Long term stability in deep mantle structure: Evidence from the ~ 300 Ma Skagerrak-Centered Large Igneous Province (the SCLIP)

Abstract

On the basis of large areal extent (~ 0.5 × 10 6 km 2), volume, brevity of eruption interval (± 4 My) and convergent dyke swarms, the flare-up of igneous activity at 297 Ma in NW Europe marks a typical Large Igneous Province (LIP): The Skagerrak-Centered LIP (SCLIP). LIPs are widely but not universally considered products of deep-seated mantle plumes: We test the idea that a Skagerrak plume rose from the core–mantle-boundary (CMB) by restoring the center of SCLIP eruption, using a new reference frame, to its ~ 300 Ma position in a Pangea A type reconstruction. That position (~ 11°N, 16°E, south of Lake Chad in Central Africa) lies vertically above the edge of the African Large Low Shear Velocity Province (LLSVP). It has previously been shown that eruption locations vertically above the edge of one or other of the Earth's two LLSVPs at the CMB characterize nearly all the LIPs erupted since 200 Ma. A deep-sourced SCLIP plume source implies that the edge of the African LLSVP at the CMB has not moved significantly with respect to the spin axis of the Earth during the past 300 My. This is a 30% longer duration for the stability of a deep mantle structure than has been previously demonstrated and suggests that the African LLSVP was at least established by early Permian (Pangea) times.