the bottom waterswere generally too low in oxygen to allow colonizationby larger soft-bodied metazoans but had just enoughoxygen to allow small low-oxygenndashtolerant specialiststo thrive

Upsection the Lower Geneseo Member is char-acterized by dark-gray shales with abundant wave andcurrent ripples graded beds and increased abun-dance of macroscopically visible bioturbation Thusthe Lower Geneseo displays an aggradation to pro-gradational succession reflecting increased sedimentsupply upsection and closer proximity to the shorelineupsection Judging from sedimentary features thesediments of the Fir Tree Limestone Member prob-ably reflect initial deposition on a shallower-watermud-dominated shelf Accelerated deepening proba-bly drowned these strata and sediment starvationled to formation of an ldquooverprintedrdquo diagenetic con-cretionary carbonate bed Newly generated accom-modation allowed renewed deposition of organic-richfine-grained clastics represented by the UpperGeneseoMember In central New York dark-gray

silty mudstones grade vertically into dark muddysiltstones as the Sherburne Formation interfingersthe Geneseo Formation This expression representsanother shallowing-upward succession as a result ofprogradation and increasing sediment supply

REFERENCES CITED

Aboussalam Z S 2003 Das ldquoTaghanic-Eventrdquo im hoherenMittel-DevonvonWest-EuropaundMarokkoMunsterscheForschungen zur Geologie und Palaontologie 97 330 p

Algeo T J R A Berner J B Maynard and S E Scheckler1995LateDevonianoceanic anoxic events andbiotic crisesldquoRootedrdquo in the evolution of vascular land plants Geo-logical Society of America Today v 5 no 3 p 45 64ndash66

Algeo T J T W Lyons R C Blakey and D J Over 2007Hydrographic conditions of the Devono-CarboniferousNorth American seaway inferred from sedimentary Mo-TOC relationships Palaeogeography PalaeoclimatologyPalaeoecology v 256 p 204ndash230 doi101016jpalaeo200702035

Baird G C and C E Brett 1986 Erosion on an anaerobicseafloor Significance of reworked pyrite deposits fromthe Devonian of New York state Palaeogeography Pa-laeoclimatology Palaeoecology v 57 no 2ndash4 p 157ndash193doi1010160031-0182(86)90012-X

Figure 8 (A) Photomicro-graphs showing enrichment ofterrestrial phytodetritus in clay-rich laminae of wave-aided hy-perpycnal flows (yellow arrows)(B) Zoom to larger phytodetritus(gt1 mm in diameter) (C) Back-scatter image detailing the cellularstructure of terrestrial phytode-tritus (D) Zoom to other region ofbackscatter image with terrestrialorganic-material detailing cellularstructure as well as enhanceddiagenetic overprint (white pyriteframboids) Det = detector HV =high voltage Mag = magnifica-tion SSD-BSD = solid statebackscattered detector WD =working distance

430 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

oxygen-restricted (but generally not anoxic) sea floorthat was intermittently swept by currents that trans-ported mud across the sea floor The general absenceof larger trace fossils suggests that the bottom waterswere generally too low in oxygen to allow colonizationby larger soft-bodied metazoans but had just enoughoxygen to allow small low-oxygenndashtolerant specialiststo thrive

Upsection the Lower Geneseo Member is char-acterized by dark-gray shales with abundant wave andcurrent ripples graded beds and increased abun-dance of macroscopically visible bioturbation Thusthe Lower Geneseo displays an aggradation to pro-gradational succession reflecting increased sedimentsupply upsection and closer proximity to the shorelineupsection Judging from sedimentary features thesediments of the Fir Tree Limestone Member prob-ably reflect initial deposition on a shallower-watermud-dominated shelf Accelerated deepening proba-bly drowned these strata and sediment starvationled to formation of an ldquooverprintedrdquo diagenetic con-cretionary carbonate bed Newly generated accom-modation allowed renewed deposition of organic-richfine-grained clastics represented by the UpperGeneseoMember In central New York dark-gray

silty mudstones grade vertically into dark muddysiltstones as the Sherburne Formation interfingersthe Geneseo Formation This expression representsanother shallowing-upward succession as a result ofprogradation and increasing sediment supply

