新生代亚洲形变与海陆相互作用

Cenozoic Deformation and History of Sea-Land Interactions in Asia

在现今各个大陆中 ,亚洲经历的新生代形变最强 .白垩纪到老第三纪时的亚洲大陆 ,不仅面积较今为小 ,而且形态偏“瘦” ;自从始新世印度与亚洲碰撞之后 ,亚洲的面积与高度急剧增大 .随着青藏高原隆升和边缘海的张裂 ,东亚原来西倾的地势发生倒转 ,形成了从大陆中央隆升区向周围辐射的亚洲大河流系 .亚洲隆升有可能是北极冰盖形成与发展的重要因素 ,因为隆升不仅改变大气环流、加剧风化作用 ,而且还使西伯利亚河系改向北流 ,通过注入北冰洋的淡水促使海水结冰、导致冰盖形成 .新生代亚洲形变 ,也使得亚洲季风系统在早中新世形成 ,又在约 8Ma与约 3Ma时强化 .同时 ,西太平洋边缘海系列的形成 ,也改变了亚洲大陆与太平洋之间的物质与能量的交换 .流经边缘海的太平洋西部边界流 ,对于洋面升降和构造运动极为敏感 ,在冰期低海面时边界流位于边缘海之外 ,使大洋输向大陆的热量和水分大为减少 .今天 ,亚洲与太平洋之间的能流与物流最为活跃 。

Of the existing continents, Asia experienced the most significant deformation during the Cenozoic. From the Cretaceous to early Paleogene, Asia was smaller and slimmer compared with the present continent. After the India-Asia collision in the Eocene, Asia significantly enlarged its size and increased its altitude. The west-tilting topography of East Asia was reversed with the uplift of the Tibetan plateau and the opening of marginal seas, resulting in an Asian fluvial system radiating from the uplifted center of the continent. Plateau uplift may have promoted the establishment and growth of the Arctic ice-sheet not only by the alteration of atmospheric circulation and enhancement of weathering, but also by the formation of north-flowing Siberian rivers, which provided the Arctic Ocean with freshwater run-off. The Cenozoic deformation of Asia was also responsible for the initiation of the Asian monsoon system during the early Miocene and its further strengthening at ∼ 8 Ma and ∼ 3 Ma. The formation of a series of seas fringing the East Asian margin has changed the material and energy flux between the Asian continent and Pacific Ocean. The western Pacific boundary currents flowing through the marginal seas are highly sensitive to eustatic and tectonic changes. During low sea-level stands caused by glaciation, the boundary currents flowed outside the marginal seas and reduced the heat and humidity supply from the ocean to the continent. Today, the most active energy and material fluxes in the Earth System occur between Asia and the Pacific, yet the role of Asia in controlling global climatic and environmental history has been underestimated.