Study On Gold-bearing Characteristics And Genesis Of The Shuiyindong Carlin-type Gold Deposit In Southestern Guizhou, China

The Shuiyindong carlin-type super large gold deposit, found in recent years, is a compound concealed gold deposit, belonged to the strata-bound type with some fault-controlled ore bodies. The Shuiyindong gold deposit is located in the Huijiabao ore field of the carlin-type gold concentrated zone in the southwestern Guizhou. As a typical deposit in the area, it has high grade and large reserves. The conclusions on the metallogenic characteristics and genesis of the deposit by the present research were proposed listed as follows:In the Shuiyindong gold deposit, the main ore-controll structures are east-west reversed faults along the axis of the Huijiabao anticline, regional level slip plane between Maokou Formation and Longtan Formation, and level strips belts. The level slip plane is the main migration pathway for metallogenetic hydrothermal water in the most area.The strata-controlled ore body is also controlled by favorable lithology. The lithology of Longtan Formation is composed of the sedimentary series of fine clastic rocks (clayrock) impurity carbonate region (biological limestone)-fine clastic rocks (clayrock). The fine clastic rocks can block metallogenetic hydrothermal water, and the impurity carbonate region is benefit to the flow of metallogenetic hydrothermal water and the deposition of ore-forming material, therefore, the main ore body is hosted strictly in impurity carbonate region. And the lithology is one key to the strata-controlled deposit’s high grade.The gold-bearing minerals of the Shuiyindong deposit are arsenian pyrites and arsenopyrites, and the arsenian pyrites are the major gold-bearing minerals. The gold-bearing pyrites further dominantly include zoned arsenian pyrites and fine-grained arsenian pyrites, followed by framboidal pyrites, coarse-grained pyrites and banded pyrites. These pyrites have complex origins, and most of them may undergo hydrothermal alterations. The characteristics of multi-rims suggest that the hydrothermal fluid acted pulsatorily. The gold-bearing pyrites further dominantly include zoned arsenian pyrites and fine-grained arsenian pyrites. In contrast, most of the gold in gold-bearing minerals occurs in solid solution (Au+), and the other gold occurs in nanoparticles of native gold (Au0).The study on rare-earth element of deposit shows partial acidic (high CO2) and reducing metallogenic environment, and reveals the characteristics of marine sedimentary. The relationship between gold content and REE of the ores is positive-ralater, and the relationship between gold content and (La/Yb)N is counter-ralated. Then the high REE could be a symbol of the high grade ore.There are some organic matter(0.11%～3.04%) in the ore body, including vitrinite, inertinite and bitumen. The organic matter is benefit to the formation of pyrites. In the total trend, when the sample contains high gold, the total organic carbon (TOC) is not low(>0.5%).The isotopes study shows the multi sources of the ore-forming materials. They may come from orogenic belt, and the origin from the mantle is dominant.