Age and origin of a Guadalupian tuff in the E'Xi rift basin in South China: Evidence for the Emeishan continental hotspot track?

Abstract

AbstractUnlike oceanic hotspot tracks, continental hotspot tracks are difficult to recognise, although they can provide unique insights into crustal deformation and intraplate magmatism. Here, we present whole‐rock geochemical and Sr–Nd isotope, and zircon U–Pb age and Hf isotope data for a tuff from the E'Xi rift basin in the South China Block. The zircons yielded a 206Pb/238U age of 267.0 ± 2.0 Ma, which coincides with the Roadian–Wordian boundary. The whole‐rock geochemical and Sr–Nd isotope data for the tuff indicate it had a mixed mantle–crust source. The zircon trace element and εHf(t) (−6.32 to +7.06) data are also consistent with such a source. Based on the sedimentological and tectonic history, and the geochronology and geochemistry of the tuff, we propose the tuff erupted in a rift and records the hidden hotspot track of the Emeishan mantle plume beneath the northern SCB.