Coats Land dolerites and the generation of Antarctic continental flood basalts

Abstract

On the basis of geochemical signatures, Mesozoic magmatism in Antarctica is divided into the Ferrar Magmatic Province and the Dronning Maud Land Province. The tholeiitic magmatism of the Ferrar Magmatic Province is distinguished by such features as low Ti/Y (< 200) and Zr/Y (< 5.0) ratios, negative εNd values (< −3) and relatively enriched initial ⁸⁷Sr/⁸⁶Sr ratios (> 0.709). All of these geochemical features indicate a major contribution from the continental mantle lithosphere in the generation of these magmas. In contrast, the Dronning Maud Land magmatism has elevated trace element ratios and εNd values (Ti/Y 250–600; Zr/Y 3.0–9.0; εNd −2 to +3) and lower initial ⁸⁷Sr/⁸⁶Sr ratios (< 0.707) relative to the Ferrar Magmatic Province. The trace element and isotopic correlations suggest that these magmas were derived by the mixing of an OIB like asthenospheric component with a continental lithosphere component. The transition between these two geochemical provinces is located in Coats Land.