摘要
The Shilu Co-Cu ore bodies hosted in lower 6th member of the Neoproterozoic Shilu Group occur between schist of 5th member of the Neoproterozoic Shilu Group and the iron ore bodies.These ore bodies are hosted by dolomite and diopsidic and tremolitic dolomite.The Shilu Co-Cu ore-forming process has experienced exhalative sedimentation,epigenetic silicification and sulfidation,and supergene enrichment stages.The homogenization temperatures of fluid inclusions in exhalative sedimentary quartz vary from 112℃to 205℃,mostly between 130℃and 205℃,similar to those of the ancient and modern seafloor exhalative sedimentary deposits.The salinitiesw(NaCleq)of sedimentary fluid inclusions vary from 1.74%to 6.59%,lower than those of many exhalative sedimentary deposits and equal to those of the lower dense exhalative sedimentary deposits.The densities of sedimentary fluid inclusions vary from 0.88 to 0.95 g/cm3.Theδ34S values of exhalative sedimentary anhydrites present a narrower range,from+21.4‰to+21.8‰,indicating that sulfur was derived directly from sea water.The homogenization temperatures of fluid inclusions in quartz,dolostone and calcite of the quartz-sulfide period are mostly concentrated on 170~270℃,with a salinityw(NaCleq)range of 1%to 7%and a dense range of 0.88 to 0.95 g/cm3,indicating that the ore-forming fluids of the quartz-sulfide period were mesothermal and had low salinities.Theδ34S values of sulfides in Co-Cu ores of the quartz-sulfide period vary from+8.1‰to+21.2‰,indicating that the sulfur was derived either directly from a anhydrite source or from a dissolution of evaporite rocks rather than being of magmatic origin.TheδD values of quartz of the quartz-sulfide period vary from-63‰to-83‰and theδ18OH2Ovalues of quartz are between+1.3‰and+6.8‰, suggesting that the ore-forming fluid was mainly from magma with the later addition of some meteoric water. The authors hold that the Shilu Co-Cu deposit is a mesothermal metasomatic and infilling deposit associated with the granitoids in the Shilu ore district.