Petrogenesis of Olivine-phyric Basalts from the Aphanasey Nikitin Rise: Evidence for Contamination by Cratonic Lower Continental Crust

Abstract

169-172) and 87 Sr/ 86 Sr (up to 0706), whereas the second In this work we investigate the olivine-phyric basalt suite of the group with low La/Th (5-9) has higher 206 Pb/ 204 Pb (177-181) Aphanasey Nikitin Rise, an intraplate volcanic structure formed and 87 Sr/ 86 Sr (up to 0713). The tholeiite composition is likely during the Late Cretaceous in the Indian Ocean. The parental melt to be controlled by contamination of the parental tholeiitic melts by of the basalt suite has a hypersthene-normative tholeiitic composition continental crust derived from cratonic Gondwanan lithosphere. This with low H 2 O content (03-05 wt %) and high SiO 2 /Al 2 O 3 conclusion, combined with other evidence for ancient crustal material (35). The basalt suite is characterized by Nb, Ta, Th and U in the Indian and Atlantic Oceans, indicates the impact of continental depletion, and uniquely low 206 Pb/ 204 Pb and 143 Nd/ 144 Nd among crust in the oceanic lithosphere. the Cretaceous tholeiitic basalts of the Indian Ocean. Our modelling demonstrates that fractional crystallization of depleted mantlederived melt and lower continental crust assimilation is a suitable model for the genesis of the parental magma of this suite. The