Tectonic Evolution from Middle-Proterozoic to Paleozoic in Guyang
|School||Chinese Geology University (Beijing)|
|Keywords||Margin sedimentary Changcheng System Bayan Obo Mesoproterozoic Rifting Basement rocks Siltstone Basalt Volcanic NCB|
Zhaertaishan Hills Changcheng System (secretary ditch group, increasing Longchang group), Bayan Obo Group Changcheng System (Du la jara group, Eagle's Nest group) for the same passive margin deposition, the former near land, which is near ocean. Changcheng System and the underlying Paleoproterozoic basement rocks and earlier ductile deformation near the interface of the same features, is the Great Wall system relative to the underlying rocks northward detachment due. Detach the end time of the Great Wall discipline, formed in the low temperature and pressure environments. Changcheng regional extension in the end, lead to basement rocks uplifted, causing regional uplift and subjected to weathering and erosion, increasing the formation of Changcheng System Longchang group top group at the top of Eagle's Nest type Ⅰ unconformity. In the regional extension uplift mechanism, Jixianian Bayan Obo, Zhaertaishan and began divided into north and south two relatively independent, but the middle of the sea linked rift basins. Early rifting have coarse clastic rocks - conglomerate, pebbly sandstones and mafic rocks - basalt, diabase dikes penetration; interim fine clastic sedimentary - carbonaceous, silty slate, siltstone , carbonaceous limestone, rough volcanic rocks and carbonatites (H8) ejected, gabbro, serpentine peridotite, K-feldspar granite intrusion. Bi Lute serpentinite was emplaced at Bi Lute rifting in the group ultrabasic rocks. Same as the deposition of the Bayan Obo rift Jixianian group Hala Huo pimple special group, Bi Lute group and Zhaertaishan Hills A Gulu ditch groups from the rocks can not be compared, Bayan Obo iron ore rock rare earth deposits neither with the Bayan Obo Group Hala Huo pimple special groups were compared, it can not compare with the Eagle's Nest group, they are unique Bayan Obo rift sedimentary assemblage. Jixianian end zone extrusion uplift, forming the top of Jixian System (A Gulu ditch group, Bi Lute group) weathering crust, resulting in Jixian System with Qingbaikouan unconformity between parallel or slightly angular unconformity. Qingbaikou early as passive margin deposits (white tone Prague group), late into the active continental margin deposits (call Geert group) and a granitic intrusions, but does not exist in the Neoproterozoic massive orogeny. Early - Middle Ordovician Rabaul Khan Figure granite base and accompanied the northern margin of the North China Block arc basin sedimentation and syn-orogenic magmatic arc granite, on behalf of the northern margin of the North China Block early Paleozoic continental margin hyperplasia. Do Upper Silurian West River Formation unconformably on it, marking the end of the Caledonian orogeny. The geological Yanshan thrust upon at the NCB, which are with the surrounding geological fault contact. \The northern margin of the North China Block \The original plan 1:200000 regional geological survey of the Upper Carboniferous to Permian Batu group of real ophiolitic melange. Blocks from the Lower Devonian volcanic rocks (398 ± 18Ma), Early Devonian ophiolite (385.6 ± 17Ma), Upper Carboniferous of the Batu group hard sandstone, limestone (including fusulinids) and Permian ophiolite rocks, basalt (285Ma ± 11Ma), tonalite rocks (252.17Ma) and other components. The matrix is ??siltstone, silty slate radiolarian cherts, which radiolarian cherts formed in the Early - Middle Permian. The ophiolitic mélange belt and foreland basin Zhesi group molasse accumulation, early, middle Permian Dashizhai margin island arc volcanic rocks together to form the area between the land and the Late Paleozoic orogenic belt. Suolunshan - Tsagaan Hada tone ophiolitic melange of SouthGobi micro-continental blocks and NCB suture, suture time in the Early Permian.