Study On The Tectonic Evolution In Wuerxun Depression Of Hailaer Basin

Using field ,exploration well and lots of seismic data, combing the new theories such as structural geology, sedimentary petrography and seismic stratigraphy, this paper analyses the stratigraphic sequence and tectonic evolution thoroughly of the research area by the method of seismic, logging and core analysis comprehensively.The character of Wuerxun Depression includes East-west zoning and South-north blocking, which can be divided into two Subsags-South Wuerxunand North Wuerxun. .Three different directional structural belts are developed in the research area. The faults zones that direct South-North, North-East and North north-East format in the early time and active for a long time, and control the formatting and evolution of the depression.According to the explanation of seismic data, regional unconformity interface was identified. The formation of Wuerxun Depression from bottom to top includes metamorphic rock of Budate Group, volcanic rock clips coal of Xinganling Group,Nantun formation, Damoguaihe formation, Yimin formation, Yuangang formation, Huzhashan formation and Quaternary.On the research of seismic profile and structure, it was found that the main body of Wuerxun Depression is single fault dustpan downfaulted basin which is controlled by SN trend Wuxi fault zone. Sunken faults mainly develops Wuxi fault zone and its assoc SN trend centripetal fault and of which id made up flower structure, NEE trend fault complex and NE trend fault zone.On the study of tectonic evolution and structural history, it was fount that the structure deformation of Wuerxun Depression have multi-stage, multi-level, multi-directivity and complex composite relation. By analysing the seismic profile, this paper account that Wuerxun Depression experienced 3 deformation stages in the early chalk, including NW-SE trend stretching action at Xinganling stage and Nantun stage , NW trend extend action at late Yimin stage and NW trend extruding action at the end of Yinmin and the start of Yuangang stage and SE-NW trend extend action and extruding action from Late Crataceous to Cenozoic era.