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Michael Oskin et al from University of California-Davis Visited China

2016/12/30 8:59:10

At the invitation of Researcher Liu Jing of State Key Laboratory of Earthquake Dynamics, Professor Michael Oskin et al from University of California-Davis visited IGL in July ~ September 2016. In this period, they and IGL studied  the tectonic landform and active faults in Altun Fault, Qilian Mountain Piedmont Fault and some other areas.

Altun Sinistral Fault is one of the most important and largest linear structures in the world. It is a matter of significance to the research of the uplift and deformation mechanisms of Tibetan Plateau. The area from Pingdingshan in the western end eastwards to Aksay Double-Bend is the middle segment of Altun Fault. In this area, the fault bears obvious linear characteristics, paleo-earthquake fracture zones are well preserved and the dislocation of river systems is obvious. The fine granular substances in Suerkal Basin and other features all provide a favorable condition for paleo-earthquake research in this segment. The investigation team researched the river morphology of Suerkal segment of Altun Fault Zone, dislocation of geomorphologic lines induced by paleo-earthquakes, terraces, scarps and geographical morphology of the fault zone by such methods as field investigation of the above area, and geological and geomorphic mapping. The team attached importance to detailed research of multiple sinistral dip-slip faults in the research area. The investigation discovered signs of a series of obvious surface fractures, inconsistent fault dislocation on related work sites, and serious weathering and denudation of the linear surface features of sinistral fault dislocation. The field study obtained Cenozoic strata deformed due to control of regional tectonic stress of horizontal compression, attitude of rock in Quaternary strata in particular. The uncertainty of strata exposure level and weathering degree to recovery of regional tectonic deformation was discussed. The above work offered a new angle of view at the strike-slip history of Altun Fault Zone, its deformation distribution and other scientific issues. During the field study in Aksay segment of Altun Fault, Professor Oskin also assisted and guided doctoral students to limit fault slip rate on a time scale of a million years by Quaternary deposit source tracing method, laying a foundation for future research of the research team on long-term evolution process of Altun Fault Zone.

Qilian Mountain-Hexi Corridor region is characterized by compression-type basin-range structure. It is a component of Tibetan Plateau, which is youngest and also has the strongest tectonic activity. Its tectonic deformation and geomorphic evolution is a window for cognizing the dynamics of Tibetan Plateau and also a basic link for evaluation of its future seismic hazard. The joint study group carried out investigation of terrace form, development features and other geological and geomorphic conditions of the Shiyou River, Beida River, Fengle River, Maying River and other piedmont rivers of Qilian Mountain, and conducted cognitive study of Yumen Fault and Fodongmiao-Hongyazi Fautl inside the basin. After the end of the field work, Veronica Prush and Chantel Jensen carried out discussion and exchange with IGL and the research group of Researcher Liu Jing.

Researcher Liu Jing, Researcher Zhang Huiping, Professor Li Youli of Peking University and the members of Liu Jing’s research group accompanied the study group. In addition of field study, they also carried out in-depth discussion on subsequent cooperation and work.