Mesozoic Tectonic Deformation And Palaeostress Field Around Lamadong And Wangjiadian Areas In Jianchang County, Western Liaoning Province

Lamadong and Wangjiadian areas of the southern Jianchang County in Western Liaoning Province is located in eastern Yanshan orogenic belt, which is the convergence region of E-W dextral strike-slip system, NE-NNE thrust fault system and extensional tectonic system. Under the combined influence of the Paleo-Asian oceanic tectonic domain and the Paleo-Pacific tectonic domain, it has formed a complicated tectonic deformation in this area since the Mesozoic. The geometry and kinematic characteristics of these tectonic deformations had been identified by previous study, but their formation epoch, interaction, structural deformation stage and the relationship to the regional tectonic system are still remain unrevealed.This article through the geometric and kinematic analysis of the faults and folds in this region, to estabilish four stages of tectonic deformation and paleostress field during the Mesozoic, combined with paleostress inversion of fault slip vector and the isotopic dating of some key geologic bodies:(1) The NS compressional stress field of pre-Early Jurassic(~ 191.6 Ma) controlled the E-W thrust system.(2) The NW-SE compressional stress field during the Late Jurassic Tuchengzi Formation to Early Cretaceous Yixian Formation(141.7 Ma ~ 126 Ma) controlled the E-W dextral strike-slip fault system, which dominated the formation of the basic tectonic framework of the Mesozoic.(3) The NW-SE or NNW-SSE extensional stress field during the sedimentation stage of the Early Cretaceous Jiufotang Formation(126 Ma ~ 119 Ma) controlled the NNE extensional fault system in this study area.(4) The NE-SW compressional stress field during the post-Early Cretaceous Jiufotang Formation to the Late Cretaceous period(119 Ma ~ 66 Ma) controlled the NW-NNW folds and faults. It changed some early structural traces, but the effect was not strong and did not change the original tectonic framework.The regional tectonic background of different stages of tectonic evolution was not identical. The NS compressional stress field was related to the lasting effect after the close of the Paleo-Asian Ocean; The E-W dextral strike-slip tectonic system suffered from the combined influence of the Paleo-Asian oceanic tectonic domain and the Paleo-Pacific tectonic domain; The NNE extensional fault system and the NW-NNW fold and fault-crack system were controlled predominantly by the subduction of paleo-Pacific Plate to Eurasian Plate.