Geochemistry and paleomagnetism of Late Cretaceous mafic dikes in Kerala, southwest coast of India in relation to large igneous provinces and mantle plumes in the Indian Ocean region

Abstract

Research Article| January 01, 2012 Geochemistry and paleomagnetism of Late Cretaceous mafic dikes in Kerala, southwest coast of India in relation to large igneous provinces and mantle plumes in the Indian Ocean region T. Radhakrishna; T. Radhakrishna † 1Center for Earth Science Studies, Trivandrum 695 031, India †E-mail: [e-mail] Search for other works by this author on: GSW Google Scholar Mathew Joseph Mathew Joseph 2Geological Survey of India, Trivandrum 695 013, India Search for other works by this author on: GSW Google Scholar GSA Bulletin (2012) 124 (1-2): 240–255. https://doi.org/10.1130/B30288.1 Article history received: 05 Mar 2010 rev-recd: 10 Oct 2010 accepted: 14 Oct 2010 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation T. Radhakrishna, Mathew Joseph; Geochemistry and paleomagnetism of Late Cretaceous mafic dikes in Kerala, southwest coast of India in relation to large igneous provinces and mantle plumes in the Indian Ocean region. GSA Bulletin 2012;; 124 (1-2): 240–255. doi: https://doi.org/10.1130/B30288.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract New geochemical and paleomagnetic results are presented on two Late Cretaceous dikes of the 85–90 Ma leucogabbroic and doleritic dikes and the 65–70 Ma dolerites in Kerala, India. The dikes are rich in incompatible elements, have fractionated patterns with light rare-earth element enrichment and are akin geochemically to Cretaceous basalts on the east coast of Madagascar. The magmas were formed at garnet lherzolite depths above the Marion plume, constituting part of a large igneous province in Madagascar. In contrast, the 65–70 Ma dolerites are moderately depleted in incompatible elements, with almost flat, rare-earth element patterns and resemble the upper formations of the Deccan Traps and the tholeiitic dikes of the Seychelles. These dolerites were formed by melting of spinel lherzolite over the Reunion plume. Paleomagnetic data from the dikes and the other coeval igneous units from south India provide the 90 Ma pole (latitude: 24°; longitude: 293°; A95 = 5.9; N = 18 sites) for India. The 65–70 Ma dolerites possess both normal and reverse polarities, and the mean pole (latitude: 36°; longitude: 283°; A95 = 5.7°; N = 10 sites) compares well with the Deccan superpole. Paleolatitude estimates indicate ∼5° southward migration for the Marion plume and a northward migration for the Reunion plume, in conformity with global mantle-circulation models; however, distinguishing migration of the Reunion plume from the effects of true polar wander is difficult. Furthermore, the geodynamic reconstructions extending the shear zones of southern Madagascar into south India are not tenable. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.