The Characteristics And Physical Modeling Of Extensional Structure In West Shandong Rise, China

Most extensional structures since late Mesozoic in West Shandong Rise, such as normal faults, developed on the base of the Mesozoic thrust fault's negative inversion. The extensional structures inherited the characteristics of earlier structures and they appeared new active characteristics in new structure stress field. Therefore, the structures are multiphasic, and the strike of the structures is changeable. So the tectonic framework of the West Shandong Rise appears to be the complex structural style. The main structure style is the extensional tilted fault block formed by the high-angle fault and low-angle décollement fault, which composes the extensional structure style of the West Shandong Rise.On the base of the field work and applying the physical modeling with similarity theory, the author studied the compound structural style and evolution of extensional structures. The results of the experiment half quantitative-quantitative verified the structure style of West Shandong Rise since the late Mesozoic. The extensional structure mainly underwent three periods of late Cretaceous, Paleocene, and Eocene. The low-angle décollement fault occurred later than steep fault, and developed widely along the Pz/Ar and C-P/O unconformity surface. Mechanically, the extensional structures were controlled by extension in direction of NE-SW and magma upwelling vertically. According to the fission track modeling and physical modeling, the results show that the Taishan Mountain went two relative rapid outstanding uplifting stages which were in the time of 44-37 Ma and 23-20 Ma. On the basis of the uplift-subsidence coupling theory, the study of extensional structure in West Shandong Rise gives the geology data to the deep structure research of the Jiyang Depression.