The Characteristics Of Ductile Shear Zones In Jianchaling And Its Control To Gold Deposit.

The prospecting area is located in Mian-lve-yang triangle area in easthern Motianlin Block between qinling orogenic zone and Yangtze Landmass,and Gold deposit of Jianchaling has the close relation with ultrabasic rock in this area, also is the rare golden ore deposit type in our country.This paper is based on the comprehensive analysis of the previous data, field work and indoor test. This paper has studied the deformation and features of the microstructures of shear zone in detail, analyzed the features of geometry, kinematics and dynamics of ductile shear zones, and discussed the characteristics of ductile shear zones and its control to gold deposit. The main conclusions are as follows:1. The NWW and NE ductile shear zone had been founded in prospecting area.The NWW ductile shear zone west to Jindongzi,east to Zhangjiashan,north to F₁⁴⁷ and south to F₁⁸,with a length of 10km and width of 2.6km.The NE ductile shear zone north to the south of ultrabasic rock,south to unconformity surface in Sinian system north of Lveyang Formation.Belong the strike to Miaoerya the length of NE ductile shear zone is 6km from Duantouya to Jianchaling,and 400m in width from Jiudaoguai to Liushugou. The types of dynamic metamorphic rock containing mylonitization rock, protomylonite, mylonite,ultramylonite and tectonic schist in two ductile shear zone.2. Comparison between the features of geometry, kinematics and dynamics of NWW and NE ductile shear zones, show that the two ductile shear zones has conjugate relation.In early stage the NWW ductile shear zones deformationed on the extensional of left handed and the NE ductile shear zones deformationed on the extensional of right handed, the maximum compressional stress orientation isσ₁≈280°∠10°and paleo-stress is about 93.7Mpa,in last stage the NWW ductile shear zones deformationed on the stress of right handed and the NE ductile shear zones deformationed on the stress of left handed, the maximum compressional stress orientation isσ₁≈124°∠16°andpaleo-stress is about 88.7Mpa.3. Jianchaling gold deposits are divided into east,west and north ore belts based on the position with ultrabasic rock.The geochemical study show that ultrabasic rock had altered by strongly hydrothermal, Mass hydrothermal flows through gold-containing ductile shear zones and formed the aiteration by H₂O⁺,the north and south ore zone formed in same stage hydrothermal process, in the mineralization process of Au, the hydrothermal and metallogenic material formed in granite-porphyry can increase the concentration of Au.4. JIANCHALING gold ore-controlling structure are located with ductile shear zone ,and the ductile shear zone is occurrenced at the contact zone of the Jianchaling ultrabasic rock mass and dolomitic mylonite.Jianchaling gold deposit evolve into production of ductile shear zone.Orebodies were line with the right lens and expose with ore-controlling ductile shear zone.And when the Inclination of zone over 70°,it is very low gold content.Hejiayan and Zhongman gold deposit are caused by ductile-brittle shear and faults left Shearing about 500m.Hangjiashan golddeposits and Serpentinite-type orebodies aare caused by ductile-brittle shear and faults left Shearing about 300m.