全球前寒武纪基底构造格局与古大陆再造问题

Tectonic Pattern of the World Precambrian Basement and Problems of Paleocontinent Reconstruction

全球前寒武纪基底构造格架与构造单元的划分是古大陆再造和泛大陆拼合的重要基础 .本文整理了基底构造单元的级别体系 ,以晋宁期和印支期为准 ,提出了一级构造域、二级陆台及地区和三级陆核、地块等 3级划分 .分出了 5个一级、14个二级和若干个三级单元 ,并予以系统编号 ,以便查询和增修 .认为超大陆是泛大陆的组成部分 ,现在重点研究的罗迪尼亚超大陆已经涉及全球 ,进入了泛大陆 -85 0的研究范围 .论证了中国 3个陆台和华夏地区在新元古代晋宁期的位置关系 ,认为它们相距不远 ,并部分相互碰撞 ,构成亚洲中轴 (大华夏 )构造域 .讨论了罗迪尼亚的流行模式及SWEAT连接问题 .指出新元古代Chuaria Tawuia宏观藻组合在东亚和北美西部的分布 ,认为大华夏构造域应作为一个松散的整体与劳伦古大陆相邻 ,并概略讨论了泛大陆 -85 0的再造格局特征 .提出了经过改进的泛大陆 -2 5 0在中二叠世 (2 80～ 2 5 7Ma)的再造模式 ,讨论了古植物和海生动物生物地理分区在古大陆再造中的意义 .

The tectonic frame and subdivision of tectonic units of the world Precambrian basement are essential for paleocontinent reconstruction. In this paper, a three rank system of tectonic units, the first rank tectonic domain, the second rank craton (continental platform) or 'Region', and the third rank continental nucleus, massif and belt, is proposed, based mainly on situations in Neoproterozoic Jinning and the Early Mesozoic Indosinian epochs. Altogether 5 domains, 14 cratons or regions, and a number of nuclei, massifs and belts within and outside of the cratons that are related to or derived from the cratons, are distinguished and catalogued for further reference and improvement (Fig.1, Table 1). We deem that a supercontinent is a constituent part of its contemporary pangea, and the present research of supercontinent Rodinia has entered into the study of its contemporary pangea, the Pangea 850 in our former use. In the early Neoproterozoic, the three Chinese cratons, Sino Korean, Yangtzean, Tarimian and the Cathaysian Region, were probably partly collided with each other through the Jinningian orogeny, and were not very far from each other. We have called the combined entirety, including the Central Asian Karakum Massif, the Axial Asian or Cathaysianan Domain. The current models for Rodinia, especially the SWEAT connection, are discussed. As the characteristic Neoproterozoic (900-850 Ma) Qingbaikouan mega algae Chuaria Tawuia assemblage were amply found both in Sino Korea and Cathaysian in eastern Asia and in the Little Dal Group in western North America, we suggest the Axial Asian or Cathaysianan Domain may have been placed near the western margin of Laurentia, and the East Gondwanan cratons may on that account be shifted southwards (on map). Other problems including the orientation of the Siberian Craton and the Pan African belts in the West Gondwanan Domain are also briefly noted. A refined reconstruction of the Middle Permian Epoch (280-257 Ma) for Pangea 250, the only recognized Pangea up to now, is presented, in which three marine biogeographical realms and constituent provinces based mainly on corals and brachiopods are subdivided. The signals for the four well known paleophytic realms, Angaran, Cathaysian, Euramerican and Gondwanan, and of some representative assemblages of the marine provinces are shown on Fig. 3, and their significance in paleocontinent reconstruction are briefly discussed.