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Journal of Palaeogeography 2024年第4期13卷 754-774页

作者： Adrita Choudhuri Prem Raj Uddandam Debarati Nag birbal sahni institute of palaeosciences Savitribhai Phule Pune University

This paper intends to unravel the depositional condition of the Basal Conglomerate/Jadukata Formation and the Lower Mahadek Formation in southern Shillong Plateau, NE India deposited during the Late Cretaceous period. The studied succession is entirely siliciclastics in composition and was built up on the Precambrian basement rocks. State-of-art facies analysis and palaeocurrent evidence helped us to reconstruct the palaeogeography and palaeoenvironment. The facies tracts reveal that frequent hyperconcentrated mass flow deposits dominated the proximal part of the river channels. Gradually, the river evolved to a sandy braided and finally mud-dominated, meandering system. The river channel changed its pattern through onlapping and progressive elimination of the accommodation space created by the tectonic subsidence/upliftment. Major shifts in palaeocurrent direction at different stages of the river evolution confirm the role of tectonics on the river channel evolution. QFL detrital modes of the sandstones reflecting lithic wacke composition and the recycled orogeny corroborate the interpretation. Rapid lateral and vertical facies transition suggests a pull-apart type basin due to ongoing rifting. Geochemical analyses also show signatures of the overlapping tectonic conditions supporting the pull-apart basin model.

关键词： Tectonics hyperconcentrated flows braided-meandering system pull-apart rift basin Late Cretaceous South Shillong Plateau

Palaeodepositional environment,implications of Glossopteris flora,and organic matter characteristics from the Lower Permian,Karo Open Cast Mine,East Bokaro Coalfield,Damodar Basin,India

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Journal of Palaeogeography 2024年第3期13卷 528-546页

作者： Sankar Suresh Kumar Pillai Rose Ann Sebastian Runcie Paul Mathews Srikanta Murthy Anju Saxena Mrutyunjaya Sahoo Suraj Kumar Sahu Gulshan Kumar Dhingra birbal sahni institute of palaeosciences 53 University RoadLucknow-226007UPIndia Academy of Scientific and Innovative Research(AcSIR) Ghaziabad-201002India Department of Geology School of Earth Science SystemsCentral University of KeralaKasaragod-671316KeralaIndia Department of Geology Ravenshaw UniversityCuttack-753003OdishaIndia Department of Botany Sri Dev Suman Uttarakhand UniversityUttarakhand-249145India

The present study deals with the Early Permian floral diversity,palaeoenvironment,palaeoclimate and depositional setting using a multiproxy approach that includes morphotaxonomy,palynology,and organic geochemistry of Karo OCM(Open Cast Mine),East Bokaro Coalfield,Damodar Gondwana Basin,*** Permian sediments of Peninsular India are widely regarded as fluvial,along with some marine *** macroplant fossil assemblage exhibits the presence of Glossopteridales,comprising Glossopteris,Gangamopteris,and Vertebraria,as well as Coniferales,which includes *** palynological assemblage encompasses the dominance of the striate bisaccate pollen Faunipollenites *** the subdominance of the non-striate bisaccate pollen Scheuringipollenites *** glossopterid *** megafloral and palynofloral assemblage confirms the biostratigraphical age to be Late Barakar palynoflora of Kungurian *** studied morphological characteristics,including small to large Glossopteris leaves exhibiting a lanceolate shape,acute apices,and acute cuneate or tapering bases,as well as entire margins with narrower lamina and narrow meshes,suggest the existence of a dense forest with the prevalence of a warm and humid climate during their *** organic geochemical characterization based on functional group and biomarker analyses reveals the diagenetic effects on organic *** symmetric(~2865-2855 cm^(-1))and asymmetric stretching(~2930-2910 cm^(-1))peaks are identifiable in coal samples,whereas they are absent in carbonaceous *** A-factor vs.C-factor plot suggests that the kerogen type is type Ⅲ,which can generate mainly gaseous *** vitrinite reflectance studies(R_(r) av.1.1%)show increased maturity of the samples,which is supported by the n-alkane distribution pattern and the absence of hopane *** Indian floral assemblages in contemporary of southern Gondwana continents reveal a stronger inclination/affinity with th

关键词： Glossopteris Palynomorph FTIR GCMS Gondwana Permian Palaeoclimate

Palaeoenvironmental reconstruction for the Permian(lower Gondwana)succession of the Godavari Valley Coalfield in southern India based on a combined palynofacies,carbon isotope,and biomarker study

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Journal of Palaeogeography 2022年第1期11卷 123-144页

作者： Neha Aggarwal Runcie Paul Mathews Arif Husain Ansari Biswajeet Thakur Shailesh Agrawal birbal sahni institute of palaeosciences 53 University RoadLucknow 226007India

