Structural Control On Gold Minerlization And Deep Metallogenic Forecast In Zhaoping Gold Belt,Jiaodong Peninsula,Eastern China

Jiaodong Peninsula is the most important gold concentration area of China.accurately determining the fault zone shallow surface ore-controlling structure and deep strucurual feature of Jiaodong gold concentration area is the urgent key issues of gold mineralization theoretical research and deep prospecting study.The thesis chooses Zhaoping gold belt as object of study,the tectonodynamics process and mechanism of gold metallogenic system as main line,focuses on ore-forming tectonic style and permeability sturucture,works on the ore-controlling mechianism of structure on Zhaoping gold belt,builds up the ore-controlling pattern of structure,conducts deep metallogenic prognosis and obtains following conclusions.1.Gold mineralization in Zhaoping gold can be divided into four types: disseminated type mineralizaion in ductile shear zone,altered rock type mineralizaion in schistositized zone,cataclastic rock type mineralizaion in brittle fault zone and quartz vein type mineralizaion in fissures.The width of the first two types mineralizaion is small,which indicates the ductile and brittle-ductile deformation occur at fault zone,the permeability of fracture zone and host rock is low,ore-forming fluid,mostly permeating flow,concentrate in fault core.The width ofthe latter two types mineralizaion is large,which indicates the permeability of fracture zone and host rock is high,ore-forming fluid,mostly tul flow,concentrate in secondary faults and fissuresin fault zone and wall rock.2.Zhaoping fault zone,a brush fault narrow and low in south,wide and high in north,is made up by one or several parallel main and secondary faults and fissures in foot wall,may be related to large-scale tectonic seismic activities.when main shock occurred,nearly-parallel fracture surfaces formed.As high permeability structure caused by main shock can't exsist too long,gold mineralization is hard to take place.But aftershocks caused by the block of fracture propagation at fault joints and turning pointsmay bring up a series of secondary faults and fissures over and under main fracture surfaces,high permeability structures caused by aftershocks maintain a longer time and gold-bearing fluid is more likely to migrate to these structures,precipitate and mineralize.3.In Zhaoping fault zone,from south to north along the longitudinal,from hanging wallto foot wall along horizontal,from shallow to deep along vertical,tectonic deformationis characterized by the change of brittle shear?ductilebrittle shear?ductile shear.In the ductile deformation stage,the permeability of rock is poor,and water-rock interaction is weak.In the brittle deformation stage,the permeability of rock is high,and water-rock interaction is strong.4.Zhaoping gold belt formed in the background when North China Craton lithosphere NW-SE extend,the gold depositsin Zhaoping gold belt are strictly controlled by the main Zhaoping fault and its secondary fracture and joint structure,the distribution and occurrence of gold mineralization is closely related to the nature of ore-forming structure and the temporal and spatial variation of fault zone permeability structure.5.Gold body mainly exists in palces where trend turns to NE,the fault surface sharp dipsor rises,multi faults intersect,secondary pinnate fracture thicker and the fault gouge beneath main fault footwall is thick.Low density,low susceptibility,high resistance and high polarization,higher electric is key prospecting information.Combined with the character of ore-controlling structure,structural combination type and wide-area electromagnetic sounding results of Xiadian and Dayingezhuang gold deposits,4 prediction targets were defined below-1000 meters in Xiadian gold deposit,5 prediction targets were definedbelow-1200 meters in Dayingezhuang gold deposit.