Abstract
Large Igneous Provinces (LIPs) are commonly attributed to mantle plumes, hot upwellings from the deep lower mantle, apparently unrelated to plate motions. However, LIPs often form in association with rifting and breakup. Using numerical modelling, we introduce a novel idea that explains plume-like mantle upwelling by plate tectonic processes. Our model indicates that rifting-induced delamination of orogenic lithosphere can perturb the thermochemical mantle stratification and induce lower mantle upwelling which causes syn-rift LIP formation followed by protracted and enhanced mid ocean ridge basalt (MORB) generation. Our model provides an explanation for the geographical correlation between the Caledonian suture, the North Atlantic Igneous Province (NAIP) and present-day Icelandic magmatism.
Highlights
Continental breakup between North America and Europe in the late Palaeocene was accompanied by the formation of the North Atlantic Igneous Province (NAIP), one of the classic Large Igneous Provinces (LIPs)
Most LIPs formed in the context of continental rifting and breakup[10] and are causally related to plate tectonic processes
The NAIP developed just where a Caledonian suture was dissected by Palaeogene rifting and breakup[11,12], and the unlikeliness of a plume coinciding with exactly this intersection has been invoked as an argument against a deep origin[13]
Summary
The employed numerical method for modelling visco-elastic-plastic flow is generally similar to that described by Gerya and Yuen[38], but differs by employing a multigrid-based approach[24,39,40] which allows for high resolution simulation in both space and time. The presented method differs from the abovementioned references in that we employ a quantitative petrological model for the calculation of density and latent heat effects[41,42]. The simulations of the present paper have a grid resolution of ~2 km for the entire 2000 km × 2000 km modelling domain and are run for 400 Myr. The method employs a combined particle-in-cell approach[38] for the coupled equations for the conservation of energy, momentum and mass in 2 dimensions, xi (i = 1, 2):
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