Dynamics of the Late Paleozoic Apart pull Basin and Its Relationship with Mineralization of Gold silver polymetallic barite siderite  Deposits in Zha ShanShang, Shaanxi Province

Key words: 
• apartpull basin /
• basin dynamics /
• tectonic lithofacies /
• hydrothermal sedimentary lithofacies /
• superimposed lithofacies of tectonic hydrothermal fluids /
•  /

Abstract:  Based on reconstruction and restoration of geotectonicpaleogeographic position and tectonic lithofacies, the Paleozoic sedimentary basin of ZhashuiShanyangShangxian in Shaanxi Province could be the apartpull basin on the north passive margin of the Qinling subplate block. This apartpull basin might have been developed on the residue oceanic basin on the north passive margin of the Yangtze plate, and undergone transformation of arcorogeny and residue oceanic basin during the SilurianDevonian age. Furthermore, this basin might be superimposed by deepsourced, alkaline hydrothermal fluid during the Late Devonian Period, resulted in lithofacies zones of ankeritealbite breccia and inversion of the basin. Finally, it had been advanced into a remainsea basin to be shrinking and closed during the Carboniferous Period. Transformation and coupling process of orogenysedimentary basinisland structure may be records form the arcland type orogeny to landland type orogeny. Obvious regional mineralization zonation in this basin may be possibly related to poly diagenesismineralization. Firstly, a variety of hydrothermal sedimentary lithofacies are well established in the basin which disclosed that hydrothermal diagenesismineralization at the large scale took place in the basin. On the one hand, this could be that hydrothermal fluids from the orogeny belt migrated at the large scale into the basin enclosed by paleolandblock and orogeny during the transformation and coupling process of orogenysedimentary basinisland structure. On the other hand, thirdand fourthorder basins controlled by NEand EWtrending synfaults offered sedimentary capacity for the hydrothermal mineralization. Mapping of sublithofacies and microlithofacies may help to delineate their distribution of topologic structure. Secondly, lithofacies zones of ankeritealbite breccia in the remainsea basin closely related to veintype of AuNiCoCu deposits at the higher grades were formed by cryptoexplosion of deepsourced, alkaline hydrothermal fluids. The fluids might be driven by mainly verticalupping force during landland type collision at the southnorthdirection shrinking of lithosphere. Finally, Carlinlike gold deposits are hosted in the upper part of basinbase structure layer and lithofacies of hydrothermal turbidity at the basin were controlled by the late brittleductile shear zone in the area.