J. Earth Syst. Sci. (2021) 130:93 Ó Indian Academy of Sciences https://doi.org/10.1007/s12040-021-01586-2 (0123456789().,-volV)(0123456789().,-volV) Impact of climate on the evolution of vegetation in tectonically active Karewa basin, Kashmir Himalayas 1, 1 1 1 ANJUM FAROOQUI *, SURESH KPILLAI ,DEEPA AGNIHOTRI ,SALMAN KHAN , 1 1 1 1 RAJNI TEWARI ,SUNIL KSHUKLA ,SAJID ALI ,ANJALI TRIVEDI , 2 1 3 1 SKPANDITA ,KAMLESH KUMAR ,GDBHAT and RAJESH AGNIHOTRI 1Birbal Sahni Institute of Palaeosciences, 53, University Road, Lucknow 226 007, India. 2Department of Geology, University of Jammu, Jammu 180 006, India. 3Directorate of Geology and Mining, Jammu and Kashmir Government, Srinagar, India. *Corresponding author. e-mail: afarooqui˙[email protected] MS received 8 September 2020; revised 19 January 2021; accepted 22 January 2021 The rise of the Himalayas governed the Indian Summer Monsoon in Karewa basin during Plio-Pleistocene. A palynological study is presented to delineate the climate-vegetation relationship using an 8.5-m thick Cuvio-lacustrine sequence of the Hirpur Formation (2.4–2.1 Ma). Our results suggest that the sediment sequence is mainly comprised of two units, namely, Unit 1 and Unit 2. Unit 1 shows the dominance of sub-tropical to broad-leaf temperate vegetation when mean annual temperature (MAT) was *17°C and mean annual precipitation (MAP) was 1025 mm. The subsequent increase in sand followed by a thin lignite layer with Trapa megafossil (fruits) demarcates Cuvial adjustments, suggesting a low altitude Cuvio-lacustrine ecosystem. Conversely, Unit 2 shows a decline in rainforest pollen with a steady increase in conifers. The abrupt dominance of diatom species Tetracyclus lacustris and related species with MAT and MAP reducing to 10°C and 770 mm reveal a colder climate with the lacustrine ecosystem. This change of tropical to cool temperate vegetation could be attributed to the altitudinal rise of the Pir Panjal Mountains and consequent obstruction of the south-west monsoon, which resulted in lower pre- cipitation and temperature during *2.4–2.1 Ma. Hence, the relic tropical Cora of Palaeogene/Neogene transformed to Himalayan temperate Cora sometime *2.1 Ma. Keywords. Palynology; diatoms; sponge spicules; sediment texture; Karewa; Indian summer monsoon. 1. Introduction (Kashmir valley, India), Kathmandu basin (Cen- tral Nepal) and Heqing basin (Yunnan, China) in A series of upliftment in Himalayas following the the Himalayan region (Fujii and Sakai 2002; collision of Indian and Tibetan plates during late Goddu et al. 2007). The organic matter buried in Cenozoic time period had a profound impact on these lacustrine sediments indicates climatic vari- global climate and also in the region through ability and landscape changes primarily inCuenced mechanical, thermal and weathering eAects (Prell by Quaternary glacial and interglacial cycles (Fujii and Kutzbach 1992; Raymo and Ruddiman 1992). and Sakai 2002; Mampuku et al. 2004). The chan- The few sedimentary archives that provide the ges in Plio-Pleistocene climate, tectonics in Pir records of climate–vegetation relationship of Plio- Panjal Range of Himalaya played a key role in the Pleistocene time period are the Karewa Group geomorphic evolution of Karewa Lake in Kashmir 93 Page 2 of 21 J. Earth Syst. Sci. (2021) 130:93 Figure 1. (a–d) The evolution of Karewa basin since 4 Ma to present and the location of the study site (modiBed after Dar et al. 2014b). Table 1. Lithology of 8.5 m river-cut section of Lower Karewa beds along Ningle Nala, Butapathri, Kashmir. Sample no. Depth Group Formation (Buta-Pathri) (cm) Colour Lithology Chronology Recent Sand Clay Gravel Holocene Karewa Nagum Formation Gravel, sand marl, sandy clay, silt, Early clay Pleistocene Hirpur Formation 12 (TOP) 541–626 Light grey Clay with parallel lamination (Lower Karewas) containing pinch and swell structures 11 494–541 Light brown Sand 10 456–494 Light greenish Corser sand with parallel yellow lamination containing pinch and swell structures 9 446–456 Black Coal (lignite) 8 422–446 Grey/light Very Bne clay/mudstone with yellow parallel lamination 7 397–422 Light grey Clay 6 355–372 Light yellow Parallel laminated clay 5 315–323 Black Coal (lignite) 4 255–315 Black Lignite band with sand 394–147 Green Clay with parallel lamination 260–80 Grey Carbonaceous shale with lignite band 1 (Bottom) 0–50 Greenish light Silty clay grey .....................Unconformity..................... Panjal Volcanics (permo-Carboniferous/Triassic Limestone) J. Earth Syst. Sci. (2021) 130:93 Page 3 of 21 93 valley (Burbank 1983; Agrawal et al. 1989; Dar Dodia et al. 1984; Gupta et al. 1985; Sharma et al. et al. 2014a, b). Studies reveal that the sedimen- 1985; Sharma and Gupta 1985; Gupta and Khan- tary sequence of the Hirpur Formation (Lower delwal 1986; Dodia 1988). The faunal records also Karewa) is known to represent the Brst interglacial support the low altitude warmer climate (Sahni period of the Quaternary period (DeTerra and and Kotlia 1983, 1985; Kotlia 1985). Paterson 1939; Wadia 1976). The most compre- The rainforest Cora that occupied the