Structural Characteristics, Stratigraphic Sequence, And Abundance Anomalies And Occurrence Of Pb, Zn, Ag, As, Sb Of Jiache Dome

Northeast Yunnan is located in the southwestern part of the Yangtze block. A series of tectonic domes hosting low temperature deposits or closely relating to low temperature deposits develop in this region. The research on the structural origin and properties of tectonic domes is beneficial to reveal the regularity of regional low temperature ore formation. Jiache dome locates at the region of northeast Yunnan from Awang town to Jiache town. Compared with other domes in northeast Yunnan, Jiache dome develop complete structure-rock assemblage, which is a typical representative of the regional tectonic domes. Through detailed geological investigation and structure analysis, sample collection for key stratum system, geochemical and EMPA analyses, combined with the regional background data, this paper focus on the structural features of the Jiache dome, determine the structural origin, deformation sequences of tectonic domes, characteristics of background anomaly for low temperature metallogenic elements, and explore the indication significance of structural features of domes on the source of low temperature ore-forming materials. The main results are as follows:1. Complete three crosscutting structure profiles of the Jiache dome and discover that the dome has experienced at least three stages of structural deformation: D1 period developed ductile rheologic structure whose deformation age is supposed to be Caledonian; D2 period was NEE trending fault propagation fold whose deformation age is speculated at the Indosinian; D3 period is NNE trending buckling fold whose deformation age is supposed to be Yanshanian.2. Results of structure analyses show that the main part of the dome is based on the NNE trending fold superposing on the NEE trending fold, and experienced multi-stage tectonic superposition and transformation. Regional comparative analyses show that the formation pattern is the primary factor for the southwest domes of Yangtze block.3. Results of geochemical analyses show that low-grade metamorphic rocks in the Kunyang group, such as muddy and silty slate, bear background anomaly of 3 to 5 times higher than background value of Pb, Zn, Ag, Sb, As, siltstone in the Chengjiang formation of Sinian and dolomite and black shale in the Dengying formation host more than background anomaly of 3 to 5 times higher than background value of Pb, Ag, As, part of black shale in the Yuhucun formation of the lower Cambrian have background anomaly of 3 to 5 times higher than background value of Pb, Zn, Ag, Sb, As. The result of EMPA analysis suggests that low temperature ore-forming elements are mainly hosted in the primary pyrite and other minerals.4. Establish regional structure-rock-low temperature ore-forming element histogram, and suggest that properties for three stages of tectonic deformation provided a favorable environmentare about the enrichment of Pb and Zn in the spatial and temporal scale.