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Wu F.-Y.,Chinese Academy of Geological Sciences | Wu F.-Y.,Key Laboratory for Continental Dynamics | Li H.-B.,Chinese Academy of Geological Sciences | Li H.-B.,Key Laboratory for Continental Dynamics | And 7 more authors.
Geological Bulletin of China | Year: 2011

In field investigation we found that Qinghai Yushu Ms7.1 earthquake occurred on April 14, 2010 produced a ~65 km long co-seismic surface rupture zone which strikes 310° and dips NE. The entire zone is composed of two parts: the west section is about 19 km long and the east section is 30 km. Between these two sections, a 15 km long zone surface rupture gap is observed. Surface ruptures displayed common sinistral lines mainly featuring right stepping en-echelon ruptures, while vertical offsets developed. The ratios between co-seismic vertical offset and horizontal offset range from 0.13 to 0.53, while the geomorphic dv/dh values of 0.27~0.63 are close to co-seismic dv/dh (0.13~0.53), indicating that the Yushu Nanshan uplift probably showed the same kinematic and dynamic characteristics. In other words, the Yushu Nanshan uplift is resulting from the cumulative vertical offsets produced by many earthquakes similar to Yushu earthquake along Yushu fault in the geological history. We conclude that we need 1800~2600 earthquakes similar to Yushu earthquake to form Yushu Nanshan. Former researchers reckon the recurrence period of the Yushu section of Ganzi-Yushu fault zone to be 120-200 years, which would make us believe that this fault section's activity started from 200~400 ka ago.

Pan J.,Key Laboratory for Continental Dynamics | Pan J.,Chinese Academy of Geological Sciences | Li H.,Key Laboratory for Continental Dynamics | Li H.,Chinese Academy of Geological Sciences | And 11 more authors.
Scientia Geologica Sinica | Year: 2010

Study on stratum, geomorphology, and tectonic deformation in Mazartagh area is significant for understand questions such as the Cenozoic tectonic evolution of the Tarim Basin, the relationship between Tarim Basin and west Kunlun Mountain, the influence of neotectonic activities on the redistribution of oil-gas resources, and changing of climate and environment in Taklimakan desert. Late Cenozoic structural features in this area were studied thoroughly based on interpretation of satellite images, observation of field deformation, surveying of geological section, and interpretation of geophysical data. The tectonic orientation, time of origin, uplift rate and shortening rate, and stretch of the Mazartagh fold-thrust belt was also discussed here. The main conclusions are as bellow: 1)Based on the analysis of regional geomorphology, surface deformation, and geophysical data, the Mazartagh fold-thrust belt was considered to be the frontier of the foreland fold-thrust belts of the west Kunlun Mountain. The Hetian River gas field, which located in the crest of the frontier thrust belt, was formed under the promotion of the Late Cenozoic tectonic deformation, which reform the tectonics of the Paleozoic and Mesozoic in the southern and central Tarim Basin; 2)The Mazartagh Mountain had experienced two tectonic uplift events, which were at the end of Miocene(about 7 Ma)and from Middle-Pleistocene(about 780 ka B. P.)respectively. The late one caused the formation of Mazartagh fold-thrust belt and present geomorphology of Mazartagh Mountain; 3)Uplift rate and shortening rate of Mazartagh fold-thrust belt since middle Pleistocene were estimated to be 0.26~0.4 mm/a and 0.9 mm/a respectively; 4)The Mazartagh fold-thrust belt should be linked to Kashi Anticline, which is also the frontier of the foreland fold-thrust belt of the west Kunlun Mountain, to the west. There might be a strike slip fault in the eastern end of the Mazartagh Mountain, near the Hetian Rive, which strike in a NE-SW direction and cause the disappear of the Mazartagh Mountain to the east.

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