A Superplume at the Heart of Pangaea

The formation mechanism of the Central Atlantic Magmatic Province (CAMP) has been hotly debated since it was suggested that a mantle plume was related to the primary mechanism for the breakup of Pangaea. Those favoring a more passive mechanism have cited the lack of geochemical evidence for the involvement of a mantle plume as well as no current hotspot. In addition mantle potential temperatures computed from primitive melts are too cold for the involvement of a mantle plume. In this study the possibility of a mantle plume origin for CAMP is investigated using updated Zr/Y -Nb/Y (delta Nb) systematics and a global database of CAMP including new data from Eastern North America. The delta Nb values found for CAMP are significantly higher than those expected from a shallow mantle source. AFC modeling shows that in most cases the delta Nb values are indicative of the involvement of an enriched plume source. The samples previously used to calculate the mantle potential temperatures for CAMP were found to be melts of the lithospheric mantle and not plume material and thus explained the computed cooler temperatures. Finally, a recent paleo-reconstruction of Pangaea places it and CAMP overtop of the current-day African LLSVP giving CAMP a possible superplume origin at the heart of the break-up of Pangea.