Lithospheric control on the spatial pattern of Azores hotspot seafloor anomalies: Constraints from a model of plume-triple junction interaction

[1] The Azores hotspot is located near a plate boundary triple junction (TJ) consisting of the Terceira Rift (TER) and two branches of the Mid-Atlantic Ridge (MAR). The seafloor expression of the Azores hotspot has a complex spatial pattern. Latitudinal anomalies in seafloor depth and other data along the MAR extend farther to the south of the inferred location of the mantle heterogeneity than to the north. Longitudinal anomalies span a greater distance to the east of the MAR (along the TER) than to the west. A finite element model is used to investigate how the divergence of three plates away from a TJ may affect the spatial dispersion of thermally buoyant material simulating a mantle plume. Prescribed plate motion vectors approximate the kinematics of the Azores TJ during a main phase of plateau formation ∼7 Ma. The plume is located off axis to the southeast of the simulated triple junction, following several studies that suggest that the present-day conduit is located near the islands of Faial and Pico. Asymmetry in the divergence of the three plates with respect to the triple junction tends to drive plume material preferentially southward and eastward, consistent with observed anomalies.