The Qinghai Qimantage Metallogenic Belt Typical Geological And Geochemical Study

The Qimantage Fe-Cu-Pb-Zn-W-Sn-Au-Co polymetallic ore belt in Qinghai is the the major component of the first order Qing (Ling)-Qi (Lian)-Kun (lun) metallogenic belt (also known as central metallogenic belt) in western China. In recent years, the geological prospecting of this metallogenic belt has made significant progress, and resources shows great potential. Therefore, the systematic geological and geochemical research of this typical ore deposits has the important scientific value and practical significance.The topic selection of this thesis combines with the Bureau of Geology and Mineral Resources Survey and Evaluation of Qinghai-Tibet Plateau special project of China Geological Survey (project number:1212010818091). According to the low level of geological research in the study area, multi-type deposits and complex mineralization, aim at Qimantage typical deposit metallogenic belt as the main object, through careful study and the anatomy of deposits, applied petrological and trace elements, isotopes, geochemistry and fluid inclusion analysis, mathematical statistics, comprehensive research methods, from the breadth and depth of the ore-prospecting target selection and prospecting target areas in western alpine desert to explore the rapid assessment technology portfolio, the thesis provides the scientific basis. The thesis achieves the following main results:(1) The thesis determines deposit types and established the model of the relationship between magmatic evolution and deposit models. Based on the regional geological background and mineral geological characteristics, the ore-controlling factors and its genesis are systematic analyzed. It concludes that deposits are multi-metal ore belt of multi-deposit type and multi-composite superimposed metallogenic system, with superior the ore-forming geological conditions and prospects and looking for SEDEX-type overlay-type Cu-Co magmatic hydrothermal polymetallic deposits, skarn-Cu-porphyry iron deposits and orogenic-type gold deposits. Kendekeke deposit belongs to SEDEX-skarn overlay-type Fe-Co polymetallic ore deposit. Kaer belongs to the magmatic hydrothermal polymetallic ore deposit, Sijiaoyanggou belongs to skarn-type lead-zinc deposit. hutouya belongs to skarn-type copper-lead-zinc silver deposit. Combination of tectonic-magmatic evolution, the thesis established tectonic-magmatic activity evolution model and the relationship between various types of deposits.(2) The typical geochemical characteristics of deposits were systematically summarized. Based on the analysis of geological features, the petrology, petrochemistry, REE, trace elements, mathematical statistics and so on, sums up the four typical geochemical characteristics of deposits. Expect the Kendekeke area can be diorite (SiO2 62.30%), other rock forming calc-alkaline granites are typical of acid (SiO2≥65%; Rittmann indexσ:0.57～2.16); REE patterns are Eu loss-LREE enrichment type (δEu: 0.56～0.76), show S-type granites and orogenic-type granites; REE distribution patterns were similar with the rock and surrounding rock, except to the ore∑REE significantly lower with a clear separation. It reflects that the mineralization and rock, surrounding rock has a close genetic relationship. The rocks are the main ore-forming geological bodies. The comparison of trace element characteristics shows that Kedekeke, Caerque close to the skarn inner contact zone are favorable to enrichment of ore-forming elements, while the external contact zone of hutouya deposit are favorable to enrichment of ore-forming elements.(3) The thesis concludes that the isotope tracer has multi-sources. Through the typical characteristics of lead isotope in ore deposits, it can be concluded that the ore lead isotopes composed with the mantle-derived magmatism lead and crust-derived lead. The ore-forming materials are processed by the multi-source contamination, and the mantle-derived substances may be involved in mineralization. The mineralization are accompanied by strong volcanic activity. The sulfur isotopic characteristics are more decentralized (-3.08‰～12.23‰).δ34S of Kaerqienei and Sijiaoyanggou focused on the 4.37‰～6.39‰, reflecting the mineralization of sulfur comes mainly from rock.(4) the typical characteristics of fluid inclusions in mineral deposits reflects that the sources of ore-forming fluid are mainly magmatic water, mineral deposit formation are two ore-forming fluid mixing. The fluid inclusions are irregular shape, size disparity (4μm～46μm), homogenization temperature, salinity range (89℃～344℃; 0.71～42.4 wt% NaCl equiv), fluid density range (0.651 g/cm3～1.033g/cm3). This feature shows that there are two ore-forming process of ore-forming fluids:high salinity-high temperature high-density fluid and low temperature-salinity-low-density fluid, reflecting the ore-forming hydrothermal mainly from magmatic water, with the heated meteoric water. It shows the common feature of hydrothermal ore deposits.(5) The thesis proposes that the study areas located at the multi-phase composite orogenic tectonic between the southwestern edge of the Qaidam Basin and East Kunlun. Based on the previous studies, it is conclude that Qimantage areas do not appear significantly island arc subduction zones, deep trench and fore-arc-arc basin sequence, and the spatial structure is the multi-phase composite orogenic belt between the southwestern edge of the Qaidam Basin and the East Kunlun orogenic belt.(6) The thesis sub-divides the study area into five metallogenic belt, and proposes minimization prospecting. Based on the geological structure, magmatic activity and comparison of deposits types, prepared Qimantage region (Qinghai Section) (3) mineralization zoning map, and five ore deposit sub-band:①Tanbeixuefeng Caledonian uplift W-Sn-Au-Cu metallogenic ore belt;②Qimantage Maeyama Caledonian-Indo-overlay composite Depression Fe-Cu-polymetallic metallogenic ore belt;③Qimantage before the Indo-orogenic uplift Mountain Cu-Mo-polymetallic ore belt;④Nalenggele river depression Fe-polymetallic ore belt;⑤Qimantage Caledonian-Indo-Chinese superposition compound uplift Cu-W-Sn-polymetallic ore belt. On this basis, the thesis discusses the different of ore belt and the deposit prospection.