Abstract:
Vegetation and climate during later part of Pleistocene to major part of Holocene (~16.6e3.5 ka) has been
reconstructed based on the palynological and magnetic susceptibility proxies from an exposed section of
lacustrine deposit at Rukti, Sangla valley, Kinnaur, western Himalaya. Study shows that along with the
general tree line succession to higher altitudes since early Holocene, the area has also captured the major
climatic events of late Pleistocene to early-mid Holocene time. The area exhibits a continuation of mixed
conifer - broadleaved forest at least since ~16.6 ka with intermittent phases of expansions of broadleaved
tree taxa especially Oaks (Quercus) or invasion of conifers especially Pine (Pinus) with an increase (moist)
or decrease (dry) of Indian Summer Monsoon (ISM) respectively. This is also supported by the variations
in the magnetic susceptibility values. The climate was warm and moist during ~16.6 ka and changed to
cool ~13.3 ka, followed by increasing ISM since ~11.5 ka. Distinct spike in the magnetic susceptibility
values between ~8.7 and ~7.8 ka could correspond to global 8.2 ka cool event thus indicating
strengthening of westerly influence and low evaporation. Subsequent warm conditions could be
generalized by the advancement of Birch (Betula) line to higher altitude following the resultant retreat of
the glacial body. Study has put forth the potential of such Himalayan sites to uncover the major climatic
events of global correlation captured by various proxies within a region.
