Abstract:
Continental flood basalts (CFB), like the Deccan Traps of India, represent magmatic events that are complementary to ocean island basalts (OIB) in the lifecycles of volcanic hotspots. Notwithstanding, establishing a geochemical relationship between CFB and OIB can be challenging because the compositions of CFB often reflect significant assimilation of felsic crustal material by their parental magmas as they ascend to the surface. The broad correlation between ε143Nd, a sensitive tracer of crustal assimilation, and μ142Nd compositions in this dataset is indicative of the effects of crustal assimilation, although the significance of the correlation is hampered by extant uncertainty constraints on μ142Nd values. However, if the Deccan parental magma is assumed to have a ε143Nd composition of +4, similar to Réunion OIB, this correlation predicts its μ142Nd composition to be ca. +1, which is consistent with published data for Réunion OIB (Peters et al., 2018 Nature). This, however, reflects an association between negative ε143Nd values, which are indicative of stronger crustal assimilation, with negative μ142Nd values, and thus predicts that regional continental crust has a negative μ142Nd composition. This is inconsistent with a recent study of Dharwar Craton felsic rocks (Ravindran et al., 2024 G-Cubed) and highlights the likelihood that Archean cratons are internally heterogeneous with respect to μ142Nd compositions.
User Contributed Keyword(s):
Deccan Traps, continental flood basalt, mantle plume, volcanic hotspot, neodymium-142, Nd isotopes