Annual Report 2011-2012 - Birbal Sahni Institute of Palaeobotany

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EBIRBAL SAHNI INSTITUT 1946 OF PALAEOBOTANY Annual Report 2011-2012 footprint and fight global warming. It is a crucial element in the balance of oxygen and carbon dioxide in the atmosphere. S.K. Basumatary, Kanupriya Gupta, S.K. Bera [& S.K. Acharya & Sneha Bera (BCKB, W. Bengal) & M. Ahmad (Goalpara College, Assam)] Prepared manuscript based on Isotope analysis (d 13 C and d 18 O) of tree-ring of Abies pindrow collected from forest near to Dokriani Bamak glacier, Uttarakhand. A. Bhattacharyya & S.K. Shah [& R. Ramesh (PRL, Ahmedabad)] Past climate and vegetation history have been analyzed from two profiles collected from Nonkremp close to Shillong, Meghalaya based on pollen data. A. Bhattacharyya, S.K. Shah & Sandhya Misra [& Pawel Prokop Polish Academy of Sciences, Poland) Studied the tree line dynamics of Himalayan silver fir (Abies spectabilis D. Don) based on its tree-ring data and age stand distribution at Langtang National Park, Central Nepal. The study shows that the average tree density of the species in the study area (total 48 plots of 20 m x 20 m) was 236 no/ha while that for sapling and seedling in the study area was 255 and 350 no/ha, respectively. The stand character and age distribution of the species showed a high level of recruitment in the recent decades, with decreased in average age along with increased altitude. Tree-growth climate relationship showed negative response with temperature of March- May. Upward advancement of tree line is expected in the coming recent decades though not necessarily uniform through the line. S.K. Shah [& R. Bhuju, Nepal Academy of S&T, Nepal)] Two Pleistocene-Holocene sedimentary profiles from Darjeeling Sub-Himalaya have been studied for palaeoclimatic reconstructions using pollen and phytolith proxies. Ruby Ghosh [& Subir Bera, University of Calcutta, Kolkata)] The ongoing collaborative work in Spiti Valley is to study for their sedimentary architecture and chronological parameters. Lithofacies analyses of relict sedimentary sequences located in the rain shadow zone of Tethyan Himalaya shows six different lithofacies. The six different lithofacies identified can be grouped into three lithofacies associations: i) glacial outwash, ii) sedimentation in channel and accreting bars under braided conditions, and iii) formation of lakes due to channel blockage by landslide activity. Abnormal Monsoon Years at 14-8 ka and 50-30 ka are responsible for the phases of channel damming and lake formation in the valley. A research paper is under review. Anupam Sharma & Binita Phartiyal [& Pradeep Srivastava & Yogesh Ray (WIHG, Dehradun)] The Spiti river basin in the NW Indian Himalaya (31–33°E:77–79°S), is tectonically unstable, exhibiting a complex topography, landscape relief and varied Quaternary sedimentation. The major geomorphic landforms are fill terraces, strath terraces, alluvial fans, debris cone, fluvio-lacustrine deposits, scree and talus cone are present throughout the valleys. The dynamics of landscape evolution of the region are currently not well understood. An attempt is made by using the geomorphometry approach to access the areas in terms of its neotectonic instability as this basin feeds the river Sutlej. The Spiti and the Parachu basin of the Sutlej valley are mapped and assessed in the valley to elucidate the spatio-temporal scale dependencies of surface have been in news several times in the last decade causing flooding downstream, due to the outburst of glacial lakes and the temporary lakes formed during the land sliding even by the processes active in the region. The Spiti river (constituting of Spiti and Parachu basins) is examined using and geomorphic field methods (Spiti basin), and OSL chronologies by Phartiyal et al., (2009) are used. During the Quaternary a ubiquitous mass movements and catastrophic land sliding transported material from steep slopes to valley bottoms is seen which was responsible of forming lakes (preserved as thick piles of fine sediment), while the outburst floods redistributed sediment down valley along with affecting life and property downstream. The morphometric approach such as Basin Asymmetry (AF), Topographic Symmetric Factor (T), Stream length Gradient Index (GI) Hydauralic Sinuosity Index (HSI), Topographic sinuosity Index (TSI) and Standard Sinuosity Index (SSI) have helped in understanding tectonic and climatic perturbation. Our observations point towards a tectonically active region with enormous piles of loose, unconsolidated sediment cover which could be disastrous during the slight shift of the climatic and tectonic forces operating in this area. Binita Phartiyal [& G.C. Kothyari (ISR, Gandhinagar)] In order to determine the mid Holocene climatic fluctuations, multi-proxy study involving palynology, phytolith, clay mineralogy, geochemistry and magnetic susceptibility are carried out on Wadhavana lake sediments of main land Gujarat area. The 2.3 m sediment profile of 42 www.bsip.res.in
