青藏高原末次快速隆升与“亚澳”陨击事件

黄土、山前磨拉石年代学最新研究成果表明青藏高原及其相邻山脉最晚一期,也是最强烈的隆升事件发生在早更新世晚期(0.9～0.8MaB.P.)。这是一次由于印度板块脉冲式陆内俯冲(A型)引起的“挤压隆升”,而不是重力均衡引起的“伸展隆升”。它对中亚及我国西部广袤区域盆-岭地貌的形成、盆地中-新生界构造变形和大范围的干旱与沙漠化起了决定性的影响。0.9～0.8MaB.P.期间发生在印度洋洋中脊三联点附近(67°E,20°S)的“亚澳”陨击事件,很可能是引起印度洋快速扩张、导致印度板块在锡瓦利克带强烈俯冲(A型),并引起了青藏高原0.9～0.8MaB.P.快速隆升的大陆动力学背景。其影响不止于印度洋周边,而且还涉及西南太平洋。0.9MaB.P.前后引起全球气候变化的“中更新世革命”(MPR)、“西太平洋暖池”的形成以及0.78MaB.P.布容期与松山期地磁极性倒转(BM界限)的发生都可能与此有关。

LAST RAPID UPLIFT OF QINGHAI-XIZANG PLATEAU AND THE AUSTRALASIAN EVENT OF METEORITES

The recent studies of loess and fore mountain molasses show that the last and the strongest uplift of Qinghai Xizang Plateau and adjacent mountains occurred in the late of Early Pleistocene (0.9～0.8MaB.P.). The uplift is a compressing uplift event resulted from the pulse (A type) inner continent subduction of Indian Plate rather than an extending uplift event resulted from the gravity equilibrium. The event definitively influenced the formation of the basin mountain topographic outlines, basin deformations in the Mesozoic Cenozoic and the large scale aridity and desert in Central Asia and Western China. The Australasian event of meteorites occurred in 0.9～0.8MaB.P. in the triangle area of Indian Ocean ridge (67°E,20°S), and probably resulted in a rapid extension of Indian Ocean ridge and pushed the Indian Plate to subduct rapidly to the north. The event provided the dynamics of the last rapid uplift of Qinghai Xizang Plateau. Its influence is not only around Indian Ocean, but also in southwestern Pacific Ocean. The 0.9MaB.P. “Middle Pleistocene Revolution”(MPR) that gave rise to the global climate changing, formation of “Western Pacific Warm Pool?” and the geomagnetic reversal between Brunches and Matsuyama epochs (B/M magnetic boundaries) during 0 78MaB.P. could be related to this event also.