现代地质2024，Vol.38Issue(4)：1092-1108,17.DOI:10.19657/j.geoscience.1000-8527.2024.063
湘南大义山地区中—新生代变形序列及其动力学背景
Mesozoic and Cenozoic Deformation Sequences and Their Dynamic Background in the Danyishan Area,Southern Hunan
摘要
Abstract
The Dayishan area is located at the junction of the Nanling tectonic belt and the Qinhang tectonic belt.It has developed multi-directional and different types of structural systems since the Early Mesozoic.Studying the deformation sequences is essential for better understanding of the tectonic evolution along and adja-cent to South Hunan.However,detailed analysis of the deformation characteristics and evolution of the stress field remains unsolved.This study employs structural analysis to correlate structural elements such as shear fractures and folds in the bedrock of the Dayishan area.The paleo-stress field of shear fractures is reconstructed using the lower hemisphere stereographic projection method.Combining the regional tectonic evolution history of South China in the Mesozoic and Cenozoic,this study defines five deformation events based on their dynamic backgrounds.The first phase(D1)of NEE-SWW compression,occurring during the early stages of the In-dosinian Movement(late Middle Triassic),resulted from the oblique intraplate under-thrusting of the Yangtze Craton beneath the Cathaysia Block in a multi-plate confining setting.The difference in local and regional shortening directions may be related to the E-W compressional stress field derived from the NW-trending Shao-yang-Chenzhou fault and the sinistral drag caused by strike-slip motion.The second phase(D2)of S-N com-pression formed during the late stage of the Indosinian Movement(Late Triassic to Early Jurassic).This phase may be related to the southward compression of the North China Craton and northward compression of the Simao-Indochina Block.The third phase(D3)of NWW-SEE compression occurred during the Early Yanshanian Movement(latest Middle Jurassic).This phase was driven by the westward subduction of the Palaeo-Pacific Plate,or the Izanazaki Plate,beneath the South China Block.The fourth phase(D4)of magmatism-related de-formation includes folding,tectonic foliations,pinch-and-swell structures,and tension-shear fractures.These structures are possibly related to episodic upward invasion and lateral flow of Late Jurassic granitic magmas along variously orientated basement faults during the post-orogenic stage of the Early Yanshanian Movement.The fifth phase(D5)of N(N)E-S(S)W compression occurred during the Middle and Late Paleogene.This phase may be related to the local compressive stress field derived from dextral strike-slip motion along previous NNE-tren-ding fault zones.Its dynamic mechanism may be the eastward escape of the Tibetan Plateau caused by the colli-sion between the Indian and Eurasian plates.Further analysis suggests that the strongest strike-slip motion of the Shaoyang-Chenzhou fault zone might have occurred in the early stage of the Indosinian Movement,thereby establishing the tectonic framework of the Mesozoic and Cenozoic in the surrounding area of this fault zone.关键词
中—新生代/构造变形/构造应力场/变形序列/构造演化/大义山地区Key words
Mesozoic and Cenozoic/structural deformation/tectonic stress field/deformation sequence/tec-tonic evolution/Dayishan area分类
天文与地球科学引用本文复制引用
陈志友,黄乐清,陈剑锋,梁恩云,许若潮,马慧英,向轲,曾广乾,柏道远,姚泽钰,王灵珏,文春华,陈旭,王勇,李彬..湘南大义山地区中—新生代变形序列及其动力学背景[J].现代地质,2024,38(4):1092-1108,17.基金项目
湖南省地质院科研项目(HNGSTP202323,HNGSTP202317) （HNGSTP202323,HNGSTP202317）
中国地质调查局地质调查项目(DD20230055) （DD20230055）
湖南省自然资源厅科研项目(20230102DZ). （20230102DZ）
