Mineralization of Luziyuan Pb-Zn skarn deposit, Baoshan, Yunnan Province, SW China: evidence from petrography, fluid inclusions and stable isotopes |
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The Luziyuan Pb-Zn skarn deposit, located in the Baoshan-Narong-Dongzhi block metallogenic belt in SW China, is hosted by marble and slate in the upper Cambrian Shahechang Formation. Three skarn zones have been identified from the surface (1495 m above sea level (asl)) to a depth of 1220 m asl: zone 1 consists of chlorite-actinolite-calcite-quartz, zone 2 of rhodonite-actinolite-fluorite-quartz-calcite, and zone 3 contains garnet-rhodonite-actinolite-fluorite-quartz-calcite. The deposit formed in four distinct mineralization stages: an early anhydrous skarn (garnet, rhodonite and bustamite) stage (Stage 1), a hydrous skarn (actinolite and chlorite) stage (Stage 2), an early quartz (coarse barren quartz veins) stage (Stage 3) and a late sulphide-forming (fine sulphide-bearing quartz veins) stage (Stage 4). The Stage 1 skarn-forming fluid temperature was at least 500 degrees C according to the geothermometer with rhodonite/bustamite trace elements measured by laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS). A decrease in ore fluid temperatures with time is consistent with the decreases in the delta O-18(fluid) and delta D-fluid values from Stage 3 to 4. This trend suggests that the ore fluid was mainly derived from magmatic water and mixed with large amounts of meteoric water during mineralization. The delta S-34 values of Stage 4 chalcopyrite, sphalerite and galena are similar to those of an Ordovician gypsum layer, and together with the high-salinity fluids in Stage 4 indicate the dissolution of evaporites in the Luziyuan region. Overall, the results of this study suggest that the Luziyuan deposit is a distal Pb-Zn skarn deposit that formed in response to multi-stage alteration associated with a combination of magmatic water and meteoric water. Publication name | GEOLOGICAL MAGAZINE, 156 (4):639-658; 10.1017/S001675681700111X APR 2019 | Author(s) | Yang, Yu-Long; Ye, Lin; Bao, Tan; Gao, Wei; Li, Zhen-Li | Corresponding author(s) | YE Lin yelin@vip.gyig.ac.cn Chinese Acad Sci, Inst Geochem, State Key Lab Ore Deposit Geochem, Guiyang 550002, Guizhou, Peoples R China. | View here for the details
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