chondrites isp. indicating late paleozoic atmospheric anoxia in …€¦ · plant fossils (figure...

Research ArticleChondrites isp Indicating Late Paleozoic Atmospheric Anoxiain Eastern Peninsular India

Biplab Bhattacharya1 and Sudipto Banerjee2

1 Department of Earth Sciences Indian Institute of Technology Roorkee Roorkee Uttarakhand 247667 India2Department of Geology Hooghly Mohsin College Chinsurah Hooghly West Bengal 712101 India

Correspondence should be addressed to Biplab Bhattacharya bbgeofesiitracin

Received 29 August 2013 Accepted 17 November 2013 Published 30 January 2014

Academic Editors U Tinivella and G Ventura

Copyright copy 2014 B Bhattacharya and S Banerjee This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Rhythmic sandstone-mudstone-coal succession of the Barakar Formation (early Permian) manifests a transition from lowerbraided-fluvial to upper tide-wave influenced estuarine setting Monospecific assemblage of marine trace fossil Chondrites ispin contemporaneous claystone beds in the upper Barakar succession from two Gondwana basins (namely the Raniganj Basin andthe Talchir Basin) in eastern peninsular India signifies predominant marine incursion during end early Permian MonospecificChondrites ichnoassemblage in different sedimentary horizons in geographically wide apart (sim400 km) areas demarcates multipleshort-spanned phases of anoxia in eastern India Such anoxia is interpreted as intermittent falls in oxygen level in an overalldecreasing atmospheric oxygenation within the late Paleozoic global oxygen-carbon dioxide fluctuations

1 Introduction

Trace fossils provide signatures of animal responses to variousecological controls including salinity and its fluctuationssedimentation rate oxygenation availability of food andtemperature Oxygen deficiency is common in deep quietwater environments where fine-grained sediments accumu-late slowly In shallower marginal marine conditions atmo-spheric oxygen content regionally controls the availability ofoxygen near the sediment-water interface Besides decom-position of large quantities of terrigenous organic detritusin wave-dominated estuaries may cause localized loweringof oxygen levels near the sediment-water interface [1] Lowoxygen concentration leads to substantial reduction in thesize of the trace fossils and their diversity [2] accompaniedby dominance of deposit-feeding burrows that maintain anopen conduit to the sediment-water interface [3] Tracefossil assemblage found in such settings includes ChondritesZoophycos Teichichnus and Trichichnus [2ndash4] Monospecificassemblages of Chondrites suggest poorly oxygenated bottomwaters [5] and are considered to be associated with prolificmarine conditions of deposition [2 3] The tracemaker ofChondritesmay be able to live in the aerobicanoxic interface

as a chemosymbiotic organism that pumps methane andhydrogen sulphide from the sediments [6]

The present paper reports the occurrence of Chondritesisp from the sedimentary successions of the early Per-mian Barakar Formation (in lower Gondwana Supergroup)exposed along the Kudaposi Nala section in the Talchir Basinand the Khudia Nala section in the Raniganj Basin easternpeninsular India Geographic distance between these twoareas is sim400 km This paper describes the occurrence ofdifferent ichnospecies of Chondrites from two widely apartGondwana basins and correlates that with the fluctuations ofatmospheric oxygen level during the late Paleozoic period

2 Geological Background

Barakar Formation (early Permian) within the Gondwanasedimentary succession is the main coal-producing horizonin Indian Subcontinent Earlier studies recorded a braided-meandering fluvial depositional system with peat-formingmires in the low-lying marshy floodplains that producedthick succession of sandstone-shale-coal cyclothems withinthe Barakar Formation [7] Recent sedimentological anal-yses from multiple Gondwana basisn of India suggested

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 434672 9 pageshttpdxdoiorg1011552014434672

2 The Scientific World Journal

strong influence of marine wave and tide on fluvial sedi-mentation during the deposition of middle-upper Barakarsuccession [8ndash10] indicating a fluvio-marine interactivedeltaicestuarine depositional settingTheBarakar Formationin the Raniganj Basin in the Koel-Damodar Valley and theTalchir Basin in the Mahanadi Valley (Figure 1) comprisesof thick sandstone-shale-coal deposits (Figure 2) manifestingsimilar depositional history The lower parts of the sedimen-tary successions in both the basins bear thick coal seams andrepresent braided-fluvial depositional setting (Figure 2)

