During the early Paleogene,greenhouse gases created warm global climates.These warm climates redistributed the habitat of marine and terrestrial biota globally.Understanding the ecology of biotas under extremely warm ...During the early Paleogene,greenhouse gases created warm global climates.These warm climates redistributed the habitat of marine and terrestrial biota globally.Understanding the ecology of biotas under extremely warm climates is important to decipher their behavior in future climate warming.Here we report two new legume fossils(Leguminocarpum meghalayensis Bhatia,Srivastava et Mehrotra sp.nov.,and Parvileguminophyllum damalgiriensis Bhatia,Srivastava et Mehrotra sp.nov.) from the late Paleocene sediments of Tura Formation of Meghalaya,northeast India.Globally,the Paleocene legume fossil records indicate that legumes most likely immigrated to India from Africa via the Ladakh-Kohistan Arc during the early Paleogene.Moreover,previously reconstructed climate data from the Tura Formation indicate that legumes were well adapted to a warm seasonal climate with monsoon rains.展开更多
With increase in shale gas exploration, inorganic and organic geochemical investigations of shale have become extremely important. Here, we explore the six argillaceous (shale) intervals (Arangi, Koldaha, Rampur, Bija...With increase in shale gas exploration, inorganic and organic geochemical investigations of shale have become extremely important. Here, we explore the six argillaceous (shale) intervals (Arangi, Koldaha, Rampur, Bijaygarh, Rewa and Sirbu shale) from Son valley sector, Vindhyan Basin with an aim to understand provenance conditions, palaeoclimate, tectonic setting and hydrocarbon generation potential. Whole rock geochemistry indicates Vindhyan sediments derived from felsic source(s) except for Sirbu shale that indicates additional influx of mafic rocks with differentiated felsic source. A comparative study of Vindhyan shale rare earth elements (REEs) points to Mahakoshals and Chhotanagpur gneissic complex (CGC) as probable sediment provenance for Vindhyan sediments. CIA analysis, after necessary corrections for K-metasomatism, suggests evolution in weathering and palaeoclimate indicating a transformation from moderate weathering conditions with warm and humid climate during lower Vindhyan deposition to intense weathering conditions with hot and humid climate during upper Vindhyan deposition. Trace (La/Y vs. Sc/Cr) and REE analysis indicates passive margin setting for Vindhyan sediments whereas a wide range spanning passive to active continental margin setting is also inferred using (Th-Sc-Zr/10) and (Th–La-Sc) ternary diagrams. However, these tectonic discriminant diagrams lack in explaining rift- or sag-related origin of any intracratonic basin such as the Vindhyan Basin. The total organic carbon (TOC) content in Vindhyan shales ranges from 0.29% to 8.44%. The thermally liberated hydrocarbon (S1) values range from 0.01 to 0.18 mg HC/g rock (milligram hydrocarbon per gram of rock sample), whereas hydrocarbon from cracking of the kerogen (S2) shows values ranging from 0.04 to 0.47 mg HC/g rock. Based on modified Van Krevelen correlation (HI vs. Tmax) diagram, organic matter from Arangi and Bijaygarh shales is characterized as thermally mature, Type III kerogen of gas prone character indicating good to very good gas generation potential.展开更多
The current article is an opinion on the sensitivity of high mountain regions which are the most fragile,sensitive and vulnerable to ongoing climate change.Its impacts are especially severe on the high mountain commun...The current article is an opinion on the sensitivity of high mountain regions which are the most fragile,sensitive and vulnerable to ongoing climate change.Its impacts are especially severe on the high mountain communities owing to their weak socio-economic profile,limited livelihood resources and agricultural land.The melting of glaciers and changes in the snow cover under the climate change scenario is leading to the scarcity of freshwater supplies,affecting both local and downstream communities.Changes in the precipitation patterns have been suggested to cause droughts,impact restricted agriculture,and limit the availability of water for domestic use.Additionally,the high mountain areas contain distinct flora and fauna,and climate change is not just altering them,but also has resulted in biodiversity loss as species are unable to adapt to the changing climate.Because of its higher altitudes and semi-arid to arid climate,the consequences of climate change are more evident in the higher Himalayas.Climate change is affecting the availability of key resources,such as freshwater and agriculture and pasture lands,resulting in food and water insecurity and their reliance on imports from other regions.As a result,high mountain communities in the Himalayas are progressively shifting to higher glacier valleys in search of suitable cultivable land with adequate irrigation.People are engaging in agro-pastoral activities around thermokarst lakes(Oasis)atop rock glaciers as part of this endeavour.Such actions underscore the crucial role of rock glaciers in dealing with and adjusting to the consequences of climate change.Despite its relevance,rock glacier research in the Himalayan region is still in its infancy.The purpose of this work is to emphasise the significance of these major climate-resilient water resources,as well as the methodology that must be adopted for their systematic and compressive investigations.展开更多
The fragmented pattern and the rapidly declining preservation of older glacial features/evidences limits the precision,with which glacial chronologies can be established.The challenge is exacerbated by the scarcity of...The fragmented pattern and the rapidly declining preservation of older glacial features/evidences limits the precision,with which glacial chronologies can be established.The challenge is exacerbated by the scarcity of datable material and limitations of dating methods.Nevertheless,the preserved glacial landforms have been fairly utilized to establish glacial chronologies from different sectors of the Indian Himalayas.The existing Himalayan glacial chrono-stratigraphies have revealed that in a single valley,past glacial advances rarely surpass four stages.Thus,local and regional glacial chronologies must be synthesized to understand glacial dynamics and potential forcing factors.This research presents an overview of glacier responses to climate variations revealed by glacial chrono-stratigraphies in the western Indian Himalayan region over the Quaternary(late).The synthesis demonstrated that,although the glacial advances were sporadic,glaciers in western Himalayas generally advanced during the Marine isotope stage(MIS)-3/4,MIS-2,late glacial,Younger Dryas(YD)and Holocene periods.The Holocene has witnessed multiple glacial advances and the scatter is significant.While previous glacial research revealed that Himalayan glaciers were out of phase with the global last glacial maximum(gLGM),weak Indian Summer Monsoon(ISM)has been implicated(ISM was reduced by roughly 20%).Recent research,however,has shown that gLGM glaciation responded to the global cooling associated with the enhanced mid-latitude westerlies(MLW).Further,the magnitude of gLGM glacier advance varied along and across the Himalayas particularly the transitional valleys located between the ISM and MLW influence.It is also evident that both the ISM and MLW have governed the late Quaternary glacial advances in the western Himalayan region.However,the responses of glaciers to ISM changes are more prominent.The insights gained from this synthesis will help us understand the dynamics of glacier response to climate change,which will be valuable for future climate modelling.展开更多