REFERENCES CITED

Aboussalam Z S 2003 Das ldquoTaghanic-Eventrdquo im hoherenMittel-DevonvonWest-EuropaundMarokkoMunsterscheForschungen zur Geologie und Palaontologie 97 330 p

Algeo T J R A Berner J B Maynard and S E Scheckler1995LateDevonianoceanic anoxic events andbiotic crisesldquoRootedrdquo in the evolution of vascular land plants Geo-logical Society of America Today v 5 no 3 p 45 64ndash66

Algeo T J T W Lyons R C Blakey and D J Over 2007Hydrographic conditions of the Devono-CarboniferousNorth American seaway inferred from sedimentary Mo-TOC relationships Palaeogeography PalaeoclimatologyPalaeoecology v 256 p 204ndash230 doi101016jpalaeo200702035

Baird G C and C E Brett 1986 Erosion on an anaerobicseafloor Significance of reworked pyrite deposits fromthe Devonian of New York state Palaeogeography Pa-laeoclimatology Palaeoecology v 57 no 2ndash4 p 157ndash193doi1010160031-0182(86)90012-X

Figure 8 (A) Photomicro-graphs showing enrichment ofterrestrial phytodetritus in clay-rich laminae of wave-aided hy-perpycnal flows (yellow arrows)(B) Zoom to larger phytodetritus(gt1 mm in diameter) (C) Back-scatter image detailing the cellularstructure of terrestrial phytode-tritus (D) Zoom to other region ofbackscatter image with terrestrialorganic-material detailing cellularstructure as well as enhanceddiagenetic overprint (white pyriteframboids) Det = detector HV =high voltage Mag = magnifica-tion SSD-BSD = solid statebackscattered detector WD =working distance

430 Sediment Transport Processes and Lateral Facies Gradients across a Muddy Shelf

Baird G C and C E Brett 1991 Submarine erosion on theanoxic sea floor Stratinomic palaeoenvironmental andtemporal significance of reworked pyrite bone de-posits in R V Tyson and T H Pearson eds Modernand ancient continental shelf anoxia Geological So-ciety London Special Publications 1991 v 58 no 1p 233ndash257 doi101144GSLSP19910580116

Baird G C and C E Brett 2008 Late Givetian Taghanicbioevents in New York New discoveries and questionsBulletin of Geosciences v 83 no 4 p 357ndash370

BairdG C C E Brett andW T Kirchgasser 1988 Genesisof black shale-roofed discontinuities in the DevonianGenesee Formation western New York State CalgaryAlberta Canada Canadian Society of PetroleumGeologistsMemoir 14 p 357ndash375

Berner R A 1990 Atmospheric carbon dioxide levels overPhanerozoic time Science v 249 no 4975 p 1382ndash1386doi101126science24949751382

Blakey R 2005 North American paleogeographic mapsMiddle Devonian (385 Ma) Paleogeography and geo-logic evolution of North America accessed January 12015 httpjanuccnauedurcb7namD385jpg

Brett C E and G C Baird 1996 Middle Devonian sedi-mentary cycles and sequences in the northern Appala-chian Basin in B J Witzke G A Ludvigson and J Dayeds Paleozoic sequence stratigraphy views from theNorth American Craton Geological Society of AmericaSpecial Papers 1996 v 306 p 213ndash241 doi1011300-8137-2306-X213

Brett C E G C Baird A J Bartholomew M K DeSantisand C A Ver Straeten 2011 Sequence stratigraphy anda revised sea-level curve for the Middle Devonian ofeastern North America Palaeogeography Palaeo-climatology Palaeoecology v 304 no 1ndash2 p 21ndash53doi101016jpalaeo201010009

Ettensohn F R 1985 Controls on development of CatskillDelta complex basin-facies in D L Woodrow andW D Sevon eds The Catskill Delta Boulder Colo-rado Geological Society of America Special Papers1985 v 201 p 65ndash78 doi101130SPE201-p65

