Study On Geological Characteristics And Genesis Of Hekoulinchang Tin Polymentallic Deposit In Heilongjiang Province

The administrative division of tin polymetallic deposit in Hekoulinchang is under the jurisdiction of Baoqing County,Shuangyashan City,Heilongjiang Province.Its geotectonic location is in Wandashan block.The metallogenic area belongs to the polymetallic metallogenic area(belt)of Wandashan orogenic belt.The mainly exposed strata in the area including Dajiahe Group of Middle Triassic and Lower Jurassic,Dalinqiao Group of Upper Triassic and Lower Jurassic,Pikeshan Group of Lower Cretaceous and Quaternary stratum.The fold and fault structures in the mining area are relatively developed.The structural line of the mining area mainly includes two groups of NE and NW directions.The main magmatic rocks exposed in the mining area are early Cretaceous granite porphyry.It is distributed in NE direction,consistent with the direction of regional tectonic line.The exploration depth of Hekoulinchang tin polymetallic deposit is still in its shallow position and the ore bodies are mostly distributed in vein shape in the NE direction,overall occurence is 280°? 50°.The ore minerals in the mining area are mainly pyrite,some tetrahedrite,sphalerite,etc.Ore textures are mainly euhedral to subhedral granular structure,xenomorphic granular structure,metasomatic texture,The ore structure is mainly disseminated,veinlet and massive structure.The typical surface alteration of porphyry type deposits is developed in the mining area,which is represented by phyllic alteration zone,argillaceous alteration zone and propylitization zone from the inside to theoutside.The distribution of ore(mineralized)bodies are strictly controlled by alteration zoning,tin mineralization is closely related to sericitization and silicification.The metallogenic period can be divided into hydrothermal mineralization and supergene oxidation period and hydrothermal phase is further divided into three stages: the I-quartz pyrite cassiterite stage,II-quartz polymetallic sulfide stage,III quartz-carbonate phases.The phase I and II is the main metallogenic stage.In this paper,we have obtained quartz vein which is closely related to includes two types: gas-liquid two-phase inclusions and multi-phase inclusions containing sub minerals.The temperature measurement of fluid inclusions shows that the ore-forming temperature is medium low temperature(154.9? ~ 359.1?,average 249.1?),and the salinity of ore-forming fluid is distributed between 2.1% ~ 8.0wt% NaCl and 39.4 ~ 42.7wt% NaCl.The metallogenic pressure is 11.29~21.17 MPa.The metallogenic depth is between 1.13 and 2.12 km.The characteristics of H-O isotopes of quartz vein and C-O isotopes of calcite vein reveal that the ore-forming fluid has the characteristics of magmatic hydrothermal fluid and in the late period,there is a mixture of atmospheric precipitation.The S-isotopics study of ore minerals show that the ore-forming materials mainly come from magma and are closely related to granitic porphyry.Based on the study of geological characteristics,ore-forming fluid characteristics and isotopic characteristics,the tin polymetallic deposit is considered to be porphyry type.