The Tectonic Evolution Of The Bayanhaote Basin And Formation Simulation

No oil and gas reservoirs of economic value have been found in Bayanhaote Basin so far.However,commercial oil flow has been discovered in the Linhe Depression in the Hetao Basin on the north side.This thesis does some job in order to deepen the knowledge of deformation characteristics and tectonic evolution of the Bayanhaote Basin,and provide suggestions for the next exploration zone selection.Based on the existing 2D(two-dimensional)seismic profiles and outcrop of the HTB(Helanshan Tectonic Belt)around the basin,we build the tectonic evolution model of the basin.And the deformation processes are simulated and verified by the analogue models.According to the seismic data,the structural characteristics of the sedimentary depressions,fault system and the structural patterns,we establish tectonic framework of the basin.To clear the tectonic evolution stages,we compare the seismic profiles in the basin and the detailed studied route in the field,analyze the variation of regional stress field and the relationship between the peripheral plates.Then,we select the representative sections to draw the balanced cross section.Finally,we carry out the physical analogue models to simulate the key deformation stages of the basin.Through the distribution and superposed features of structural elements,we could verify the deformation process of the basin.Basing on the above analysis,we have drawn the following conclusions:(1)The Bayanhaote Basin experienced six key evolution stages.Basin crystalline basement formation stage,Caledonian continental margin stage,Hercynian compression stage,Indochina compression stage,Yanshanian accommodation stage and Cenozoic strike-slip reconstruction stage.(2)Since the early Triassic,the basin experienced the subduction collision from the northern and southern plates,and nearly E-W striking reverse faults and NE-SW trending compression folds occurred.NW-SE trending contraction tectonic environment from the Jurassic to the Early Cretaceous Lisangou formation sedimentary period caused reverse faults with NE-SW striking and folds with NE-SW axial plane.Two main compression events resulted in tectonic framework of segmented and belted in our study basin.Extensional faulted basin in the Early Cretaceous formation sedimentary period to the Paleogene were developed from the superposed structures of pervious folding.And readjusted by the pure shear in the Himalayan period.(3)From the cross-sections of the superposed direction of the superposed structures under orthogonal compression,the duplication of the sedimentary layers on the hanging walls was identified.Interference patterns were confined by the pop-up structures and fault-related folds,which were represented as cubic domes and duplicate structures that are cut by reverse faults.The basal decollement added the uncertainty of the positions of the thrusts and pop-up structures,leading to scattered superposition.