Ettensohn F R 1987 Rates of relative plate motion duringthe Acadian Orogeny based on the spatial distributionof black shales Journal of Geology v 95 no 4p 572ndash582 doi101086629150

Ettensohn F R M L Miller S B Dillman T D ElamK L Geller D R Swager G Markowitz R D Woockand L S Barron 1988 Characterization and implica-tions of theDevonian-Mississippian black-shale sequenceeastern and central Kentucky USA Pycnoclines trans-gression regression and tectonism MemoirmdashCanadianSociety of Petroleum Geologists v 14 p 323ndash345

Faill R T 1985 TheAcadian orogeny and theCatskill Deltain D L Woodrow and W D Sevon eds The CatskillDelta Boulder Colorado Geological Society of AmericaSpecial Paper 1985 v 201 p 15ndash38 doi101130SPE201-p15

House M R and W T Kirchgasser 1993 Devoniangoniatite biostratigraphy and timing of facies movements

in the Frasnian of eastern North America inE A Hailwood and R B Kidd eds High resolutionstratigraphy Geological Society London SpecialPublications 1993 v 70 p 267ndash292 doi101144GSLSP19930700119

Johnson J G 1970 Taghanic onlap and the end of NorthAmerican Devonian provinciality Geological Society ofAmerica Bulletin v 81 no 7 p 2077ndash2106 doi1011300016-7606(1970)81[2077TOATEO]20CO2

Johnson J G G Klapper and C A Sandberg 1985Devonian eustatic fluctuations in Euramerica GeologicalSociety ofAmerica Bulletin v 96 no 5 p 567ndash587 doi1011300016-7606(1985)96lt567DEFIEgt20CO2

Lazar O R K M Bohacs J H S Macquaker J Schieberand T M Demko 2015 Capturing key attributes offine-grained sedimentary rocks in outcrops cores andthin sections Nomenclature and description guidelinesJournal of Sedimentary Research v 85 no 3 p 230ndash246doi102110jsr201511

Murphy A E B B Sageman D J Hollander T W Lyonsand C E Brett 2000 Black shale deposition and faunaloverturn in the Devonian Appalachian basin ClasticStarvation seasonal water-column mixing and efficientbiolimiting nutrient cycling Paleoceanography v 15no 3 p 280ndash291 doi1010291999PA000445

Sageman B B A E Murphy J P Werne C A VerStraeten D J Hollander and TW Lyons 2003 A taleof shales The relative roles of production decompositionand dilution in the accumulation of organic-rich strataMiddle-Upper Devonian Appalachian basin ChemicalGeology v 195 p 229ndash273 doi101016S0009-2541(02)00397-2

Taylor AM andRGoldring 1993Description and analysisof bioturbation and ichnofabric Journal of the Geo-logical Society v 150 no 1 p 141ndash148 doi101144gsjgs15010141

Ver Straeten C A 2004 K-bentonites volcanic ash pres-ervation and implications for Early to Middle Devonianvolcanism in theAcadian orogen easternNorthAmericaGeological Society of America Bulletin v 116 no 3ndash4p 474ndash489 doi101130B252441

Werne J P B B Sageman TW Lyons andD J Hollander2002 An integrated assessment of a ldquotype euxinicrdquo de-posit Evidence for multiple controls on black shale de-position in the middle Devonian Oatka Creek formationAmerican Journal of Science v 302 p 110ndash143 doi102475ajs3022110

Wilson R D and J Schieber 2014 Muddy prodeltaic hy-perpycnites in the lower Genesee Group of central NewYork USA Implications for mud transport in epiconti-nental seas Journal of Sedimentary Research v 84no 10 p 866ndash874 doi102110jsr201470

Wilson R D and J Schieber 2015 Sedimentary facies anddepositional environment of the Middle DevonianGeneseo Formation of New York USA Journal ofSedimentary Research v 85 no 11 p 1393ndash1415 doi102110jsr201588

WILSON AND SCHIEBER 431