caa a22 4500 60614997X CHVBK 20210128100536.0 cr unu---uuuuu 210128e20150701xx s 000 0 eng 10.1007/s00531-015-1160-8 doi (NATIONALLICENCE)springer-10.1007/s00531-015-1160-8 Microstructural and mineral analysis on the fault gouge in the coseismic shear zone of the 2008 M w 7.9 Wenchuan earthquake [Elektronische Daten] [Ren-mao Yuan, Bing-liang Zhang, Xi-wei Xu, Chuan-yong Lin, Zhu-jun Han] The 2008 M w 7.9 Wenchuan earthquake formed two coseismic surface rupture zones with the trend of N35°E, known as the Beichuan-Yingxiu rupture and the Pengguan rupture. The Beichuan-Yingxiu rupture is the principle one with abundant fault gouge development along its length. In the exploratory trench at the Saba village along the Beichuan-Yingxiu rupture, the new fault gouge zone is only ~3mm wide, which suggests that fault slip was constrained in a very narrow zone. In this study, we thus carried out detailed microstructural and mineral component analysis on the oriented fault gouge samples from the Saba exploratory trench to understand their features and geological implication. The results show that different microstructures of localized brittle deformation can be observed in the fault gouges, including Y-shear, R1-shear, R2-shear, P-shear as well as tension fracture, bookshelf glided structure and so on. These microstructures are commonly recognized as the product of seismic fault slipping. Furthermore, within the area between two parallel Y-shears of the fault gouge, a few of microstructures of distributed ductile deformations were developed, such as P-foliation, elongation and asymmetrical trailing structure of detrital particles. The microstructure features of fault gouges implicate the thrust movement of the fault during the Wenchuan earthquake. In addition, the fault gouge has less quartz and feldspar and more clay than the surrounding rocks, which indicates that some quartz and feldspar in the surrounding rocks were transformed into clay, whereas the fault gouge has more illite and less illite/montmorillonite mixed layers than the surrounding rocks, which shows that the illite/montmorillonite mixed layer was partly converted into illite due to temperature increasing induced by coseismic fault slipping friction (also being affected partly by the chemical action of solutions). Such microstructures features and mineral component changes recorded the information of fault slip and provide criterions for discussing the genesis of fault gouge and recognition of the direction of fault movement. Springer-Verlag Berlin Heidelberg, 2015 The 2008 Wenchuan earthquake nationallicence Fault gouge nationallicence Microstructure nationallicence Mineral component nationallicence Yuan Ren-mao Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut Zhang Bing-liang Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut Xu Xi-wei Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut Lin Chuan-yong Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut Han Zhu-jun Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut International Journal of Earth Sciences Springer Berlin Heidelberg 104/5(2015-07-01), 1425-1437 1437-3254 104:5<1425 2015 104 531 https://doi.org/10.1007/s00531-015-1160-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00531-015-1160-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Yuan Ren-mao Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut NATIONALLICENCE 700 1- Zhang Bing-liang Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut NATIONALLICENCE 700 1- Xu Xi-wei Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut NATIONALLICENCE 700 1- Lin Chuan-yong Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut NATIONALLICENCE 700 1- Han Zhu-jun Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, A1#, Huayanli, Chaoyang District, 100029, Beijing, China aut NATIONALLICENCE 773 0- International Journal of Earth Sciences Springer Berlin Heidelberg 104/5(2015-07-01), 1425-1437 1437-3254 104:5<1425 2015 104 531