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The South Xinjiang metallogenic belt has as its basement crystalline rocks related to the Cathysia terrane to the south. Since the Proterozoic it has experienced three episodes of basin opening and closing, resulting in the development of three sets of ore-forming rocks and three minerogenetic series: volcanic-exhalative sulphides resulting from Proterozoic bimodal rift magmatism; sedimentary-exhalative sulphides related to submarine felsic volcanism; and hydrothermal polymetallic mineralisation related to Yanshanian continental volcanism and intrusion. Large-scale deposits have formed by the combination of a number of different geological factors., The South Xinjiang metallogenic belt has as its basement crystalline rocks related to the Cathysia terrane to the south. Since the Proterozoic it has experienced three episodes of basin opening and closing, resulting in the development of three sets of ore-forming rocks and three minerogenetic series: volcanic-exhalative sulphides resulting from Proterozoic bimodal rift magmatism; sedimentary-exhalative sulphides related to submarine felsic volcanism; and hydrothermal polymetallic mineralisation related to Yanshanian continental volcanism and intrusion. Large-scale deposits have formed by the combination of a number of different geological factors.

The primary gold deposits in this important placer district can be classified into three categories: sedimentary-metamorphic reformation type; magma-superimposed reformation type; and micro-fine grained disseminated type. The geology, occurrence, mineral association and alteration are described for each type. Results of the study indicate a favourable future for gold prospecting in the area., The primary gold deposits in this important placer district can be classified into three categories: sedimentary-metamorphic reformation type; magma-superimposed reformation type; and micro-fine grained disseminated type. The geology, occurrence, mineral association and alteration are described for each type. Results of the study indicate a favourable future for gold prospecting in the area.

The deposits, of the all-vein type, are hosted by low-grade metamorphic rocks of the Lengjiaxi Group. Analysis of the distribution of Au and associated elements in the host rocks and of the REE and isotope geochemistry of the ores and host rocks demonstrates that the veins formed mainly as a result of the mobilisation of dispersed gold from Lengjiaxi Group rocks during tectonic and thermal reforming. Gold and associated elements were mobilised mainly during the Wulingian-Caledonian period, with remobilisation mainly in the Indonian-Yanshanian period. Both mobilisation and remobilisation were fluid-assisted., The deposits, of the all-vein type, are hosted by low-grade metamorphic rocks of the Lengjiaxi Group. Analysis of the distribution of Au and associated elements in the host rocks and of the REE and isotope geochemistry of the ores and host rocks demonstrates that the veins formed mainly as a result of the mobilisation of dispersed gold from Lengjiaxi Group rocks during tectonic and thermal reforming. Gold and associated elements were mobilised mainly during the Wulingian-Caledonian period, with remobilisation mainly in the Indonian-Yanshanian period. Both mobilisation and remobilisation were fluid-assisted.

The Yongmei basin in south China is an important metallogenic belt containing Cu, Fe and polymetals. Discussion is presented of the regional ore-control structures and metallogenic modelling of Cu and associated Ag deposits in the belt. Emphasis is on sedimentary environment, lithofacies, ore-bearing formations, structures, volcanism and geothermal water activity and their controlling effects on mineralisation. It is concluded that the metallisation of Cu and Ag occurred during an extensional stage of geotectonic evolution; the orebodies are located in depressions formed by syngenetic faulting, interstratified broken zones and volcanic structures; mineralisation had a close relationship with volcanic and geothermal activities; and the metallogenic process had multistage superimposition and reformation., The Yongmei basin in south China is an important metallogenic belt containing Cu, Fe and polymetals. Discussion is presented of the regional ore-control structures and metallogenic modelling of Cu and associated Ag deposits in the belt. Emphasis is on sedimentary environment, lithofacies, ore-bearing formations, structures, volcanism and geothermal water activity and their controlling effects on mineralisation. It is concluded that the metallisation of Cu and Ag occurred during an extensional stage of geotectonic evolution; the orebodies are located in depressions formed by syngenetic faulting, interstratified broken zones and volcanic structures; mineralisation had a close relationship with volcanic and geothermal activities; and the metallogenic process had multistage superimposition and reformation.