The use of bioactive compounds and probiotic bacteria against the viral diseases in human is known for a long time.Anti-viral,anti-inflammatory and anti-allergic properties of bioactive compounds and bacteria with pro...The use of bioactive compounds and probiotic bacteria against the viral diseases in human is known for a long time.Anti-viral,anti-inflammatory and anti-allergic properties of bioactive compounds and bacteria with probiotic properties in respiratory viral diseases may have significance to enhance immunity.This review highlights some of the important bioactive compounds and probiotic bacteria,suggesting them as a ray of hope in the milieu of the COVID-19 management.展开更多
A rare occurrence of a microspherule has been found in the infratrappean sediments,encountered below338 m thick Deccan volcanic cover in KLR-1 scientific borehole,drilled in the epicentral zone of the 1993 Killari ear...A rare occurrence of a microspherule has been found in the infratrappean sediments,encountered below338 m thick Deccan volcanic cover in KLR-1 scientific borehole,drilled in the epicentral zone of the 1993 Killari earthquake(Maharashtra,India).Palynological studies of the sediments indicate their age as Early Permian(Asselian,298-295 Ma) for deposition.Transmission electron microscope studies reveal that the spherule from the infratrappeans,is having a similar composition to that of the Neoarchean amphibolite to granulite facies mid crustal basement.The spherule is non-spherical in nature,containing mostly FeO(10.70±0.20 wt.%),CaO(13.8±0.5 wt.%),Al203(7.78±0.30 wt.%),MgO(6.47±0.3 wt.%),Si02(47,46±0.50 wt.%),Ti02(2.47±0.3 wt.%).K20(1.89±0.20 wt.%).and Cl(0.33±0.05 wt.%).Since the Fe composition of the spherule is almost same as the basement rock(10.5 wt.%),and the chlorine content is also in the same range as the basement(0.04-0.24 wt.%),it would suggest possibility of an extraterrestrial impact over the Indian terrain during the erstwhile Gondwana sedimentation period that may be associated with the Permian-Triassic mass extinction,the most severe one in the Earth's history.展开更多
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 ...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 India.Morphometric 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 coprolites.Scanning 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 diet.Furthermore,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 deposition.To 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.展开更多
The Koyna region of Maharashtra located in the western part of the~65 Myr old Deccan traps province,overlying the Neoarchean cratonic granitoid basement of peninsular India,has been experiencing recurring seismicity s...The Koyna region of Maharashtra located in the western part of the~65 Myr old Deccan traps province,overlying the Neoarchean cratonic granitoid basement of peninsular India,has been experiencing recurring seismicity since 1962 after the impoundment of the Shivajisagar Reservoir behind the Koyna Dam.展开更多
The oldest Asian record of alpheid shrimps,assigned to genus Alpheus,based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin,western India reported herein,extends the fossil record o...The oldest Asian record of alpheid shrimps,assigned to genus Alpheus,based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin,western India reported herein,extends the fossil record of the family Alpheidae from Asia by~22 million years.An early Miocene(Aquitanian)age is estimated based on the associated assemblage of calcareous nannofossils,Sphenolithus disbelemnos,Cyclicargolithus floridanus,and Reticulofenestra haqii.The co-occurring microbiota includes bony fish otolith remains,identified as“genus Gobiidarum”,isolated teeth of Dasyatis rays,Sphyrna sharks,and teleosts,ctenoid and placoid scales,ostracods,belonging to the genera Paractinocythereis,Alocopocythere,Ruggieria,Aglaiocypris,Bairdoppilata,and echinoid spines.Taken together,the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy,X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow(neritic)to coastal marine(intertidal)depositional paleoenvironment.The present investigation also provides the oldest fossil evidence on the co-occurrence of Alpheus and gobiids(based on otoliths)that strongly advocates that the mutualistic association between these animal groups had developed by the Aquitanian.展开更多
Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia.Palms(Arecaceae)are a d...Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia.Palms(Arecaceae)are a diverse family of typical thermophilous plants with a relatively low tolerance for freezing.In this study,we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin,northern Vietnam.Characters of the fossil leaves,such as a fan-shaped costapalmate lamina,an unarmed petiole,a costa slightly enlarged at the base that then tapers distally into the blade,and well-preserved amphistomatic leaves with cuticles,suggest that they represent a new fossil species,which we herein designate Sabalites colaniae A.Song,T.Su,T.V.Do et Z.K.Zhou sp.nov.Together with other paleontological and palaeoclimatic evidence,we conclude that a warm climate prevailed in northern Vietnam and nearby areas during the Oligocene.展开更多
The Deccan Volcanism during the Late Cretaceous was a globally significant geological event, coinciding with the Cretaceous-Paleogene Boundary. The magma outpouring occurred in three phases. The flora that got preserv...The Deccan Volcanism during the Late Cretaceous was a globally significant geological event, coinciding with the Cretaceous-Paleogene Boundary. The magma outpouring occurred in three phases. The flora that got preserved during the first phase (30N) was a mixed gymnosperm and angiosperm flora ranging from dry to moist forest vegetation. The second phase (29R) flora is mostly represented by pteridophytes and tropical to sub-tropical angiosperm plant families. The palynofloral records from the third phase (29N) are mostly tropical angiosperms. This floral turn-over is driven by latitudinal shifting of the Indian plate from sub-tropical to tropical zone. It is surmised that the latitudinal shifting of Indian plate during the span of 4 Ma during the Late Maastrichtian led to the development of new ecological conditions favoring successful dominance of angiosperms over gymnosperms.展开更多
