The Geological Features And Genesis Of Yangshan Iron Deposit, Dehua County, Fujian Province.

Yangshan iron deposit is located in southeast of Yongmei geotectogene and southeast of Zhenghe-Dafu fault zone in southwestern Fujian Province, which is Upper Paleozoic.The exposure layers are including Lindi formation of Lower Carboniferous;Q ixia formation,Wenbi formation and Tongziyan formation of Lower Permian.Two main structures are folds and fractures. Intrusive rocks are mainly granite and quartz porphyry during early Yanshan tectonic period.In the paper,Yangshan iron deposit is research object,to study genetic types which has great significance to explorate in edges and deeps in crisis mine. At present, there are many differences of genetic types.One is that Yangshan iron deposit belongs to calcium skarn type iron deposit. Another is that the deposit is a volcanic sedimentory and hydrothermal superimposed reformation iron deposit.Testing protogenesis inclusions exploding temperature and the temperature estimated by two- feldspar thermometry, the temperature of forming skarn in this area is lower than skarn which is formed by intermediate to acidic rock mass intrude into carbonate rocks. Vickers hardness values of magnetite vary a lot with skarn deposit’s values.The mainly orebody is layered, like- layered which is produced in qixia formation and has synchronous fold deformation with strata.It suggest that the genetic type of iron deposit in this area is different with skarn iron deposit.Studying the Late Carboniferous sedimentary palaeogeographic environment of southwestern Fujian Province, stratabound characteristics of ore deposit,The morphology and distribution features of ore body and ore structure characteristics,consider that the deposit is a typical sedimentary mineralized deposit.By means of rocks chemical composition characteristics analysis, ores and minerals chemical composition characteristics analysis,concluding that ferruginous of Yangshan ore mainly comes from terrigenous sediment.Based on early Permian sedimentary deposit mineralization, regional metamorphism thermal action in variscan and analysis and study of hydrothermal superimposed reformation in early Yanshanian. divided into three stages, sedimentary mineralization, metamorphic mineralization and hydrothermal mineralization,which establishes sedimentary- metamorphic hydrothermal superimposition reformation metallogenic model. In addition,determine the strata of Qixia formation, skarnization(ferritization) and magnetic anomaly characteristics and other important prospecting marks.Through the analysis and study of regional strata, magmatic rocks, structure s, geological characteristics of alteration and mineralization, as well as the 1:50000 aeromagnetic data in western Fujian, Yangshan iron mining peripheral area also be found some aeromagnetic positive abnormal,which is consistent with Late Paleozoic strata, speculated that most of the anomalies caused by concealed mineralizat ion. Analyze from strata, intrusive rocks, structures, and magnetic anomalies, near the contact zone of rock mass and the Carboniferous- Permian strata,has a good explorating prospective. Key words: Yangshan iron deposit;geological features;deposit genesis;Dehua...