秦岭造山带及相邻地块元古代基性岩墙群研究综述及相关问题探讨

Synthetic study on Proterozoic basic dyke swarms in the Qinling Orogenic Belt and its adjacent block as well as a discussion about some questions related to them.

基性岩墙群是重建古陆块聚合、伸展乃至裂解的关键标志之一。通过对秦岭造山带及相邻的华北地块、扬子地块元古代基性岩墙群的时空对比综合分析表明 ,华北地块区发育 2 30 0 Ma±和 170 0～ 12 0 0 Ma的两期基性岩墙群 ,分别代表了新太古代和古元古代华北古陆块的聚合、伸展过程 ;扬子地块区发育 80 0～ 6 2 0 Ma的基性岩墙群 ,反映了新元古代扬子古陆块的聚合、伸展过程。认为前震旦纪华北地块和扬子地块可能是独立古陆块或不同古陆块的组成部分。晋宁造山作用 ( 110 0～85 0 Ma)和澄江伸展、裂解作用 ( 80 0 Ma± )是可与新元古代 Rodinia超大陆聚合、裂解过程进行对比。

The basic dyke swarms is one of key indicators to construct the convergence and extension rifting of ancient continental block. The synthetic analysis of the time space correlation of Proterozoic basic dyke swarms developed in Qinling orogenic belt and its adjacent North China block and Yangtze block shows that there were two periods of basic dyke swarms formed in 2300Ma and 1700~1200Ma, respectively, reflecting the convergence and extension of ancient North China block in the Neo Proterozoic and Paleo Proterozoic. While basic dyke swarms of 800~620Ma in the Yangtze block indicates the convergence and extension in the Neo Proterozoic. Therefore, it can be concluded that the North China block and Yangtze block were separated from each other in Pre Sinian, and they were quite different blocks and possibly made up by different ancient continental blocks at that time. So the orogenic process of Jining Period (1100~850Ma) and extension rifting of Chengjiang Period (800Ma±) are very important periods which could be parallel with the periods of convergence and rifting of Neo Proterozoic Rodinia super continent.