EBIRBAL SAHNI INSTITUT Annual Report 2011-2012 1946 OF PALAEOBOTANY wadhavana lake shows deposition of silty clay with frequent sandy intervals in the lower part followed by predominance of silt in the middle and sandy silt in the upper part. The lower part of the succession shows predominance of evergreen and moist deciduous arboreal pollen taxa, fresh water algae, festucoid grass phytoliths indicating high lake stand and prevalence of winter precipitation leading to cool and moist climatic conditions during ~5,665-4,824 yrs BP. Presence of pollen taxa represented by Madhuca, Meliaceae, Asteraceae and abundant micro-charcoal with burnt wheat husk remains provide evidence of Harappan influence during the time span. At 4,824 yrs BP replacement of freshwater algae with cyanobacteria and considerably high values of phytolith aridity indices and considerably low susceptibility values indicates fall in lake level, formation of playa and onset of aridity in this region. The continuous higher values of phytolith aridity indices and absence of pollen provided evidence of extreme moisture deficient conditions in the lake ~4,200-~3,500 yrs BP and prevalence of arid climatic conditions in the surrounding region. Monsoon regains its strength ~3,380 yrs BP however the lake level did not reach to its original level. Phytolith studies shows change in seasonality from cool and moist climate of mid Holocene to warm and humid climate of late Holocene with prominent pre-monsoonal warm conditions somewhat similar to present day. Vandana Prasad, Anjum Farooqui Anupam Sharma& Binita Phartiyal [& Supriyo Chakraborty (IITM, Pune)] Pollen and organic-inorganic carbon analysis of a 2.8 m deep sediment profile from Jalesar Lake, Unnao district (UP) reveals that a little prior and between 42,490 to 13,560 cal yrs BP this region supported grassland largely comprising grasses with scanty trees of Syzygium and Prosopis under a cool and dry climate. The sediments deposited during 13,560 to 5,260 cal yrs BP are palynologically barren and also coarser in nature may be linked to the upwarping phase of the Ganga Plain, resulting into rapid deposition/erosion and reworking of the sediments including calcrete formation. Between 5,260 and 4,760 cal yrs BP with the immigration of more trees viz., Holoptelea, Acacia, Bombax ceiba, Aegle marmelos, etc groves of forest interspersed with grassland got established due to amelioration climate. Interestingly, the debut of Cerealia pollen denotes the initiation of cereal-based agricultural practice in the region. Around 4,760 to 3,260 cal yrs BP, the incursion of a large number of trees viz., Madhuca indica, Emblica officinalis, Sterculia, Adina cordifolia, besides existing earlier and consistently high organic carbon values implies that the forest groves became diversified with the onset of a warm and humid climate in response to active SW monsoon. The rising trend of Cerealia pollen reflects the acceleration of agricultural practice in the region. Between 3,200 and 1,200 cal yrs BP the forest groves turned sparse owing to reduction in monsoon precipitation leading to prevalence of a less-humid climate in the region. Since 1,200 cal yrs BP the diminishing trend of arboreals signifies further decline in rainfall witnessing a warm and dry climate. Anjali Trivedi, M.S. Chauhan, Anupam Sharma & C.M. Nautiyal [& D.P. Tiwari (Dept. of AIH & Archaeology, Lucknow)] Work carried out on Makran samples for hazard potential study. C.M. Nautiyal [& C.P. Rajendran & Associates (IISc, Bengaluru)] Work has been initiated on Lake sediments involving dating as well as major element analysis by ICP- AES. C.M. Nautiyal [& P. Singh & P.K. Gautam (Univ. of Pondicherry, TN)] Work on charcoal from archaeological sites in Kangra and Kinnaur (HP) is being explored and initiated involving radiocarbon dating, XRD and other geochemical techniques. C.M. Nautiyal [& Researchers (from HNBGU, Srinagar & IIT, Roorkee)] Detailed systematic studies on floral elements of Weller Formation (Early Permian of Allan Hills, South Victoria Land, Transantarctic Mountains, Antarctica visà-vis correlation with flora of Gondwana sedimentary basins of India is in progress. Rajni Tewari [& Sankar Chatterjee (Texas Tech University, Lubbock, USA)] Finalized a manuscript on ‘Palaeobotanical evidence of wildfire in the Upper Permian of India: Macroscopic charcoal remains from the Raniganj Formation, Damodar Basin’. Macroscopic fossil charcoal has been discovered in the carbonaceous shales associated with Seam-VI of Raniganj Formation, Upper Permian. A pycnoxylic gymnosperm wood is described and confirms the occurrence of palaeo-wildfire in this area during the Late Permian. The integration of the data presented in the current study with previously published data for the Raniganj Formation, principally related to the occurrence of (pyrogenic) inertinites within coal layers, www.bsip.res.in 43
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Annual Report 2011-2012 - Birbal Sahni Institute of Palaeobotany

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