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Geoscience ›› 2024, Vol. 38 ›› Issue (04): 1092-1108.DOI: 10.19657/j.geoscience.1000-8527.2024.063

• Ore-controlling Mechanism and Exploration Applications of Tectono-physicochemistry • Previous Articles     Next Articles

Mesozoic and Cenozoic Deformation Sequences and Their Dynamic Background in the Danyishan Area, Southern Hunan

CHEN Zhiyou1(), ZENG Guangqian2(), BAI Daoyuan2, YAO Zeyu1, WANG Lingjue2, WEN Chunhua2, CHEN Xu2, WANG Yong2,3, LI Bin2,3, HUANG Leqing2,4,5, CHEN Jianfeng2, LIANG Enyun2, XU Ruochao2, MA Huiying2, XIANG Ke2   

  1. 1. Southwest Energy and Mine Construction Engineering Co., Ltd., Guiyang, Guizhou 550081, China
    2. Geological Survey Institute of Hunan Province, Changsha, Hunan 410014, China
    3. School of Geosciences and Info-physics, Central South University, Changsha, Hunan 410083, China
    4. Hubei Key Laboratory of Paleontology and Geological Environment Evolution, Wuhan, Hubei 430205, China
    5. Institute of Geological Survey, China University of Geosciences (Wuhan), Wuhan, Hubei 430074, China
  • Online:2024-08-10 Published:2024-10-16
  • Contact: ZENG Guangqian

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 adjacent 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 Indosinian 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 compression 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 deformation 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-trending fault zones.Its dynamic mechanism may be the eastward escape of the Tibetan Plateau caused by the collision 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.

Key words: Mesozoic and Cenozoic, structural deformation, tectonic stress field, deformation sequence, tectonic evolution, Dayishan area

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