内蒙古临河-集宁深断裂中段早期韧性剪切带及其构造演化

EARLY DUCTILE SHEAR ZONE AND TECTONIC EVOLUTION IN THE MIDDLE SECTION OF LINHE-JINING DEEP FAULT, INNER MONGOLIA

临河 -集宁深断裂是一条具长期活动历史的复杂断裂带 ,以往对其早期演化研究甚少 .在 1∶5万区调工作基础上 ,测制了 5条 1∶2 0 0 0构造剖面 ,室内进行了大量的显微构造观察和组构测量 .研究表明 ,该断裂太古宙末表现为高角闪岩相—麻粒岩相的高温韧性剪切带 ,古元古代地壳在伸展体制下抬升之后又叠加有浅层次的绿片岩相低温韧性剪切活动 .中元古代之后转化为脆性断层活动 ,控制着不同时期的沉积和岩浆建造 .

The deep fault from Linhe to Jining, a complex long_term active fault zone has not been under thorough investigation in terms of its early evolution for the past years. However, in the present research, five tectonic sections in the proportion 1∶2?000 are mapped on the basis of the 1∶50?000 regional geological surveying. In addition, a great number of micro_structural observations and fabric measurements are completed in the laboratory. The research shows that the evidence of the Neo_Archean fault is expressed by the high_temperature ductile shear zone of high amphibolite facies_granulite facies that is overprinted by the low_temperature ductile shear zone of the greenschist in the shallow layers after the Lower Proterozoic crust was elevated in the extension system. After the Middle Proterozoic, this ductile shear zone is transformed into brittle fault, controlling deposition and magma formation in different periods.