甘肃省板块构造单元划分及其构造演化

PLATE-TECTONIC UNITS AND TECTONIC EVOLUTION IN GANSU

本文将甘肃省板块构造单元划分为三级；其中一级单元包括西伯利亚板块、塔里木板块、华北板块、华南板块，它们之间的分界线分别以红石山断裂带、阿尔金走滑断裂带、泽库－武山断裂带所分割；并进一步细分为８个二级单元，１９个三级单元。同时，对各级构造单元的基本地质特征和演化特点，作了概略的探讨。认为在中晚元古代时期，四大板块的基底均已固结成大陆型地壳，稍后即以大陆核（或地台）为板块的生长中心，其间则为古亚洲洋（北山洋区）、祁连海槽、秦昆大洋所分隔；自显生宙起到古生代末期，全区板块轮廓已基本定型，形成了褶皱带与地台（或地块）镶嵌拼贴的构造格局。作者还提出北山北带应划归西伯利亚板块，而北山中带和南带则属于塔里木板块范畴，北祁连北缘的过渡带应为华北地台西南部稳定大陆陆坡区等，一些新的观点。

In this paper the plate-tectonic units in Gansu Province fall into three orders. The first-or-der units include the Siberian plate, Tarim plate, North China plate and South China plate. Theirboundaries are the Hongshishan fauIt belt, Altun strike-slip fault beIt and Zeku-Wushan faultbelt respectively. Eight second-order and 17 third-order tectonic units are further distinguished. Besides, the basic geological features and evolution of the three orders of tectonic units are dis-cussed brierfly. The basements of the four plates had been consolidated into continental crust inthe Mid-Late Prolerozoic. Then the plates grew with the continental nuclei (or platforms) as thecenters; they were separated by the Paleo-Asiatic Ocean (Beishan Ocean region), Qilian seatrough and Qinling-Kunlun Ocean. From the Phanerozoic to terminal Paleozoic, the plate config-urations of the whole region were finalized, forming a mosaic framework of fold belts and plat-forms (or blocks). The authors also suggest that the north belt of Beishan should be assigned tothe Siberian plate, while the central and south belts of Beishan belong to the Tarim plate and thetransitional belt on the northern margin of North Qilian should be the slope of the stable conti-nent on the southwestern margin of the North China platform.