Study on Geological Characteristics and Metallogenic Regularity of the Donggouba Polymetallic Deposit in Lueyang，Shaanxi Province

The Donggouba depost is located at north margin of Xiakouyi-Heimulin Meso-Neoproterozoic basement structure zone, east of the Motianling block. It is a special Au-Ag-Pb-Zn polymetallic medium deposit related to the Marine volcanic rocks of Bikou island arc in the Jinning Period. By integrating the latest progress on the exploration and previous scientific research data, we systematically summarized the geological characteristics of deposit, investigated the pits, analyzed the sulfur isotope of the ores and, finally, studied the metallogenic regularity of the deposit in terms of the classification of metallogenic periods, tracing the metallogenic materials and the genetic analysis of the deposits. The main results are as follows: ①the deposit is located within the Neoproterozoic volcanic arc rocks of Bikou Group, and is characterized by multi-stage mineralization superimposition. The mineralization process mainly include three stages: quartz-pyrite-sphalerite initial pre-enrichment mineralization stage; gold-silver-barite main mineralization stage; barite-carbonate late mineralization stage.②the sulfur isotope(δ³⁴S) of minerals show an order of barite ＞ pyrite ＞ sphalerite ＞ galena, which suggests that the sulfur isotope fractionation had basically reached equilibrium when the deposit was formed. The δ³⁴S_V-CDT values of the Donggouba deposit generally display the characteristics of granitic sulfur with a small quantity of mantle-derived sulfur, indicating that the sulfur in Donggouba deposit may be dominantly derived from the lower crust magma source with minor mantle material. The sources of the ores may come from the volcanic magmatism of the Jinning island arc.③Donggouba deposit is formed by the polyphase tectonic superimposition of ore-bearing hydrothermal fluids derived from Marine intermediate-acid volcanic rocks in the Jinning period. It is a typical volcanic massive sulfide(VMS) type gold, silver, lead and zinc polymetallic deposit.④the deposit formed on the active continental margin in Jinning Period, and belongs to the metallogenic geological event related to the breakup and assembly of the Meso-Neoproterozoic ancient continental blocks. It is speculated that the diagenesis and mineralization process of the deposit could be caused by the subduction and convergence of the eastern and western ancient Yangtze microplates and the subsequent tectonic superposition during Jinning period.