The Tectonic Features And The Establishment's FEM Simulation Of Metamorphic Core Complex In Yiwulv Mountains

Metamorphic core complex in Yiwulv Mountain is in the west of Beining in Liaoning province. It is in the middle of Yiwulu Mountains. Tectonic location is at the eastern of Yanshan Orogenic Belt, and at the western edge of Liaohe Basin. In Pre-Mesozoic, it was at the northern part of the North China Craton. Its basement was Archeozoic crystalline rock. In The Meso and Neoproterozoic, it was at the northeast of Yanliao aulacogen, deposited thick changcheng system, Jixian system, and qingbaikou system; In Paleozoic, its had geological typical features of the platform; In Mesozoic, this region happened a strong tectonic-thermal event. In 1996, throught analysis of previous work , Professor Cui Shengqin realized that Yiwulushan might be a metamorphic core complex.Metamorphic core complex in Yiwulv mountain mainly contains the metamorphic core, the detachment fault and the upper caprock, The metamorphic core consist s of late Yanshanian adamellite and Archaean metamorphic rock, and was surrounded by the ductile deformation of Meso proterozoic. The upper of caprock is Cretaceous fragmentary rock with brittle deformationWith the development of metamorphic core complex study, it is not only important to study metamorphic core complex's geometry, but also to be on dynamic and regional tectonic setting. The knowledge of structure not only examine its spatial characteristics, but also discuss the accurate formation of geological research. A white granite (B057-1) was Collected from the granite structure. Its rock isotope can be used to determine the age of metamorphic core complex formation age. Its'weighted average of 152.5 Ma, probably mid-late Jurassic Yanshan.This paper utilized finite element software establish FEM's model of metamorphic core complex and explored metamorphic core complex formation mechanism. Simulation results show that: 1) the main extension of tectonic movements, at the same time of extending, it resulted in ground settlement, and formed grabens; it didn't provide the stress conditions and temperature conditions for metamorphic core complex; 2) the hot magma uplift of the main role of the tectonic movement, Its displacement stress and temperature distribution show that this tectonic movement provided all conditions for the formation of metamorphic core complex. In summary, The heat uplifting occupy a very important position in the formation of metamorphic core complex.According to the gathered information and research results, utilize ANSYS, establish 3D finite element model of metamorphic core complex in Yiwulv mountain, and utilize thermal-structural coupling simulate the temperature field and the tectonic stress field of metamorphic core complex changes, and then discuss metamorphic core complex's formation mechanisms in Yiwulv mountain. Yiwulv region has experienced at least two period stress, the first was pressure stress distribution, it make crustal thicken and partial melting; the second was extensional stress distribution. it made magma upwelled andinvade into Archeozoic metamorphic rock, and then formed metamorphic core complex in Yiwulv mountain.