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A coupled environmental system formed at about 2.5 Ma in East Asia

1992; Elsevier BV; Volume: 94; Issue: 1-4 Linguagem: Inglês

10.1016/0031-0182(92)90120-t

1872-616X

Zhongli Ding, Nat Rutter, Han Jingtai, Tungsheng Liu,

Geomagnetism and Paleomagnetism Studies

The somewhat abrupt commencement of loess deposition on a large scale in north-central China is palaeomagnetically measured at about 2.5 Ma. The formation of the dynamical conditions responsible for windblown loess processes implies a reorganization of the atmospheric circulation over eastern Asia. It is speculated that at that time, the accelerated uplift of the Tibetan Plateau had reached a threshold height, giving rise to the intensification and northward shift of the Siberian high and deepening of the cyclone in the lee of the Tibetan Plateau. The uplift of Tibet and the resulting reorganization of atmospheric circulation at about 2.5 Ma would initiate a coupled environmental system: Tibetan Plateau-inland desert-Loess Plateau in eastern Asia that could be a key system in understanding the onset of glaciation in Northern Hemisphere and climatic change in the Quaternary. The climatic shift from near-continuous warm condition before 2.5 Ma to frequent and chaotic fluctuations after is speculated to be triggered to a significant extent by the uplift of the Tibetan Plateau. An orography-cold surge-albedo-temperature feedback mechanism is developed in explaining the harsher climate over East Asia during glacial time and is thought to be one of the major contributors in promoting glacial development on the globe.