广西大瑶山西侧层控矿床稳定同位素特征

本文通过对大瑶山西侧成矿带泥盆系层控矿床中的铅、硫、碳、氢、氧等稳定同位素组成特征研究,探讨了本区成矿物质的来源和含矿溶液性质。认为,铅主要源于上地壳泥盆系—寒武系岩石,后生阶段有部分印支—燕山期幔源铅(基性岩)加入:重晶石硫源于寒武—泥盆纪海水硫酸盐,而硫化物矿物硫源于细菌还原海水硫酸盐成的H_2S;矿物包裹体流体水的氢、氧同位素组成说明后生期含矿热液属于大气降水深循环形成的热囱水,部分碳、氧同位素组成反映了成矿带北段可能有岩浆期后热液的叠加。据此,将本区划为前泥盆纪、泥盆纪、印支期等三期成矿作用,形成了成岩、成岩—后生和后生层控矿床系列,具有多源、多期、多阶段特点。

THE CHARACTERISTICS OF THE STABLE ISOTOPES OF STRATABOUND DEPOSITS WESTERN DAYAOSHAN MOUNTAIN, GUANGXI

With the research Pb-S-C-H-O isotope compositions, the author has a discussion on the source of the ore-forming materials and properties of the ore-forming solution in Devonian stratabound deposits in western Dayaoshan Mountain, Guangxi. The features of lead isotope compositions show that the lead was mainly derived from the Devonian and Lower Paleozoic in the upper earth's crust, the other from the lead of the Indonian content in mantle. The sulfur isotope compositions were sedimentary sulfur. The sulfur content in barite was derived from sulfosalt in sea water, while the sulfur content in the sulfide minerals from H2S which reducted the sulfate in sea water by bacteria. Hydrogen and oxygen isotope compositions in minerals inclusions fluid dictated that the epigenetic ore-forming solution was thermal brine producted by precipitate water, some carbon and oxygen isotope composition were formed postmagmatic thermal fluid superimposition in the North of the metallogenenic belt. In this region, three metallogenic epochs can be grouped: Precambrian, Devonian and Indonian. The stratabound deposits may have formed during diagenesis deposit, diagenetic-epigenetic deposit and epigenetic deposit. They are polygenic sediment, multi-epoch and multistage.