奥陶纪到志留纪全球板块重建:中国三大陆块位置及其洋陆格局的运动学检验

GLOBAL PLATE RECONSTRUCTION FROM ORDIVICIAN TO SILURIAN:KINEMATICS TEST OF THEIR LOCATIONS OF THREE CHINA′S CONTINENTS AND OCEAN-CONTINENT CONFIGURATION

中国三大陆块是全球奥陶纪到志留纪板块与洋陆格局重建的关键,涉及到古亚洲洋与原特提斯洋的演化。综合了全球奥陶纪到志留纪的古地磁、古生物、古气候以及地球化学的相关证据,重建了中国三大陆块在这一时期的板块演化与洋陆格局,并将它们与全球板块演化模型结合到一起,特色在于通过板块运动的速度场分析,厘定了全球重要的板块边界及其性质。得到以下新认识:在奥陶纪到志留纪,中国三大陆块独立地位于地球的低纬地区,并且不依附于任何大的陆块,离散分布于原特提斯洋与古亚洲洋之间,原特提斯洋与古亚洲洋不断消减俯冲。其中,华北陆块早期靠近西伯利亚大陆东缘,华南陆块在奥陶纪早期沿着冈瓦纳大陆西侧漂移,塔里木陆块在奥陶纪进行了一个南北向的大范围的运动后,在志留纪开始向西漂移。中国三大陆块在这一时期不断地相互作用。在奥陶纪到中志留纪,原特提斯洋不断地俯冲冈瓦纳大陆与华北大陆,直到晚志留纪,随着古特提斯洋的扩张,原特提斯洋开始逐渐闭合。

The positions of the three China^s continents, the continents of North China, Tarim and South China, are the key issues to the reconstruction of Ordovician and Silurian global plate framework and o cean-land distribution pattern, since it concerns the reconstruction of the paleo-Asian land and the proto- Tethyan ocean. In this paper, we have made a review of evidence in paleomagnetism,geochemistry, paleontology and paleoclimate, then reconstructed the ocean-continent pattern and plate evolutionary history of the three China＇s continents, upon the global plate recoristruction model. Plate velocity field is used to i- dentify the plate boundary and its attribute. Our data suggests that the three China＇s continents were all in the lower latitude throughout the Ordovician and Silurian, and independent from other continents, dis cretely located in the paleo-Asian and proto-Tethyan oceans. The North China Block occurred not far from the eastern part of the Siberia in early Ordovician, the South China Block drifted along the Gondwana throughout the Ordovician and Silurian, Whereas the Tarim Block moved for a long distance from the southern to the northern hemisphere during the Ordovician, then westward drifted in Silurian. The three China＇s continents were not far from each other, and sometimes interacted with each other. During this period, the proto-Tethyan Ocean subducted under the Gondwana and North China Block constantly until the opening of the paleo-Tethyan Ocean.