Geochemistry of Komatiitic Basalt Dyke from Schirmacher Oasis, Queen Maud Land, East Antarctica

Geochemistry of a Neoproterozoic/Phanerozoic basalt dyke of komatiitic affinity, in the Precambrian metamorphosed gneissic terrain of Schirmacher Oasis, Queen Maud Land, East Antarctica is reported here. The dyke is composed of olivine (Fo_87-90) which is largely pristine, clinopyroxene, magnesiochromite and devitrified glass. Clinopyroxene exhibits microspinifex texture. It has moderately high MgO (14.10-15.10 %), Cr (569-813 ppm), Ni (457-629 ppm) and low K₂O (0.46-0.68 9%) and TiO₂, (0.93-1.00 %) contents and high CaO/AI₂O₃ (1.11-1.22) ratios. The dyke shbws Al-depleted (low Al₂O₃, TiO₂, = 8.36-8.72, depleted HREE Gd_N = Yb_N = 1.66-1.96) signature. suggesting that the source magma was generated by low degree of partial melting of the mantle with garnet in the residue. LREE enrichment (La_N/Yb_N = 3.01-3.51) and negative Nb anomalies in the dyke samples further suggest crustal contamination of the source magma during ascent through the continental crust.