Angiosperm evolved and diversified during Cretaceous. During this course of evolution and radiation, various pollen of uncertain origin had evolved. Aquilapollenites represents the early stock of angiosperms attaining...Angiosperm evolved and diversified during Cretaceous. During this course of evolution and radiation, various pollen of uncertain origin had evolved. Aquilapollenites represents the early stock of angiosperms attaining its acme with respect to diversity and dominance during Campanian and Maastrichtian age. It was globally present (except Antarctica) however more dominant in northern hemisphere (Canada, North America, Sakhlain Oblast and China). In India, the Aquilapollenites sp. is present in Maastrichtian aged deposits. The pollen affinity has been associated with Loranthaceae and Santalaceae plant families. Here, a comparative description of all the Aquilapollenites sp. comprising a wide range of morphological diversity has been discussed. The wider morphological diversity and ecological adaptability of Aquilapollenites sp. infer that it is globally significant and warrants a more detailed study.展开更多
The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia. The high species diversity of...The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia. The high species diversity of Dipterocarpaceae in SE Asian rain forests suggests its origin from SE Asia. However, its fossil history is much younger, from Oligocene, from the region. Based on the pollen fossil records from the late Cretaceous-early Paleogene sedimentary sequences of Indian subcontinent and the contemporaneous distribution of its extant taxa, evolutionary history of Dipterocarpaceae has been traced. The study suggests a West Gondwanan origin for this family. Present study also provides first evidence of Dipterocarpaceae genus Vateriopsis (endemic in Seychelles) type fossil pollen record from the late Cretaceous and early Palaeogene sedimentary sequences of western Indian margin.展开更多
The present study deals with the textural characteristics of the sediments from the exposed palaeochannel situated at Dhyangla village near Ladwa, district of Kurukshetra in north-western Haryana. It is a part of vast...The present study deals with the textural characteristics of the sediments from the exposed palaeochannel situated at Dhyangla village near Ladwa, district of Kurukshetra in north-western Haryana. It is a part of vast alluvial plains of India. Samples were taken from a 3 m thick exposed section. Grain size distribution and Palynofacies analyses of these sediments were carried out to study their textural parameters and the organic matter content respectively. Sediments are mostly fine to medium grained sand with silt percentage increasing upwards in the section. These sediments are mostly unimodal showing the grain size population controlled by a single type of grain size, mostly sand. Further the sand samples are moderately well sorted and mesokurtic in nature. Samples with silt are poorly sorted and leptokurtic with positive skewness, denoting those sediments have already sorted elsewhere in the high energy environment and are now transported and modified by the low energy environment. Palynofacies analysis also shows the presence of amorphous particles in the silt samples which indicate low energy environment of the sequence while presence of black debris in the sand samples indicates high energy depositions environment.展开更多
Himalayan glaciers‒the store house of fresh water outside the polar region contributes~45%of the total river flow by glacial melt in the Indus,Ganga and Brahmaputra watersheds which supports the livelihood of~500 mill...Himalayan glaciers‒the store house of fresh water outside the polar region contributes~45%of the total river flow by glacial melt in the Indus,Ganga and Brahmaputra watersheds which supports the livelihood of~500 million people[1].The sustainability of these rivers is being questioned because of the growing evidences of accelerated glacier retreat in the recent decades,which is expected to have cascading effects on the mountainous areas and their surrounding lowlands.展开更多
In the northeastern(NE) Arabian Sea,the fluctuation in terrestrial and freshwater runoff directly depends on southwest monsoon(SWM) precipitation as well as the meltwater flux provided by Indus River.Therefore,analysi...In the northeastern(NE) Arabian Sea,the fluctuation in terrestrial and freshwater runoff directly depends on southwest monsoon(SWM) precipitation as well as the meltwater flux provided by Indus River.Therefore,analysis of multi-proxy spectral signatures was carried out to trace the high-resolution SWM periodicities and their influence on the productivity,regional sea level fluctuations and depositional processes in the NE Arabian Sea.The time series data of stable isotopes of oxygen(δ^18 O(G.ruber)).carbon(δ^13 C(G.ruber) and δ^13 C(org)) and nitrogen(δ^15 N).Total Organic Carbon(TOC),planktic-benthic foraminiferal ratio(P/B ratio) and>63 μm coarse fraction(CF) were used from two coastal sedimentary cores located offshore Saurashtra,NE Arabian Sea(Core SK-240/485 having 88 m water depth;Core GC/SK-240/496 having 174 m water depth).The REDFIT based spectral analysis recorded significant periodicities(>90% significance) in δ^18 0 time series centered at^1609,~667,~525,~296,~290 and^256 years.Further,the significant periodicities recorded in carbon isotopes time series(δ^13 C(G.ruber) and δ^13 C(org))centered at^681,~512,~471,~452,~438,~360,~292,~275,~269,~245 and^209 years.The significant periodicities in TOC include^471 and-322 years whereas δ^15 N time series recorded significant periodicity centered at-360 years.The significant periodicities in P/B ratio time series centered at^512,~388,~304,~250,~235,~217,~152,~139 and^135 years while CF recorded^268,~216,~209,~198,~188,~173 and^140 years significant periodicities.The observed periodicities in the multi-proxy record consist of similar cycles(within the radiocarbon dating error) which also natch with previously reported solar insolation influenced SWM and other global and regional cycles.Further,the stationarity of the data has been verified using wavelet analysis and shows similar periodicities as observed in REDFIT analysis.Thereafter,the depositional behaviour was studied using correlation analysis of the common periods of δ^18 0 time series of both the cores.The result suggests that the depositional behaviour was different for both the core sites during the early Holocene and became similar during the middle Holocene.The correlation analysis of Total Solar Index(TSI) with δ^18 O time series reveals a significant correlation with the core SK-240/485 whereas an insignificant correlation with the core GC/SK-240/496.These observations suggest that the solar insolation has been a leading factor responsible for the SWM trends during the Holocene which may have further influenced the productivity.regional sea level fluctuations and depositional conditions in the NE Arabian Sea.However,these trends are better preserved in shallow marine sediments as compared to the deeper marine sediments.展开更多
