Abstract:

The Lengshuikeng ore field in Jiangxi Province is one of the most important AgPbZn deposits in northern Wuyi Mountains, China. It is a rare typical porphyry AgPbZn deposit in the world and a volcanic sedimentaryhydrothermal reworked deposit with unique features, so it is worthy of detailed research. The δ34S values of chalcopyrite, pyrite, sphalerite, and galena sulfides collected from the Lengshuikeng ore field range from -380‰ to +694‰ with an average of +187‰. The narrow distribution of δ13C values around -411‰ and the δ34S values with ~+2‰ peak value suggest that the sulfur and carbon of the oreforming fluid were derived from hypomagma, but it did not exclude the possibility that a certain amount of sulfur and carbon were provided by the hosted strata. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of sulfide ores range respectively within 1777117867, 1556415685 and 3823538652. But, the volcanic rock, volcanicsedimentary rock, and metamorphic rock contain higher radiogenic lead with the 206Pb/204Pb ratios of 1789918220, showing both relevance and disparity between rock lead and ore lead. However, the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of the ore and granite porphyry leads are similar and lie on the same lines in the diagrams of 208Pb/204Pb vs. 207Pb/204Pb and 207Pb/204Pb vs. 207Pb/204Pb. For the mixing lines, the two end members are respectively upper crust and mantle, which means mixing the matters of the upper crust and of the mantle. All the evidences strongly support that the metallogenic elements were carried by the porphyry magmatic system and strata. Therefore, the Lengshuikeng ore field is a typical magmatichydrothermal type of ore deposit associated with subvolcanic rocks, and formed on the intracontinental setting in Eastern China during the midYanshanian period.

Key words: Lengshuikeng Ag-Pb-Zn ore field, isotope geochemistry, metal sources, metallogenic mechanism, Wuyi Mountains