Characteristics Of Mesozoic Tectonic Deformation In Taqian Fuchun Area,Northeastern Jiangxi Province

Taqian Fuchun structural belt is located in the eastern part of Pingle depression between Cathaysian plate and Yangtze plate.This area has experienced a long-term complex tectonic magmatic metamorphic event,forming a unique structural style,and has the largest tungsten deposit in the world Zhuxi copper tungsten deposit in Northeast Jiangxi.The tectonic framework with thrust nappe structure as the main body in this area has been widely recognized,but the specific tectonic process in different periods is still controversial,which restricts the further study of the tectonic model and deformation history in this area.In view of the above problems,this paper analyzes the deformation characteristics of different structural layers in the study area,and studies the microstructure and EBSD fabric of metamorphic rock samples in different areas of the study area.Through the observation of macrostructure in the field,the superimposed folds in the metamorphic basement and folds in the caprock are compared,and the deformation characteristics of different stages are obtained.The microstructural characteristics of the metamorphic rocks in the study area are mainly ductile deformation,and brittle-ductile,brittle structures are also developed in some samples,recording the deformation since Mesozoic era.Through the analysis of the growth characteristics of micro veins,the differences of late extension rates at different depths are obtained.The characteristics of microstructure and preferred orientation of EBSD show that the metamorphic rocks in this area have undergone low temperature ductile brittle deformation since Mesozoic,and the samples in zhenzhushan area have recorded high temperature deformation events related to magmatism.Kinematic vorticity reflects that the shear action in the area is mainly simple shear action,which may be a manifestation of the well-developed interlayer shear structure of metamorphic rocks in the area.The above research shows that large-scale basement folds have been formed in the study area before Mesozoic,and the associated foliation is the main level of subsequent deformation;The Indosinian tectonic movement laid the foundation for the scale and form of thrust nappe structure;After the subsequent intracontinental compression deformation,thrust faults developed in the weak part of folds and formed imbricate fan style thrust nappe structure in the process of subsequent compression.The extensional environment in the late Yanshanian area reformed the early contact relationship and opened a channel for magmatic activity.Finally,the existing structural form of the study area is formed.