Metallogeny And Prospecting Potential Of Gold Deposits In Asia Gold Belt,Western Tianshan

The Asia Gold Belt in the western Tianshan,which is endowed with numerous large and superlarge orogenic gold depositsscattered around the middle Tianshan and its two sides,extends eastward to China along Narati region with promising prospecting potential.In this contribution,the geological setting,ore deposit geology and geochemistry of the Unkurtash large gold deposit in Kyrgyzstan as well as the Niyazitiekexie and Alastuo gold deposits in Xinjiang,China have been studied.Subsequently,metallogenic regularity of the orogenic gold deposits in Asia Gold Belthas been summarized in order to investigate the mineralization mechanism,exploration criterions and prospecting potential of the Narati region.The following achievements have been withdrawn in this study.1.The Unkurtash gold deposit in Kyrgyzstan was formed during the period of Late Carboniferous to Early Permian(316~293 Ma)in a transition setting from subduction to collision or in a conllisional setting.Underplating of the basaltic magma that derived from a metasomatized lithosphere mantle origin ascends along translithosphere brittle-ductile faults system,resulting in the formation of ilmenite type Andagul calc-alkaline granodiorite.The magma-exsolved fluids and metals formed sheeted quartz veins and alteration aureole under the control of NE treding fracture zones.2.The Niyazitiekexie and Alastuo gold deposits in the Narati cluster were formed in Silurian to Early Devonian(429~404 Ma)and Carboniferous(353~335 Ma),respectively,during the subduction of South Tianshan Ocean beneath Middle Tianshan.Partial melting of the lower crust induced by underplating of subduction-metasomatized mantle magma led to a hybrid magma.Magma derived fluids carried metals of multiple source origin and precipated in widely distributed secondary fractures,with the formation of lenticular and banded orebodies.3.The orogenic gold deposits in Asia Gold Belt were formed during Early Paleozoic and Early Carboniferous subduction accretionary and Late Carboniferous to EarlyPermian continental collision settings.They are featured with mesothermal alteration assembladge,including sillification,beresitization and chloritization,and the metals are dominanted by pyrite,arsenopyrite and native gold or electrum.Sulfur is mainly from magma,whereas the metals could be of multiple source origin.Preenrichment in the ancient crust,remobilization during metamorphism or deformation activities in subduction/collisional setting and superimposition of deep derived hybrid magma and hydrothermal fluids are plausibly key controls and prospecting cretarias of the orogenic gold deposits in Asia Gold Belt.4.Narati gold cluster in Xinjiang western Tianshan is tectonicly the eastward extension of Asia Gold Belt.An orogenic gold deposit,or termed fracture-altered rock-type,model has been established on the basis of regional metallogenic regularity study,in combinzation of the study in Niyazitiekexie,Alastuo and Kateba'su gold deposits.Multiple information of geological settings,geophysic,geochemical and remote sensing are also considered.Finally,13 prospectin areas have been delineated and 779394 kg of total Au resourcehas been evaluated,including 91323 kg identified and 688071 kg referred.