Skarn And Ore Genesis Studying In Yamansu Iorn Deposit, Eastern Tian Shan, Xinjiang

Eastern Tianshan region in one of Chian’s major mineral resources area, as well,it’s one of the most important iron ore, nonferrous metal and precious metal collection area. Among, Aqi mountain-Yamansu-Shaquanzi belt is the major iron mineralization.Yamansu iron region is located in the middle of the mineralization belt, which is the large open-pit iron ore mining area. This paper based on collecting predecessors material and detailed field survey of the geological background, focused on the study of geological characteristics, skarn minerals assemble, fluid inclusion, stable isotope,mineral constituents and metallogenetic, mineralization mechanism, achieving the summaries as follows.1) Yamansu iron ore belong to the third section of the Lower Carboniferous lithologic Yamansu Formation, direct ore wall rock is andesitic tuff glass, surrounding by the skarns minerals. The ore bodies is hosted in skarns, which occurs as layered,stratoid or lenticular and granite is existed in district. The ore occurs as aggregated and disseminated, locally banded. Ore minerals are relatively simple, mainly magnetite,with a minor amount of hematite, pyrite, chalcopyrite and sphalerite, etc. Gangue minerals are garnet, diopside, actinolite, epidote, chlorite, followed by feldspar, quartz,calcite etc.2) According to ore fabrics, mineral paragenesis and output characteristics,can be divided into two mineralization periods, which are early and late mineralization periods. Further can be divided into three stages, Magnetite-garnetepidote stage, magnetite-feldspar-epidote stage, carbonate-sulfide stage.3) The analytical results of electron microprobe show that the main component of garnet is in andradite- grossular series of skarn in Yamansu iron deposit.It is indicated as calcium skarn in metasomatism. The magnetite can be divided into the early and the late stages in Yamansu iron deposit. Most of the early-stage magnetite has component features of magma type, whereas the late-stage magnetitehas metasomatic genesis features. It is suggested that the formation of Yamansu iron deposit is related to magmatic hydrothermal metasomatism.4) Yamansu ore fluid is based on NaCl-H2 O system, precipitation and early fluid mixing leads to cooling fluid dilution process. Skarn mineral inclusions in lower temperatures compared to skarn deposits in the world. But from the early stages of skarn â†'alteration stage â†' degradation carbonate- sulfide stage temperature and salinity decreased, which are similar to the fluid nature of the mineralization and skarn deposits in the world forming fluids.5) Rare earth element data of magnetite and skarn in Yamansu iron deposite proved that magnetite and skarn have certain relationship with volcanic, the sulfide and rare earth element data of rocks and ores suggest that the ore-forming materials is mainly derived from the amphibolite, ore minerals and ore fluid mainly come from volcanic and magmatic hydrothermal.6) Carbon, oxygen, isotopic composition indicates that the carbon of ore-forming fluid not from limestone in surrounding rock but deep magma or mantle.7) Yamansu iron deposit is belong to metasomatic skarn deposits of the marine volcanic rocks and Ore-bearing hydrothermal of related with magmatic along faults occur metasomatic contact with volcanic rocks and limestone in the vicinity,and then formation of magma and skarn.