The studied rocks preserved in both the Kudaposi Nalasection Talchir Basin and the Khudia Nala section Rani-ganj Basin (Figure 1) represent part of the upper Barakarsedimentary succession (Figures 2 and 3)The upper Barakarsedimentary successions of both the Damodar Valley and theMahanadi Valley have been assigned the age of Kungurian(post-Artinskian) with an approximate time frame of 278ndash271Ma [11] The studied rocks are characterized by thick-bedded (1ndash25m thickness) coarse-grained trough cross-stratified to plane-laminated sandstone facies (Figures 4(a)and 4(b)) overlain by cm thin sandstone-siltstone-claystonealternations facies (Figures 5(a) and 5(b)) Thickness of thesandstone-siltstone-claystone alternation facies varies from15m to 43m The sandstone beds within this facies arecharacterized by wave ripples and wave-modified ripplestidal bundles represented by mud-draped foresets climbingripples flaser beddings bidirectional ripples mutually oppo-site cross-strata sets vertical and lateral accretion of cross-strata sets with prominent reactivation surfaces and so forthEach sandstone bed grades upward to a siltstoneclaystoneThe claystone beds are occasionally very thick (thickness1ndash18m) and are characterized by abundant Chondrites ispon the bedding plane The sandstonesiltstone-claystoneheteroliths that underlie and overlie such thick claystonebeds are often characterized by sparse to abundant tracefossil associations dominantly Planolites isp Thalassinoidesisp and Paleophycus isp along with abundant plant fossilsThe successions show coarsening upward trend with gradualincrease in the deposition of sandstone towards top andfinally overlain by a thick-bedded trough cross-stratifiedcoarse-grained sandstone facies

The sedimentary facies architecture closely resemblesthose described from Barakar sedimentary succession of theSatpura Basin and the Raniganj Basin respectively [9 10]The sedimentation patterns changed from a basal braidedchannel to an uppermeandering channel system where rapidmigration of the channels and lateral accretioncoalescingof bars led to deposition of thick trough cross-stratified toplane laminated sandstone [8] Open marine tide and waveinfluences producedmultiple fining upward successions withcharacteristic sedimentary features and indicate episodicdrowning of the fluvial channels by marine water [10]Dominant fining-upward succession indicates oversteppingoverbank levees within a meandering fluvial-marine interac-tive estuarine setting [12 13] A coarsening-upward succes-sion comprising of coarse-grained channel-filling sandstonefacies overlies this succession indicating progradation of themeandering channel system over the estuarine deposits

3 Ichnogenus Chondrites Sternberg

Chondrites Sternberg is considered as an infaunal deposit-feeding system [14] It comprises a regularly branching tunnelsystem consisting of a small number of master shafts opento the surface which ramify at depth to form a dendriticnetwork [14ndash17] In the present paper we describe fourdifferent species of Chondrites from the Barakar FormationnamelyChondrites patulus (fromKudaposi Nala)Chondritestargionni (from both Kudaposi Nala and Khudia Nala)Chondrites affinis (from both Kudaposi Nala and KhudiaNala) and Chondrites recurvus (from Khudia Nala) In boththe study sections all the ichnoforms are hosted in fine-grained massive claystone mostly preserved as epichnialsandsilt-filled ridges on the claystone bedding surfaces Thefollowing is a description of all the ichnospecies recordedfrom the two areas under study

31 Ichnospecies Chondrites patulus (Figures 6(a) and 6(b))These are small straight unlined branching burrow systempreserved on the claystone bedding surfaces These ichno-forms show filling by fine-grained sandstonesiltstone andcharacteristically lack spreiten laminae Offshoots branch outfrom the main stem on both sides making obtuse anglewith the stem Individual branches are 025 to 03 cm wideand 12 cm in length Offshoots do not show any furtherbranching

32 Ichnospecies Chondrites targionii (Figures 6(b) and 6(c))This ichnospecies is represented by straight to dendriticunlined smooth walled burrow system with few branchespreserved on the claystone bedding surface Traces are par-allel to bedding surface and radiate at an angle varying fromlow to high angle Secondary branching is absent Lengthof the branches varies between 12 and 15 cm and width upto 022 cm Burrow fills are commonly coarser-grained sed-iments with respect to the host sediments Spreiten lamellaeare characteristically absent

33 Ichnospecies Chondrites affinis (Figures 6(a) 6(b) and6(c)) These are represented by relatively larger epireliefbedding parallel concave tubes These are preserved withinclaystone as straight to curved sandsiltstone ridges withlocally preserved spreiten lamellaeThe tubes are unlined andrarely show branching Main stem is 41ndash65 cm in length and025 cm wide with the branches varying in length between04ndash08 cm and 025 cm in width Secondary branching isabsent The tubes locally overly other such tubes

34 Ichnospecies Chondrites recurvus (Figures 6(a) and 6(c))These ichnoforms are represented by short curved epirelieftraces Branching intensity is relatively high with respectto other ichnoforms in the study area The branches arepeculiarly curved following the main stem Length of themain stem is approximately 25 cm whereas the branches areup to 04 cm in length Locally these traces are not clear dueto poor preservation of the off-suits

The Scientific World Journal 3

Calcutta

0 100 300 500

(km)

