Gold Metallogenic Geological Characteristics And Ore-prospecting Criterialn South Of Tibet Gully, In Golmud Qnghai Province

The study area is located in north Bayan Har Mountains metallogenic belt, wherelittle geological work has been done before, except small scale basic regional survey.A group of large, medium, and small scale ore deposits, scuh as Dachang gold minewere found from the beginning of the21st century, revealing that the west part of thebelt is of great exploration potential.To systematically study gold deposit geological features and gold ore guide, andthen guide gold prospecting work in study area even the west part of north Bayan HarMountains metallogenic belt, the author comprehensively studied the latest geologydata and mineral resources data, especially original geological documentation data,specimen identification result, and specials test data.The metallogenic model of the study area is like that of the metallogenic belt. Inearly Triassic period, there was a set of burbidite in Tibet Gully region, accompaniedby deposition of gold element. In late Indochina period and Yanshan period, magmaintrusion and intense tectonic movement happened, and thus some hidden granites,multiple folds, and a series of lineal fractures came into being. Magmatichydrothermal solution carring part of ore-forming element and atmospheric watercirculated, and then leached some gold ore-forming substance, so that goldmineralizing fluid formed. The fluid related to gold mineralization was the result ofCO2-NaCl-H2O system’s immixing and cooling. Fluid immixing happened at236℃～275℃，resulted in the separation of two main gold mineralizing fluids: CO2-H2Ofluid and NaCl-H2O fluid. The fluid rised along structural fractures, and then gatheredand formed gold ore in the place of favorable structural, geophysical, andgeochemical conditions. The gold grade was related to the rock’s mud content. Ingeneral, higher good content could be found in sandstone layer of silicification andpoint pyritization.The analysis of previous prospecting methods revealed a successful work circuit:find gold anomalies by means of soil survey firstly, make pits in the surface secondly,arrange drilling holes thirdly, and circle gold mineralization body finally.