中国大陆地壳“镶嵌与叠覆”的结构特征及其演化

Structural characteristics of crustal “mosaicking and superimposition”of the continent of China and its evolution

初步探讨了中国大陆地壳“块带镶嵌多层叠覆”的结构特征和多阶段的构造演化过程。中国大陆地壳新元古代中期以来的一级构造单元有中朝、塔里木、扬子、敦煌4个陆块和中央、西北、东北、西南、东南5个造山区(带)。中朝陆块的形成源于古元古代期间发生的古大陆裂解;扬子、塔里木和敦煌陆块的形成源于新元古代早期发生的古大陆裂解。西北造山区的形成源于古生代晚期洋盆关闭、大陆碰撞并叠加新生代陆内再造山;东北造山带的形成过程包括古生代碰撞造山及中生代增生、碰撞造山;中央造山带至三叠纪大陆碰撞才最后形成并叠加有新生代再造山;东南造山带的形成经历了古生代至新生代的多次造山作用;西南造山带主要是中—新生代造山作用的产物。这些单元都具有“块带镶嵌多层叠覆”的结构特征和多阶段构造演化的特点。中国大陆地壳的形成与演化可以划分为太古宙—古元古代、中元古代—新元古代早期、新元古代中期—古新世和始新世以来4个构造阶段,每个阶段都对应不同的超大陆裂解-聚合旋回。其中新元古代中期以来的地壳形成演化与全球洋陆格局中的古亚洲洋、古特提斯洋、古太平洋、特提斯洋和太平洋5个动力学体制有关,相应地可以归结为古亚洲、古特提斯、古太平洋、特提斯和太平洋5个造山域。

This paper discusses the structural characteristics of 'block-zone mosaicking and multi-layer superimposition' of the continental crust of China and its multi-stage tectonic evolution. The first-order tectonic units of the continental crust of China since the middle Neoproterozoic include the Sino-Korean, Tarim, Yangtze and Dunhuang blocks and Central, Northwest, Northeast, Southwest and Southeast orogenic regions (belts). The Sino-Korean block formed by breakup of an ancient supercontinent during the Paleoproterozoic, and the Yangtze, Tarim and Dunhuang blocks formed by breakup of the ancient supercontinent during the Neoproterozoic. The Northwest orogenic region originated by closing of an ocean basin and continent-continent collision during the Late Paleozoic, superimposed by Cenozoic intracontinental re-orogeny; the formation of the Northeast orogenic belt involved Paleozoic collisional orogeny and Mesozoic accretion and collisional orogeny; the Central orogenic belt had not formed until Triassic continental collision and was superimposed by Cenozoic re-orogeny; the formation Southeast orogenic belt went through multiple orogenies during the period from the Paleozoic to Cenozoic; and the Southwest orogenic belt is mainly the product of Meso-Cenozoic orogeny. All these tectonic units have the structural characteristics of 'block-zone mosaicking and multi-layer overlapping' and the features of multi-stage tectonic evolution. The formation and evolution of the continental crust of China may fall into four stages: Archean-Paleoproterozoic, Mesoproterozoic-early Neoproterozoic, middle Neoproterozoic-Paleocene and Eocene-present, with each stage corresponding to a breakup-convergence cycle of the supercontinent. The crustal formation and evolution since the middle Neoproterozoic is related to the dynamic regimes of the Paleo-Asian Ocean, Paleo-Tethys Ocean, Paleo-Pacific Ocean, Tethys Ocean and Pacific Ocean in the global land and ocean pattern, which may be correspondingly ascribed to the Paleo-Asian, Paleo-Tethys, Paleo-Pacific, Tethys and Pacific orogenic domain. It is just the multi-stage breakup-convergence cycles of the supercontinent and superimposition of multiple tectonic regimes that formed the structural characteristics of 'block-zone mosaicking and multi-layer superimposition' of the continental crust of China.