RaniganjBasin

TalchirBasin

26∘

26∘

86∘

86∘

94∘

94∘

Peninsular Gondwana Basins

(a)

Talchir FormationKarharbari FormationBarakar FormationBarren measures formationRaniganjKamthi Formation

Basement gneissgranulitesUnconformity

Unconformity

PrecambrianLate Carboniferous

Early Permian

Middle PermianUpper Permian

KhudiaNala

F

F

F FF

F

F

F F

FF

F

0 5 Barakar R

86∘40

998400

Damodar R

(km)

N Barakar

23∘

50998400

Low

er G

ondw

ana

supe

rgro

up

(b)

21∘

05998400

Dahibar

Anuli R

N

Gouduni R

Kudaposi R

84∘54

998400



Unconformity


Early Permian


Low

er G

ondw

ana

supe

rgro

up

2km

(c)

Figure 1 (a) Map of eastern India showing the distribution of the Gondwana Basins Note the location of the Raniganj Basin and the TalchirBasin (b) Geological map of the north-western part of the Raniganj Basin showing the distribution of different lithounits (c) Detailedgeological map of the central part of the Talchir Basin showing the distribution of different lithounits The legend shows the ages of thelithounits Study areas are shown by rectangles in both the maps ((b) and (c))


PebbleSandMud

F MC0

10

20

(m)

Coal

Study section

SandstoneMudstoneCoalTrough cross-stratification

Channel form

Pebble layerHummocky cross-stratificationCurrent ripple cross-laminationWave ripple cross-laminationFlat-topped wave rippleSoft sediment deformation structuresBioturbationPlant fossils

(Figure 3(a))

(a)

Coal

(m)

0

20

PebbleSandMud

FMC

Coal

Study section

SandstoneMudstone

Trough cross-stratification

Channel form


(Figure 3(b))

(b)

Figure 2 Generalized sedimentary logs of the Barakar Formation in (a) Raniganj Basin and (b) Talchir BasinThe study sections are markedand are detailed in Figure 3(a) (Khudia Nala) nad Figure 3(b) (Kudaposi Nala) respectively


lowast

0

5

10

15

20

25

30

(m)

Lower and middle Barakar succession

lowast

Sandstone

Siltstone

Claystone

Current ripple

Wave rippleClimbing ripple


Plane lamination

Monospecific assemblage of Chondrites isp

Soft-sediment deformation structures Thalassinoides-Paleophycus-Planolitestrace fossil assemblage

(a) Khudia Nala

lowast


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination


Thalassinoides-Paleophycus-Planolitestrace fossil assemblage

0

5

10

15

20

25

30

(m)

Soft-sediment deformation structures

(b) Kudaposi Nala

Figure 3 Vertical sedimentary logs of the upper Barakar succession in (a) Khudia Nala Raniganj Basin and (b) Kudaposi Nala TalchirBasin Note the occurrence of the claystone beds containing monospecific assemblage of Chondrites isp


(a) (b)

Figure 4 (a) Trough cross-stratified sandstone facies within Barakar Formation Khudia Nala Ranjiganj Basin Length of the hammer is305 cm (b) Amalgamated sandstone beds showing multiple sets of planar and trough cross-stratification Barakar Formation KudaposiNala Talchir Basin Length of the pen is 146 cm

(a) (b)

Figure 5 (a) The sandstone-siltstone-claystone facies exposed in the Kudaposi Nala Talchir Basin (b) Details of the sandstone-siltstone-claystone facies exposed in the Khudia Nala Raniganj Basin Diameter of the coin is 23 cm

Ca

Cr

Cp

(a)

Ct

Ca

Cp

(b)

Ca

Cr

Ct

(c)

Figure 6 Claystone bedding surfaces within upper Barakar succession showing associations of Chondrites patulus (Cp) Chondrites targionii(Ct) Chondrites affinis (Ca) and Chondrites recurvus (Cr) (a) and (b) are from Kudaposi Nala Talchir Basin and (c) is from Khudia NalaRaniganj Basin Diameter of the coin is 23 cm in (a) and (b) and 25 cm in (c)


4 Discussion

The ichnoform Chondrites is considered as an indicator of-poor oxygenation (dysaerobic-exaerobic) conditions [5 18ndash22] and has been described from several late Paleozoic sedi-mentary successions including shallow marine argillitesstorm-led sediments and flysch deposits These three-dim-ensional branched straight to curved dendritic burrow sys-tems are considered as deposit-feeding traces [14]Thesewerereinterpreted as complex agrichnial traces based on theirchemosymbiotic activitieswithin predominantly anoxic envi-ronment [5] Polychaete worms are considered as the mostlikely producers of Chondrites as they can tolerate oxygen-deficient conditions [23ndash26] Chondrites-like deposit-feedingburrows with open connections to the sediment-waterinterface are typical of facies associated with extremely lowoxygen levels in interstitial and bottom waters [3]