entire hensive chronology of sedimentary deposits from Indian sub-continent during the Palaeogene/Neo- the Kashmir basin has been earlier discussed in gene is now conBned to South-Western Ghats and detail by Singh (1982), Burbank (1982) and Bur- north-eastern part of India because of relatively bank and Johnson (1983). Recently, a palaeomag- high rainfall only in these regions (Prasad et al. netic data between 4.4 and 0.77 Ma was recorded 2009; Farooqui et al. 2010). An overall tendency of from Romushi river cut section (Basavaiah et al. increasing dry climate and downfall of the rain- 2010). These Bndings suggest Indian Summer forest from Tertiary to the late Pleistocene has Monsoon (ISM) weakened over the Kashmir valley been observed and these go well with Bndings in after *1.95 Ma. The remains of Cora from Hirpur Siwalik sediments of northwest India, Karewa Formation (Lower Karewa Lake sediments) are deposits of Kashmir valley and lacustrine deposits scant but indicate low altitude, tropical rainforests of Tibetan Plateau (Basavaiah et al. 2010; Singhvi pollen and diatoms (Gandhi and Mohan 1983; et al. 2011). The ISM variability during the Qua- ternary period has been studied earlier (An et al. 2011; Saraswat et al. 2014 and references therein). However, the details of the vegetation in equilib- rium with the Quaternary climatic spasms are Figure 2. Lithology details of the Ningle Nala section, Figure 3. A comparative account of chronology and lithology Butapathri, Kashmir. of the Ningle Nala section, Butapathri. 93 Page 4 of 21 J. Earth Syst. Sci. (2021) 130:93 Figure 4. Palynological spectrum and climatic phases of Ningle Nala section, Butapathri, Kashmir. Figure 5. Relative percentages of freshwater diatoms and sediment texture of Ningle Nala section, Butapathri, Kashmir. scant (Krishnamurthy et al. 1986; Agrawal et al. subsequent shift in Indian Summer Monsoon in 1989; Farooqui et al. 2014) from the Indian the Himalayan region during early–middle sub-continent. Scant palynological records (Nair Pleistocene. 1960; Mohan and Vora 1987) are only available from the exposed sedimentary sections of Lower Karewa. Therefore, here we provide an extensive 1.1 Stratigraphic background of the study area record of more than 80 taxa of subtropical to temperate rainforest diversity, diverse diatom and The Kashmir valley is an intermontane basin in the freshwater sponge species and sediment Western Himalayas of Indian sub-continent. On depositional environment responding to the rise of the west, it is Canked by Tethyan belt and the Pir Pir Panjal mountain ranges and the time period of Panjal mountain ranges, and on the eastern side by J. Earth Syst. Sci. (2021) 130:93 Page 5 of 21 93 Figure 6. Relative percentages of freshwater sponges (microscleres and gammoscleres) of Ningle Nala section, Butapathri, Kashmir. Figure 7. Cumulative record of different proxies and climatic/ecological interpretations of Ningle Nala section, Butapathri, Kashmir. the Greater Himalayas (Bgure 1a). Around 4 Ma intercalated lignite beds and unconsolidated con- ago, the Kashmir basin was Blled with a massive glomerates (Bhatt 1975, 1976; Singh 1982). lake (Bgure 1b) and later on the lake boundary was Stratigraphically, Karewa Group is divided into pushed against the Himalayan Cank (Bgure 1c) due two formations namely, older Hirpur Formation to ongoing orogenic eAects of Pir Panjal mountain and younger Nagum Formation separated by an ranges (Godwin-Austen 1864; Lydekker 1878; angular unconformity (table 1) and the type sec- Drew 1975). The orogenically uplifted lake sedi- tion is exposed in Hirpur area. The Hirpur For- ments came to be known as Karewa Group mation has been divided into older Dubjan (Bgure 1d). The entire sedimentation in Karewa Member (600 m) followed by Rembiara Member Group is controlled by the tectonics (Burbank (200 m) and the top Methawoin Member (400 m) 1982; Burbank and Johnson 1983). About 1300-m (Bhatt 1989). The sedimentation in the Karewa thick Karewa Group is made of clays, sands with basin has been punctuated by conglomerate 93 Table 2. Vegetation type inCuenced by climate and tectonic changes in two units of Ningle Nala sedimentary section, Butapathri, Kashmir. Early Pleistocene epoch (Lower Karewa Formation) Unit 1 Unit 2 Page 6 of 21 Assemblage type Phase 1 Phase 2 Phase 3 Phase 4 1. Warm temperate Alnus, Betula, Juglans, Quercus, Ulmus, Acer, 17.3 16 9.7 9.7 Fagus, Carpinus, Corylus, Larix, Salix 2. Cool temperate Pinaceae type 11.5 14.7 77.9 77 Abies pindrow, Abies sp., Cupressus, Juniperus, (Pinus Picea, Abie, 65%) Pinus roxburghii, P. wallichiana, Picea sp., Rhododendron 3. Rain forest Arboreal Pollen 3.7 2.7 (Rosaceae) 4 4 Ericaceae, Meliaceae, Ilex, Sapindus, Toona, All Palaquium, Caraya, Proteaceae, Rosaceae, Symplocos, Annonaceae, Prinsepia utilis, Turpinia, Mallotus, Randia, Malvaceae Shrubs/herbs 12.45 10.7 (Celastrus, Rubus, 3.1 – Ainsliaea latifolia, Anemone, Anthriscus Anthriscus, (Anemone, Asteraceae, caucalis, Asteraceae,Campanula, Celastrus, Chenopodiaceae, Chenopodi–aceae, Chenopodiaceae, Chrysanthemum type, Asteraceae, Impatiens) J.