Metallogenesis Of Jibote Iron Deposit In Altay,Xinjiang

The South of Altay orogenic belt is important iron,copper and gold metallogenic belt in China.Among which multiple large polymetallic deposits in marine volcaniclastic-sedimentary rocks.Jibote is a small iron deposit in maizi basin,and the ore bodies are interbedded with the upper Silurian to Lower Devonian metamorphosed volcanic-sedimentary rocks and display same distortion as wall rocks,which is always associated with intensely skarn alteration.And marine volcanic type iron deposits in northern Xinjiang has similar characteristics However,there are several causes of this type of deposit is still disputed.This article object from Jibote iron deposit,studied mineralogy,geochronology,ore and ore-forming fluid characteristics and sources in order to study on the forming mechanism of the marine volcanic type iron deposit basis,providing guidance for the type iron deposit exploration.Made aware:(1)The orebody is located in the second lithologic section of the subgroup of the upper Silurian to Lower Devonian Kangbutiebao Formation.The direct rock is amphibolite,rhyolite,metamorphosed volcanic rock,granulite,leucoleptite and marble.Ore body roughly parallel to the parallel arrangement consistent with the attitude of strata near,multi-bedded,and lenticular.LA-ICP-MS U-Pb zircon dating on the weighted ages of the rhyolite is 380.8±4.1Ma and epidote skarns is 393.3±2.1Ma.Indicating that the Jibote iron deposits formed later than early-middle Devonian.(2)Ore types are contains garnet magnetite ore,garnet diopside magnetite ore,diopside magnetite ore,epidote magnetite ore and sulfide magnetite ore.The ore is mainly composed of massive,agglomerate,disseminated,banded and vein structures,common fine granular structure,coarse and unequal grain structure,and occasionally metasomatic structure.The metallogenic period can be divided into magmatic metallogenesis,magmatic hydrothermal period and regional metamorphic period.(3)The garnet is mainly composed of andradite-almandite,which is similar to hydrothermal metasomatism.Magnetite is characterized by high purity of magnetite and low content of manganese and magnesium,which is similar to the chemical composition of magnetite in calcium silicite in typical contact metasomatic deposit.Skins and magnetite similar to the characteristics of rare earth elements that iron mineralization and skarn is closely related.(4)The inclusions in skarn minerals are more complex,and the garnet has a lot of inclusions types: melt inclusions,melt-fluid inclusions,fluid inclusions and solid inclusions.Diopside and epidote has two-phase liquid-vapor(L+V)and three-phase liquid-vapor-solid(L+V+S)fluid inclusions type.Quartz has two-phase inclusions(L+V),three-phase liquid-vapor-solid inclusions(L+V+S)and CO2-containing heterogeneous inclusions(LH2O+LCO2+VCO2).Calcite has two-phase inclusions(L+V).Combined with the study of temperature and composition of inclusions,we believe that iron mineralization is closely related to the role of magma,which may be the result of the interaction between magma liquation and fluid exsolution.(5)The isotope geochemistry such as C,H,O,He,Ar of the garnet,quartz,calcite and pyrite,the garnet DV-SMOW is-97.75‰,?18OH2O is 2.94 ‰.The quartz of DV-SMOW is-104.2‰ and ?18OH2O is-2.43‰.Indicates that the formation of the garnet is related to the magmatism.The ore-forming material is from the magma;the ore-forming fluid is complex the magmatic water,ore-forming fluid mixed with a small amount of atmospheric water in the late.