Estuaries are characterized by numerous ecologicalstresses on potential trace-making organisms including fluc-tuating salinity levels high water turbidity rapid sedimenta-tion rates and low oxygen levels in bottom and interstitialwaters These paleoecological factors control the trace fossilassemblage in estuaries Trophic generalists are able to adapttheir feeding strategy in response to changing environmentalcontrols under brackish-water settings producing complexburrow morphologies characteristic of marine ecologicalsystem [27] This is the case observed in the estuarinedeposits of the late Paleozoic upper Barakar Formationeastern India Thick claystone beds within the sandstone-siltstone-claystone alternation facies represent deposition inlow-lying swampy interdistributary plains This claystonebears themonospecific assemblage ofChondrites ichnoformsThe overlying and underlying sequence of thin-beddedsandstone-mudstone heteroliths formed by open marinetide-wave reworkings near the distributary mouth contain-ing sparse to dense assemblage of Planolites isp Thalassi-noides isp and Paleophycus isp The overall Thalassinoides-Planolites-Chondrites ichnocoenoses is characteristic of estu-arine setting

TheChondrites-bearing claystone beds attest to dominantmarine inundations (maximum flooding surface (MFS)) ofthe estuary with prevalence of anoxic phases in the ambienceOccurrence of abundantChondrites ichnoassemblage inmul-tiple narrow but identical sedimentary horizon (claystone) inwidely apart geographic locales in eastern peninsular Indiapoints tomultiple short but predominant anoxic phases in thedepositional realm that possibly persisted all over the easternpeninsular India during the end early Permian time As theoverlying and underlying sediments contain plenty of plantfossils and this part of the lithosuccession is devoid of anyintermittent coal layers hence the possibility of developmentof low oxygenation due to decomposition of large organicdetritus is negated So such localized anoxia within the upperBarakar estuarine system can be correlated with fluctuationsin the atmospheric oxygen level Sequential transition frommonospecific Chondrites assemblage to a mixed Planolites-Thalassinoides assemblage indicates gradually increasing oxy-genation in the ambience [4 5]

5

10

20

25

15

30

35

01

02

03

04

05

0100200300400500600

Present day concentration

O2 co

ncen

trat

ion

()

CO2 co

ncen

trat

ion

()

Age (Ma)

Upper Barakar sedimentation (278ndash271Ma)

Figure 7 Plot showing concentration of O2and CO

2in the

atmosphere during the Phanerozoic time (modified after 31 32)Note the O

2and CO

2concentrations during the upper Barakar

sedimentation (278ndash271Ma)

Atmospheric oxygen levels showwide fluctuations duringthe late Paleozoic timeThe oxygen level reached amaximumof 35 at the end Carboniferous causing enhancement ofrespiration and gigantism in organismsThis was followed bya significant drop to 15 at the end Permian leading to massextinction at the Permo-Triassic boundary Concomitantlythe carbon dioxide content was raised through the Devonianand Carboniferous followed by an approximately tenfoldreduction during the middle to late Paleozoic time [28 29]During Permian extensive coal deposition resulted fromlesser extent of decomposition of terrestrial plant ecosystemsand increased carbon fixation by carbon-reducing organ-isms Such disequilibrium between free and stored carbonconcentration extensive oxygen release due to post-Silurianterrestrialization by plants together with changes in con-tinental weathering organic carbon deposition and bioticdecomposition dramatically modified the atmospheric car-bon dioxide and oxygen levels [28 30] The time frame 278ndash271Ma (upper Barakar sedimentation) demarcates a steadyfall in the atmospheric oxygen level (sim32ndash25) accompaniedby a very slow-rising carbon dioxide concentration (lt01) inglobal scale (Figure 7) [31 32] Record of anoxia demarcatedby the Chondrites ichnoassemblage followed by Planolites-Thalassinoides ichnoassemblages in the overlying and theunderlying successions within the upper Barakar successionin eastern India can be correlated with intermittent drops inoxygen level within a steady phase of decreasing oxygenationwithin an overall fluctuating atmospheric condition duringthe early Permian period

5 Conclusion

Postglacial marine invasion of different terrestrial areaswithin the Gondwanaland during the Permian is well known


and the Permian Gondwana sediments from India are notexception to this Under this framework in recent timescoal-bearing terrestrial-fluvial sequences of the Barakar For-mation are reinterpreted as marine wave-tide influenceddeltaicestuarine deposits based on different sedimentolog-ical and ichnological attributes Different ichnoforms of theChondrites isp are reported for the first time from theupper Barakar succession which provides further supportfavouring suchmarine inundation Abundance of this typicalmarine ichnocoenoses in laterally distant areas within severalnarrow time frames demarcate short phases of anoxia ineastern India during end early Permian period In thispaper we correlate such anoxic fluctuations with periods offalling-oxygenation within the global oxygen-carbon dioxidefluctuation in the late Paleozoic atmosphere Record of suchatmospheric fluctuation and resultant sediment-organisminteraction pattern will be useful in the understanding andthe reconstruction of the paleoecological and paleoenviron-mental changes within the Permian Gondwanaland-Tethyssystem

