全球变化知识资源中心

Paleoclimate investigations and reconstruction using the lake sediment cores of Kashmir Valley have been rarely attempted. The basin is influenced by Indian Summer Monsoon, Westerlies and the local katabatic winds. In the present study, an 80 cm undisturbed sediment core was retrieved from the Manasbal Lake situated in North western Himalaya. Sediments were dated using C-14 method, and the age-depth model indicated a depositional history extending from similar to 3345 yrs BP to the present. Grain size, major and trace elements, TOC, OM contents C/N ratio and diatom assemblages were applied to reconstruct the paleoenvironmental changes around the area. The A-CN-K diagram displays that the weathering intensity of the Manasbal lake sediments are moderate to highly weathered and the sediments have been derived from nearby and mixed source origin. Several wet and cold phases were identified during similar to 3300 yrs BP to similar to 2500 yrs BP and -1800 yrs BP to -1300 yrs BP due to intense precipitation reflect high lake level. These wet phases are marked by higher sand and silt content, C/N ratio and high allochthonous input with less abundance of diatom species, clay, OM, TOC contents and high CIA values. Consequently, low lake level and dry and cold period from similar to 3345 yrs BP to similar to 3300 yrs BP and similar to 2500 yrs BP to similar to 1800 yrs BP is observed. These inferences are corroborated with the trace elemental ratios CIA and CWI data. Our data indicate that the Westerlies and localised katabtic winds rather than the Indian summer monsoons played a major role in controlling the past climate around the Manasbal lake, Kashmir Valley.