Gold deposits Laowangzhai rock characteristics and ore-forming mechanism analysis

Title: Gold deposits Laowangzhai rock characteristics and ore-forming mechanism analysis
　　Author: Cai Feiyue
　　Degree-granting units: Chengdu University of Technology
　　Keywords: Laowangzhai gold deposit;; petrography;; element geochemistry;; structure ore;; the crust-mantle mixing dyed mine
　　Summary:
　　Ailao Shan Gold Belt is an important metallogenic belt one. Laowangzhai gold plate and the Indo-China in the Yangtze fold belt plate collision squeezed the deep fault zone controlled by the three: nine A1 Ink West River fault, central Ailaoshan fracture, the Strong magnets eastern Red River fault. According to regional geological background data analysis, the band Luliang construction phase of deformation and metamorphism transformed, and after subduction, the main period of the collision orogeny, then subjected to the Himalayan orogeny, the superposition of the development of major tectonic evolution, culminating in today's landscape. Active role in the area shelled mantle, tectonic movement complexity, its special geological features revealed deposits mantle fluids and ore-controlling structure in the ore played a significant role. In this paper, the Ailao Shan metallogenic belt of gold deposits Laowangzhai for the study, through rock deposits (mineral) ore petrography, rock (ore) rock major elements, trace elements, rare earth elements and structure analysis ore-controlling mechanism, initially revealed the formation of the deposits forming the crust-mantle contamination superimposed on the genetic mechanism.
　　Laowangzhai gold deposit in a fault structure for the nine hectares - Mojiang fracture, and both sides of the fault zone, often with the structure in the same direction, a linear extension of the distribution of ultramafic rocks is important to control mining rock and mineral guide structure; two faults are distributed in nine on a broken plate, as the steep thrust fault under the delay, the direction of thrust from the north east to the southwest; spatial distribution of the ore body consistent with the trend and fracture bending occur simultaneously; three faults is the ore-deposit structure, in which the positioning of ore directly, so ore body shape, by its occurrence and size control. Special tectonic framework, the mineralization has created favorable geological conditions, as follows: the main ore bodies are produced in the region in the east-west thrust fault or shear zone in the north west, faults not only control the rock (pulse) the distribution of adult students, and it is the direct output of ore space, reflecting the ore-controlling fracture of the importance of controlling rock; Moreover, structural composite parts, is a deposit (the body) output of the best locations. In addition, multi-term tectonic activity, resulting in a multi-stage gold mineralization characteristics, and the more intense tectonic activity and its role in the more intense alteration and mineralization.
　　Rock Laowangzhai the main gold deposit types: altered ultramafic rocks, altered mafic volcanic rocks, altered lamprophyres, carbonaceous slate (phyllite) and metamorphosed quartz porphyry and altered greywacke . Obtained by microscopic analysis of mineralized carbonate alteration is mainly oriented, sulfide-based, silicification, pyritization, their relationship with gold mineralization is most closely, especially in multi-phase superposition of favorable mineralization alteration, and alteration of the more intense the higher the degree of mineralization. Rock (ore) in the development of stone along the grain, the crack or amphibole cleavage pattern of penetration or interspersed with black opaque cryptocrystalline ultra-microscopic solids, the electron probe and scanning electron microscopy and spectroscopy analysis identified mainly by the ultra- British micro-spar, and carbonate and silicate melt was sulfide from the cross-student relationship, rutile, scheelite and mirror iron ore (magnetite) component. The study suggests that ultra-microscopic black opaque cryptocrystalline solid material and the http://www.chinamagnets.biz/ main mineralization alteration (silicification, carbonate and sulfide-based technology) basically the same, suggesting that the ultra-microscopic black opaque cryptocrystalline substance is a cause to promote and mine the role of altered mantle fluid.
　　Deposits by the rock (mineral), quartz and calcite veins of the constants, trace and REE analysis obtained: (1) alteration of quartz sandstone, (antimony mineralized) quartz porphyry, carbonaceous slate, silicified lamprophyre rock SiO2 content is higher than the other, most of the rock after the alkali has increased by alteration; (2) rock (ore) of trace elements in rock and veins characterized by enrichment in large ion lithophile element model curve has a more pronounced "hump" type; Th significantly enriched, Ta is the relative enrichment; from rock to rock to the ore mineralization lithophile elements and high field strength elements corresponding to the weak performance of the rich set to significantly enriched, Cr and Ni loss from weak to strong losses; (3) REE patterns similar to the figure showed an enrichment of light rare earth-based right-wing, REE characteristics of rock and ore in the Ce, Eu unusual combination with a significant difference, indicating that the ore-forming fluid and not from the surrounding rock, at least not primarily provided by the surrounding rock. Studies have shown that deposits in the rock (ore) stone was enriched LREE, is the mantle fluid in the area an important indicator of mineralization, suggesting that mineralization may be subject to a uniform LREE enrichment of the mantle fluids, combined with the analysis of structural characteristics, The fluid involved in alteration of the process, inevitably lead to contamination and the crust-mantle superimposed mineralization.