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

Biplab Bhattacharya is grateful to the Department of Scienceand Technology (DST) Government of India for financialassistance (FAST TRACK Research Scheme for Young Sci-entists no SRFTPES-1702010) Authors are grateful to theanonymous reviewers and the editorial board for reviewingthis paper

References

[1] I Coates and J A McEachern ldquoThe ichnological signature ofwave- and river-dominated deltas Dunvegan and Basal BellyRiver formations West-Central Albertardquo in Digging DeeperFinding a Better Bottom Line B Wrathall G Johnston AArts et al Eds Canadian Society of Petroleum Geologists ampPetroleum Society 1999 Core Conference paper no 99-114C

[2] C E Savrda and D J Bottjer ldquoTrace-fossil model for recon-structing oxygenation histories of ancient marine bottomwaters application to upper cretaceous niobrara formationColoradordquo Palaeogeography Palaeoclimatology Palaeoecologyvol 74 no 1-2 pp 49ndash74 1989

[3] A A Ekdale and T R Mason ldquoCharacteristic trace-fossil asso-ciations in oxygen-poor sedimentary environmentsrdquo Geologyvol 16 no 8 pp 720ndash723 1988

[4] C E Savrda ldquoTrace fossils andmarine benthic oxygenationrdquo inTrace FossilsmdashConcepts Problems Prospects W Miller III Edpp 149ndash158 Elsevier Amsterdam The Netherlands 2007

[5] R G Bromley Trace FossilsmdashBiology Taphonomy and Applica-tions Chapman amp Hall London UK 1996

[6] A Seilacher ldquoAberrations in bivalve evolution related to photo-and chemosymbiosisrdquo Historical Biology vol 3 pp 289ndash3111990

[7] J J Veevers and R C Tewari ldquoGondwana master basin ofPeninsular India between Tethys and the interior of the Gond-wanaland Province of Pangeardquo Geological Society of AmericaMemoirs vol 187 pp 1ndash73 1995

[8] A Gupta ldquoEarly Permian palaeoenvironment in Damodarvalley coalfields India an overviewrdquo Gondwana Research vol2 no 2 pp 149ndash165 1999

[9] S K Ghosh C Chakraborty and T Chakraborty ldquoCombinedtide and wave influence on sedimentation of Lower Gondwanacoal measures of central India Barakar Formation (Permian)Satpura basinrdquo Journal of the Geological Society vol 161 no 1pp 117ndash131 2004

[10] B Bhattacharya S Bandyopadhyay S Mahapatra and SBanerjee ldquoRecord of tidewave influence on the coal-bearingPermian Barakar Formation Raniganj Basin Indiardquo Sedimen-tary Geology vol 267-268 pp 25ndash35 2012

[11] G Mukhopadhyay S K Mukhopadhyay M Roychowdhuryand P K Parui ldquoStratigraphic correlation between differentGondwana Basins of Indiardquo Journal of the Geological Society ofIndia vol 76 no 3 pp 251ndash266 2010

[12] H G Reading Sedimentary Environment and Facies BlackwellScientific Publication 1996

[13] G Nichols Sedimentology and Stratigraphy Wiley-BlackwellLondon UK 2nd edition 2009

[14] R G Osgood Jr ldquoTrace fossils of the Cincinnati areardquo Palaeon-tographica Americana vol 6 pp 281ndash444 1970

[15] F T Fursich ldquoIchnogenus rhizocoralliumrdquo PalaontologischeZeitschrift vol 48 pp 16ndash28 1974

[16] W Hantzschel ldquoTrace fossils and problematicardquo in Treatise onInvertebrate Paleontology Part W Miscellanea Supplement 1C Teichert Ed p 269 University of Kansas and GeologicalSociety of America Boulder Colo USA 2nd edition 1975

[17] A Uchman ldquoTaxonomy and palaeoecology of flysch tracefossils the Marnosoarenacea Formation and associated facies(Miocene Northern Apennines Italy)rdquo Beringeria vol 15 pp3ndash115 1995

[18] A Uchman K Bak and F J Rodrıguez-Tovar ldquoIchnologicalrecord of deep-sea palaeoenvironmental changes around theOceanic Anoxic Event 2 (Cenomanian-Turonian boundary) anexample from the Barnasiowka section Polish Outer Carpathi-ansrdquo Palaeogeography Palaeoclimatology Palaeoecology vol262 no 1-2 pp 61ndash71 2008

