中国大陆主要变形系统

Major deformation systems in the Mainland of China

地壳中的构造变形是已有岩石在地质应力作用下发生结构构造和空间位置变化的产物,因而是资源勘查开发和地质灾害防治不可忽视的重要地质现象。然而,地壳中的构造变形能否像岩石及岩石组合一样,也可以为一个地区的地质历史重建提供约束,在已有文献中没有系统的论述。文中针对这一问题,在系统研究了全球不同地球动力学环境构造变形特征的基础上,提出了变形系统的概念,将其定义为在一定区域范围内、同一地球动力学背景下同时形成的、具有不同几何学和运动学特征的各种构造变形的集合,并根据其产出的地球动力学环境,将其划分为11种类型。基于这一认识,在系统收集研究了中国大陆已有构造变形资料的基础上,简要介绍了中国大陆古生代以来的14个变形系统,探讨了中国大陆构造分区和构造演化的几个问题。根据与全球典型变形系统的对比,基于中国大陆古生代以来主要变形系统的时空分布,笔者提出:(1)中国东部新生代伸展变形系统的成因主要与澳大利亚板块向北运动有关;(2)中国东部海域可能隐伏有中生代晚期弧陆碰撞带;(3)中国东部白垩纪地球动力学环境可能类似于现今北美西部科迪勒拉型大陆边缘;(4)秦岭山脉南北两侧晚侏罗世至早白垩世挤压构造变形可能是蒙古—鄂霍茨克造山带陆缘碰撞的远程响应;(5)敦煌—阿拉善地块在早古生代期间是中国大陆独立的第四大古陆块体;(6)西准噶尔和西天山北部属于哈萨克斯坦古板块北部增生边缘,准噶尔—吐哈盆地基底及其以北的东准噶尔和阿尔泰山属于西伯利亚古板块古生代增生边缘;(7)小兴安岭和张广才岭东侧的原黑龙江群是大兴安岭地区西伯利亚古陆古生代增生边缘的向东延伸,不是侏罗纪增生杂岩或早古生代碰撞带的残片;(8)中国北方及邻区古生代至中生代期间经历了多次碰撞造山。中国大陆古生代以来变形系统的初步研究,表明变形系统的研究可以为大陆构造单元划分、构造演化和古地球动力学环境的重建提供重要的约束。

Structural deformation in the crust is the product of the change of the texture and structure of the rocks and their spatial positions in the crust under the geological stress, and is the main geological phenomenon that geologists can not overlook in the resource exploration, geological environment evaluation and disaster prevention. However, whether the research in the geological structure may provide some constraints on the reconstruction of geological history of an area, as the one in rocks and petro-chemistry does, can not be found out in the available publications. This paper defines the concept of the Deformation System as a assemblage of all the structural deformations with various geometry and kinematics simultaneously formed in the same scale of the region under the same geodynamic setting based on available structural data from global typical geodynamic settings, and 14 kinds of the deformation system are distinguished, which are formed in various geodynamic settings, such as the continental rifting, doming, impacting, mid-ocean-ridge, Andes, Cordilleran, Rocky mountain, East-Asian continental margin, Southwest Pacific, Qinghai-Xizang Plateau, and Alpine types. And then, 11 deformation systems in the mainland of China are briefly described. Structurally, some hot debated issues on the tectonic division and evolution of China are preliminarily discussed. Some new viewpoints are achieved as follows： （1） extensional deformation in East China, a part of the East-Asian continent-marginal type of deformation system, was originated from the northward movement of the Australian plate; （2） an arc-continent collisional zone occurred in the end of the Cretaceous may have been buried under the Cenozoic sediment in the East .Sea; （3） Cretaceous geodynamic setting in East China is probably similar to Paleozoic; （6） northern West Tianshan and West Junggar regions of Northwest China were parts of northern accretionary margins of Kazakstan paleoplate, northern part of the East Tianshan, Junggar Block, East Junggar and Altay Mountain were parts of accretionary margin of the Siberian paleoplate; （7） the previously so-called ＂Heilongjiang Group＂ exposed along the east foots of Little Xingan Range and Zhangguangcai Range east of Heilongjiang Province, northeast China are relics of the Paleozoic accretionary margins of the Siberian paleoplate, but not the Jurassic accretionary complexes along the east Asian continental margin; and （8） multiple collisional orogeny took place in the northern China and adjacent Phanerozoic orogenic region from the latest Paleozoic to the middle Mesozoic. Our primary study on the deformation system in the mainland of China indicates that the research in the structural deformation may provide some constraints on the tectonic division and evolution, and the reconstruction of geodynamic settings in the geological history of the continent.