| Xihe-Chengxian basin is a pull-apart basin, which were formed by nonuniform pull-apart when Qinling plate were separated from yangtze passive Continental margin in Early Devonian period and then subduct forward to Huabei plate. One of the most important concentrate metallizing area in Qinling Gold and Lead-Zinc polymetal metallogenic belt. With a feature of upgrowth hydrothermal-sedimentary metallizing, Xihe-Chengxian area experience hydrothermal sedimentary lithogenic period in Devonia period, regional fold and metamorphism period in indosinia epoch. After that closed and uplifted period under tectonic background of Continet-continent orogengy and intracontinental orogengy in Qinling in late Indosinia-yanshania epoch. The research region lies in the west-southern of Xihe-Chengxian basin. There are many Lead-Zinc deposits and Gold deposits in this area, Such as Dengjiashan Lead-Zinc deposits and Xiaogouli-Sanyangba Gold deposit. The two kinds of ore deposits have a close association in time-space, Which are make up Gold deposits and Lead-Zinc deposit metallogenic series. Based on analysis of tectonic background, palaeogeographic reconstruction and the analysis of typical ore deposits, this paper draws a few conclusion as follow: 1.Lead-Zinc deposits in this region belong to Strong reformed deposits, whose orebearing rocks are larbonate rocks. Gold deposits in this area belong to quasi-Carlin type gold deposits. 2. Gold and Lead-Zinc mineralizations are Strictly controlled by Sedimentary enviroment and precipitation. The subsidence sags which were caused by Ew trend synsedimentary faults, are the common sedimentary enviroment of two kinds ore deposits's orebearing formation. From north to South, Jianqianshan-Anjiacha, Jianaigou-Xiaogouli and Dengjiashan-Shanhuazui subsidence sags occurrence the Gold and Lead-Zinc recombination mineralizing belts in order. 3. A lots of elements, Such as Au,Ag,Cu,As,Sb,Hg,Ba, et al, are concertrated while carbonate rocks-sillicalite-argillaceous rocks of Lead-Zinc orebearing formation are formed by hydrothermal sedimentary. This process supply a part of gold for upper sulfide-bearing classtic rock as well. Each of ore deposits kinds has identical or alike mineral and mineralizing element assemblage; Lead isotopic,Sulfur isotopic,δD value and δ18O value of inclusions water et al. Show that ore metals of two kinds deposits were mainly derived from pre-Devonian basement. To sum up, a conclusion may be reached that ore metals provenance of Gold deposits and Lead-Zinc deposits is alike. Consanguinity of Gold and Lead-Zinc is a foundation, which caused follow paragenesis: one hand, Gold and Lead-Zinc is associate one with another. on the other hand, metallizing of Gold and lead-Zinc is take place in difference Strata rock. 4. All of ore deposits have same experience that ore metals preconcentrated in matemorphism period, and formed minable deposits in tectonic-hydrothermal reformed period. However, the difference of deformability of orebearing strata rocks cause the difference of reforming pattern of two kinds ore deposits: Sillicalite in Lead-Zinc ore- bearing formation has powerful deformability, So fold and fault are main reforming pattern that ore metals such as lead and zinc et al occurrenced in orebearing strata rocks were concerntrated by replacement and remelting and relocation in short distance. But Gold ore bearing formation is a poweless deformability strata rocks that ore metals of Gold et al were activated and relocation and concentration by shears. As state above, The differnce of reforming pattern between Gold and Lead-Zinc metallizing is essetial mechanism that two kinds deposit's close association in time-space. 5. Mineralizing fluid inclusions of Gold deposits and Lead-Zinc deposits studies shows: There are many types mineralizing fluid have a role in metallogenesis of two kinds deposit's, include submarine hydrothermal solution, atmospheric water and Sedimentary formation water which were heated by metamorphism or mag... |
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