The study presents integrated palynofacies,organic carbon isotope,and biomarker data to reconstruct palaeoenviromental setting for the Permian sediments(borehole MGK-6)of the Kachinapalli block of the Godavari Valley Coalfield,southern *** palynofacies data reveal three distinct palynofacies(A-C)as *** A is dominated by abundant arborescent vegetation(glossopterids and conifers)along with structured organic matter,suggesting freshwater forest swamps in proximal *** B is dominated by abundant degraded organic matter and amorphous organic matter,suggesting lakeshore/flooded palaeomires in slightly dismal *** has a high water level in the hinterland,which enables bacterial degradation of organic matter and establishes low-oxygenation conditions within the water *** conditions would have provided grounds for the accumulation of either degraded or amorphous organic *** C is dominated by the abundance of charcoal/opaque phytoclasts,indicating prolonged transportation or postdepositional alteration,suggesting a highly-oxidizing condition in distal *** bulk organic δ^(13)C range(-25.1‰ to-20.9‰)in the borehole MGK-6 is in close agreement with the global Permian *** study also shows a weak but statistically significant correlation with the major forms of palynofacies A and *** interlinked behaviour of bulk organic δ^(13)C and palynofacies suggests that the changes in palaeobiogeography/palaeodepositional settings were most likely driven by the change in mean annual *** biomarker study shows the presence of n-alkane from C_(15) to C_(31) with unimodal and bimodal distribution patterns,revealing the source materials as vascular plants and microbially-altered organic *** combined palynofacies,organic carbon isotope,and biomarker data provide vital clue to salient findings for the development of environmental conditions of Godavari Valley Coalfield during lower Gond

关键词： Artinskian Guadalupian Depositional environment Carbon isotope Biomarker Godavari valley coalfield

Glacier-Glacial Lake Interactions and Glacial Lake Development in the Central Himalaya,India(1994–2017)

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Journal of Earth Science 2021年第6期32卷 1563-1574页

作者： Pratima Pandey Sheikh Nawaz Ali Prashant Kumar Champati Ray Indian institute of Remote Sensing DehradunIndia birbal sahni institute of palaeosciences LucknowIndia

Despite several regional glacier and glacier lake inventories, the relationship between receding glacier, glacial lake evolution(glacial-lake interactions) and their sensitivity to different forcing factors have not been properly understood yet. To better understand these processes, we used satellite images collected in 1994, 2015 and 2017 to monitor the spatially-explicit evolution of glacial lakes and glacier changes. The results show a total of 1 353 glacial lakes covering an area of 7.96 km;in the year 2015. Out of these, a total of 137 glacial lakes having an area of >0.01 km;and located within 2 km periphery of mother glacier have been selected for the monitoring of spatial development between 1994 and 2017. We found an increase in the total lake area from ~4.9 to ~7.73 km;between 1994 and 2017,corresponding to an overall expansion of ~57%. The total area covered by the glaciers associated with these lakes reduced from ~365 km;in 1994 to ~358 km^(2) in 2017, accounting for a glacier loss of ~7 km^(2) and corresponding to ~1.92% reduction. Our study results are in agreement with global glacier behavior, revealing a rapid glacier recession and accelerated glacial lake expansion under an unprecedented climate change scenario. In addition, the results suggest a significant reduction in the glacier area and a close relationship between the glacier melting and lake changes.

关键词： glacial lake expansion glacier change glacier-lake interaction Central Himalaya climate

Palaeodiet of Miocene Producers and Depositional Environments:Inferences from the First Evidence of Microcoprolites from India

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1574-1590页

作者： Vivesh VKAPUR Kamlesh KUMAR P.MORTHEKAI Amritpal Singh CHADDHA birbal sahni institute of palaeosciences 53University RoadLucknowUttar Pradesh 226007India

This paper reviews research on coprolites from India,providing the first evidence of microcoprolites from the early Miocene(Aquitanian)Khari Nadi Formation sedimentary succession,exposed about 1.5 km northeast of the village of Kotada,Kachchh(Kutch)District,Gujarat State,western *** and size comparisons(in a statistical framework)with known coprolites from the Mesozoic-Cenozoic successions of India(including those recorded herein)and globally suggest that fishes were the likely producers of the Kotada *** electron microscopy confirms the presence of fish dental remains within the coprolites,while both Scanning Electron Microscopy(SEM)and Energy Dispersive X-ray Spectroscopy(EDS)reveal the phosphatic nature of the microscopic coprolite specimens(recorded herein)hinting that the producer(s)were predominantly carnivorous(ichthyophagous)in their ***,X-Ray Fluorescence(XRF)analysis of the host and associated lithologies allows us to deduce that the Kotada coprolites were deposited in a shallow marine environment,with possible aerial exposure of the host lithology occurring at some point after *** the best of our knowledge,the present report is the first record of microscopic fish coprolites from India,as well as being the first from the Aquitanian of India and the oldest Neogene record from India.

