Ore-forming Geologic Background And Ore-forming Feature Of Ag-Cu-Pb-Zn, Eastern Guangdong, China

Research area is in the southeast of South China fold system. It's geologic evolution history underwent three development stages :geosynclne, paraplatform and continental margin mobile belt; and the crustal movement underwent Caledonian movement, Indosinian movement and Yanshanian movement. Caledonian orogeny took place at the end of Silurian Period, which made the geosyncline to close and form fold basement. Devonian Period to middle Triassic epoch in the research area was in the stage of paraplatform development. At the end of middle Triassic epoch, Indosinian movement took place, which end the history of paraplatform development and make research area to get into continental margin mobile belt. Yanshanian movement took place during the end of early Jurassic epoch to the end of Cretaceous epoch , it was the most violent structure-magma activated period and was the most important ore-forming period nonferrous metal deposit in Eastern Guangdong. According to the regional geologic futures, research area can be divided into two tectonic elements: the Meixian-Feiyang late Palaeozoic Era downwaping region and the Eastern Guangdong upwarping region.There are plentiful in nonferrous metals deposit in the areas.Writer has been undergoing in looking for minerals in this area for a long time. Through the analysis of the regional geologic background in Eastern Guangdong and the geologic exploration practice of looking for mineral deposit and the research of the characteristics of large -middle scale Ag-Cu-Pb-Zn deposits, some main achievements and knowledge are as follows:①According to the analysis of regional geologic feature and mineralization feature, A middle scale Pb-Zn deposit was discovered in Gianbidong, Fongshun. Through geologic exploration, the geologic feature and mineralization feature of mineral district was confirmed. Some new opinions of mineral-forming mechanism, mineral-forming process was put forward, which showed that the mineralization took place in the embryonic stage of fracture-forming process and the mineral-forming solution took part in the formation of mineral-hosting structure. The research shows that the genetic type of mineral deposit is post-magmatic hydrothermal deposit, which is related to the crust-mantle type magma.②According to the research of regional stratum and structure and igneous rock feature combining with the theory of plate tectonics, a close relationship between the geologic evolution and plate movement in the research area was put forward, the geologic evolution history of Eastern Goangdong is deduced preliminary.③The geology, mineralization and deposit geochemistry characteristics of 4 large-middle scale Ag-Cu-Pb-Zn deposits in the research area are studied, and the genetic types of these mineral deposits is discussed also.④Through attentive research for the geologic feature and mineralization feature and trace elements feature, combining with regional geologic background, a new deposit genetic type of volcanogenic post-magmatic hydrothermal vein of Shongxi deposit is put forward. Shongxi deposit has a relationship to Jurassic epoch land facies volcanic action.⑤Through the research of regional ore-forming geologic background and mineral deposit geologic feature of large-middle scale Ag-Cu-Pb-Zn deposits in Eastern Guangdong, the source of ore-forming materials of Ag-Cu-Pb-Zn is discussed, which showed that the Ag-Cu-Zn mainly came from lower crust-upper mantle and the Pb mainly came from upper crust and sedimentary status. Mineralization had a close relationship with Yanshan period structure-magma action.⑥The mineralization model of Ag-Cu-Pb-Zn deposit in Eastern Guangdomg is preliminary set up. The Ag-Cu-Pb-Zn deposit of this area is post-magmatic hydrothermal vein deposit that is controlled by rupture.⑦Through analysis predecessors data , the structure circumstances of volcanism and the genetic types of volcanic magma is discussed. Volcanism took place in the background of Pacific plate subduction to Eurasian plate. Original volcanic magma came from lower crust or upper mantle part melt.⑧According to the analysis of regional geologic feature and mineralization feature and ore-forming geologic condition combining the knowledge of looking for deposit practice, a prospective area that have a good prospect in finding Ag-Cu-Pb-Zn deposits has put forward, that is Meixian -Chaoan prospective area.