The Burma Terrane has yielded some of the earliest pieces of evidence for monsoonal rainfall in the Bay of Bengal.However,Burmese ecosystems and their potential monsoonal imprint remain poorly studied.This study focus...The Burma Terrane has yielded some of the earliest pieces of evidence for monsoonal rainfall in the Bay of Bengal.However,Burmese ecosystems and their potential monsoonal imprint remain poorly studied.This study focuses on the late Eocene Yaw Formation(23°N)in central Myanmar,which was located near the equator(c.5°N)during the Eocene.We quantitatively assessed the past vegetation,climate,and depositional environments with sporomorph diagrams,bioclimatic analysis,and sequence biostratigraphy.We calculated the palynological diversity and drew inferences with rarefaction analysis by comparing with four other middle to late Eocene tropical palynofloras.Palynological results highlight a high floristic diversity for the palynoflora throughout the section formed by six pollen zones characterized by different vegetation.They indicate that lowland evergreen forests and swamps dominated in the Eocene Burmese deltaic plains while terra firma areas were occupied by seasonal evergreen,seasonally dry,and deciduous forests.This vegetation pattern is typical to what is found around the Bay of Bengal today and supports a monsoon-like climate at the time of the Yaw Formation.Bioclimatic analysis further suggests that in the late Eocene,the Yaw Formation was more seasonal,drier,and cooler compared to modern-day climate at similar near-equatorial latitude.More seasonal and drier conditions can be explained by a well-marked seasonal migration of the Intertropical Convergence Zone(ITCZ),driver of proto-monsoonal rainfall.Cooler temperatures in the late Eocene of central Myanmar may be due to the lack of adequate modern analogues for the Eocene monsoonal climate,while those found at other three Eocene Asian paleobotanical sites(India and South China)may be caused by the effect of canopy evapotranspirational cooling.Our data suggest that paleoenvironmental change including two transgressive-regressive depositional sequences is controlled by global sea level change,which may be driven by climate change and tectonics.The high diversity of the Yaw Formation palynoflora,despite well-marked seasonality,is explained by its crossroads location for plant dispersals between India and Asia.展开更多
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 ...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 India.The palynofacies data reveal three distinct palynofacies(A-C)as follows.Palynofacies A is dominated by abundant arborescent vegetation(glossopterids and conifers)along with structured organic matter,suggesting freshwater forest swamps in proximal settings.Palynofacies B is dominated by abundant degraded organic matter and amorphous organic matter,suggesting lakeshore/flooded palaeomires in slightly dismal settings.It has a high water level in the hinterland,which enables bacterial degradation of organic matter and establishes low-oxygenation conditions within the water column.These conditions would have provided grounds for the accumulation of either degraded or amorphous organic matter.Palynofacies C is dominated by the abundance of charcoal/opaque phytoclasts,indicating prolonged transportation or postdepositional alteration,suggesting a highly-oxidizing condition in distal settings.The bulk organic δ^(13)C range(-25.1‰ to-20.9‰)in the borehole MGK-6 is in close agreement with the global Permian records.This study also shows a weak but statistically significant correlation with the major forms of palynofacies A and C.The 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 precipitation.The 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 matter.The 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 Gondwana sedimentation.展开更多
A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A(DNG)(2800–2746 m depth)from the Krishna-Godavari Basin,Indi...A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A(DNG)(2800–2746 m depth)from the Krishna-Godavari Basin,India.The last appearance datum of marker species of dinoflagellate cysts and planktonic foraminifera was considered for the construction of the biostratigraphic framework.The study shows dominance of Early Cretaceous marker dinoflagellate cysts Cassiculosphaeridia magna,Cribroperidinium perforans,Hystrichodinium voigtii,Kleithriasphaeridium eoinodes,and planktonic foraminifera Hedbergella aptiana,Hedbergella mitra,Hedbergella praelippa,Hedbergella tardita,Microhedbergella miniglobularis and Hedbergella mitra species.In addition to this,the dinoflagellate cyst data were compared with the dinoflagellate biozones of Austral and Tethyan provinces.Based on earlier micropalaeontological records from the Krishna-Godavari Basin and the present study,a latest Barremian-early Aptian age has been determined for the earliest marine transgression in the Krishna-Godavari Basin.The early marine incursion during late Barremian-earliest Aptian in the Krishna-Godavari Basin compared to Albian age in Cauvery Basin suggests the opening of east coast from north to south.展开更多
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 b...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.展开更多
文摘During the early Paleogene,greenhouse gases created warm global climates.These warm climates redistributed the habitat of marine and terrestrial biota globally.Understanding the ecology of biotas under extremely warm climates is important to decipher their behavior in future climate warming.Here we report two new legume fossils(Leguminocarpum meghalayensis Bhatia,Srivastava et Mehrotra sp.nov.,and Parvileguminophyllum damalgiriensis Bhatia,Srivastava et Mehrotra sp.nov.) from the late Paleocene sediments of Tura Formation of Meghalaya,northeast India.Globally,the Paleocene legume fossil records indicate that legumes most likely immigrated to India from Africa via the Ladakh-Kohistan Arc during the early Paleogene.Moreover,previously reconstructed climate data from the Tura Formation indicate that legumes were well adapted to a warm seasonal climate with monsoon rains.
