Determination of early stage of early cretaceous compressive event in Hailar basin, NE China, and its tectonic significance

© 2016, Editorial Department of Earth Science. All right reserved.The Mesozoic Mongol-Okhotsk orogeny in Northeast Asia is a significant tectonic event which has attracted interest of many geologists. A tectonic unit involved in strong contractional deformation has been identified under the Early Cretaceous rifting sequences in the Beier depression of the Hailar basin, based on the newly obtained petroleum exploration data including seismic reflection, drilling and well logging. Structural analyses show that the structural system is composed of one major ENE trending overthrust fault and associated thrusting-folding deformations. Lithological and stratigraphic characteristics and dating results of detrital zircon U-Pb show that the strata consist of Late Jurassic terrigenous clastic rock, as a part of the Upper Jurassic Tamulangou Formation in this region. Considering the time of the development of overlying faulted basins and the emplacement of coeval metamorphic core complexes in surrounding area, it is suggested that the thrusting-folding event of the Hailar basin mainly occurred during early stage of the Early Cretaceous (145-133 Ma), which is a key structural record resulted from the Mongol-Okhotsk collisional orogeny during the Late Mesozoic.