关键词： coprolites palaeodiet palaeoenvironment Energy Dispersive Spectroscopy(EDS) X-Ray Fluorescence(XRF)analysis Miocene(Aquitanian)

Legumes from the Paleocene sediments of India and their ecological significance

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Plant Diversity 2023年第2期45卷 199-210页

作者： Harshita Bhatia Gaurav Srivastava R.C.Mehrotra birbal sahni institute of palaeosciences 53 University RoadLucknow 226007India Academy of Scientific and Innovative Research(AcSIR) Ghaziabad 201002India

During the early Paleogene,greenhouse gases created warm global *** warm climates redistributed the habitat of marine and terrestrial biota *** the ecology of biotas under extremely warm climates is important to decipher their behavior in future climate *** we report two new legume fossils(Leguminocarpum meghalayensis Bhatia,Srivastava et Mehrotra ***.,and Parvileguminophyllum damalgiriensis Bhatia,Srivastava et Mehrotra ***.) from the late Paleocene sediments of Tura Formation of Meghalaya,northeast ***,the Paleocene legume fossil records indicate that legumes most likely immigrated to India from Africa via the Ladakh-Kohistan Arc during the early ***,previously reconstructed climate data from the Tura Formation indicate that legumes were well adapted to a warm seasonal climate with monsoon rains.

关键词： Fabaceae Global warming Fruits Damalgiri Tura Rhynchosia

Holocene Floral and Faunal Remains Revealed Concealed Neotectonic Disturbance (Saria Tal, Kumaun Himalaya, India)

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Acta Geologica Sinica(English Edition) 2010年第1期84卷 69-76页

作者： Asha GUPTA birbal sahni institute of Palaeobotany

Palynological and paleontological investigations supported by the radiocarbon dates of the lacustrine sediments of two profiles from the temperate lake Saria Tal, in Naini Tal District, Kumaun Himalaya, have revealed the presence of a concealed fold at the region. The profile from bore cores represents the upper part of the Late Holocene and the profile from exposed sections from the Middle Holocene to the over middle part of the Late Holocene. The data generated from different investigations have uniformly indicated that the former profile represents normal superposition, while the latter represents the reverse order. The contemporary pollen as well as molluscan zones of both profiles are situated at different elevations but consist of similar bioremains - indicating continuation of the same strata in two profiles. The presence of reverse order of superposition, continuation of the same strata in two profiles at different elevations, and the orientation of biozones, have indicated that the revealed folding is of syncline type. The present study has also given an idea about the origin of this lake.

关键词： concealed fold Holocene bio-remains Saria Tal Kumaun Himalaya

Cenozoic flora of western India and its significance in palaeoclimatic and palaeophytogeographic interpretation

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科学通报 2013年第S1期58卷 134-141页

作者： SHUKLA Anumeha MEHROTRA Rakesh Chandra birbal sahni institute of Palaeobotany

The Cenozoic flora of western India(Rajasthan and Gujarat) is adversely affected by the tectonic activity such as collision of the Indian subcontinent with the Eurasian plate which is responsible for the Himalayan and Tibetan Plateau uplift. This collision and its resultants affected the ubiquitous tropical lowland vegetation of the Indian subcontinent(including western India) and are responsible for different types of topographic regions as seen today in the Indian subcontinent. The region is important as it has witnessed a drastic change in climate of the region since the Cenozoic time and also provided opportunities to the western and eastern flora to intermingle. The main basins in western India comprising Cenozoic sequences are: Bikaner-Nagaur, Jaisalmer and Barmer in Rajasthan and Kachchh, Mainland and Saurashtra in Gujarat. These basins are very rich in lignite which is the main source of electric power generation in western India. This lignite is mainly of Eocene in age. The Cenozoic flora of western India was almost tropical growing in well drained areas as compared to arid to sub-humid regions with xeric vegetation today. The reported fossils are represented by leaves, woods, fruits and seeds. The leaves are abundant in the Palaeogene as compared to the Neogene. The Neogene period can be marked by the abundant legumes and dipterocarpaceous remains. The important families viz., Anacardiaceae, Annonaceae, Arecaceae, Calophyllaceae, Clusiaceae, Combretaceae, Euphorbiaceae, Flacourtiaceae, Icacinaceae, Lauraceae, Lythraceae, Meliaceae, Moraceae, Myrtaceae, Pandanaceae and Sonneratiaceae have been reported from the Palaeogene sediments, whereas Anacardiaceae, Araucariaceae, Arecaceae, Combretaceae, Dipterocarpaceae, Fabaceae, Lauraceae, Lecythidaceae, Lythraceae, Malvaceae, Meliaceae, Moraceae, Podocarpaceae, Rhamnaceae, Rhizophoraceae, Rutaceae, Sapindaceae and Sonneratiaceae are known from the Neogene sediments. All the recovered elements strongly indicate th

