Structure styles of scientific deep drilling in South Hunan and implications for regional metallogenic prediction
The scientific deep drilling in south Hunan is located in the Baoshan mining area in Guiyang County,where is the middle section of intersection part of the Qin-Hang combinet belt and Nanling metallogenic belt,with the borehole end depth at 3008.93 m.A series of refined profiles/columns about lithology,structure,mineralization-related alteration,geochemistry and petrophysical properties were established based on detailed geological and geochemical drill-core record compiling and logging.The deep structures revealed by scientific deep drilling can be divided into three structural layers from the top to the bottom,including the upper(ductile)brittle structural layer mainly characterized by brittle fracture and followed by interlayer sliding and plastic deformation,the mid-dle brittle-ductile structural layer mainly showing bedding cambered seratification,and the lower ductile structur-al layer mainly displaying plastic deformation and followed by interlayer sliding and plastic shear.The deep struc-ture is represented by the north-east Yanling-Chenzhou-Linwu deep fault belt.The intense Yanshanian activity in-duced magma emplacement to the hanging wall of the deep fault(northwest part of the deep fault),resulting in formation of the Baoshan-Dafang granodiorite porphyry dyke belt and associated Cu-Pb-Zn-Ag-Au deposit,the Huangshaping quartz porphyry dyke swarm and associated Pb-Zn-Ag deposit,and the Huangshaping granite por-phyry dyke swarm and associated W-Sn-Mo-Pb-Zn deposit.The δ34S values of the sulfide ore samples collected from the tunnel and deep drill core indicate that the sulfur of skarn-type Cu-Pb-Zn deposit sourced from magma,whereas sulfur of the vein-type Pb-Zn-Ag deposit sourced from a mixture of magma and strata.Combining the da-ta of deep structure,magma emplacement and geophysics,three exploration target areas are proposed:the depth more than-1350 m in the central region of Baoshan has potential for exploration of skarn-type Cu ores;the Mis-haijing area between the Baoshan area and Dafang area has good potential for exploration of northeast-extending vein-like Pb-Zn-Ag-Au ores;The Huangshasi mining area may have a hidden granodiorite porphyry body and granite porphyry body in the deep part,which may be a prospecting target for W-Sn-Mo-Bi-Cu-Pb-Zn ores.
scientific deep drilling in South Hunanprospecting targetQinzhou-Hangzhou Bay orogenic juncture belt
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