基金funding from the Department of Science and Technology(DST#/SR/S4/ES-528/2010)New Delhi and infrastructural facility from Department of Geology,University of Delhi.Research funding from the Council of Scientific and Industrial Research(CSIR#09/045(1021)/2010-EMR-I)the University of Delhi(Sch./UTA/2010/58053)is also gratefully acknowledged.
文摘With increase in shale gas exploration, inorganic and organic geochemical investigations of shale have become extremely important. Here, we explore the six argillaceous (shale) intervals (Arangi, Koldaha, Rampur, Bijaygarh, Rewa and Sirbu shale) from Son valley sector, Vindhyan Basin with an aim to understand provenance conditions, palaeoclimate, tectonic setting and hydrocarbon generation potential. Whole rock geochemistry indicates Vindhyan sediments derived from felsic source(s) except for Sirbu shale that indicates additional influx of mafic rocks with differentiated felsic source. A comparative study of Vindhyan shale rare earth elements (REEs) points to Mahakoshals and Chhotanagpur gneissic complex (CGC) as probable sediment provenance for Vindhyan sediments. CIA analysis, after necessary corrections for K-metasomatism, suggests evolution in weathering and palaeoclimate indicating a transformation from moderate weathering conditions with warm and humid climate during lower Vindhyan deposition to intense weathering conditions with hot and humid climate during upper Vindhyan deposition. Trace (La/Y vs. Sc/Cr) and REE analysis indicates passive margin setting for Vindhyan sediments whereas a wide range spanning passive to active continental margin setting is also inferred using (Th-Sc-Zr/10) and (Th–La-Sc) ternary diagrams. However, these tectonic discriminant diagrams lack in explaining rift- or sag-related origin of any intracratonic basin such as the Vindhyan Basin. The total organic carbon (TOC) content in Vindhyan shales ranges from 0.29% to 8.44%. The thermally liberated hydrocarbon (S1) values range from 0.01 to 0.18 mg HC/g rock (milligram hydrocarbon per gram of rock sample), whereas hydrocarbon from cracking of the kerogen (S2) shows values ranging from 0.04 to 0.47 mg HC/g rock. Based on modified Van Krevelen correlation (HI vs. Tmax) diagram, organic matter from Arangi and Bijaygarh shales is characterized as thermally mature, Type III kerogen of gas prone character indicating good to very good gas generation potential.
文摘The current article is an opinion on the sensitivity of high mountain regions which are the most fragile,sensitive and vulnerable to ongoing climate change.Its impacts are especially severe on the high mountain communities owing to their weak socio-economic profile,limited livelihood resources and agricultural land.The melting of glaciers and changes in the snow cover under the climate change scenario is leading to the scarcity of freshwater supplies,affecting both local and downstream communities.Changes in the precipitation patterns have been suggested to cause droughts,impact restricted agriculture,and limit the availability of water for domestic use.Additionally,the high mountain areas contain distinct flora and fauna,and climate change is not just altering them,but also has resulted in biodiversity loss as species are unable to adapt to the changing climate.Because of its higher altitudes and semi-arid to arid climate,the consequences of climate change are more evident in the higher Himalayas.Climate change is affecting the availability of key resources,such as freshwater and agriculture and pasture lands,resulting in food and water insecurity and their reliance on imports from other regions.As a result,high mountain communities in the Himalayas are progressively shifting to higher glacier valleys in search of suitable cultivable land with adequate irrigation.People are engaging in agro-pastoral activities around thermokarst lakes(Oasis)atop rock glaciers as part of this endeavour.Such actions underscore the crucial role of rock glaciers in dealing with and adjusting to the consequences of climate change.Despite its relevance,rock glacier research in the Himalayan region is still in its infancy.The purpose of this work is to emphasise the significance of these major climate-resilient water resources,as well as the methodology that must be adopted for their systematic and compressive investigations.
基金The authors are thankful to the Director,Birbal Sahni Institute of Palaeosciences,Lucknow for constant support and providing infrastructural facilities.
文摘The fragmented pattern and the rapidly declining preservation of older glacial features/evidences limits the precision,with which glacial chronologies can be established.The challenge is exacerbated by the scarcity of datable material and limitations of dating methods.Nevertheless,the preserved glacial landforms have been fairly utilized to establish glacial chronologies from different sectors of the Indian Himalayas.The existing Himalayan glacial chrono-stratigraphies have revealed that in a single valley,past glacial advances rarely surpass four stages.Thus,local and regional glacial chronologies must be synthesized to understand glacial dynamics and potential forcing factors.This research presents an overview of glacier responses to climate variations revealed by glacial chrono-stratigraphies in the western Indian Himalayan region over the Quaternary(late).The synthesis demonstrated that,although the glacial advances were sporadic,glaciers in western Himalayas generally advanced during the Marine isotope stage(MIS)-3/4,MIS-2,late glacial,Younger Dryas(YD)and Holocene periods.The Holocene has witnessed multiple glacial advances and the scatter is significant.While previous glacial research revealed that Himalayan glaciers were out of phase with the global last glacial maximum(gLGM),weak Indian Summer Monsoon(ISM)has been implicated(ISM was reduced by roughly 20%).Recent research,however,has shown that gLGM glaciation responded to the global cooling associated with the enhanced mid-latitude westerlies(MLW).Further,the magnitude of gLGM glacier advance varied along and across the Himalayas particularly the transitional valleys located between the ISM and MLW influence.It is also evident that both the ISM and MLW have governed the late Quaternary glacial advances in the western Himalayan region.However,the responses of glaciers to ISM changes are more prominent.The insights gained from this synthesis will help us understand the dynamics of glacier response to climate change,which will be valuable for future climate modelling.
