• 文章目录 •

### 右江褶皱带有金属矿床成矿系列初步研究

1. [1]南京大学内生金属矿床成矿机制研究国家重点实验室 [2]南京大学地球科学系
• 收稿日期:1997-06-20 修回日期:1997-06-20 出版日期:1997-06-20 发布日期:1997-06-20

### PRELIMINARY STUDY ON METALLOGENETIC SERIES OF NONFERROUS METAL DEPOSITS IN YOUJIANG FOLD BELT

Hua Ren-min, Zhu Jin-chu, Zhao Yi-ying, Zhou Jian-ping Wu Yan-yu, Chen Xiao-dong

1. Department of Earth Sciences, Nanjing University
• Received:1997-06-20 Revised:1997-06-20 Online:1997-06-20 Published:1997-06-20

Abstract: The Youjiang fold belt is located in southwestern China, and is geotectonically a portion of the South China Caledonian Fold System, which was generally formed by alternating tension and compression from mid-Proterozoic to early Devonian. Initiated in the late stage of early Devonian period, a northwest trending rifting took place in Youjiang area. Deep faults and consequent grabens and horsts were developed in the bottom of this rift, resulting in structural complex of this area. This particular background offered good conditions for the formation of many ore deposits, especially those of Sn, Cu, Ag, Sb etc. Several large to superlarge deposits have been found. Although different deposits have different characteristics, they can be classified into two major metallogenetic series. The first series is Sn-Cu-(Pb Zn)-Ag series related to granitoids, which can be genetical1y attributed into the crust-remelting type, or transformation type. In Youjiang fold belt, tin is the dominant metal, which differs from the other parts of South China Caledonian Fold System, such as southern Jiangxi, where tungsten is more dominant. Another feature of these deposits is that they are mostly polymetallic deposits. Therefore the zoning of elements is commonly developed, which display from Cu-Sn to Pb-Zn to Ag. Based on the spatial relation between ore deposits and related granitic rocks, this series can be divided into two sub-series. One is the Cu-Sn sub-series of which the deposits have close spatial relation with granites. The other is the Ag sub-series, of which relationship between ore bodies and granites is more obscur. This lead to different explanations on the ore genesis, such as the sedimentary exhalation hypothesis. However, there are still much evidence showing that further or deeper emplaced granitic plutons are the key control of ore formation. The second series is the strata bound Sb deposits of sedimentation-reworking type. They mainly occur in Devonian strata. The most favourable lithological assemblage for Sb mineralization is an ore-bearing siliceous bed, combined with an overlying shale and an underlying carbonate bed. No granitic rocks can be found in the mining and vicinity areas. The Sb mineralization is closely related with structural deformation. Geological evidence and age dating show that they are epigenetic. Thus the term reworking is used for their genesis. The mineralization took place in the Yanshanian period,when fluid circulation of large extent generated by deep fracturing desolved and transported Sb to form ore bodies.