The Age And Ore-forming Process Of MVT Deposits In The Boundary Area Of Sichuan-Yunnan-Guizhou Provinces, Southwest China

The boundaries area of Sichuan-Yunnan-Guizhou provinces is an importantlead-zinc metallogenic belt in China. Till now, there are more than400lead-zincdeposits has been found in this region. Most of them are structural controlledepigenetic ore deposits and can be classified into MVT lead-zinc deposits. However，the relationship between the mineralization of MVT deposits and major geologicalevents remains ambiguous. Moreover, the understanding of ore field structures andthe process of ore-forming is unclear. Focus on these scientific issue,we got somemain understanding as follows：1. The ore-controlling structures can be divided into the three main types. Theyare duplex thrust, wedging thrust and fracture zone of interlayer slip. Combined withregional tectonic evolution history, these structures could be the product of thecompressional event, which caused deforms of the strata, in the paleo-land.2. Systematic study of geochemistry and ore-forming fluids, with complementedby new technologies such as LA-ICPMS and Zn-Fe isotopes, reveal some depositscould have a close relationship between the oil-gas system and the Lower Cambrianblack shale, and some others are the products of the metal-enriched homogenizingfluids.3.An exploratory study on the Re-Os dating of bitumen from the Chipu depositconstraints the age of lead-zinc mineralization in the range of200Ma～165Ma. Thehigh-precision Sm-Nd dating of the Daliangzi and Jingshachang deposits reveal themetallogenic age are about200Ma in the border of Sichuan and Yunnan provinces.Based on the evolution of the regional tectonic and ore-controlling structures, webelieve that most of the MVT deposits in this area could be formed during the stage ofIndosinian orogeny which could drive the large-scale migration of ore-forming fluids.