Mantle-derived mafic-ultramafic xenoliths and the nature of Indian sub-continental lithosphere

摘要: Mantle derived xenoliths in India are known to occur the Proterozoic ultrapotassic rocks like kimberlites from Dharwar and Bastar craton Mesozoic alkali igneous lamrophyres, nephelinites basanites. The represented by garnet harzburgites, lherzolites, wehrlite, olivine clinopyroxenites kyaniteeclogite varieties. PT conditions estimated for suggest that lithosphere was at least 185 km thick during Mid-Proterozoic period. ultrabasic eclogite have been depths of 100–180 75–150 respectively. Kalyandurg Brahmanpalle clusters sampled typical Archaean subcontinental lithospheric mantle (SCLM) with a low geotherm (35 mW/m2) harzburgitic lherzolitic median Xmgolivine > 0.93. base depleted 185–195 depth is marked 10–15 layer strongly metasomatised peridotites (Xmgolivine ∼0.88). Anampalle Wajrakarur 60 NW show distinctly different SCLM; it has higher (37.5 40 contains few subcalcic = 0.925. In contrast, Uravakonda WK-7 quite fertile (median ∼0.915) SCLM an elevated (> mW/m2).