Earth history has been punctuated by episodes of short-lived (<10 m.y.), high-volume (>106 km3) magmatism. The origin of these events and their manifestations as large igneous provinces (LIPs) with associated continental flood basalts do not fit in the current plate-tectonic paradigm. Upper-mantle processes have been invoked for some LIPs, whereas the origin of others appears to be related to plumes rising from the deep mantle. The Paraná-Etendeka LIP has remained enigmatic and highly contested in terms of plume versus upper-mantle models. Here, we provide evidence for a plume origin based on new isotopic (He, O, Sr, Nd, Pb) and trace-element data from olivine-rich dikes from Namibia. The composition of the dikes can be explained by mixing at shallow depths between a plume source with high 3He/4He (>26 RA) and ambient asthenospheric mantle, before ascent through the thinning lithosphere.
Helium isotope evidence for a deep-seated mantle plume involved in South Atlantic breakup
Nicole A. Stroncik, Robert B. Trumbull, Marc-Sebastian Krienitz, Samuel Niedermann, Rolf L. Romer, Chris Harris, James M.D. Day; Helium isotope evidence for a deep-seated mantle plume involved in South Atlantic breakup. Geology 2017 doi: 10.1130/G39151.1
Download citation file: