Mid-late holocene climatic reconstruction using core sediments from Khajjiar lake, Himachal Pradesh, India

Abstract

We present results of our investigations on 7.65 m long core sediments from the Khajjiar lake, Himachal Pradesh, aimed at reconstructing palaeoclimate variability in the climatically sensitive region affected by both ISM (Indian Summer Monsoon) and IWM (Indian Winter Monsoon). Based on the multi-proxy approach, including organic geochemistry (carbon isotopes), magnetic susceptibility as primary proxies and inorganic geochemistry (major oxides) with grain size analysis as secondary proxies, climate of the mid-late Holocene (∼4600 yr) has been established on centennial to millennial scale. The chronology of the sediments is constrained by five AMS radiocarbon dates. The sedimentological data reveal variations in sediment grain size related to palaeo-precipitation. The first high resolution multi-proxy record from the Khajjiar lake core indicates less humid conditions during ∼4600–4185 cal yr BP except an extreme peak of dry and arid climate at around ∼4370 cal yr BP. Intensified monsoon with more wet and humid conditions has been interpreted during ∼4185–3790 cal yr BP. ∼3790–3300 cal yr BP, ∼2845–2115 and ∼1555–405 cal yr BP, and ∼2990–2845 cal yr BP and fluctuations are observed from ∼2115 to 1555 cal yr BP. The results suggest two major climatic phases corresponding with the 4.2 ka and Roman Warm Period (RWP). A regional comparison of mid-late Holocene climate records reveals a broad synchronicity, but with considerable spatial variation. The timing and duration of climate events varied across regions.