亚洲中部中更新世以来气候环境变化——来自天山北坡黄土沉积的证据

Climate changes in center Asia since the middle pleistocene——Study from loess sediment in north slop of Tianshan Mt.

亚洲中部干旱区的形成演化对于理解干旱区大气粉尘的全球气候环境效应等具有极重要的科学价值。天山北坡沙湾县东湾镇厚71m的风成黄土为探讨该区环境演化提供了极好素材。对该剖面气候代用指标分析表明,中更新世以来气候环境经历了3个时期,在0.60和0.25 Ma左右发生了重要气候事件,现在干旱气候格局是0.25Ma左右形成延续至今。

The formation and variation of arid region, climate changes and temporal--spatial evolution of deserts, aeolian dust events series in center Asia is helpful to scientific understanding the im- pact of aeolian dust on climate changes in Asian arid region during the Quarternary, and study on the thick loess strata and paleoenvironmental record. Well located at the northern margin of Tianshan Mt, nearly 71m depth loess deposition in Dongwan Town of Shawan County provides good opportunity to investigate the regional environmental change. Systemic studies of climatic indicators including loess grain size, magnetic susceptibility, were carried out in aeolian loess section. Our study indicates that climatic and environmental evolution in northern Xinjiang region experienced three stages since middle Pleistocene. A relative wet climate dominated at the period of 0. 80-0. 60MaBP, aridity evolving at the period of 0. 60-0. 25MaBP and dry from 0. 25MaBP to present. Climate became more and more arid over the time. Two important events were detected at the 0. 60MaBP and 0. 25MaBP respectively, which accelerated the aridity process in the region. Arid controlled climate today is formed no later than 0. 25Ma.