关键词： megafossil Rajasthan Gujarat palaeoclimate phytogeography

Organo-petrographic and geochemical characteristics of Gurha lignite deposits,Rajasthan,India:Insights into the palaeovegetation,palaeoenvironment and hydrocarbon source rock potential

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Geoscience Frontiers 2020年第3期11卷 965-988页

作者： Runcie Paul Mathews Bhagwan DSingh Vikram Partap Singh Alpana Singh Hukam Singh Mahesh Shivanna Suryendu Dutta Vinod A.Mendhe Rimpy Chetia DST-birbal sahni institute of palaeosciences Lucknow226007India Department of Earth Sciences Indian Institute of Technology BombayMumbai400076India CSIR-Central institute of Mining and Fuel Research Dhanbad826015India

The sedimentary sequence containing lignite deposits in Gurha quarry of the Bikaner-Nagaur Basin(Rajasthan)has been *** samples from lignite and allied shale horizons were evaluated for petrographical,palynological,palynofacies and organic geochemical inferences,to depict the source flora and to reconstruct the palaeodepositional conditions prevailed during the *** assessment for the hydrocarbon generation potential of these deposits has also been *** results revealed the dominance of huminite macerals and phytoclasts organic matter(OM) indicating the existence of forested vegetation in the vicinity of the depositional site.A relatively high terrigenous/aquatic ratio(TAR) and the carbon preference index(CPI) are also suggesting the contribution of higher plants in the peat ***,the n-alkane distributions,maximizing at n-C17 and n-C29,showed inputs from the algal communities along with the higher plant derived organic *** palynomorphs of the families Onagraceae,Meliaceae,Arecaceae,Rhizophoraceae,Rubiaceae,Ctenolophonaceae, *** with oleanene and ursane types of triterpenoids suggest the contribution from angiosperms source ***,the presence of Araucareaceae and Podocarpaceae pollen grains shows the existence of gymnosperms ***,the presence of tetracyclic diterpanes;demethylated entbeyerane,sandaracopimarane,pimarane,and Kaurane type of compounds confirms the contribution of *** variation in the values of the coefficient of non-equality(H:0.68%-7.56%),the standard deviation(8:0.04%-0.16%) and the coefficient of variability(V:16.10%-46.47%),also shows the heterogeneity in the source organic *** various petrographical indices,palynological entities,and geochemical parameters indicate that the peatforming vegetation was accumulated under a mixed environment and fluctuating hydrological *** interpretation of palynofacies data on APP(Amorphous organ

关键词： Palynofacies Biomarkers Rock-Eval Palaeocene deposits Bikaner-Nagaur Basin

Low latitude floral assemblage from the Late Oligocene sediments of Assam and its palaeoclimatic and palaeogeographic significance

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科学通报 2013年第S1期58卷 156-161页

作者： SRIVASTAVA Gaurav MEHROTRA Rakesh Chandra birbal sahni institute of Palaeobotany

There are many outcrops of the Tertiary sediments in northeast India and a large number of plant megafossils have been described from there. Among all, the Late Oligocene sedimentary basin of Makum Coalfield is very important because there is no other exposure having such a rich palaeofloral assemblage not only from northeast India but also from the whole country. The assemblage is also important to confirm whether the suturing between the Indian and Eurasian plates was complete to facilitate plant migration or not. All the reported plant fossils clearly indicate the prevalence of tropical climate in the region during the deposition of the sediments. As the majority of taxa occur in tropical evergreen to moist deciduous and littoral and swampy forest, a warm and humid climate may be envisaged in Upper Assam during the Late Oligocene. The abundance of palms and pantropical megathermal plant families in the Makum Coalfield indicate that the cold month mean temperature(CMMT) was not less than 18°C. The quantitative palaeoclimate reconstruction indicates a monsoonal climate during the period with the same intensity as that of the modern day. The absence of Southeast Eurasian elements in the fossil assemblage provides clear evidence that suturing between the Indian and Asian plates was not complete till the Late Oligocene. Several modern analogues of the fossil taxa are now endemic to the Western Ghats which lies in the same palaeolatitude.

关键词： northeast India Makum Coalfield megafossil monsoon