摘要
In this paper,the east ore section of the Pulang porphyry copper deposit is selected as the research object.The micro-thermometer and laser Raman spectroscopic technique are utilized to study the parameters of ore-forming fluids such as pressure,temperature,and compositions.In the meantime,the fractal models,including the perimeter-area(P-A)model and number-size(N-S)model,are introduced to quantify the shape of fluid inclusions,and distinguish the stages of ore-forming fluids,respectively.The results show that the types of fluid inclusions are diversified,namely two-phase liquid-rich type,two-phase vapor-rich type,three-phase CO2-rich type,three-phase halite-bearing type and pure liquid type.The fluids of main mineralization stage are characterized by medium-high temperature(170.2–421.4°C),medium-high salinity(9.3 wt.%–33.3 wt.%),and low density(0.73–1.06 g/cm3).With the migration and evolution,the temperature,salinity,and pressure of ore-forming fluids gradually decrease,while the density of fluids increases.The liquid-phase compositions mainly include H2O,and the vapor-phase compositions consist of H2O,CH4,N2,and CO2,indicating the characteristics of reducing fluids and the mixing of atmospheric precipitation.In general,the characteristics of ore-forming fluids in the east ore section are similar to those of the first mining area,suggesting that the ore-forming fluids in the east ore section may not migrate from the first mining area.And the east ore section may be a relatively independent metallogenic system.Moreover,the fractal analysis results demonstrate that the shape of fluid inclusions formed in the same hydrothermal activity features self-similarity.The DAPvalues of fluid inclusions in B veins,ED veins,andD veins are 1.04,1.06 and 1.10,respectively,showing a gradually increasing trend from the main stage to the late stage of mineralization.Meanwhile,the shape of fluid inclusions ranging from B veins to D veins becomes increasingly irregular.It also reveals that the homogenization temperature sati
基金
supported by the National Key R&D Program of China(No.2016YFC0600508)
the Open Fund of the Research Center for Petrogenesis and Mineralization of Granitoid Rocks,China Geological Survey(No.PMGR202011)
China Geological Survey(No.DD20190385)。