文摘The use of bioactive compounds and probiotic bacteria against the viral diseases in human is known for a long time.Anti-viral,anti-inflammatory and anti-allergic properties of bioactive compounds and bacteria with probiotic properties in respiratory viral diseases may have significance to enhance immunity.This review highlights some of the important bioactive compounds and probiotic bacteria,suggesting them as a ray of hope in the milieu of the COVID-19 management.
基金PLANEX,Physical Research LaboratoryISRO-Space Application center,Ahmedabad for financial supportingsupported by the CSIR-Emeritus Scientist project sanctioned to O.P.Pandey
文摘A rare occurrence of a microspherule has been found in the infratrappean sediments,encountered below338 m thick Deccan volcanic cover in KLR-1 scientific borehole,drilled in the epicentral zone of the 1993 Killari earthquake(Maharashtra,India).Palynological studies of the sediments indicate their age as Early Permian(Asselian,298-295 Ma) for deposition.Transmission electron microscope studies reveal that the spherule from the infratrappeans,is having a similar composition to that of the Neoarchean amphibolite to granulite facies mid crustal basement.The spherule is non-spherical in nature,containing mostly FeO(10.70±0.20 wt.%),CaO(13.8±0.5 wt.%),Al203(7.78±0.30 wt.%),MgO(6.47±0.3 wt.%),Si02(47,46±0.50 wt.%),Ti02(2.47±0.3 wt.%).K20(1.89±0.20 wt.%).and Cl(0.33±0.05 wt.%).Since the Fe composition of the spherule is almost same as the basement rock(10.5 wt.%),and the chlorine content is also in the same range as the basement(0.04-0.24 wt.%),it would suggest possibility of an extraterrestrial impact over the Indian terrain during the erstwhile Gondwana sedimentation period that may be associated with the Permian-Triassic mass extinction,the most severe one in the Earth's history.
基金funding support from BSIP in the form of In-house Project No.2.17(XIII five-year plan)。
文摘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 India.Morphometric 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 coprolites.Scanning 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 diet.Furthermore,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 deposition.To 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.
基金conducted under the project sponsored by the Ministry of Earth Sciences,Govt.of India[Project Code-Mo ES/P.O.(Seismo)/1(374)/2019]
文摘The Koyna region of Maharashtra located in the western part of the~65 Myr old Deccan traps province,overlying the Neoarchean cratonic granitoid basement of peninsular India,has been experiencing recurring seismicity since 1962 after the impoundment of the Shivajisagar Reservoir behind the Koyna Dam.
基金granted by the BSIP LucknowIndia in the form of an In-house Project No. 3 (2021–2025)
文摘The oldest Asian record of alpheid shrimps,assigned to genus Alpheus,based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin,western India reported herein,extends the fossil record of the family Alpheidae from Asia by~22 million years.An early Miocene(Aquitanian)age is estimated based on the associated assemblage of calcareous nannofossils,Sphenolithus disbelemnos,Cyclicargolithus floridanus,and Reticulofenestra haqii.The co-occurring microbiota includes bony fish otolith remains,identified as“genus Gobiidarum”,isolated teeth of Dasyatis rays,Sphyrna sharks,and teleosts,ctenoid and placoid scales,ostracods,belonging to the genera Paractinocythereis,Alocopocythere,Ruggieria,Aglaiocypris,Bairdoppilata,and echinoid spines.Taken together,the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy,X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow(neritic)to coastal marine(intertidal)depositional paleoenvironment.The present investigation also provides the oldest fossil evidence on the co-occurrence of Alpheus and gobiids(based on otoliths)that strongly advocates that the mutualistic association between these animal groups had developed by the Aquitanian.
基金supported by National Natural Science Foundation of China(NSFC)(31800183,41922010,42002020,41661134049)Yunnan Basic Research Projects(202001AU070137,2019FB026)+2 种基金Chinese Academy of Sciences"Light of West China"Program(2020000023)the CAS 135 program(2017XTBG-T03)Project“Study,collection of fossil woods in Vietnam for exhibition in System of Vietnam National Museum of Nature”(CT0000.01/19-21).
文摘Recent paleobotanical investigations in Vietnam provide a good opportunity to improve our understanding of the biodiversity and paleoclimatic conditions in the geological past of Southeast Asia.Palms(Arecaceae)are a diverse family of typical thermophilous plants with a relatively low tolerance for freezing.In this study,we describe well-preserved fossil palm leaves from the Oligocene Dong Ho Formation of Hoanh Bo Basin,northern Vietnam.Characters of the fossil leaves,such as a fan-shaped costapalmate lamina,an unarmed petiole,a costa slightly enlarged at the base that then tapers distally into the blade,and well-preserved amphistomatic leaves with cuticles,suggest that they represent a new fossil species,which we herein designate Sabalites colaniae A.Song,T.Su,T.V.Do et Z.K.Zhou sp.nov.Together with other paleontological and palaeoclimatic evidence,we conclude that a warm climate prevailed in northern Vietnam and nearby areas during the Oligocene.
