虎头崖多金属矿床成矿物质来源及演化

Origin and evolution of ore-forming material of Hutouya polymetallic deposit

虎头崖矿床是祁漫塔格成矿带中一个典型的铅锌多金属矿床。依据野外矿床地质调查和室内光薄片鉴定工作将该矿床划分为4个成矿期,7个成矿阶段。16件具代表性硫化物矿石单矿物硫、铅同位素测试显示,硫、铅同位素具有如下特征:δ(34S)变化范围为+0.6×10-3^+9.8×10-3,平均值为+5.2×10-3,从岩体边部至远离岩体处硫同位素含量呈逐渐增大趋势;铅同位素变化范围小,208Pb/204Pb为38.717~38.261,207Pb/204Pb为15.718~15.560,206Pb/204Pb为19.502~18.476。结合矿床地质特征和前人研究成果,分析硫、铅同位素特征,估算地幔、地壳中各组分,获得地幔、地壳中Pb组分分别为0.07~0.22、0.78~0.93,并推断矿床成矿物质来源为以地壳成分为主、含地幔成分的岩浆岩。成矿物质演化为在靠近岩体处S主要来源于岩体,远离岩体处地层物质含量逐渐增加,但主要为岩浆成分。

Hutouya deposit is one of the typical Pb-Zn polymetallic deposits in Qimantage region. This deposit was divided into 4 metallogenic epoches and 7 mineralization stages based on geological characteristics of ore and identification of polished sections and thin slices. There were 16 representative minerals selected from sulfides and measured to determine the values of S and Pb isotopes. The results show that the values ofδ(34S) range from+0.6×10-3 to+9.8×10-3, in which the average value is+5.2×10-3, and increase gradually from the edges of intrusions to the distal end of them, while the range of Pb isotope is small, with 38.717-38.261 for 208Pb/204Pb, 15.718-15.560 for 207Pb/204Pb, 19.502-18.476 for 206Pb/204Pb. Associated with characteristics of the ore deposit and the results of the former researchers, the characteristics of S and Pb isotopes were analyzed, and the proportions of Pb in the crust and mantle are estimated to be 0.07-0.22 and 0.78-0.93, respectively. The sources of metallogenic material are speculated from the magmatite that is composed of large ratio of crust matter and small proportion of mantle. The evolution of metallogenic material is that S element has higher proportion of igneous rocks’ matter when mineralization is adjacent to magmatite, and with larger percentage of strata in distal area;however, the main materials still originate from intrusions.