Persisting influence of continental inheritance on early oceanic spreading

Abstract

Formation of new lithosphere at mid-oceanic ridges occurs through magmatic crustal accretion and cooling of the asthenosphere, and is essentially controlled by the spreading-rate, ridge segmentation, and eventual arrival of deeply-sourced hot mantle plumes. Its dependence on long-term inheritance is supposedly weak, except in cases where ridge segmentation is preconditioned by the reactivation of continental weak zones during the rifting phase. Here, we provide the first evidence that pre-rift lithospheric thickness variations constitute another forcing that may transmit influence from past Wilson cycles beyond the stage of continental break-up. This long-term control involves differential redistribution of heat/melt sources along young laterally-confined plume-assisted rifts. This is demonstrated here in the case of the Red Sea from the correlation between on-axis volcano-tectonic patterns, distribution of onshore volcanism, and lithospheric thickness variations of the rifted margins.