Tectonic Evolution From Middle-Proterozoic To Paleozoic In Guyang

The Changcheng System of Zhaertaishan Group (Shujigou and Zenglongchang Formation) and Baiyunebo Group (Dulahala and Jianshan Formation) were the sediments of a pasive continental margin. The former is near the main land, and the latter is near the ocean. The characteristics of the ductile-shearing deformation developed between the basal rock system (Neoarchaeozoic-Seertengshan Group Complex,and Neoarchaeozoic-Paleoprozoic gneissic granitoids) and the Changcheng System (Dulahala,Jianshan, Shujigou,Zenglongchang Formations ) are identical. The tectonic background of the ductile-shearing deformation is the extensional detachment of the Changcheng System. The deformation environment belongs to lower temperature-pressure one,and the age when the ductile-shearing deformation began is the end of the Changcheng period. Extensional detachment in the end of the Changcheng System resulted in rising of the basal rock system, and the "I"type unconformity on the top of Zhenglongchang, Jianshan Formation were formed as the weathering and eroding in the later. In the Jixian System, two relative independent rifting basin that be connected by the water began to form on the background of the regional extension and upwarping in Baiyunebo (located in the north )and Zhaertaishan ( located in the south ) area. On the initial stage of the rifting, the sediments were mainly coarse clastic rocks include conglomerates and sandstones, and the basic rocks—basalts and dolerites intruded at the same time. On the middle stage of the rifting, the sediments were thin clastic rocks that include carbonaceous silty slates, siltstone and carbonaceous limestone, and the trachy volcanic rocks and carbonatite(sH8)erupted, and the gabbros, serpentinized peridotites and syenogranites intruded. The Bilute serpentinites were ultrabasic rocks that intruded into Bilute Formation during the rifting. Rock assemblages of Halahuogete and Bilute Formation belonging to Baiyunebo Group can not compared with those of Agulugou Formation of Zhaertaishan Group. The country rocks of Baiyunebo Fe-REE deposit were particular sedimentary assemblages of the Baiyunebo Rift, and could not compare with the rocks of Halahuogete and Jianshan Formation. In the end of the Jixian System, The acient weathered crust had been formed on the top of the Jixian System (the top of Agulugou and Bilute Formation) as the rising in this region,which resulted the parallel or tiny-angular unconformity between the Jixian System and the Qingbaikou System. Baiyinbulage Formation formed in the early Qingbaikou System is the sediment of the passive continental margin. In the later Qingbaikou System, Hujierte Formation was formed on the active continental margin, and the granites intruded. There were no large-scale orogenic movements in the middle and upper Proterozoic. Baoerhantu Group is the sediment of the back-arc basin, and the intrusive rocks companied with...