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Geoscience ›› 2021, Vol. 35 ›› Issue (05): 1251-1259.DOI: 10.19657/j.geoscience.1000-8527.2020.064

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Numerical Simulation on Distribution and Evolution of Double-cross Surface Pattern in the Neo-Cathaysian Structural System

LÜ Guxian1(), WANG Hongcai1,2, HAN Lu1, ZHANG Baolin3, HU Baoqun4, LÜ Chengxun5, MA Licheng1, JIAO Jiangang6, BI Minfeng7   

  1. 1. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China
    2. Key Laboratory of Neotectonic Movement and Geohazard, Beijing 100081, China
    3. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences,Beijing 100029, China
    4. School of Earth Sciences, East China University of Technology, Nanchang,Jiangxi 330013, China
    5. Geological Survey Center, China Geological Survey, Beijing 100037, China
    6. School of Earth Sciences and Resources, Chang’an University, Xi’an,Shaanxi 710054, China
    7. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
  • Received:2020-03-20 Revised:2020-07-24 Online:2021-10-10 Published:2021-11-04

Abstract:

The structural system is composed of multi-directional, multi-stress-strain properties and different multi-order structures, which have relatively consistent distribution patterns in the stress field. Through geological study of regional metallogenic belts, orefields, and ore deposits, we reveal that the structural plane of the Neo-Cathaysian tectonic system includes three types, i.e., conjugate shear, extrusion, and tensional, forming a double-cross pattern. Using the stress-strain finite element simulation method, the formation of three-stage double-cross pattern is analyzed: the stage-1 conjugate structure developed the NNW 345° (Dayishan-type) tension-torsion fault and NEE 75° (Taishan-type) compression-torsion structure; stage-2 extrusion structure developed the NNE 25° extrusion fracture and fold; stage-3 transverse-tension structure developed the NWW 300° (Yangtze-type) cross-tension fracture. This gives the stress-strain field characteristics favorable of ore control and provides direction for future geological prospecting. The main regional tensile stress is the largest in the stage-1 NNW-trending tectonic belt, followed by the stage-3 NWW-trending “Yangtze” tectonic belt, and then by the stage-2 NNE-trending and stage-1 NEE-trending tectonic belts. The main tensile stress decreases first from the highest to the lowest and then rises again. The maximum compressive stress of the three stages increases from the stage-1 NEE-trending tectonic belt to the largest in the stage-2 NNE-trending tectonic belt, and then decreases to the minimum in the NWW-trending “Yangtze” tectonic belt and the NNW-trending tectonic belt. This shows a trend that increases to the maximum compressive stress and then decreases to the minimum.

Key words: Neo-Cathaysian structural system, double-cross tectonic pattern, FEM tectonic stress field modeling, stain-stress analysis

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