Geochemical characteristics and geological significance of diamond indicator minerals in Xiawengshao area,Shibing County,eastern Guizhou Province
Diamond indicator minerals pyropes and Cr-spinels from Xiawengshao area of Shibing County,East Guizhou,were subjected to electron microprobe (EMPA) major elements analysis and LA-ICP-MS micro-area in-situ trace element stesting.The results indicate that these pyropes mainly belongs to G9 type (ca.87％),followed by G12 type (ca.11％) and G3 type (ca.2％),with the source rock being lherzolite and wehrlite.When coexisting with olivine,equilibrium temperatures (tNi) range from 686 to 1225℃ and pressures (PCr) range from 1.9 to 4.0 GPa,with a few falling within the main pressure-temperature range for diamond formation (pressure ca.4.0～6.5 GPa,temperature ca.950～1300℃).Cr-spinel mainly originates from xenocrysts captured by peridotite (Xen) (ca.90％),with a small portion being chromite (Chr) (ca.10％),and a few falling within the range of chromite inclusions in primary diamonds worldwide.The study suggests that reconstructing the paleogeography since the Caledonian orogeny,identifying the source rock/new rock of diamond indicator minerals,and conducting comparative studies on minerals are crucial.Particularly,in-depth investigations into the composition of mantle materials,lithospheric thickness,and thermal state since the Caledonian orogeny in the region will have significant scientific implications for the evolution of the South China Continent,analysis of deep mantle structure,and diamond mineralization events.
pyropeCr-spinelindicator minerals for diamondeastern Guizhou
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维普