[19] N B Carmona L A Buatois J J Ponce and M G ManganoldquoIchnology and sedimentology of a tide-influenced delta LowerMiocene Chenque Formation Patagonia Argentina trace-fossil distribution and response to environmental stressesrdquoPalaeogeography Palaeoclimatology Palaeoecology vol 273 no1-2 pp 75ndash86 2009

[20] D Knaust ldquoCharacterisation of a Campanian deep-sea fansystem in the Norwegian Sea by means of ichnofabricsrdquoMarineand Petroleum Geology vol 26 no 7 pp 1199ndash1211 2009

[21] A Giannetti ldquoInfluence of climate sea-level changes andtectonics on ichnoassemblages distribution in a carbonate-dominated deep-marine environment (Upper PaleoceneZumaya section)rdquo Palaeogeography Palaeoclimatology Palaeoe-cology vol 285 no 1-2 pp 104ndash118 2010

[22] A Wetzel R Tjallingii and M G Wiesner ldquoBioturbationalstructures record environmental changes in the upwelling areaoff Vietnam (South China Sea) for the last 150000 yearsrdquoPalaeogeography Palaeoclimatology Palaeoecology vol 311 no3-4 pp 256ndash267 2011


[23] R G Bromley and A A Ekdale ldquoChondrites a trace fossilindicator of anoxia in sedimentsrdquo Science vol 224 no 4648pp 872ndash874 1984

[24] C E Savrda and D J Bottjer ldquoTrace-fossil model for recon-struction of paleo-oxygenation in bottom watersrdquo Geology vol14 no 1 pp 3ndash6 1986

[25] J P Cummings and D M Hodgson ldquoAssessing controls on thedistribution of ichnotaxa in submarine fan environments theBasque Basin Northern Spainrdquo Sedimentary Geology vol 239no 3-4 pp 162ndash187 2011

[26] M K Gingras J A MacEachern and S E Dashtgard ldquoProcessichnology and the elucidation of physico-chemical stressrdquoSedimentary Geology vol 237 no 3-4 pp 115ndash134 2011

[27] J D Howard and R W Frey ldquoCharacteristic physical andbiogenic sedimentary structures in Georgia estuariesrdquo AAPGBulletin vol 57 pp 1169ndash1184 1973

[28] R A Berner ldquoAtmospheric carbon dioxide levels over phanero-zoic timerdquo Science vol 249 no 4975 pp 1382ndash1386 1990

[29] R A Berner ldquoGEOCARB II a revised model of atmosphericCO2over Phanerozoic timerdquo American Journal of Science vol

294 no 1 pp 56ndash91 1994[30] H Visscher H Brinkhuis D L Dilcher et al ldquoThe terminal

paleozoic fungal event evidence of terrestrial ecosystem desta-bilization and collapserdquo Proceedings of the National Academy ofSciences of the United States of America vol 93 no 5 pp 2155ndash2158 1996

[31] R Dudley ldquoAtmospheric oxygen giant Paleozoic insects andthe evolution of aerial locomotor performancerdquo Journal ofExperimental Biology vol 201 no 8 pp 1043ndash1050 1998

[32] R A Berner ldquoAtmospheric oxygen over Phanerozoic timerdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 96 no 20 pp 10955ndash10957 1999


strong influence of marine wave and tide on fluvial sedi-mentation during the deposition of middle-upper Barakarsuccession [8ndash10] indicating a fluvio-marine interactivedeltaicestuarine depositional settingTheBarakar Formationin the Raniganj Basin in the Koel-Damodar Valley and theTalchir Basin in the Mahanadi Valley (Figure 1) comprisesof thick sandstone-shale-coal deposits (Figure 2) manifestingsimilar depositional history The lower parts of the sedimen-tary successions in both the basins bear thick coal seams andrepresent braided-fluvial depositional setting (Figure 2)

The studied rocks preserved in both the Kudaposi Nalasection Talchir Basin and the Khudia Nala section Rani-ganj Basin (Figure 1) represent part of the upper Barakarsedimentary succession (Figures 2 and 3)The upper Barakarsedimentary successions of both the Damodar Valley and theMahanadi Valley have been assigned the age of Kungurian(post-Artinskian) with an approximate time frame of 278ndash271Ma [11] The studied rocks are characterized by thick-bedded (1ndash25m thickness) coarse-grained trough cross-stratified to plane-laminated sandstone facies (Figures 4(a)and 4(b)) overlain by cm thin sandstone-siltstone-claystonealternations facies (Figures 5(a) and 5(b)) Thickness of thesandstone-siltstone-claystone alternation facies varies from15m to 43m The sandstone beds within this facies arecharacterized by wave ripples and wave-modified ripplestidal bundles represented by mud-draped foresets climbingripples flaser beddings bidirectional ripples mutually oppo-site cross-strata sets vertical and lateral accretion of cross-strata sets with prominent reactivation surfaces and so forthEach sandstone bed grades upward to a siltstoneclaystoneThe claystone beds are occasionally very thick (thickness1ndash18m) and are characterized by abundant Chondrites ispon the bedding plane The sandstonesiltstone-claystoneheteroliths that underlie and overlie such thick claystonebeds are often characterized by sparse to abundant tracefossil associations dominantly Planolites isp Thalassinoidesisp and Paleophycus isp along with abundant plant fossilsThe successions show coarsening upward trend with gradualincrease in the deposition of sandstone towards top andfinally overlain by a thick-bedded trough cross-stratifiedcoarse-grained sandstone facies

