Construction of Quaternary 3D geological model and analysis of buried faults in the urban area of Chengdu
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    Abstract:

    Detecting the buried faults is an important part of urban geological survey. The urban area of Chengdu is located in the eastern part of Chengdu Plain, which is a fault- controlled intracontinental thrust fault basinwith steep slope in the west and gentle slope in the east, and underlain by thick Quaternary sand and gravel units. The nature of the concealed faults in the study area remains unclear and it is a challenge to identify them. In this contribution, based on a wealth of borehole data supported by geotechnical engineering geological investigations (metro, housing construction, hydrological and foundation pit exploration etc.) and field observations, the well- organized integration databases have been created. Subsequently, a comprehensive three- dimensional geological model was created by the systematic modeling program and visualization technology. Combined with the measured borehole profile, three major NE- trending hidden faults are identified through the 3D bedrock relief surface that was tremendously valuable for determining the specific location and distribution shape of these buried faults in the study area. The distribution of the overlying sand and pebble layer displayed in the 3D model indicates that the Pujiang- Xinjin- Chengdu fault is the main controlling fault, which was active in the early Pleistocene.The Shuangqiaozi- Baojiangqiao fault is its secondary fault and became active in the early Late Pleistocene. In addition, a depression zone that may be controlled by the fault and penetrates the urban area was newly found. Furthermore, the synthesized 3D geological model and the isopach map of each sedimentary layer reveals that the NE- trending fault structures play an important role in the regional sedimentation. The subsiding center of coarse clastic sequences (sand, gravel etc.) had a tendency to gradually migrate from the northwest to the southeast over time. According to the bedrock relief surface model revealed in our 3D geological model program, the specific location and key features of the concealed faults are depicted, which could provide essential geological information for rational utilization of urban underground space, scientific planning and seismicity risk assessment.

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Wang Shiming, Zhang Ming, Lin Gang, Wu Tengfei, Song Tongwei, Pei Qiuming, Wu Xiyong.2021. Construction of Quaternary 3D geological model and analysis of buried faults in the urban area of Chengdu[J]. Acta Geologica Sinica,95(8):2601-2612

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History
  • Received:January 31,2021
  • Revised:May 25,2021
  • Adopted:
  • Online: June 30,2021
  • Published: