Mineralization And Genesis Of The Galinge Iron Polymetallic Deposit, Qinghai Province

Abstract:Galinge deposit, located in the eastern section of Qimantage of the Eastern Kunlun Mountains Orogenic Zone and the south eastern section of North Qimantage composite magmatic arc tectonic, is one of the most important deposits in the Qimantage polymetallic metallogenetic belt.Based on field geology survey, microscope observation,element analysis of rocks and ores,and sulfur and lead isotope analyses, igneous rocks,ores and stratum in deposit have been studied deeply,to discuss the genesis of igneous rocks,the relationship among ores, igneous rocks and stratum,and the origin of deposit.Galinge deposit lies between granite and the Tanjianshan Group. The orebody appears in bedded, near-bedded and lenticular shapes and is controlled by interformational fracture zone.Magnetite, pyrite, pyrrhotite, galena and sphalerite are the important ore-minerals; Garnet,diopside and epidote are the main gangue mineral. Skarnization is closely related with magnetite mineralization. The deposit can be divided into two metallogenic periods, Skarn period and Quartz-sulfide period, and five metallogenic stages that are early skarn stage, terminal skarn stage,oxide stage,early sulfide stage and terminal sulfide stage. The terminal skarn stage is the main metallogenic stage of magnetite.The magmatic rocks are the metaluminous and belong to calc-alkaline series. The geochemical characteristics of the magmatic rocks are as follows:rich in LREE, poor in HREE, negative Eu anomaly, enrichment of LILE (Th、U、Rb、Ba) and depletion of HFSE (Ta、Nb、Sr、Ti、Zr、Hf), which show the rocks belong to Volcanic arc granitoids and the magma originated from upper mantle and contaminated by earth crust.Geochemical characteristics of ores show close relationship between formation of magnetite and igneous rocks. S、Pb isotope compositions reflect the source of ore material is related to intermediate acidic intrusions.Magmatism provides the material source and metallogenic hydrothermal solution for Fe mineralization. Geological and geochemical characteristics of Galinge deposit show the genesis of deposit is associated with the intrusion of the Indo-Chinese and early Yanshan stage middle acidite magma. Galinge Iron Polymetallic Deposit is a skarn deposit which formed by contact metasomatism.