Genetic Mineralogy Study Of Liaoshang Gold Deposit In Shandong Province

Liaoshang Gold Deposit in Shandong province is the first superlarge gold deposit in the Northeast margin of the Jiaolai Basin.The ore is characterized by the vein of Pyrite and Dolomite,which is a new type of deposit,namely the Pyrite-Carbonate vein gold deposit controlled by fault.This paper focuses on the study of mineralogy and petrollogy of Liaoshang Gold Deposit in order to find out the relationship between ore minerals and gold mineralization,and provide guide to support the prospecting of ore deposits.Acquring the following main achievements:?1?In this study the mineral symbiosis combination has been identified.Most gold minerals of the Liaoshang Gold Deposit are native gold,followed by a few electrums,which existed in pyrite and dolomite.The fineness of gold is from 969.87 to 779.51,averaging value of 890.25;The early pyrite-dolomite stage is the main metallogenic stage.Liaoshang Gold Deposit is a hydrothermal deposit related to magmatism,whose metallogenic hydrothermal fluid is a relatively alkaline medium-temperature,medium-shallow hydrothermal.The deposit may be formed in the Cenozoic era.?2?We studied the characteristics of pyrite.Pyrite is the most important gold-being mineral in Liaoshang Gold Deposit.?The pyrite here mostly occurs as cube and pyritohedron,medium-coarse subhedral-anhedral grains;?Trace element mapping shows that pyrite is closely correlated to hydrothermal activity during the main mineralization phase in Liaoshang.?Pyrite thermal-electrical analysis shows that the pyrite in Liaoshang Gold Deposit is dominated by N type,accounting for the rate of 73.53%;The pyrite temperature is mainly concentrated on 330-350?;The degree of denudation of the ore body is high,and there is still a certain scale extension in the deep part,which can be further searched for it;The gold grade?high-?value mainly appears in the elevation of 850 to 1000m.The occurrence rate of P-type Pyrite and the average value of the thermoelectric coefficient are closely related to the spatial distribution of gold grade.We speculated that the area of 1100m depth and the beneath of exploration.Line 4 and 12 may be the high-value grade area of gold.There is a good expection of mineral prospecting.?3?The characteristics of dolomite and its relationship with gold ore are preliminarily proved.Dolomite is an important gold-bearing mineral in Liaoshang Gold Deposit,which is very rare.The Chakra minerals are mainly Dolomite,and there are a small amount of Quartz,Gypsum,Dolomite,Chlorite.The value of Ca/Mg is between 1.09 and 2.15,and with an average value is of 1.47.The Dolomite veins in the Liaoshang mining area may be formed in the alkaline environment.The Carbon isotope composition of Dolomite in the main mineralized stage of the deposit is relatively stable.The value of ?¹³C/‰ is between-3.6 and-4.6,and the average value is-4.0.?¹⁸O-?¹³C diagram shows that the points fall in the magma Carbonate area.The Carbon source is mainly almost from Granite.The metallogenic fluid is a high oxygen fugacity alkaline fluid rich in CO₂.It activates and migrates Au into the tectonic fracture.The formation of Dolomite and the Potassium petrochemicals of the surrounding rocks reduce the fluid oxygen fugacity and drop the PH value,and Au precipitates.Dolomite and Pyrite formed the main mineralized ore body of Liaoshang Gold Deposit.