Bogala vein graphite hydrothermal genesis: CO2-rich fluid inclusions in quartz selvages?

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Lucas Rock915 rep

What fluid inclusion homogenization temperatures confirm the hydrothermal deposition of solid lump vein graphite in high-grade shear zones?

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Accepted Answer

Vein graphite deposits at Bogala and Kahatagaha are unique in global economic geology, formed through hydrothermal fluid precipitation rather than metamorphism of carbonaceous sediments. Quartz and calcite selvages bordering graphite veins preserve microscopic fluid inclusions. Microthermometric heating-stage analysis reveals that these fluids were supercritical, CO2-rich mixtures with homogenization temperatures between 650°C and 750°C at pressures of 4 to 6 kbar. Precipitation was triggered by fluid cooling and reduction of carbonic fluids (CO2 + CH4 -> 2C + 2H2O) during rapid tectonic uplift along deep shear zones.

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Dr Bandula Crust1860 rep

Carbon isotope analysis (delta-13C values ranging from -7 to -10 per mil) confirms that carbon was derived from deep mantle or sub-crustal metamorphic degassing.

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Lucas Rock915 rep

The veins cut across Precambrian country rock gneiss, forming sharp, planar sheet contacts with pure metallic-lustered graphite.

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Elena Lumens910 rep

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