地质科学2024，Vol.59Issue(6)：1500-1515,16.DOI:10.12017/dzkx.2024.104
海安凹陷断裂体系及区域构造差异性成因
Fault system in the Hai'an Sag and genesis of regional tectonic differentiation
摘要
Abstract
The Hai'an Sag is located in the southeast edge of the Subei Basin,and has a different basin structure and fault system from the rest of the sags.The present work uses geophysical and regional geological data to clarify the inner and outer differentiation of fault system and its genesis of the Hai'an Sag based on a detailed analysis of the fracture orientation,activity intensity,tectonic properties,basin structure and tectonic polarity,and combined with the regional geological background and tectonic comparative analysis.The Hai'an Sag can be divided into two parts,north and south,by the boundary of the Haizhong fault uprising belt(HFUB),with completely different features in terms of tectonic properties,fracture orientations and tectonic polarity.The transtensional tectonics is dominant in the north,while the extensional tectonics is dominant in the south;the faults are usually dominated by NEE strike and NNW trend in the north,while EW strike and S trend in the south.Compared with the Jinhu,Gaoyou and Qintong sags,which are also south of the Jianhu uplift,the Hai'an Sag has a very different degree of segmentation,basin structure,basin property,sedimentation mode and extension strength;the Hai'an Sag has the characteristics of strong segmentation,dispersed depression,multi⁃directional half graben and weak extension,while the rest of the sags are characterized by weak segmentation,concentrated depression,overlapped in the north and strong extension.In addition,the Hai'an Sag is significantly different from the rest of the depressions in terms of the orientation of fracture spreading,fault property,and activity intensity,etc.The main faults of the Hai'an Sag are characterized by NEE⁃EW strike,north⁃dipping in the north and south⁃dipping in the south,whereas the rest of the depressions are dominated by NE⁃NEE strike and NW tendency.We suggests that locating at the edge of the tectonically strong polarity zone,the edge of the foreland thrust frontal zone,the edge of the active relaxation zone,the boundary between the Indosinian and the Yanshanian basement,the outer edge of the foreland crust thickening zone,and the weak side of the extrusion transfer zone,are the key factors caused distinctive basin structure and fault system between Hai'an and other sags.The Indosinian and Yanshanian basement tectonics are separated on both sides of the HFUB,which is the key reason for the north⁃south tectonic variability of the Hai'an Sag.The existence of the Indosinian extrusion transfer zone not only causes the regional tectonic differences between the east and west parts of the Subei Basin,but also is the main reason why the Qutang sub⁃sag of the Hai'an Sag is different from the rest of the sub⁃sags.The existence of the Tan⁃Lu fault zone is the key reason for the variation in the orientation of the regional tectonic line,and the basement faults in the Hai'an Sag and their reactivation are both weakest influenced by the Tan⁃Lu fault zone.The existence of the Tan⁃Lu fracture zone is the key reason for the orientation shift of the regional tectonic line in the Subei Basin,and the fundamental reason for the resurrection of the regional basement fractures in the late stage of differentiation.The Indosinian and Yanshanian tectonic basement are separated on both sides of the HFUB,which is the key reason for the north⁃south tectonic variability of the Hai'an Sag.The Indosinian extrusion transfer zone not only causes the regional tectonic differences between the east and west parts of the Subei Basin,but also is the main reason why the Qutang sub⁃sag of the Hai'an Sag is different from the rest of the sub⁃sags.The Tan⁃Lu fault zone on the west side of Subei Basin is the key reason for the variation in the orientation of the regional tectonic line,and the basement faults in the Hai'an Sag and their reactivation are both weakest influenced by the Tan⁃Lu fault zone.关键词
海安凹陷/印支运动/燕山运动/断裂成因/构造差异性/盆地结构Key words
Hai'an Sag/Indosinian/Yanshanian/Fault genesis/Tectonic differentiation/Basin structure分类
天文与地球科学引用本文复制引用
夏连军,季红军,谢成龙,张弛,刘俊成,韦祥..海安凹陷断裂体系及区域构造差异性成因[J].地质科学,2024,59(6):1500-1515,16.基金项目
国家自然科学基金面上项目(编号:42372265,41772210)资助 （编号:42372265,41772210）
