福建早侏罗世火山作用的动力学机制及大地构造学意义探讨

Dynamical Mechanism and Tectonics Significance of Early Jurassic Volcanism in Fujian Province

通过对福建早侏罗世火山作用的研究,对中生代大地构造演化提出了新的看法。研究认为华南地区的早中生代火山作用是印支运动后造山大陆裂解(伸展)形成的,与古太平洋板块俯冲无关;中侏罗世是区域中生代构造-岩浆活动性质发生重大变化的主要时期,由于古太平洋板块作用导致印支后造山裂解大陆的闭合,构造域转换发生在中侏罗世。中侏罗世太平洋板块往北西方向俯冲碰撞和持续挤压,早侏罗世的火山-沉积盆地逐渐开始闭合,开始从东西向特提斯构造域向北东向太平洋构造域的体制转换,在地球动力学体制上,由后造山阶段的伸展应力体制转换为挤压应力体制。

Based on the study of Fujian early Jurassic volcanic action, we bring on a new idea about the meaning of Mesozoic tectonics evolution on the south part of Chinese inshore. That is, early Mesozoic volcanic action form on the stage of the hinter orogeny continental extension, having nothing to do with subducted of palaeo-pacfic plate. Middle Jurassic is the most important stage of the magnitude change about the formation of regional Mesozoic structure and magma action, because the movement of palaeo-pacfic plate bring to the close of continental extension of the hinter orogeny, and the area of structure take place at Middle Jurassic. On this stage, the Pacific plate begin to underriding collide and continual compress from the direction of northwest, and the volcanic sediment basin of early Jurassic also gradually begin to close, and the framework convert from the Tethys structural domain of East-west direction into the Pacific structural domain. On the geodynamical framework, the extension stress of the hinter orogeny movement stage converts into the squeezed one.