中国晚元古代古构造与古地理

本文所指晚元古代时限为距今1000—600百万年。中国晚元古代可分为两个阶段,自1000—800百万年一段暂不建纪,因为这一时期的地层在全国的对比还存在很多问题,生物面貌远不明确,所以我们仍称青白口群,不用青白口系。自800—600百万年这一段即现称震旦纪。根据地层沉积类型和分区,我们编制了三幅古构造古地理图(图1—3)。

UPPER PROTEROZOIC TECTONO PALEO-GEOGRAPHY IN CHINA

The Upper Proterozoic here used covers the time span of 1000-600 my BP and may be subdivided into an earlier Qinsbaikou (ea. 1000 -800 my BP) and a, later Sinian (ca. 800-600 my BP) period. In this interval of time, sedimentation domains recognized in China comprise: 1. North stable domain, including Sino-Korean and Tarim Platforms, 2, Central mobile tract, consisting of western Kunlun, Altyn, Chilian and Qinling, 3. South stable domain. Yangtze and Eaidam Massifs and 4. South mobile tract covering major parts of South China which border the Yangtze Massif. Other regions, such as Xing’an-Mongolia and Himalaya, remain still obscure.In Late Proterozoic the northern massifs have already consolidated and received stable type sedimentation except in the eastern border of Sino-Korea and the northern border of Tarim. The southern massifs assumed their protoform after Qinning Movement Ⅰ (ca. 1000 my BP) and were not completely consolidated until after Qinning Movement Ⅱ (ca. 800 my BP), when genuine cover strata of Sinian age began to form. From Late Proterozoic on, continuing indeed into Early Paleozoic, there had developed a series of island arcs and interarc marine basins over the broad tract of South China, which seemed to have continuously shifted easterwards to the Pacific. The Central mobile tract extending east-west across whole China, the long known major geological boundary between North and South China, probably represents a huge belt of complex sea troughs and has undergone recurrent crustal collision and consumption.