Petrology and Mineralogy of Ankaramite in the Deccan Volcanic Province of Rajkot District, Saurashtra, Gujarat

The occurrence of ankaramite in the Deccan Volcanic Province of Saurashtra is reported here. The ankaramite occurs as a small dyke intruding into horizontal basalt flows. Petrographically it is characterised by the presence of large phenocrysts of ctinopyroxene (chromian diopside) and olivine (Fo 83 ) in a groundmass of plagioclase (An 60 ), iron oxides and accessory brown amphibole (kaersutite). Chemically it is characterised by enrichment in high field strength and light rare earth elements as compared to the picritic olivine dolerites of the area. It is concluded that the ankaramite magma represents a primitive sample of High-Ti type of tholeiitic basaltic magma while majority of the olivine dolerites and dolerites found in the area are representative of Low-Ti type of tholeiitic magma.