Ni-Mo deposits in Zhangjiajie Tianmen region Geological and geochemical characteristics and genesis of

Title: Ni-Mo deposits in Zhangjiajie Tianmen region Geological and geochemical characteristics and genesis of
　　Author: Ma Liyan
　　Degree-granting units: Chengdu University of Technology
　　Keywords: black shales;; Ni-Mo metal;; geological features;; geochemistry;; causes
　　Summary:
　　To construct metallogeny, geochemistry of mineral deposits and theoretical guidance in the study on the basis of tectonic setting of formation, deposit occurrence, ore fabrics, minerals and other geological survey, combined with geochemical data to analyze the genesis . The results showed that: (1) Proterozoic, the crystalline basement of the Yangtze platform by Neodymium Magnets submarine volcanic eruption and emplacement of magma upward to form the base of the volcanic rocks. In the 850Ma-800Ma, the deposition of base plate Creek flysch with clastic tuffaceous rocks, deposited first Sinian sand is pebbly mudstone, and then a period of moraine Nantuo conglomerate, Late Sinian deposition of phosphorus is dolomite, carbonaceous shale, dolomite and then the lights in the group. To Early Cambrian sedimentary organic matter in a rich black shales. (2) deposits in layered and layered distribution; constructed mainly disseminated ore, debris banded; nickel-molybdenum ore structure clastic texture, subhedral structure, he shaped structure of the main account of the other shows like the structure. Ore minerals are mainly pyrite, nickel sulfide, "carbon-sulfur molybdenum 'collection, sphalerite, chalcopyrite, transparent set of ore minerals are mainly phosphate, barite, quartz and calcite. Nickel and molybdenum in the ore occurrence in different forms, which exist in the form of nickel in sulfides, such as needles of nickel ore, nickel and arsenic disulfide Hui nickel; and molybdenum mainly in the form of mineral aggregates, previous more known as "carbon-sulfur molybdenum mine" minerals. Contact relationship between the Ni-Mo is: Mo-Ni sulfide mineral aggregates and pyrite inclusions. (3) and nickel sulfide symbiotic space of six pyrite n (S) / n (Fe) ratio of less than 2. (4) test the ore-bearing section Zhangjiajie village of Sancha in Ni, Mo, V and P2O5 content discovery, in which the Ni content of 0.0082% - 0.36%, the content of the ore bed at 0.36%, the value reached the minimum deposit exploitation grade of 0.3%. Mo content of 0.033% to 0.67% in the seam at the content of 0.67%, much larger than the industry average grade of 0.06% mining. V content at 0.019% to 0.19%, and its content in the ore bed at 0.19%, and most rich, than deposits associated with industrial grade components that can be taken 0.02%. P2O5 content was 0.03% to 23%, 23% ledge at the content, the value of phosphate rock ore grades three. Nickel-molybdenum ores in Ni, Mo, V, P2O5 enrichment were significantly higher than the surrounding rock, is also higher than the lower Dengying dolomite abundances. (5) combination of elements enriched in the ore and the overlying black shale formation there are obvious differences in ore enriched in elements Ni, Mo, V, U, Cu, Pb, Zn, Cd, Tl, Ba and other pro-sulfur elements and transition elements, compared to the ledge above the black shale pro-sulfur significantly reduced with the transition elements, and can represent terrigenous sources Nb, Ta, Zr, Hf, Rb and large high-field strength LILE content was significantly increased; (6) Ni-Mo-REE ore: ore chondrite-normalized of Eu / Eu *= 1.24 ~ 1.69; Ce / Ce *= 0.53-2.75, most located in the 0.5 to 0.7 between; Y / Ho ratio of 48.5 ~ 58.77; ΣREE content of big changes, from 3.63 ~ 251.81 × 10-6, mostly about 10 × 10-6. Cambrian bottom of the same type of nickel-molybdenum mine phosphate rock in the LREE / HREE = 4.48 ~ 6.95, LREE enrichment; chondrite-normalized Eu / Eu *= 0.73 ~ 1.59; Ce / Ce *= 0.32 ~ 0.60 , expressed as a negative Ce anomaly; Y / Ho ratio of 46.40 ~ 54.41; ΣREE content changed little, the same order of magnitude, for the 156.69 ~ 273.85 × 10-6. Shale rock in the ore also has significant LREE enrichment, LREE / HREE = 2.60 ~ 9.25; chondrite normalized Eu / Eu *= 0.03 ~ 0.34, ratios were <1, negative Eu anomalies; Ce / Ce *= 1.51 ~ 2.75, showed positive Ce anomaly; Y / Ho ratio of 22.16 - 35.60; ΣREE shale content in the range from 75.86 到 212.95 × 10-6.
　　Comprehensive results of previous research and the following conclusions: (1) that from Proterozoic to early Paleozoic, Hunan region has experienced from the island arc or continental rift basin to the edge to the passive continental margin evolution. Considering the following conditions: there may be broken with a passive continental margin of Health, the southeastern margin of the Yangtze Platform in Guizhou and other places found traces of magma activities and http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets the existence of ore-forming elements can provide the source of the ancient crystalline basement of these conditions, that in such geological context for the Early Cambrian large-scale activities to provide the possibility of hydrothermal mineralization. (2) the contact relationship between mineral mineral formation sequence is divided into three phases: phase deposition, hydrothermal stage and transformation stage. The first phase of the main product are: pyrite, molybdenum-containing phosphate minerals and phosphate minerals; pin nickel ore, nickel ore Hui arsenic, sulfur nickel side, "carbon-sulfur molybdenum", sphalerite, and brass mine for the second stage of the product; quartz and calcite as the third stage of the product. (3) probes observed molybdenum mineral phosphate and symbiotic relationship exists between that have identical or similar between the two enrichment methods. This is a new study found that this finding can be provided for the study of the causes of their control. (4) most closely associated with nickel mineral pyrite n (S) / n (Fe) were less than 2, which indirectly reflects the Ni-Mo ore with hydrothermal. (5) ore have shown Eu / Eu *> 1 the characteristics, REE REE value is so similar to modern hydrothermal vents. (6) proposed the following mode of seafloor hydrothermal mineralization: a passive continental margin in the side, the source of phosphorus from the land slowly imported into the ocean. With the continent stretching to the Early Cambrian, the lateral edge of the ridge is still retained, resulting in the catchment basin from the outside world. Enclosed within the catchment basin biota flourish. At the same time, the leaching of the crystalline basement of Proterozoic iron, nickel and molybdenum hot brine, along the tensile fracture (fracture with students) into the catchment basin, hot brine in the role of iron and nickel and bacteria produce the reduction of sulfur to form pyrite and nickel sulfides. Them as "particles" surrounded by biological surface growth. Particle surface in the biological or chemical adsorption of the earlier presence of molybdenum in seawater, and ultimately the formation of molybdenum sulfide mineral aggregates wrapped. In the region, due to the background and with similar geological conditions, resulting in a mineralization (bed) large-scale distribution pattern.
　　Degree Year: 2010