Abstract
Continental breakup can occur with or without extensive magmatic activity. Numerical simulations show that magmatic and amagmatic rifts can develop in the same tectonic setting, if a rising mantle plume is deflected to one side of the continent.
Highlights
Many continental rifts and passive margins are magmatic, some are not[1]
Many features in rift zones and passive margins are commonly explained by models of passive lithospheric stretching[7]
Broad zones of low seismic velocity observed throughout the upper mantle beneath some continental rifts cannot be inferred from small-scale mantle convection induced by passive stretching of the lithosphere—for example in the East African[8,9] or Rio Grande[10] rift systems
Summary
Of deep structures, geologic evolution and recent kinematics, together with new cutting edge numerical modelling techniques[26] (see Methods) to design a three-dimensional (3D) ultrahighresolution viscous-plastic thermo-mechanical numerical model that accounts for the thermo-rheological structure of the lithosphere and captures the essential geophysical features of the central EAR (CEAR). The evolution of the system changes markedly when a cratonic block is embedded into the normal lithosphere (Supplementary Table 2 and Supplementary Figs 2–11) In these experiments a double-rift system forms almost systematically as result of splitting and deflection of the plume head by the cratonic keel. Surface topography first reacts by domal uplift, soon after (
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