Mineralization And Metallogenic Regularity Of Gold Deposits In The Southern Of Zhao Ping Fault Zone,Jiaodong Peninsula

Jiaodong gold deposit is mainly distributed in Northwestern Jiaodong,Mu-Ru,Qi-Peng-Fu and other metallogenic areas.In northwest Jiaodong area,gold deposits are mainly controlled by sanshandao,Jiaojia and Zhaoping fault zones,among which the Zhaoping fault zone is the largest ore-controlling fault.The previous researches on zhaoping fault zone mainly focused on the middle and north section,and the research degree on the south section was relatively low,which did not systematically summarize the mineralization and metallogenic regularity,which to a certain extent restricted the accurate understanding of the genesis of the deposit and the next prospecting.On the basis of previous studies,the gold deposits in Jiudian and Shanhou are selected as research objects to systematically study the gold mineralization and metallogenic regularity in the southern segment of zhaoping fault zone.The ?³⁴S of the gold deposit in the southern section of zhaoping fault zone is between4.2‰and 9.1‰,with an average value of 7.0‰.The sulfur isotope homogenization is high and the overall sulfur isotope is rich in ³⁴S,which corresponds well to the sulfur isotope composition of the host rock.The sulfur source may be magma sulfur originally derived from the mantle,which mixed a lot of crust sulfur in the process of upper transgression.H-O isotope composition shows that ?D=-92.0‰?-74.2‰,?¹⁸O=-3.28‰?5.14‰.The diagram of ?D_H2O-?¹⁸O_H2Oshows that the ore-forming fluid is mainly derived from magmatic hydrothermal fluid,with atmospheric water mixed in the late stage.The characteristics of fluid inclusions indicate that the ore-forming fluid is medium-low temperature and low salinity ore-forming fluid,which belongs to the H₂O-CO₂-Na Cl fluid system containing CO₂.Since the Mesozoic,extensive and intense magmatic activities have taken place in jiaodong area,resulting in a series of NNE and NE trending fault structures.When ore-bearing hydrothermal fluids migrate to the shallow part,when they meet the tectonic interface such as the wide expansion space of faults or the position with significant change of dip Angle,the gold-bearing complexes are unstable and decomposed,and the gold deposits are enriched and ore-forming.The mineralized intensity of zhaoping fault zone weakens successively from north to south,and the fracture properties show a trend of transition from brittleness to brittle toughness,indicating that the depth of fracture development increases.Although the ore-controlling structures in the north and south sections are slightly different,their metallogenic backgrounds,physical conditions and sources of ore-forming materials are the same.The gold deposits in the southern section of zhaoping fault zone are zoned around the NNE trending ore-controlling faults,and the gold deposits in the fault zone are roughly evenly spaced and have consistent lateral collapse law.The ore bodies are distributed along the contact zone boundary between the Linglong rock mass and the Jiaodong rock group,and often occur in the dip angle of the main fault,the intersection with other faults,and the structural expansion space,etc.The structural extension area is preferentially enriched and ore-forming.The ore-body of altered rock type has the law of expansion and contraction,branch compound and pinch-out reappearance,while the ore-body of quartz vein type has the law of parallel oblique sequence.The enrichment degree of gold deposit is positively correlated with the degree of fragmentation,alteration intensity and metal sulfide species.