Pleistocene paleoenvironmental changes in the high mountain ranges of central China and adjacent regions

Abstract

Abstract During several joint Chinese–German expeditions, the Quaternary landscape and paleoclimatic evolution of the mountain ranges and grabens surrounding the Loess Plateau of central China was studied. The results are compared with proxy data from the interior Loess Plateau, to help reconstruct atmospheric circulation during Late Pleistocene times. Middle to Late Pleistocene alluvial terraces and fans, capped with loess units and paleosols, show that aggradational episodes correlate with periods of glaciation and increased loess accumulation. In turn, degradation correlates with interglacials or interstadials and increased soil formation. This implies that climate is the primary control on Quaternary paleohydrology and alluvial sedimentation and erosion. The high mountains, which barely reached the last glacial ELA, were only glaciated during the most favourable climatic period of glaciation. The glaciation, the glacial and alluvial forms point to a cool early to maximum glacial period with increased precipitation and to a maximum to final period with cold–dry conditions. During the last glaciation, the maximum advance of the small glaciers took place towards the end of a relatively humid and cold period between ca. 32 and 23 ka. The following dry–cold stage between ca. 23 and 13 ka was rather unfavourable for glacial advance. Proxy data from the Loess Plateau supports the view, that glaciations were more or less dominated by cold–dry winter monsoon climate, whereas during the interglacial/interstadials a warmer and more humid climate prevailed, implying a strengthening of the summer monsoon influence. The results prove variations of the monsoon, that in turn modulates paleohydrology, periglacial dynamics, glacier advances, dust flux and soil formation.