A regional record of expanded Holocene wetlands and prehistoric human occupation from paleowetland deposits of the western Yarlung Tsangpo valley, southern Tibetan Plateau

Abstract

The Asian Monsoon, which brings ~80% of annual precipitation to much of the Tibetan Plateau, provides runoff to major rivers across the Asian continent. Paleoclimate records indicate summer insolation and North Atlantic paleotemperature changes forced variations in monsoon rainfall through the Holocene, resulting in hydrologic and ecologic changes in plateau watersheds. We present a record of Holocene hydrologic variability in the Yarlung Tsangpo (YT) valley of the southern Tibetan Plateau, based on sedimentology and 14C dating of organic-rich black mats’ in paleowetlands deposits, that shows changes in wetlands extent in response to changing monsoon intensity. Four sedimentary units indicate decreasing monsoon intensity since 10.4 ka BP. Wet conditions occurred at ~10.4 ka BP, ~9.6 ka BP and ~7.9–4.8 ka BP, with similar-to-modern conditions from ~4.6–2.0 ka BP, and drier-than-modern conditions from ~2.0 ka BP to present. Wetland changes correlate with monsoon intensity changes identified in nearby records, with weak monsoon intervals corresponding to desiccation and erosion of wetlands. Dating of in situ ceramic and microlithic artifacts within the wetlands indicates Epipaleolithic human occupation of the YT valley after 6.6 ka BP, supporting evidence for widespread colonization of the Tibetan Plateau in the early and mid-Holocene during warm, wet post-glacial conditions.

Human genetic history on the Tibetan Plateau in the past 5100 years

“…and was widespread along the entire Yarlung Tsangpo River valley by 2000 B.P. The wide span of the southern plateau ancestry is likely related to prehistoric human migration up the river, possibly facilitated by favorable environmental conditions for humans along this river valley ( 27 , 28 ).…”

“…Tsangpo River before 3400 B.P. The Yarlung Tsangpo River (27) is the greatest river on the Tibetan Plateau, with its headwaters in the Ngari prefecture from the western regions of the plateau. It spans across the entire southern plateau, running west to east, from the Ngari prefecture through the Shigatse, Shannan, and Lhasa prefectures of the southwestern and southern plateau, and out through the Nyingchi prefecture in the southeastern plateau (Fig.…”

Mallines en la Sierra de Comechingones, Sierras Pampeanas, Argentina. Caracterización geológico-geomorfológica y reconstrucción paleoambiental durante el Holoceno

“…Por otra parte, y considerando las características que poseen los humedales en general, como ambientes receptores de agua y sedimentos, el estudio sedimentológico y del registro biológico preservado en ellos (e.g., polen o diatomeas) permite inferir condiciones paleoambientales y paleoclimáticas, especialmente durante el Cuaternario (e.g., Quade et al, 1995;Pigatti et al, 2010Pigatti et al, , 2014Owen et al, 2004;Hudson et al, 2016).…”