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Facies analysis and palaeoecology of the Jurassic Spiti Shale Formation in the Spiti area,Northern India

Journal of Palaeogeography 2021年第4期10卷 438-462页

作者： Franz T.Fürsich Matthias Alberti Dhirendra K.Pandey Ketan Chaskar Suraj Bhosale FG Palaoumwelt GeoZentrum Nordbayern der Friedrich-Alexander-Universitat Erlangen-NürnbergLoewenichstrasse 2891054ErlangenGermany State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringCentre for Research and Education on Biological Evolution and Environment and Frontiers Science Center for Critical Earth Material CyclingNanjing210023China Department of Geology Under the School of EarthBiological and Environmental ScienceCentral University of South BiharSH 7Gaya-Panchanpur RoadVillage KarharaPost FatehpurGaya824236BiharIndia Department of Earth and Environmental Science K.S.K.V.Kachchh UniversityBhuj370001India

The Spiti Shale Formation is a widely distributed stratigraphic unit of the passive northern margin of the Indian craton,deposited between the Callovian and earliest *** siliciclastic strata are dominated by dark-grey to black argillaceous *** the formation has undergone intense tectonic stress involving folding and faulting,it is very difficult to document a complete *** the type area,the Spiti Valley,six sections have been measured that document parts of the three informal members of the formation,the Lower,Middle,and Upper *** its uniform appearance,eight facies/biofacies types could be distinguished,ranging from the anoxic shale facies,with ammonites and belemnites as the only faunal elements,to the dysoxic Malayomaorica and Bositra biofacies,and the oxic to anoxic offshore shelf facies,which are characterized by low-diversity macrobenthos *** facies are the condensed glauconiticphosphoritic mudrock facies and the Fe-oolitic siltstone facies(both characterized by sediment starvation),the aerated argillaceous silt-sandstone facies,and the tide-influenced nearshore shelf *** benthic macrofauna represents four bivalve-dominated associations all characterized by a very low to low species *** are the Bositra buchii,the Australobuchia spitiensis,the Palaeonucula cuneiformis-Pruvostiella hermanni-Indogrammatodon egertonianus,and the Malayomaorica sp.-Australobuchia spitiensis-Retroceramus haasti *** and macrobenthic associations indicate that the Spiti Shale Formation represents outer to inner shelf environments,which for much of the time were subjected to upwelling and anoxic to dysoxic *** shallowing at the top characterizes the transition to the overlying Lower Cretaceous Giumal Formation.

关键词： Jurassic palaeoenvironments biofacies Macrobenthic communities Black shales Deoxygenation Upwelling Himalayan mountains

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Foraminifera in Cenozoic Paleoenvironments

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Journal of China University of Geosciences 2005年第3期16卷 200-218页

作者： Brian Mc Gowran School of Earth & Environmental Sciences Mawson Building DP313 The University of Adelaide Adelaide SA 5005 Australia

Paleontologists search the fossil record for evidence of age, ancient environments, phylogenetic reconstructions and ancient communities. Cenozoic foraminifera preserve evidence for all of these simultaneously from the water column and from at, above and below the sediment/water interface. As our understanding of foraminiferal assemblages and their place in the strata （biofacies） becomes more sophisticated, so are foraminiferal biofacies challenged to contribute to more subtle problems in Cenozoic earth and life history. Progress is described as a series of five ＂integrations＂. （Ⅰ） The quantification of foraminiferal biofacies was an advance on simple presences and absences of species meeting such questions as marine or nonmarine, or shallow or deep. （Ⅱ） Foraminiferal shells carry geochemical signals especially isotopes of oxygen （temperature, ice volume）, carbon （nutrition and the carbon cycle）, and strontium （seawater ratios through time）. （Ⅲ） From modern foraminiferal biology we have lifestyle insights leading to a model of oceans and paleo-oceans called the trophic resource continuum, a valuable way into greenhouse-icehouse comparisons and contrasts. （Ⅳ） biofacies changes in space and time are sometimes abrupt with little evidence of diachrony, and sometimes gradual. These patterns are clarified in the context of sequence stratigraphy （which they enrich in turn）. （Ⅴ） The paleobiological counterpart of sequence stratigraphy is evolutionary paleoecology, reconstructing communities in deep time. The foraminifera are perfectly suited to investigate the possibility （or likelihood） that global environmental shifts have controlled community turnover in the pelagic, neritic and terrestrial realms.

关键词： foraminifera biofacies stratigraphy paleoecology paleoenvironment evolution Cenozoic trophic resource continuum

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Characterization of the Upper Cretaceous Sediments in the Ikpankwu-Ihube Axis, Okigwe, Southeastern Nigeria

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International Journal of Geosciences 2019年第6期10卷 724-744页

作者： Samuel Okechukwu Onyekuru Chukwuma Julian Iwuagwu Joy Okenyi Kelechi Denis Opara Ukamaka Nwachiani Nwigbo Department of Geology Federal University of Technology Owerri Nigeria

Detailed characterization of the outcropping sediments in the Ikpankwu and Ihube axis was undertaken to validate lithostratigraphic boundaries and nomenclatures which had stirred up debates amongst scholars in recent times. Stochastic method established dominant facies associations and preferred stacking patterns, which were used to interpret environments of deposition (EODs), while foraminiferal and palynological analyses fingerprinted both paleo depths and age of the sediments. The results established the dominance of similar lithofacies at the basal parts of both sections indicating mappable geological units and members of the same lithostratigraphic unit. The basal lithofacies are succeeded up section, however, by different lithological units in both the KM 75 and Ikpankwu sections. Interpretations of EODs using lithofacies successions predicted fluvial to tidally-influenced shallow marine deposits, which are environments in close affinity with each other. Interpretations using abundance and diversity of micro fauna supported non-marine (coastal-deltaic) to middle neritic paleo-water depths also, typical of marginal to shallow marine EODs. Recovered foraminiferal assemblages in the shale samples from the upper parts of both sections, however, depicted deposits of Nsukka Formation despite variations observed in lithofacies assemblages because the identified Haplophragmoides species that populate the upper units had been used to define the Late Maastrichtian-Paleocene age. Sediments at the basal parts with mappable lithological units at both sections were rather populated by species that connote the Campanian-Maastrichtian age when the Mamu Formation sediments were deposited. Palynomorphs recovered from both the basal and upper sections also suggested Campanian-Maastrichtian and Late Maastrichtian-Paleocene age, indicative of Mamu and Nsukka Formation sediments, respectively.

关键词： Assemblages biofacies Characterization Environment Formation Lithofacies

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