Facies analysis and paleoenvironmental interpretation of Piacenzian carbonate deposits from the Guitar Formation of Car Nicobar Island,India

Facies characterization of Piacenzian （late Pliocene） carbonate sediments of the Guitar Formation in Car Nicobar Island,India and the subsequent integration of paleoecological data have been applied to interpret the paleoenvironment of the coralline algal-reef deposits.Thin-section analysis reveals that Amphiroa,Corallina and Jania are the dominant geniculate corallines,while Lithothamnion,Mesophyllum,Phymatolithon,Lithophyllum,Spongites and Lithoporella are the major non-geniculate corallines contributing to the sedimentary facies.Numerous small and larger benthic foraminifera also dominate the biogenic assemblages.Corals,barnacle shells,echinoid spines,fragments of bryozoans,mollusks and ostracodes are the subordinate constituents.Grainstones dominate the studied facies while packstones and boundstones （with wackestone elements） are the sub lithofacies showing a fair representation.Six carbonate facies presenting a complete reef complex have been distinguished that were deposited in shallow intertidal,back-reef shelf/lagoon,reef and deeper fore-reef shelf settings.Evidences of coralline algal and benthic foraminiferal assemblages,taphonomic signatures of abrasion and fragmentation,grain size,angularity and encrustation indicate a shallow to relatively deeper bathymetric horizon of approximately 10-60 m that corresponds to a regime of high to moderate hydrodynamic conditions.

Deterioration of Early Holocene coral reef due to sea level rise along west coast of India:Benthic foraminiferal testimony

A total of 103 surface sediment samples collected from the water depth range of 15-3300 m along Vijaydurg-Karwar stretch of central west coast of India were analyzed for foraminiferal content. Relict benthic foraminiferal assemblage was noted within 50--135 m water depth. The relict benthic foraminiferal assemblage that includes Amphistegina, Operculina and Alveolinella in sediment samples within the water depth of 85-- 135 m indicates presence of coral reef at this depth during Early Holocene. The presence of barnacle fouling on Relict foraminifera at 60--90 m confirms the paleo-shoreline. The shallow depth zone is characterized by presence of agglutinated relict foraminifera. The agglutinated forms indicate freshwater influx, which eventually increased the sea level and subsequently deteriorated the paleo-coral reef.

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

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.

Palynomorphs and Oribatid Mites—From the Denwa Formation, Satpura Basin, Madhya Pradesh, India

Palynological investigation of the Denwa Formation exposed along Denwa river succession at Saptadara picnic point near village Jhirpa, Satpura Basin, Madhya Pradesh, has revealed the presence of spore-pollen, fungal remains and Oribatid mites. Here, the mites are on record for the first time. Presence of fungal remains strongly depicts the prevalence of a very humid climate with high temperature and rainfall in the region. Poor occurrence of spore-pollen restricts the age determination of the studied section;hence, its age assessment is relative. Thus, an over-view of spore-pollen along with dinocysts and insects reported earlier from the subsurface strata comprising Denwa Formation, from other two localities in the nearby area of village Anhoni, is dealt herein, and that had inferred an age—range from Carnian to Rhaetic for the palynoflora and fauna.

Glossopterids survived end-Permian mass extinction in North Hemisphere

Recently,more attention has been paid to Glossopteris,the most significant representative fossil of the Gondwanan Supercontinent in the Paleozoic.It has been regarded as an important clade of Angiophytes on the basis of its reproductive organ related to Angiosperms.Since Brongniart erected Glossopteris in 1928,reliable Glossopterids attached by fertile organs were only collected from the Permian Gondwanaland.Here,the authors found a new element of Glossoptetids,Sinoglossa sunii gen et sp.nov.,with attached female organs from the Middle Triassic Linjia Formation in Benxi,Northeast China.This demonstrates that Glossoptetids not only distributed in South Hemisphere,but also in North Hemisphere,and successfully survived the end-Permian mass extinction in North Hemisphere.The distinguished environment in Northeast China influenced by both warm and cold currents,probably resulted in the Paleozoic relic elements,such as Glossopterids associated with Lobatannularia successfully survived the end-Permian mass extinction.

