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A Possible Tectonic Response Between the Qingchuan Faultand the Beichuan‐Yingxiu Fault of the Longmen Shan Fault Zone? Evidence From Geologic Observations by Paleoseismic Trenching and Radiocarbon Dating
Author(s) -
Liang Mingjian,
Ran Yongkang,
Wang Hu,
Li Yanbao,
Gao Shuaipo
Publication year - 2018
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/2017tc004949
Subject(s) - geology , seismology , fault (geology) , tectonics , sinistral and dextral , thrust fault , trench , stress field , strike slip tectonics , fault scarp , physics , finite element method , thermodynamics , chemistry , organic chemistry , layer (electronics)
The Qingchuan fault is located along the eastern margin of the Tibetan Plateau and connects to the Beichuan‐Yingxiu fault of the Longmen Shan fault zone (LMSF), which produced the 2008 M W 7.9 Wenchuan earthquake and 2013 M W 6.6 Lushan earthquake. After the two devastating earthquakes, whether the Qingchuan fault could produce a large earthquake or not and its tectonic activity is highly debated. Based on the detailed field investigations and paleoseismic trenching combined with multiple radiocarbon dating, we suggest that the Qingchuan fault might not show intense fault activity (or specific dextral strike‐slip deformation) since the late Quaternary. The deformation evidence revealed in the trench indicates a pattern of tensional deformation in the strata, which is inconsistent with the regional compressional tectonic stress field. Moreover, the timing of these deformation events coincides with that of paleoearthquakes that occurred on the Beichuan‐Yingxiu fault. Therefore, we speculate that the large earthquakes that occurred on the northern segment of the Beichuan‐Yingxiu fault highly likely contribute to the formation of the tensional structures observed along the Qingchuan fault. The uplift of the Minshan Mountain affects the tectonic deformation and seismic activity of the northern segment of the LMSF. However, considering that the LMSF shows forward‐thrust characteristics, the fault activity of the Qingchuan fault was possibly the most affected by the uplifting of the Minshan Mountain. In other words, this specific regional tectonic frame might constrain the buildup of tectonic stress and seismic potential for generating large earthquakes on the Qingchuan fault.