Sulphide minerals in early Archean chemical sedimentary rocks of the eastern Pilbara district, Western Australia

摘要: The occurrence and paragenesis of sulphide minerals in chemical sedimentary rocks from the McPhee Towers Formations Warrawoona Group, eastern Pilbara Craton were examined, order to evaluate Archean environment. facies both formations are comprised chert or chertcarbonate units, which highly depleted detrital materials. cherty mostly composed microcrystalline quartz, containing significant types syndepositional (or diagenetic) minerals. In particular, Formation (North Pole Chert, Marble Bar Chert) include primary minerals, such as pyrite, chalcopyrite, sphalerite, monoclinic pyrrhotite, pentlandite, gersdorffite millerite. This assemblage measured FeS content (8.4–10.4 mol%) sphalerite associated with Fe-sulphide suggest that formed under reducing conditions at temperatures below 200°C (about 150°C), also metamorphic temperature was less than 325 °C. Furthermore, virtual absence materials minor element compositions imply Block by rapid precipitation hydrothermal solutions.