| tween the North China plate and the Yangtze plate, the grand and lofty Qinling orogen., lying across the center of the China,is a famous continental orogen and a polymetalic minerogenic belt in the world. As an important part of it, the western Qinling orogenic belt enriched in mineral resources, with a long geologic evolutionary history, which is divided into several distinct stages characterized by different tectonic regimes, has unique and complex lithospheric composition and structure. A lot of gold deposits were found at Xihe-Chengxian (Xi-Cheng) region in 90 after Changba-Lijiagou,Dengjiasan,Bijiasan et al. Large-scale Pb-Zn deposits explored between 70 and 80 . Today there are many geochemical anomalies and ore spots will be appraised. The mine prospects very well.Under the direction of modern mineralization theory, the Pb-Zn deposits are formed by sedimentary-exhalative(sedex) metallization after extensive contrast and thorough study of geological features of the ore deposits.According to the complicated tectonic evolution and special mineralization in the western Qinling orogenic belt, this paper stresses the studies of the regional geological features, the nature and dynamic mechanism of mineral-formation basins, the geological and geochemical characteristics and origin of Pb-Zn ore deposits. The space-time and essential relations between Au,Pb-Zn ore deposits and sedex mineralization are revealed. The main results and achievements are as follows:1.Based on the synthetics analyses of strata sequence, deformation and metamorphism, magmatism and features of geophysics,geochemistry,remote sensing image and deep crust structure, the western Qinling orogenic belt is divided into three crustal-scale tectonic elements which contain the North China craton southern margin zone,the Northern Qinling zone and the southern Qinling zone(the Qinling microplate).2.By deep study of rocks, biocoenosium composition and sedimentary environment of the Western Qinling Devonian, this paper first put forward that Xi-Cheng basin is a complex rift basin having experienced a process from narrow rift to wide rift. In early period it formed mostly by passiverifting, which had features of rift basins. In late Period it transPOrted tosupradetaChInent because of piling up active rifting.3. The western Qinling orogenic belt with 6 tectono-development Periods is atypical composite continental orogenic belt evolved by different systems. Itwas formed by collision mountain-building movement that three platessubduct along two suture zones in main mountain-building Period.Not to beignored was also the strong intracontinental mountain-building movement inYallshan-Xishan period.Plate tectonics of the Qinling orogenic belt ensuesmainly the Non-Wilson Cycle charaterized by archiPelagic ocean,softcollision and multicyclicity.4. According to the tectono-envorimeni, sedimentary formation andore-forming elements association, the sedex type ore depoisits are dividedinto 6 subtyPe.5. Early Hercynian rift controlled the occurrence of the regional metallogeneticbelt.Rift basins, structural movements, synsedimentary faults and seafloorhydrothermal activities determined the distribution of the dePOsits.Sedirnentary facies and environments constrained the emplacement of theorebodies. The main orebodies are conformable bedded or bedway developedsyndepositional fabrics and hydrothermal mineral assemblage.There aremany kinds of seafloof hydrothermal sedimentary rocks,such as silicaroc k, al bi ti te, bari tite, c hl o riti te in the area.6. A preliminary study on gold metallogenetic featUres in Xi-Cheng areaindicate tha gold dePOsits which can be divided into 4 types are controlledby strata, rock facies and structUres. Its origin is reformed sedex. The goldore-forming relate to the method and extent of refOrmation.7. The nature relation betWeen Au and Pb-Zn deposits is probed. Au and Pb-ZndePOsits with the sarne sedex origin occurs in sarne geological unit. However,...
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