文摘The Deccan Volcanism during the Late Cretaceous was a globally significant geological event, coinciding with the Cretaceous-Paleogene Boundary. The magma outpouring occurred in three phases. The flora that got preserved during the first phase (30N) was a mixed gymnosperm and angiosperm flora ranging from dry to moist forest vegetation. The second phase (29R) flora is mostly represented by pteridophytes and tropical to sub-tropical angiosperm plant families. The palynofloral records from the third phase (29N) are mostly tropical angiosperms. This floral turn-over is driven by latitudinal shifting of the Indian plate from sub-tropical to tropical zone. It is surmised that the latitudinal shifting of Indian plate during the span of 4 Ma during the Late Maastrichtian led to the development of new ecological conditions favoring successful dominance of angiosperms over gymnosperms.
文摘Angiosperm evolved and diversified during Cretaceous. During this course of evolution and radiation, various pollen of uncertain origin had evolved. Aquilapollenites represents the early stock of angiosperms attaining its acme with respect to diversity and dominance during Campanian and Maastrichtian age. It was globally present (except Antarctica) however more dominant in northern hemisphere (Canada, North America, Sakhlain Oblast and China). In India, the Aquilapollenites sp. is present in Maastrichtian aged deposits. The pollen affinity has been associated with Loranthaceae and Santalaceae plant families. Here, a comparative description of all the Aquilapollenites sp. comprising a wide range of morphological diversity has been discussed. The wider morphological diversity and ecological adaptability of Aquilapollenites sp. infer that it is globally significant and warrants a more detailed study.
文摘The Dipterocarpaceae plant family, that shows a disjunct distribution in Gondwanan continents and Southeast Asia, is a dominant constituent of the tropical rain forests of Southeast Asia. The high species diversity of Dipterocarpaceae in SE Asian rain forests suggests its origin from SE Asia. However, its fossil history is much younger, from Oligocene, from the region. Based on the pollen fossil records from the late Cretaceous-early Paleogene sedimentary sequences of Indian subcontinent and the contemporaneous distribution of its extant taxa, evolutionary history of Dipterocarpaceae has been traced. The study suggests a West Gondwanan origin for this family. Present study also provides first evidence of Dipterocarpaceae genus Vateriopsis (endemic in Seychelles) type fossil pollen record from the late Cretaceous and early Palaeogene sedimentary sequences of western Indian margin.
文摘The present study deals with the textural characteristics of the sediments from the exposed palaeochannel situated at Dhyangla village near Ladwa, district of Kurukshetra in north-western Haryana. It is a part of vast alluvial plains of India. Samples were taken from a 3 m thick exposed section. Grain size distribution and Palynofacies analyses of these sediments were carried out to study their textural parameters and the organic matter content respectively. Sediments are mostly fine to medium grained sand with silt percentage increasing upwards in the section. These sediments are mostly unimodal showing the grain size population controlled by a single type of grain size, mostly sand. Further the sand samples are moderately well sorted and mesokurtic in nature. Samples with silt are poorly sorted and leptokurtic with positive skewness, denoting those sediments have already sorted elsewhere in the high energy environment and are now transported and modified by the low energy environment. Palynofacies analysis also shows the presence of amorphous particles in the silt samples which indicate low energy environment of the sequence while presence of black debris in the sand samples indicates high energy depositions environment.
文摘Himalayan glaciers‒the store house of fresh water outside the polar region contributes~45%of the total river flow by glacial melt in the Indus,Ganga and Brahmaputra watersheds which supports the livelihood of~500 million people[1].The sustainability of these rivers is being questioned because of the growing evidences of accelerated glacier retreat in the recent decades,which is expected to have cascading effects on the mountainous areas and their surrounding lowlands.
基金SERB-DST Project No.SR/FTP/ES-53/2013Council of Scientific and Industrial Research(CSIR)(Grant No.09/528/0022/2018/EMR-1)for the financial assistance in the form of fellowshipssupported by fast-track grant of SERB-DST under project No.SR/FTP/ES-53/2013
文摘In the northeastern(NE) Arabian Sea,the fluctuation in terrestrial and freshwater runoff directly depends on southwest monsoon(SWM) precipitation as well as the meltwater flux provided by Indus River.Therefore,analysis of multi-proxy spectral signatures was carried out to trace the high-resolution SWM periodicities and their influence on the productivity,regional sea level fluctuations and depositional processes in the NE Arabian Sea.The time series data of stable isotopes of oxygen(δ^18 O(G.ruber)).carbon(δ^13 C(G.ruber) and δ^13 C(org)) and nitrogen(δ^15 N).Total Organic Carbon(TOC),planktic-benthic foraminiferal ratio(P/B ratio) and>63 μm coarse fraction(CF) were used from two coastal sedimentary cores located offshore Saurashtra,NE Arabian Sea(Core SK-240/485 having 88 m water depth;Core GC/SK-240/496 having 174 m water depth).The REDFIT based spectral analysis recorded significant periodicities(>90% significance) in δ^18 0 time series centered at^1609,~667,~525,~296,~290 and^256 years.Further,the significant periodicities recorded in carbon isotopes time series(δ^13 C(G.ruber) and δ^13 C(org))centered at^681,~512,~471,~452,~438,~360,~292,~275,~269,~245 and^209 years.The significant periodicities in TOC include^471 and-322 years whereas δ^15 N time series recorded significant periodicity centered at-360 years.The significant periodicities in P/B ratio time series centered at^512,~388,~304,~250,~235,~217,~152,~139 and^135 years while CF recorded^268,~216,~209,~198,~188,~173 and^140 years significant periodicities.The observed periodicities in the multi-proxy record consist of similar cycles(within the radiocarbon dating error) which also natch with previously reported solar insolation influenced SWM and other global and regional cycles.Further,the stationarity of the data has been verified using wavelet analysis and shows similar periodicities as observed in REDFIT analysis.Thereafter,the depositional behaviour was studied using correlation analysis of the common periods of δ^18 0 time series of both the cores.The result suggests that the depositional behaviour was different for both the core sites during the early Holocene and became similar during the middle Holocene.The correlation analysis of Total Solar Index(TSI) with δ^18 O time series reveals a significant correlation with the core SK-240/485 whereas an insignificant correlation with the core GC/SK-240/496.These observations suggest that the solar insolation has been a leading factor responsible for the SWM trends during the Holocene which may have further influenced the productivity.regional sea level fluctuations and depositional conditions in the NE Arabian Sea.However,these trends are better preserved in shallow marine sediments as compared to the deeper marine sediments.
