王家坪金矿床地质地球化学特征及成因探讨

王家坪金矿床赋存于上泥盆统星红铺组碳酸盐岩地层中,矿体受主构造旁侧的次级张性断裂控制,呈透镜状产出,主要蚀变类型有黄铁矿化、硅化、雌黄化、雄黄化、碳化和铁碳酸盐化等。矿区内Au与Hg、Sb与As的相关性较好,为一套低温元素组合。矿石∑REE总量为94.71×10-6~141.03×10-6,平均值为117.3×10-6,(La/Sm)N为3.86~4.52,Sm/Nd变化范围为0.17~0.19,与围岩有明显差异,表明成矿物质并非来源于赋矿地层,可能来自深部岩浆和下伏地层柱。氢氧同位素特征表明,本区水的来源为大气降水和岩浆水。δ34S范围为-1.51‰~12.80‰,平均值为6.54‰,硫可能为岩浆热液与地层硫的混合成因。主成矿温度为90~140℃,成矿流体属于中低盐度、低密度流体,成矿压力平均值为133 MPa。矿床成因类型为中浅成低温热液型矿床。

Geological Geochemical Characteristics and Genesis of Wangjiaping Gold Deposit

Wangjiaping gold deposit is hosted in carbonate formation of upper Devonian Xinghongpu Group,and ore bodies are occur as lenticular,controled by secondary tensional fault around the main fault.Wall rock alterations include pyritization,silicification,orpiment,realgar,carbonization and iron carbonate and so on.In the mining area,Au and Hg,Sb and As are low temperature elements,which have linear correlation.The total amount of rare elements in ores is 94.71×10-6 to 141.03×10-6,average is 117.3×10-6,(La/Sm)N changes in the range from 3.86 to 4.52,which are different from the wall rocks.This shows that the source of ore-forming materials is not wall rocks,but probably come from the deep magma and underlying rock column.Hydrogen and oxygen isotopic characteristics show that the source of the water mainly originated from are magmatic and rain water.The range ofδ34S is from -1.51‰ to 12.8‰ ,the average value is 6.54‰ ,sulfur may originated from mixture of magmatic hydrothermal and sour formation.The range of major metallogenic temperature is from 90 ℃ to 140 ℃ ,the mineralizing fluid is medium salinity and low density fluid,and average value of metallogenic pressure is 133 MPa. The genetic type of the deposit belongs to medium and shallow low temperature hydrothermal type deposit.