Damming of River Indus during Late Quaternary in Ladakh Region of Trans-Himalaya, NW India: Implications to Lake formation-climate and tectonics

Indus river valley basin in Northwest Indian Himalaya is tectonically unstable, exhibiting a complex topography, landscape relief and varied Quaternary sedimentation. A 422 km transact along the Indus river valley from Nyoma to Batalik in Ladakh(Trans Himalayas) reveals the damming of the river four places and existence of four major palaeolakes in the Late Quaternary Period. The commencement and breeching of the palaeolake sequences and the seismites preserved therein mark of the tectonic pluses in the area but the contribution of climate cannot be ruled out. The major geomorphic landforms are alluvial fans, debris cones, unsorted pedestals, fluvio-lacustrine deposits, scree, talus cone etc. Ubiquitous mass movements and catastrophic land sliding, due to tectonic activity and abnormally high precipitation has transported the material from steep slopes to valley bottoms, was responsible of forming lakes(preserved as thick piles of fine sediment), while the outburst floods redistributed the sediment down valley. Chronologies of two lakes are available which reveal the presence of one during post LGM times around 17000 a BP which breached out prior to Older Dryas indicating of warmer and congenial rainfall and melt water supply between these two globally marked cold episode. Other lake was formed after the Younger Dryas and existed till ~1000 a BP indicative of the Holocene warming responsible for its sustenance.

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

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.

Palynofloral changes in the Upper Paleozoic and Mesozoic of the Deocha-Pachami area, Birbhum Coalfield, West Bengal, India

The study of Upper Paleozoic and Mesozoic palynomorphs in three boreholes from the Deocha-Pachami area, Birbhum Coalfield, West Bengal, India, has allowed dating of the Talchir, Barakar, Dubrajpur, and Rajmahal formations, and revealed many hiatuses. The lowermost unit, the Talchir Formation, yielded earliest Permian palynomorphs. The Barakar Formation, which includes coal-bearing strata, was previously dated as Early Permian. However, data presented herein indicate an Early Permian to earliest Triassic age for this unit,containing actually the Karharbari, Barakar s.s., Kulti, and Ranigang formations as well as the basal part of the Panchet Formation. The overlying Dubrajpur Formation is Jurassic (Callovian to Tithonian), with an unconformity at its base. The uppermost Dubrajpur Formation is Tithonian-Berriasian. The palynomorphs from the intertrappeans within the Rajmahal Formation suggest an Early Cretaceous age. The revised ages of the Barakar and Dubrajpur formations are of major regional significance. The distribution patterns of spore-pollen may provide a broad spectrum of paleoclimate during Permian, Late Jurassic, and Early Cretaceous times, as there is no record of marine signatures in the study area.

Diversity of Middle Eocene Coralline Red Algae from the Prang Limestone(Shella Formation) of Jaintia Hills, Meghalaya, NE Himalaya, India with special emphasis on palaeoenvironment

Palaeocene-Eocene carbonates of shallow marine sequence belonging to Shella Formation of Jaintia Group are well developed in the south of the Jaintia Hills, Meghalaya and represent an excellent outcrop of shelf sediments in North Eastern Himalaya, India. These outcrops are exposed along the southern fringe of Shillong Plateau. The Prang Limestone is the uppermost lithostratigraphic unit of the Shella Formation within the Jaintia Group. It is overlain by sand-shale alternation of the Kopili Formation and underlain by the Narpuh Sandstone. A rich assemblage of larger foraminifera including Nummulites, Discocyclina etc. has been recorded earlier from the Prang Limestone and based on the foraminiferal assemblage, a Middle Eocene to Early Late Eocene age has been assigned to the Prang Limestone. Thin section analysis of the Prang Limestone revealed the abundance of well preserved coralline red algae along with other well preserved and significant biogenic elements. Morpho-taxonomical study reveals that the algal flora is represented by seven species belonging to the families Hapalidiaceae(Subfamily: Melobesioideae), Corallinaceae(Subfamily: Mastophoroideae) and Sporolithaceae. The dominance of melobesioid and mastophoroid forms is the characteristic feature of this algal assemblage. Coralline algae occur mostly in encrusting growth form with orbitoid foraminifera and occasionally the coralline algae form rhodoliths. On this basis of algal forms it can be inferred that they thrived in a shallow, warm, shelf environment of normal salinity.

Further contribution to the Neogene petrified wood forest of Mizoram, India

Mizoram, a state situated in the northeast corner of India, is very rich in fossil woods belonging to the Tipam Group(Late Miocene-Early Pliocene in age). Four new fossil woods, namely Swintonioxylon hailakandiense Prakash & Tripathi, Bombacacioxylon tertiarum Mehrotra et al., gen. et sp. nov., Dipterocarpoxylon jammuense Guleria et al. and Bischofia palaeojavanica Awasthi are described from there. They resemble the modern taxa, namely Swintonia Griff.(Anacardiaceae), Dipterocarpus C.F. Gaertn.(Dipterocarpaceae), Bischofia Blume(Euphorbiaceae) and the taxa of the family Bombacaceae. The distribution of the modern equivalents of the present and previously described taxa indicates the existence of warm and humid climate in Mizoram during the depositional time.

