Combined 182W – 142Nd data for the Deccan Large Igneous Province and the role of crustal and lithospheric reservoirs

Recently, high precision isotope measurements revealed anomalies of the short-lived ¹⁸²W and ¹⁴²Nd system in modern Ocean Island Basalts (OIBs) [1, 2]. These anomalies indicate the presence of an ancient primordial component within OIB sources, however, their origin remains enigmatic. Core-mantle interaction [2] or the involvement of early differentiated and isolated silicate reservoirs [e.g. 3] are the most plausible scenarios to account for the observed isotope anomalies. To better understand the involvement of primordial components within OIBs, comparing plume heads and tails might be key to answering this question since the amount of incorporated material changes during the lifetime of plumes [4].
Here, we present new ¹⁸²W and ¹⁴²Nd data for basalts from the Deccan Large Igneous Province (DLIP; 65Ma). By investigating Pb and ¹⁴³Nd isotopes as well as W-Th-Ta systematics, we investigated the role of crustal and lithospheric contamination during plume ascent on the short-lived isotope compositions. Our combined ¹⁴²Nd-¹⁸²W data for pristine DLIP lavas fall within the range of Réunion lavas [1, 5] that were interpreted as late-stage eruptions tapping the Deccan-Réunion plume. Consequently, while the short-lived isotope compositions can be altered due to lithosphere assimilation, pristine DLIP lavas display the same short-lived isotope compositions as their respective tail. In contrast to previous studies [4], this argues for a consistent entrainment of the same primordial components into a plume head and tail.

[1]Peters et al. (2021), G-Cubed. [2]Mundl et al. (2017), Science. [3]Tusch et al. (2022), PNAS. [4] Jones et al. (2019), EPSL. [5]Jansen et al. (2022), EPSL.