Giant radiating mafic dyke swarm of the Emeishan Large Igneous Province: Identifying the mantle plume centre

摘要

In many continental large igneous provinces, giant radiating dyke swarms are typically interpreted to result from the arrival of a mantle plume at the base of the lithosphere. Mafic dyke swarms in the Emeishan large igneous province (ELIP) have not received much attention prior to this study. We show that the geochemical characteristics and geochronological data of the mafic dykes are broadly similar to those of the spatially associated lavas, suggesting they were derived from a common parental magma. Based on the regional geological data and our field observations, we mapped the spatial distribution patterns of mafic dyke swarms in the ELIP, and recognized six dyke sub-swarms, forming an overall radiating dyke swarm and converging in the Yongren area, Yunnan province. This location coincides with the maximum pre-eruptive domal uplift, and is close to the locations of high-temperature picrites. Our study suggests that the Yongren area may represent the mantle plume centre during the peak of Emeishan magmatism.