Earth Science Frontiers ›› 2024, Vol. 31 ›› Issue (3): 470-481.DOI: 10.13745/j.esf.sf.2023.10.36

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Formation mechanism and tectonic implication of Xinyi earth fissures in Tan-Lu fault transition section

XU Jishan1(), PENG Jianbing2,3,*(), SUI Wanghua1, AN Haibo4, LI Zuodong5, XU Wenjie1, DONG Peijie1   

  1. 1. School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China
    2. School of Geology Engineering and Geomatics/Shaanxi Academy of Yellow River Science/Research Institute of Geological Hazard, Chang’an University, Xi’an 710054 China
    3. School of Engineering and Technology, China University of Geosciences(Beijing), Beijing 100083, China
    4. Qingdao Institute of Geological Exploration, Shandong Provincial Geo-mineral Engineering Exploration Institute, Jinan 250014, China
    5. Zhejiang Institute of Communications Company Limited, Hangzhou 310030, China
  • Received:2023-02-21 Revised:2023-10-13 Online:2024-05-25 Published:2024-05-25

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Abstract:

The Xinyi area is located in a crucial transitional zone of the Tan-Lu Fault Zone. Since the 1970s, a total of 28 earth fissures have been discovered in this region. These fissures are mainly concentrated in the area west of Nanmaling Mountain and east of Yihe River-Luoma Lake, covering an affected area of approximately 100 km2. The formation of Xinyi earth fissures is closely linked to the stratigraphic structure, seismic activity, and groundwater exploitation, leading to various perspectives on the subject. Recent on-site investigations and exploration methods have revealed the fundamental characteristics of Xinyi earth fissures, including consistent strike, longitudinal pinchout, and localized mass occurrence. These features align closely with the adjacent fault (secondary fault F3 of the Tan-Lu Fault Zone) and are classified as regional tectonic-type earth fissures. Drawing on the geological structure of the Xinyi area, a physical experimental model was developed to simulate the formation of earth fissures under reverse fault action. The experimental findings suggest that fissure development areas are delineated on the ground surface, progressing through stages of shear-cracking, separation, and “bending-cracking” with increasing fault displacement of the reverse fault. Considering the “graben-horst-graben” composite structure in the Xinyi area, the genesis of Xinyi earth fissures can be conceptualized as a seesaw-style tectonic model. Tectonic stress, gravity stress, groundwater fluctuations, among other factors, compress the subsidence section while causing bending and cracking in the rising section, ultimately resulting in the formation of earth fissures. The investigation of earth fissures in the Xinyi area holds significant importance in elucidating structural changes within the “north-middle-south” segment of the Tan-Lu Fault Zone and the interconnected “deep-shallow-surface” structural configurations.

Key words: earth fissure, Tan-Lu Fault Zone, earthquake, reverse fault, tectonic stress, North China Plate

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