The sedimentary facies architecture closely resemblesthose described from Barakar sedimentary succession of theSatpura Basin and the Raniganj Basin respectively [9 10]The sedimentation patterns changed from a basal braidedchannel to an uppermeandering channel system where rapidmigration of the channels and lateral accretioncoalescingof bars led to deposition of thick trough cross-stratified toplane laminated sandstone [8] Open marine tide and waveinfluences producedmultiple fining upward successions withcharacteristic sedimentary features and indicate episodicdrowning of the fluvial channels by marine water [10]Dominant fining-upward succession indicates oversteppingoverbank levees within a meandering fluvial-marine interac-tive estuarine setting [12 13] A coarsening-upward succes-sion comprising of coarse-grained channel-filling sandstonefacies overlies this succession indicating progradation of themeandering channel system over the estuarine deposits

3 Ichnogenus Chondrites Sternberg

Chondrites Sternberg is considered as an infaunal deposit-feeding system [14] It comprises a regularly branching tunnelsystem consisting of a small number of master shafts opento the surface which ramify at depth to form a dendriticnetwork [14ndash17] In the present paper we describe fourdifferent species of Chondrites from the Barakar FormationnamelyChondrites patulus (fromKudaposi Nala)Chondritestargionni (from both Kudaposi Nala and Khudia Nala)Chondrites affinis (from both Kudaposi Nala and KhudiaNala) and Chondrites recurvus (from Khudia Nala) In boththe study sections all the ichnoforms are hosted in fine-grained massive claystone mostly preserved as epichnialsandsilt-filled ridges on the claystone bedding surfaces Thefollowing is a description of all the ichnospecies recordedfrom the two areas under study

31 Ichnospecies Chondrites patulus (Figures 6(a) and 6(b))These are small straight unlined branching burrow systempreserved on the claystone bedding surfaces These ichno-forms show filling by fine-grained sandstonesiltstone andcharacteristically lack spreiten laminae Offshoots branch outfrom the main stem on both sides making obtuse anglewith the stem Individual branches are 025 to 03 cm wideand 12 cm in length Offshoots do not show any furtherbranching

32 Ichnospecies Chondrites targionii (Figures 6(b) and 6(c))This ichnospecies is represented by straight to dendriticunlined smooth walled burrow system with few branchespreserved on the claystone bedding surface Traces are par-allel to bedding surface and radiate at an angle varying fromlow to high angle Secondary branching is absent Lengthof the branches varies between 12 and 15 cm and width upto 022 cm Burrow fills are commonly coarser-grained sed-iments with respect to the host sediments Spreiten lamellaeare characteristically absent

33 Ichnospecies Chondrites affinis (Figures 6(a) 6(b) and6(c)) These are represented by relatively larger epireliefbedding parallel concave tubes These are preserved withinclaystone as straight to curved sandsiltstone ridges withlocally preserved spreiten lamellaeThe tubes are unlined andrarely show branching Main stem is 41ndash65 cm in length and025 cm wide with the branches varying in length between04ndash08 cm and 025 cm in width Secondary branching isabsent The tubes locally overly other such tubes

34 Ichnospecies Chondrites recurvus (Figures 6(a) and 6(c))These ichnoforms are represented by short curved epirelieftraces Branching intensity is relatively high with respectto other ichnoforms in the study area The branches arepeculiarly curved following the main stem Length of themain stem is approximately 25 cm whereas the branches areup to 04 cm in length Locally these traces are not clear dueto poor preservation of the off-suits


Calcutta

0 100 300 500

(km)

RaniganjBasin

TalchirBasin

26∘

26∘

86∘

86∘

94∘

94∘


(a)



Unconformity


Early Permian


KhudiaNala

F

F

F FF

F

F

F F

FF

F

0 5 Barakar R

86∘40

998400

Damodar R

(km)

N Barakar

23∘

50998400

Low

er G

ondw

ana

supe

rgro

up

(b)

21∘

05998400

Dahibar

Anuli R

N

Gouduni R

Kudaposi R

84∘54

998400



Unconformity


Early Permian


Low

er G

ondw

ana

supe

rgro

up

2km

(c)



PebbleSandMud

F MC0

10

20

(m)

