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Geoscience ›› 2019, Vol. 33 ›› Issue (01): 36-44.DOI: 10.19657/j.geoscience.1000-8527.2019.01.04

• Structural Geology and Stratigraphy • Previous Articles     Next Articles

Fractal Analysis of Dynamically Recrystallized Quartz Grains and Rheological Parameter Estimation of Wulian Detachment Fault Zone

SUN Yujie1,2(), NI Jinlong1,2(), SHI Xiaoxiao3, GUO Ying4   

  1. 1. College of Geological Sciences and Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266590, China
    2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China
    3. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
    4. Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276000,China
  • Received:2018-01-10 Revised:2018-07-10 Online:2019-02-26 Published:2019-02-28
  • Contact: NI Jinlong

Abstract:

Distinct ductile deformation features are developed in the quartz grains of the Wulian detachment fault zone, which displays the ribbon or wire shape in the field and multi-grain quartz ribbons, subgrain rotation (SR) and bulging recrystallization (BLG) under the microscope. This indicates that the detachment fault zone was developed under medium-low temperatures, approximately 300 ℃ to 450 ℃. Fractal analysis shows that the boundaries of both SR and BLG recrystallized grains are statistically self-similar, with the fractal dimension values of 1.260-1.319 (avg. 1.276) and 1.217-1.297 (avg. 1.256), respectively. The paleo-stress values estimated from the SR and BLG recrystallized quartz grains are 7.84-21.58 MPa and 18.51-56.65 MPa, respectively. The strain rate results of ductile deformation by SR and BLG are different from each other. Values based on the fractal analysis are 10-8.4-10-7.7 s-1 and 10-10.5-10-9.7 s-1. According to the quartz rheology law method, the SR and BLG values are estimated to be 10-12.88-10-11.73 s-1 and 10-13.72-10-12.46 s-1. The strain rate results deduced from the method is slightly higher than those of most general ductile zones, which may be related to a rapid extensional detachment of the Wulian fault zone.

Key words: dynamic recrystallization, fractal, strain rate, paleo-stress, Wulian detachment fault zone

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