Spatio-temporal climatic variations during the last five millennia in the Ladakh Himalaya (India) and its links to archaeological finding(s) (including coprolites) in a palaeoecological and palaeoenvironmental context: A reappraisal

摘要

Ladakh region (Trans-Himalaya) is strategically placed as far as movement, demographic shifts and rich multicultural heritage is concerned owing to being a meeting point between Central Asia and South Asia i.e., utilization of the world famous "Silk Route" during the last two millennia. Further, the Ladakh region has in the past decade gained attention of geoscientists interested to understand the Holocene climate variability and its effect(s) on the region's geomorphology, flora, and fauna (including humans) as being positioned within the transitional zone of the Indian Summer Monsoon and the Westerlies. In the present article, we reassess the available records on climatic variation(s) for the past five millennia in this important region. Our reappraisal of the previously available palaeoclimatic reconstructions from sediment records viz. Tsokar, Tso-moriri, Pulu (north and south), Upshi, and Pensila allowed us to demarcate four broad climatic zones -Temporal-cultural Phase 1 [cold and arid; 5 to similar to 2.5 ka (terminal Neolithic to early Historical)], Temporal-cultural Phase 2 [moderately cold and arid; 2.5 to similar to 1.5 ka (early Historical to later Historical)], Temporal-cultural Phase 3 [warm and wet; 1.5 to similar to 0.9 ka (later Historical continued)], and Temporal-cultural Phase 4 [cold and arid; 0.9 ka onwards (early Medieval period)] since the past five millennia. In addition, the known archaeological records (petroglyphs and other artifacts) from Ladakh in a chronological, palaeoenvironmental, and palaeoecological context also support prevalence of an arid climate from 0.9 ka to present in the region. Further, considering nonexistence or absolute rarity of research on Holocene coprolites (palaeofeces) from India, a first detailed record on coprolites (represented by four morphotypes linked to Lagomorphs, Chiropterans, and Aves) from a cave site (Rumtse), Ladakh Himalaya is presented herein that corroborates our findings on prevalence of cold and arid climate. Finally, the Ladakh region certainly holds potential for recovery of ichnofossils (particularly coprolites), associated faunal remains and other archaeological features (e.g., petroglyphs) from the Holocene interval. Thus, future archaeological endeavors can become quite instrumental in furthering our knowledge to understand any change(s) in the dietary pattern(s) within individual faunal groups (including humans) and their surrounding ecology linked to change(s) in the climate of the Ladakh sector.