【摘要】 围绕IODP 683号建议书,介绍东亚东倾地形格局与季风系统演化历史的相关研究。新生代全球宏观环境格局发生了一系列重大变化,表现为岩石圈活动强烈,板块漂移导致海陆格局和地貌格局的变化,并引发洋流和大气环流的改组,最终导致全球气候的重大变化。新生代岩石圈运动和气候变化表现最为典型的地区是亚洲,其中最具标志性和全球意义的地质事件是喜马拉雅山和青藏高原的隆升及亚洲季风系统的形成与演化。青藏高原隆升最直接的结果是亚洲地区现代地貌格局的形成,大江大河的发育,并在很大程度上影响了亚洲季风系统的形成与演化。综合大洋钻探计划683号航次建议书,计划在长江中下游盆地和东海陆架盆地实施钻探,以获得长江历史演化和东亚季风演化的地质记录,并为研究青藏高原的演化提供新的证据。更多还原

【Abstract】 Ocean drilling in the Bengal Fan has revealed the uplift history of the Himalayas and Indian monsoon,but there is no analogous deep-water fan in the Western Pacific marginal seas that can be drilled and used to constrain the Tibet uplift history from its eastern side.The Yangtze river,originating from northeastern Tibet and draining a large area prevailed by monsoon precipitation,is highly sensitive to plateau uplift and monsoon evolution.A systematical study of the Yangtze river deposits will test various hypotheses concerning plateau uplift and its link with monsoon evolution.Along the modern Yangtze river,the upper reach is decoupled from the lower reach by the Three Gorges.About 30% of the total sediment load from the Yangtze river is laid in the Jianghan Basin immediately out from the Gorges,~40% is deposited in the lower reach and delta,and only ~30% is transported to the East China Sea.Therefore,a combination of ocean and continental drilling along the Yangtze River will recover records useful for carving the history of uplift and monsoon.A close timing of tectonic and climatic events mainly at four time intervals has been proposed as evidence for a link between Tibet uplift and the Asian monsoon initiation: the late Pliocene(2~3 Ma),the late Miocene(~8 Ma),the early-middle Miocene(~15 Ma) and the latest Oligocene(~25 Ma).On the basis of the Three Gorges incision or delta development data,however,the history of the Yangtze River can be traced back only to the late Pliocene or early Pleistocene,and the East China Sea came into existence only in the latest Miocene.A younger Yangtze river is in a sharp contrast to the early uplift of Tibet.In the Paleogene,a broad belt of aridity stretched across China from west to east,and numerous lake basins developed in rift grabens,prohibiting any east-flowing large rivers.Large rivers like the Yangtze river could have developed only since Neogene with the advent of an east-tilting topography and monsoon in East Asia.The proposed joint IODP/ICDP project will provide sediment records from marine and terrestrial basins to help clarify the most puzzling issues in East Asian environmental evolution and to test the hypothetical link between Tibetan uplift and monsoon climate from the eastern side of the plateau.更多还原