辽吉地区古元古代造山作用的大陆动力学过程及其壳内响应

INIRACRUSTAL RESPONSE TO CONTINENTAL DYNAMIC PROCESSES OF THE PALEOPROTEROZOIC OROGENY IN LIAO-JI AREA

古元古代是地质演化历史中一个重要转折时期，探讨其大陆动力学特征、机制、过程及其壳内响应具有重要的科学意义．本文以辽吉地区古元古代造山带为例，结合同位素年代学资料，综合分析了该区大陆动力学过程的构造、变质、岩浆、沉积等方面壳内响应特征最后，将该区深部大陆动力学过程划分为三大历史阶段：1）造山期前伸展阶段，包括建造伸展期和改造伸展期，深部底侵发生，壳内响应出现基底裂解、盖层顺层滑脱、拉张型垂向递增变质、岩浆呈席状侵位等；2）造山期挤压收缩阶段，俯冲碰撞，岩石田地幢可能出现拆沉，壳内响应出现招皱逆冲、双侧造山、侧向递增变质、碰撞型岩浆作用发生、早期岩浆底辟再就位等；3）造山期后伸展塌陷阶段，大陆岩石田在重力均衡作用下发生微弱伸展塌陷，出现环斑花岗岩侵位，等压冷却为特征的退变质表明没有明显的伸展剥蚀，没有出现明显的山根．

Paleoproterozoic is an important transition pened of geological history. The features,mechanism and processes of continental dynamics and their intracrustal response in this pened have significant scientific implication. The intracrustal resPOnse, including tectonism,metamorphism, magmatism and sedimentation and so on, of continental dynamic processes of Paleoproterozoic orogen in Liao-Ji area, is described by means of integrated, multidisciplinaly studies with geochronological data. The processes of continental dynamics are divided into three stages: 1) Pre-orogenic extension stage is subdivided into extensional construction stage and extensional deformation stage. The intracrustal resPOnse includes rifting of the basement,gravitational bedding-sliding of the sedimentary coverl vertically-progressive prograde metamorphism at the extensional setting, layered-emplacement of magma; 2) Orogenic crustal shortening is perhaps derived from subduction or collision, sometimes accompanying with delamination of mantle lithosphere in collisional orogen. The intracrustal response includes folding, thrusting, doubly-vergent compression, laterally-progressive prograde metamorphism, collisional magmatism, re-diapirism of the previous magma under the control of folding, and so on; 3 ) Post-orogenic extensional collapse occurred due to the gravitationally isostatic uplift of continental lithosphere. Isobaric cooling retrograde metamorphism shows weak uplift, no strongly extensional denudation or no mountain root in the Liao-Ji Paleoproterozoic orogen.