研究目的
To describe the features of El Vapor gold deposit, focusing on the hydrothermal conditions of its formation, including morphological, mineralogical, and paragenetic descriptions, fluid inclusion study, estimation of temperature, pressure, pH, and oxygen fugacity conditions, and discussion of gold transport and deposit mechanisms.
研究成果
Hydrothermal fluids in El Vapor were responsible for gold transport and deposition, characterized by a CO2 + CH4 + N2 + H2O + NaCl system with low to moderate salinity, near-neutral pH, trapping temperatures of 213-340°C, pressures of 50-300 MPa, and depths of 2-10 km. Gold deposition was likely due to isothermal fluid mixture and reduction processes with host rocks, similar to orogenic deposits worldwide.
研究不足
The study is limited to the first mineralization event due to the size and deformation of quartz crystals in other events. Pressure estimates are based solely on fluid inclusion isochores without other geo-barometers, and there is an inherent error in volume calculations from 2D data. The nonexistence of certain fluid inclusion types restricts conclusions on immiscibility processes.
1:Experimental Design and Method Selection:
The study uses petrography, microthermometry, and Raman spectroscopy to analyze fluid inclusions in quartz veins from the El Vapor gold deposit. Methods are based on traditional techniques and principles from Roedder (1984) and Goldstein (2003).
2:3).
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: Six rock samples of mineralized milky quartz veins from the El Vapor district were selected, representing the first mineralization event. Samples were collected from both sides of the El Nús fault.
3:List of Experimental Equipment and Materials:
Equipment includes a Linkam THSM 600 stage coupled to an Olympus BX41 petrographic microscope for microthermometry, and a Nicolet Almega Raman spectrometer with a 532nm laser. Materials include doubly polished thin sections (110-130μm thickness) and synthetic inclusion standards for calibration.
4:Experimental Procedures and Operational Workflow:
Thin sections were prepared and analyzed. Microthermometry involved cooling/heating routines to record phase changes (e.g., CO2 melting temperature, ice melting temperature). Raman spectroscopy identified molecular species in fluid inclusions. Data were analyzed using software programs like ICE, Q2, and BULK from the Fluids package.
5:Data Analysis Methods:
Salinity, density, molar volume, and composition were calculated using empirical equations and state equations (e.g., Peng & Robinson, 1976). Statistical analysis of temperature and salinity ranges was performed.
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