基金the China Scholarship Council(CSC grant 201604910677)the University of Amsterdam+1 种基金the European Research Council Consolidator Grant(MAGIC 649081)the ANR grant ANR-19-ERC7-0007.
文摘The Burma Terrane has yielded some of the earliest pieces of evidence for monsoonal rainfall in the Bay of Bengal.However,Burmese ecosystems and their potential monsoonal imprint remain poorly studied.This study focuses on the late Eocene Yaw Formation(23°N)in central Myanmar,which was located near the equator(c.5°N)during the Eocene.We quantitatively assessed the past vegetation,climate,and depositional environments with sporomorph diagrams,bioclimatic analysis,and sequence biostratigraphy.We calculated the palynological diversity and drew inferences with rarefaction analysis by comparing with four other middle to late Eocene tropical palynofloras.Palynological results highlight a high floristic diversity for the palynoflora throughout the section formed by six pollen zones characterized by different vegetation.They indicate that lowland evergreen forests and swamps dominated in the Eocene Burmese deltaic plains while terra firma areas were occupied by seasonal evergreen,seasonally dry,and deciduous forests.This vegetation pattern is typical to what is found around the Bay of Bengal today and supports a monsoon-like climate at the time of the Yaw Formation.Bioclimatic analysis further suggests that in the late Eocene,the Yaw Formation was more seasonal,drier,and cooler compared to modern-day climate at similar near-equatorial latitude.More seasonal and drier conditions can be explained by a well-marked seasonal migration of the Intertropical Convergence Zone(ITCZ),driver of proto-monsoonal rainfall.Cooler temperatures in the late Eocene of central Myanmar may be due to the lack of adequate modern analogues for the Eocene monsoonal climate,while those found at other three Eocene Asian paleobotanical sites(India and South China)may be caused by the effect of canopy evapotranspirational cooling.Our data suggest that paleoenvironmental change including two transgressive-regressive depositional sequences is controlled by global sea level change,which may be driven by climate change and tectonics.The high diversity of the Yaw Formation palynoflora,despite well-marked seasonality,is explained by its crossroads location for plant dispersals between India and Asia.
基金funded by the Birbal Sahni Institute of Palaeosciences,Department of Science and Technology,Lucknow,India(BSIP/RDCC/Publication no.63)。
文摘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 India.The palynofacies data reveal three distinct palynofacies(A-C)as follows.Palynofacies A is dominated by abundant arborescent vegetation(glossopterids and conifers)along with structured organic matter,suggesting freshwater forest swamps in proximal settings.Palynofacies B is dominated by abundant degraded organic matter and amorphous organic matter,suggesting lakeshore/flooded palaeomires in slightly dismal settings.It has a high water level in the hinterland,which enables bacterial degradation of organic matter and establishes low-oxygenation conditions within the water column.These conditions would have provided grounds for the accumulation of either degraded or amorphous organic matter.Palynofacies C is dominated by the abundance of charcoal/opaque phytoclasts,indicating prolonged transportation or postdepositional alteration,suggesting a highly-oxidizing condition in distal settings.The bulk organic δ^(13)C range(-25.1‰ to-20.9‰)in the borehole MGK-6 is in close agreement with the global Permian records.This study also shows a weak but statistically significant correlation with the major forms of palynofacies A and C.The 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 precipitation.The 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 matter.The 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 Gondwana sedimentation.
基金funded By Ministry of Earth Science,Govt.of India under the sponsored project no.Mo ES Geo.Sci.(Po/36/2014).
文摘A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A(DNG)(2800–2746 m depth)from the Krishna-Godavari Basin,India.The last appearance datum of marker species of dinoflagellate cysts and planktonic foraminifera was considered for the construction of the biostratigraphic framework.The study shows dominance of Early Cretaceous marker dinoflagellate cysts Cassiculosphaeridia magna,Cribroperidinium perforans,Hystrichodinium voigtii,Kleithriasphaeridium eoinodes,and planktonic foraminifera Hedbergella aptiana,Hedbergella mitra,Hedbergella praelippa,Hedbergella tardita,Microhedbergella miniglobularis and Hedbergella mitra species.In addition to this,the dinoflagellate cyst data were compared with the dinoflagellate biozones of Austral and Tethyan provinces.Based on earlier micropalaeontological records from the Krishna-Godavari Basin and the present study,a latest Barremian-early Aptian age has been determined for the earliest marine transgression in the Krishna-Godavari Basin.The early marine incursion during late Barremian-earliest Aptian in the Krishna-Godavari Basin compared to Albian age in Cauvery Basin suggests the opening of east coast from north to south.
基金procured from the National Remote Sensing Centre (NRSC) Hyderabad under the project “Assessment of Potential Vulnerability of Western Himalayan Glaciers to Climate Change”funded by the Indian Space Research Organisation,Department of Space,India.
文摘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.
