对青海锡铁山矿区几个关键地质问题的认识

锡铁山矿区晚奥陶世滩间山群与早元古代达肯大坂群间的接角关系为隐蔽不整合，其间发育基底剥离断层（Ｆ１），基底剥离断层之下的“过渡带”实际上是一条退条质的下滑型韧性剪切带。而滩间山群则被构造肢解为Ｏ３ｔｍ＾ａ－ｂ褶叠层与Ｏ３ｔｎ＾ｃ－ｄ褶皱冲断岩片，其间发育上剥离断层（Ｆ２），两条剥离断层面上、下因构造剥蚀充失了大厌地层。并认为和里东晚期的伸展构造体制形成锡铁山变质核杂岩，海西期的抗日压构造体制形成褶

THE RECOGNITION ON A FEW KEY GEOLOGICAL PROBLEMS OF XITIESHAN MINE AREA,IN QINHAI PROVINCE

The contact between Ordovician Tanjianshan Group and Early Proterozoic Dakendaban Group in Xitieshan mine was a blind unconformity, in which a base detachment fault (F 1) was developed. In fact, the transitional zone under the base detachment fault was a downslide ductile shear zone of retrogressive metamorphism. Tanjianshan Group was divided into folding beds (O 3 tn a-b ) and fold thrust microlithon (O 3 tn c-d ),among which an upper detchment fault(F 2) was developed. The part of stratum near the two detachment fault faces was cut away because of tectonic erosion. It is believed that Xitieshan metamorphic core complexes wore formed in Caledonion extending structure system and the fold thrust microlithon was formed in Hercynian compressional structure system.