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

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 the presence of much better climatic conditions in the region during the Cenozoic as compared to the present. More importantly, a fossil fruit of Cocos L. described from the Eocene sediments of Rajasthan further indicates the presence of sea in the nearby area at the time of deposition of the sediments. The recovery of a few African elements from western India provides the evidence of establishment of land connections between India and Africa up to the Plio-Pleistocene through which these elements could enter the Indian subcontinent.

Plant Remains from an Archaeological Site as Indicators of Vegetation and Agricultural Practice Between(3 320±400) and(2 080±80) yr BP in Gangetic West Bengal,India

Diverse plant remains recovered from an archaeological site of Chslcollthlc-Early Historic age in the Bhalrabdanga area of Pakhanna （latitude 23°25′N, longitude 87°23′E）, situated on the west bank of the Damodar river, Bankura district, West Bengal, India, include food grains, wood charcoals, and palynomorphs. Radiocarbon dating of the recovered biological remains reveal the age of the site as （3 320 ± 400） to （2 080± 80） yr BP. The food grains were Identified as Oryza sativa L. and Vigna mungo L, and seeds of Brassica cf. campestris L. were also found; these indicate the agricultural practice and food habits of the ancient people living at Pakhanna from the Chalcolithlc to the Early Historic period. Sediments Including plant remains have been broadly divided into two zones, considering archaeological findings and radiocarbon dating. Analysis of the plant remains （I.e, wood charcoals and palynomorphs） in addition to cultivated food grains has revealed that a rich vegetation cover existed in this area, with a prevailing tropical and humid climate, comprising the timber-yielding plants Shores sp., Terminalia sp., and Tamarindus sp., with undergrowths of diverse shrubs and herbs during the Chalcolithic period （zone I） dated （3 320 ± 400） yr BP. Comparatively poorer representation and frequency of plant remains Indicate a drier climate during the Early Historic period （zone Ⅱ） dated as （2 110 ± 340） to （2 080 ± 80） yr BP. Comparisons of the archaeobotanical data recovered from the Chalcollthic and Early Historic period and also a principle components analysis Indicate a change In the climate of the area from tropical and humid at （3 320 ± 400） yr BP to tropical and drier conditions at （2 110 ± 340） to （2 080 ± 80） yr BP. The present-day tropical, dry deciduous vegetation of the area suggests that climate change has occurred in the area since the contemporaneous past. The plant remains database has been utilized to reconstruct the settlement pattern of the community living in the site between （3 320 ± 400） and （2 080 ± 80） yr BP. The community settled near the riverbank, practicing cultivation.

Man-environment interaction and its impact since ca. 3600 years BP in West Bengal, India: A multiproxy approach

Climatic variability during the Holocene and corresponding anthropogenic response have gained considerable attention in different parts of India, but surprisingly very little is known on climate-human interrelationship from eastern India especially from the Gangetic plains of West Bengal. As climate has played significant role behind the collapse of many of the ancient human civilizations hence, to explore the reason behind the abandonment of any archaeological site, understanding of the climate of the contemporaneous past is a prerequisite. Agricultural development, subsistence strategies and dynamic behavior of climate in the Lower Gangetic plains of West Bengal since ca. 3600 cal a BP(Chalcolithic period) and post-Chalcolithic period(ca. 2350–2120 cal a BP to recent) were explored using multiproxy approach including plant-animal macro remains, wood charcoals and pollen and non-pollen palynomorphs from an archaeological site at Pakhanna, district Bankura in West Bengal, India. Evidences from palynological and phytolith data suggest that a warm-moist tropical climate during ca. 3600 cal a BP supported the spread of a village farming community in this part of lower Gangetic plains of West Bengal who practiced double-cropping as evidenced by the recovery of cereals(rice) and pulses(black gram) from the cultural deposits of Chalcolithic and Early Historic periods. In addition, a plenty of animal remains(opercula of carp fishes, fragments of plastron of Indian Soft Shelled Turtle, Indian Flap Shelled Turtle, ramus of mandible with teeth of Indian Boar) from similar cultural deposits indicate their probable inclusion in dietary list. The climate started changing during the onset of Early Historic period ca. 2350 cal a BP as revealed by pollen and phytolith proxies and became warmer and drier than that in earlier phase which is continuing till recent. The observations of palynological and phytolith data were also corroborated by the results of correspondence analysis(CA) and canonical correspondence analysis(CCA) respectively. Recovery of rice and mustard from Early Historic deposits suggests their continued cultivation at a later phase. Rich assemblages of animal macro remains from the post-Chalcolithic deposits(ca. 2350–2120 cal a BP) indicate their use as food resources in later phase too. Considering the database obtained from all the proxies it can be concluded that a moist-tropical climatic condition was prevailing during Chalcolithic period(ca. 3600 cal a BP) and later gradually shifted to a slight drier condition in lower Gangetic West Bengal.