| The Haerchulutu Pb-Zn polymetallic deposit is located in the northwest of the Keshiketeng Banner in Chifeng City,Inner Mongolia,within the polymetallic metallogenic belt of the southern section of the Greater Xing'an Mountains.Since the discovery of the deposit in 1989,has not carried out research on mineral deposit,so the research of the deposit is particularly urgent.The ore bodies are occur as vein type and the surrounding rock is diorite.The deposit is strictly controlled by the NW-trending torsional fault structure,and the ore body mainly exists in it.The boundary between the ore body and the surrounding rock is clear,and the main erosion is silicification,sericitization,fluorite,pyrolysis and limonite mineralization.The main conclusions of this paper are:?1?The deposit is divided into three metallogenic stages:I quartz-calcite-cassite-sphalerite-chalcopyrite stage,II quartz-polymetallic sulfide stage,III quartz-fluorite-Calcite stage.?2?The of fluid inclusions are rich in the deposit and most are gas-liquid two-phase inclusions,gas-liquid ratio are under 40%.The first stage's homogenization temperatures is from 263 to 393°C,fluid salinity is from 5.71 wt.%NaCleqv to 10.61wt.%NaCleqv,fluid density is from 0.634 to 0.858 g/cm3.The second stage's homogenization temperatures is from 150 to 316°C,fluid salinity is from 3.39 wt.%NaCleqv to 10.36 wt.%NaCleqv,fluid density is from 0.747 to 0.977 g/cm3.The third stage's homogenization temperature is from 144 to 241°C,fluid salinity is from 2.07 to8.55 wt.%NaCleqv,fluid density is from 0.848 to 0.967g/cm3.It indicates that the ore-forming fluid of the deposit is a medium-high temperature,low salinity,medium-low density hydrothermal fluid.With the progress of mineralization,the ore-forming temperature and salinity of ore-forming fluid are gradually reduced,the density of the fluid gradually increases.The results of laser Raman spectroscopy showed that the inclusion components are mainly H2O and CH4.?3??18OV-SMOW are from 9.8‰to 11.2‰and?DV-SMOW are from-119.3‰to-106.7‰,the characteristics are mixed fluid of magmatic water and atmospheric precipitation.The?34S value of the sulfide in the ore is from-0.1‰to+2.7‰,indicating that the sulfur in the deposit is mainly from magma.The results of lead isotope studies indicate that the ore-forming materials of the deposit are mainly derived from the deep crust.?4?The U-Pb dating result of cassiterite is 128.8±2.7Ma,which indicates that the mineralization of the deposit occurred in the Early Cretaceous,which is basically consistent with the mineralization age of the Weilasituo and other deposits in the area.In summary,the Halchulutu Pb-Zn polymetallic deposit is a medium-high temperature magmatic hydrothermal vein type polymetallic deposit formed in the Yanshanian period,the mineralization of the deposit is related with the acid magma intrusion in the Early Cretaceous and tin,copper,lead,zinc and silver mineralization in the area. |
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