Geophysical Identification and Characterization of Mafic-Ultramafic Intrusions in Plume Centre Regions

Gravity and magnetic data from the EGM2008 and EMAG2 datasets are used for a global study of geophysical anomalies in LIP plume centre regions with the goal of identifying mafic-ultramafic intrusions linked to those LIPs. Geophysical anomalies within eighteen LIPs are investigated. Four of these LIPs are selected for detailed modelling: the Mackenzie, High-Arctic, Kunene-Kibaran, and Deccan LIPs. Modelling supports that these anomalies are produced by large (radius >30 km) and generally deep-seated crustal intrusions, with densities consistent with mafic-ultramafic rock and magnetic susceptibilities consistent with serpentinized ultramafic rock. Modelling also indicates that these values remain consistent within a LIP, particularly regarding density and depth. Lastly, we recognize three types of spatial distributions for intrusions in plume centre regions: 1) intrusions that circumscribe the plume centre emplaced along circular fault systems, 2) intrusions emplaced along rifts, in some cases rifts that converge towards the plume centre, and 3) single/unclassified intrusions.