印尼海道的两度关闭与西太平洋暖池的形成和兴衰

TWO CLOSURES OF THE INDONESIAN SEAWAY AND ITS RELATIONSHIP TO THE FORMATION AND EVOLUTION OF THE WESTERN PACIFIC WARM POOL

世界海洋表层水温最高的西太平洋暖池,是全球驱动大气环流的最大热源之一,也是全球热盐环流传输带的热源。新生代晚期印尼海道的关闭是暖池得以形成的基本条件。在印尼海道区划出了对印度尼西亚穿越流起阻挡作用的5道屏障,分析了5道屏障的形成过程和年代,据此提出了印尼海道两度关闭的模式。板块运动导致印尼海道关闭,有利于暖池发展,同时也存在不利的负面影响,本区构造运动对暖池的演变具有特有的双向复合控制作用;由此出发勾勒了近1000多万年来西太平洋暖池的形成和兴衰史:11～9MaBP为原始暖池形成期,9～6MaBP为暖池演化的第一衰退期,6MaBP以来为现代暖池的孕育和发展期,其间在1～0 2MaBP穿插着暖池演化的第二衰退期。上述暖池兴衰史的演化模式,得到了暖池区ODP1143站浮游有孔虫组合所反映的古海水温跃层深度的验证。

With the highest sea surface temperature in the present world, the Western Pacific Warm Pool (WPWP) is the thermal dynamo for the global atmosphere circulation which greatly influences the tropical Pacific ocean circulation. The closures of the Indonesian seaway provide the tectonic background for the formation of the WPWP during late Cenozoic. Five land barriers are identified within the region and serve as blockages to the Indonesian throughflow. Based on the evolution history of these barriers, a two-closure model for the Indonesian seaway is proposed. While the closures of the Indonesian seaway facilitate the formation of the WPWP, the related northward movement of the Australian plate is not favorable for the formation of the WPWP by blocking the flow of tropic warm water from the Pacific. Thus the evolution of the WPWP is a combined product of these positive and negative effects of the plate tectonic movement. The history of the WPWP can be divided into the following stages. The proto-WPWP was formed during 11~9 Ma. 9~6 Ma is the period when the WPWP experienced its first waning. The formation and evolution of the modern WPWP were since 6 Ma. 1~0.2 Ma is the period when the WPWP experienced its second waning. The above evolution scheme of the WPWP is preliminarily testified by the paleoceanographic data from ODP site 1143.