Coal

Study section


Channel form


(Figure 3(a))

(a)

Coal

(m)

0

20

PebbleSandMud

FMC

Coal

Study section

SandstoneMudstone


Channel form


(Figure 3(b))

(b)



lowast

0

5

10

15

20

25

30

(m)


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



(a) Khudia Nala

lowast


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



0

5

10

15

20

25

30

(m)


(b) Kudaposi Nala



(a) (b)


(a) (b)


Ca

Cr

Cp

(a)

Ct

Ca

Cp

(b)

Ca

Cr

Ct

(c)



4 Discussion




5

10

20

25

15

30

35

01

02

03

04

05

0100200300400500600


O2 co

ncen

trat

ion

()

CO2 co

ncen

trat

ion

()

Age (Ma)



2in the


2and CO




5 Conclusion






Acknowledgments


References




































Calcutta

0 100 300 500

(km)

RaniganjBasin

TalchirBasin

26∘

26∘

86∘

86∘

94∘

94∘


(a)



Unconformity


Early Permian


KhudiaNala

F

F

F FF

F

F

F F

FF

F

0 5 Barakar R

86∘40

998400

Damodar R

(km)

N Barakar

23∘

50998400

Low

er G

ondw

ana

supe

rgro

up

(b)

21∘

05998400

Dahibar

Anuli R

N

Gouduni R

Kudaposi R

84∘54

998400



Unconformity


Early Permian


Low

er G

ondw

ana

supe

rgro

up

2km

(c)



PebbleSandMud

F MC0

10

20

(m)

Coal

Study section


Channel form


(Figure 3(a))

(a)

Coal

(m)

0

20

PebbleSandMud

FMC

Coal

Study section

SandstoneMudstone


Channel form


(Figure 3(b))

(b)



lowast

0

5

10

15

20

25

30

(m)


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



(a) Khudia Nala

lowast


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



0

5

10

15

20

25

30

(m)


(b) Kudaposi Nala



(a) (b)


(a) (b)


Ca

Cr

Cp

(a)

Ct

Ca

Cp

(b)

Ca

Cr

Ct

(c)



4 Discussion




5

10

20

25

15

30

35

01

02

03

04

05

0100200300400500600


O2 co

ncen

trat

ion

()

CO2 co

ncen

trat

ion

()

Age (Ma)



2in the


2and CO




5 Conclusion






Acknowledgments


References




































PebbleSandMud

F MC0

10

20

(m)

Coal

Study section


Channel form


(Figure 3(a))

(a)

Coal

(m)

0

20

PebbleSandMud

FMC

Coal

Study section

SandstoneMudstone


Channel form


(Figure 3(b))

(b)



lowast

0

5

10

15

20

25

30

(m)


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



(a) Khudia Nala

lowast


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



0

5

10

15

20

25

30

(m)


(b) Kudaposi Nala



(a) (b)


(a) (b)


Ca

Cr

Cp

(a)

Ct

Ca

Cp

(b)

Ca

Cr

Ct

(c)



4 Discussion




5

10

20

25

15

30

35

01

02

03

04

05

0100200300400500600


O2 co

ncen

trat

ion

()

CO2 co

ncen

trat

ion

()

Age (Ma)



2in the


2and CO




5 Conclusion






Acknowledgments


References




































lowast

0

5

10

15

20

25

30

(m)


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



(a) Khudia Nala

lowast


lowast

Sandstone

Siltstone

Claystone

Current ripple



Plane lamination



0

5

10

15

20

25

30

(m)


(b) Kudaposi Nala



(a) (b)


(a) (b)


Ca

Cr

Cp

(a)

Ct

Ca

Cp

(b)

Ca

Cr

Ct

(c)



4 Discussion




5

10

20

25

15

30

35

01

02

03

04

05

0100200300400500600


O2 co

ncen

trat

ion

()

CO2 co

ncen

trat

ion

()

Age (Ma)



2in the


2and CO




5 Conclusion






Acknowledgments


References




































(a) (b)


(a) (b)


Ca

Cr

Cp

(a)

Ct

Ca

Cp

(b)

Ca

Cr

Ct

(c)



4 Discussion




5

10

20

25

15

30

35

01

02

03

04

05

0100200300400500600


O2 co

ncen

trat

ion

()

CO2 co

ncen

trat

ion

()

Age (Ma)



2in the


2and CO




5 Conclusion






Acknowledgments


References




































4 Discussion




5

10

20

25

15

30

35

01

02

03

04

05

0100200300400500600


O2 co

ncen

trat

ion

()

CO2 co

ncen

trat

ion

()

Age (Ma)



2in the


2and CO




5 Conclusion






Acknowledgments


References







































Acknowledgments


References



































chondrites isp. indicating late paleozoic atmospheric anoxia in …€¦ · plant fossils (figure...

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