Structural Features And Deformation Evolution Sequences Of Labudalin Basin, Inner Mongolia

The research of formation and evolution process of basin is an important scientific issue in the field of basin research. Although lots of controversy exists in the research of structural geometry and kinematical features of Labudalin Basin, the well developed strata with great thickness, plus abundant 2-d seismic data, drilling data and logging data made it a natural laboratory for the research of structural features and deformation sequences of basin.This paper aims at the research of structural features, deformation sequences of Labudalin Basin and its relationship with Hailar Basin in terms of structural geometry and kinematics of basin structure. First, the author summarized the problem and shortage in predecessors'research of structural features, deformation sequences of Labudalin Basin. Then, based on the fine interpretation of plenty of 2-d seismic sections (including in-line and cross-line),plus references of drilling cores, logging data and sedimentary data, combined with the theory of growth fault related folds in structure geology and latest achievement in the technique of equilibrium section recovery home and abroad, the author analyzed major structural style and features of structural assemblage in different spreading directions, established structural geometric and kinematical model of faults in the study area. After that, by the analysis structural history of major seismic sections of study area using the method of equilibrium section, the author summarized the deformation sequences of Labudalin Basin on the basis of research of structural features in study area. Finally, the author compared it with adjacent Hailar Basin in Early Cretaceous Epoch based on the research of basin structure and deformation.By the research schemes above, this paper discussed structure features and deformation sequences of Labudalin Basin and its relationship with Hailar Basin in Early Cretaceous Epoch, concluded opinions below:(1) The structures developed in Labudalin Basin could be divided into three groups of faults by trending: NE, NEE and NW. The NE group are mainly listric normal faults and associated co-current normal fault combination, the NEE group are characterized by shear-normal fault, the NE and NEE groups are depression- controlling faults formed during Tamulangou-Yiliekede Period, they are structures formed in the same stress field but have different mechanical properties. The NW group formed later and cut through the NE and NEE group, it is characterized by sinistral strike-slip. The three group of faults divided Labudalin Basin into five first-order structural units including three depressions and two uplifts.(2) The basin underwent relatively large-scale compression during Damoguaihe Period, thus caused the inversion of former NE-trending depression-controlling normal faults and formed fault-band fold, fault-propagation fold.(3) Labudalin Basin is that formed in Cretaceous, under went 4 phases of deformation in Early Cretaceous Epoch: NW-SE trending extension during Tamulangou-Yiliekede Period, NW-SE trending compression during Damoguaihe Period, near EW extension trending during Yimin Period, near EW extension between Yimin Period and Late Cretaceous Epoch.(4) Compared with Hailar Basin, Labudalin Basin has the nearly the same structural features and deformation sequences in Early Cretaceous Epoch, and they are adjacent in space, so the author concluded that they are one larger basin in Early Cretaceous Epoch.