Deccan-related magmatism west of the Seychelles-India Rift

The rocks of the Seychelles can be divided into two age groups, namely Precambrian granites and younger (Cretaceous/Tertiary) and intrusive rocks. The latter can be further subdivided into alkaline ring complexes and basic dykes. Evidence from offshore seismic work and drill holes suggests that Cretaceous/Tertiariy magmatism occurred over the whole Seychelles Bank, producing both flood basalts and central voclanic complexes. The younger igneous rocks of the Seychelles show close similarities to the Deccan igneous rocks of India. In India, alkaline magmatism post-dates the tholeiitic magmatism; the age difference is of the order of 3 Ma. This is similar to the age difference between shield-building and rejuvenated-stage magmatism on Hawaiian volcanoes, which has been related to reactivation of the volcanoes by the passage of the Hawaiian Arch. The authors propose that the Deccan alkaline magmatism is a continental equivalent of oceanic rejuvenated-stage volcanism. -from Authors