Yunnan Machangqing metal copper-molybdenum-gold deposit genesis

Title: Yunnan Machangqing metal copper-molybdenum-gold deposit genesis
　　Author: Cai Yongwen
　　Degree-granting units: Chengdu University of Technology
　　Keywords: Machangqing;; Geological;; petrography;; geochemical tracer;; genesis
　　Summary:
　　Machangqing copper-gold deposits of molybdenum, "three rivers" ore belt and Himalayan alkali-rich porphyry deposits related to the typical one, produced in the collision of Indo-China plate and Yangtze plate tectonic environment. Studies have shown that Machangqing which region experienced early Permian subduction of oceanic crust, in the Triassic collisional orogeny, the Late Triassic post-orogenic extension, into the early Tertiary orogenic intracontinental Strong magnets convergence stage, by the Qinghai-Tibet uplift of the plateau collision impact, forming a series of strike-slip pull-apart basin, the Jinsha River - the Ailao Shan fault zone and porphyry belt. Magmatic activity in the area frequently, crust-mantle interaction active, complex tectonic movement, the spheres of material and energy exchange frequent, significant mineralization.
　　Through the study of wall-rock alteration, that alteration of molybdenum ore block in two phases: early and silicified microcrystalline micrite carbonation, silicification and advanced with further superposition of fine-grained pyrite and molybdenite mineralization of; copper section and silicification, carbonation and pyrite are closely related; gold of the sections of silicification and carbonate; concurrent alteration in mineralization throughout the now black opaque material, by electron microprobe analysis, obtaining the material composition in order to measure silicate-based, a preliminary analysis that the substance is a black opaque nature of the fluid by a melt condensation through the formation of ultra-fast micro-cryptocrystalline solid, is involved in mineralization of mantle fluid microscopic traces of a realistic also lead to the crust-mantle wall-rock alteration and mineralization superimposed contamination an important material source and power source.
　　By isotopic tracer studies show that: in Machangqing molybdenum (copper) ore block, minerals and fluids into the mantle source of the main display; random cave in the mountain of copper (molybdenum) ore block, it shows the crust-mantle mixed source; Qing gold in the gold plant section, showing the main crustal source, which has been the general rule is: copper from molybdenum ore block → Section → gold segment, its minerals and fluids into the source of contamination in the crust and mantle, mantle source of contamination gradually weakened, a gradual increase of crustal contamination.
　　Through the ore veins, mineralized rock REE and trace element geochemistry studies have found that various types of REE patterns of samples significantly enriched in light rare-earth based on the performance of a slight negative Eu anomalies, and LREE enrichment is mantle fluids one of the salient features; ore veins and mineralized rock trace element distribution patterns in the overall performance of large-ion lithophile elements and high field strength elements are relatively enriched. Comprehensive studies have shown that Machangqing copper-gold-molybdenum mineralization process may be subject to uniform LREE enriched mantle fluids, and its mechanism can be summarized as:
　　When the alkali-rich magmatic fluid to the crust and mantle to carry the process of migration, if the system is closed better, mantle flow is accompanied by the crystallization of alkali-rich magma to synchronize over Chengdui Fu alkaline porphyry alteration from the account, or deep in the formation of porphyry body molybdenum (copper) deposits; if this occurs during the diagenetic mineralization tectonic disturbances, the alkali-rich porphyry mantle fluids into http://www.chinamagnets.biz/ contact with the rock band or a rock formation near the contact zone of alteration in the account of mineralization, the formation of contact zone of Cu-Mo (associated gold) deposits; if magma and fluid migration and development of deep fault system, in a relatively open environment, the alkali-rich mantle fluids along the diagenetic processes of magma from the magma into the channel along the branch breaks away from the rock body in the account of the different strata of rock alteration mineralization, composition altered rock type gold deposits. Which constitutes Machangqing copper-gold-molybdenum mineralization zoning and series mineralization.
　　Degree Year: 2010