Structural Deformation Characteristics Of Ganzi-litang Ophiolitic Melange Belt In Xinlong Region

Ganzi-Litang ophiolitic melange belt located between Songpan-Ganzi orogenic belt and Zhongza block in the Sanjiang Tethyan orogenic belt.It is a typical Non Smith stratigraphy.Its overall feature are disorderd or disorderd mostly ordered fractionally.Studying fractuer geometry structure,kinematics,kinetics is important to the research of the formation and evolution of the Sanjiang Tethyan orogenic belt.I try to differentiate rock blocks and matrixes based on the“Lithology+Structure”methods.And summarize the lithologic features,tectonic deformation featuresa and combination form of the rock blocks and matrixes.And analyze the structural sequence of study area,Finally preliminary discuss the geological evolution and formation mechanism of Ganzi-Litang ophiolitic melange belt.This thesis devides 3 parts of matrixes inclouding rifting formation,passive continental margin formation and distal island-semount formation.And devides 3 parts of rock blocks inclouding slope island-semount formation,proximal island-semount fromation and mid-oceanic ride formation.In addition,there are a lot of small rock blocks mixed in the ophiolitic melange belt,like pyroxene peridotite block,gabbro block,diabase block,basalt block,siliceous block,limestone block and so on.The deformation of matrixes are always strong,with the folds,cleavages,faults and ductile shear zone are widespread developed.The deformation of rock blocks are always weak,because of its rigidity.They are wrapped around by matrixes and assume lenticular.But the ductile deformation can be developed in the border area.Combined with the formation,magmatic rock and structure,the geological evolution of study area can be devided into 6 stages,development stage of rift valley?D?,development stage of ocean basin?C₁-T₁?,oceanic crust subduction stage?T₂-T₃?,arc-contient collision orgenic stage?T₃-K?,intracontinental deformation stage?E?,plateau uplift stage?N-Q?.The current very complex geologic structure in Ganzi-Litang ophiolitic melange belt was taken shape by suffering many mineralization stages and periods of tectonic deformation.