Fluid Inclusions Evidences For The Mineralization Of The Organic Fluid In The Yanwuping Mercury Deposit, Guizhou

The Yanwuping mercury deposit located at the contiguous areas of southestmargin of Yangzi platform and south china fold belt. In order to be able to achieve anin-depth understanding on ore-forming fluid characteristic、source、evolution and therole of organic matter of mineralization, the works about the inclusions have beenstudying much systematically in this thesis.The Yanwuping mercury deposit is located in the Middle Region of Tong-Fengmercury belt, which is located in Tongren-Wanshan paleo-reservoir. The Mining Areais mainly hosted of Middle Cambrian Aoxi formation, which is composed of marineargillaceous carbonate, enriching organic. The leading ore-controlling structure of thisdeposit is Yanwuping faults. The producing morphology of ore-body can be classifiedas layer, stratifyorm-like and vein. The main metallic mineral are cinnabar, nativemercury, stibnite, pyrite, realgar, orpiment. The nonmetallic mineral are dolomite,quartz, calcite, barite, fluorite and asphalt. The structures of ores are mainly massivestructure, lamellar structure, disseminated structure, vein structure, brecciformstructure and miarolitic structure. The ore texture are euhedral granular texture,hypidiomorphic-granual texture, xenomorphic-granual texture and common boundarytexture. Dolomitization, silicification, calcitization, baritization and bituminization aremain wall rock alteration types in Yanwuping mercury deposit.There are several types of inclusions in this deposit, including H₂Oinclusions,hydrocarbon-H₂O inclusions, hydrocarbon inclusions and solid cinnabarinclusions. The homogenization temperatures of the gas-liquid H₂O inclusions varywithin the range of82.4～176.5℃while the salinity13.40％～21.75％NaCl anddensity1.05～1.10g/cm³. The ore-forming fluid is oilfield brine with high salinity andhigh density. The testing results of laser raman indicate that, the liquid composition of fluid inclusions is H₂O，and their vapor composition are mainly CH₄. Asphalt andcinnabar are always found in the same micro fissures, while asphalt inclusions can beseen captured in the cinnabar crystal. Asphalt wraps cinnabar particles whilehydrocarbon inclusions and solid cinnabar inclusions are coexisted. These evidencesshow that the mercury mineralization is closely related to the organic matter, whichprovides important information for the study of the role of organic matter in themercury mineralization process.In the deposition stage, strong adsorption of organic matter prompts metalprecipitates to high abundance of ore source beds. During the Petroleum formation,most metals are extracted by oilfield brines enriched in petroleum, and both of themdeposit into the oil reservoir, leading to the formation of metal-rich elements oil andgas reservoir. As crude oil cracking, the hydrocarbon decomposing, and the metalelement is released and returns to brine phase of ore-forming fluid to remove. Whenthe fluid removes upward along fractures to interlaminar fracture zones and fracture,the pressure dropping results in separation between oil gas and hydrothermal ore.organic matter react with sulfate of strata that causes mercury mass sentimented tomineral partly, at the same time because of meteoric water dilutes the ore-bearinghydrothermal system leading to a large of mercury mass precipitate...