CONTINENTAL LITHOSPHERE AND MANTLE PLUMES (Invited Presentation)

Cratons, the ancient cores of continents, have been remarkably resilient since their formation over 2.5 Ga ago. Their thick lithosphere is compositionally buoyant, mechanically strong and resistant to erosion by ordinary convection currents in the mantle, as evidenced by its stability in many cases. Yet, growing evidence indicates unexpectedly widespread destruction of cratonic lithosphere by extraordinary convection currents, the hot mantle plumes rising from the core-mantle boundary.

Seismic tomography can now image the lithosphere of cratons, as it is at present, at fine regional scales across entire continents. Diamondiferous kimberlites give us a glimpse into the past, testifying to the existence of thick cratonic lithosphere at the time of their eruption. The distribution, timing and chemistry of Large Igneous Province (LIP) intraplate volcanism probably relate to the activity and properties of the mantle plumes. Together, these lines of evidence reveal erosion of portions of cratonic lithosphere following the emplacement of LIPs in their vicinity and elucidate intricate feedbacks between the evolution of continental lithosphere and that of plume heads.

References

Celli, N.L., S. Lebedev, A.J. Schaeffer, C. Gaina. African cratonic lithosphere carved by mantle plumes. Nature Communications, 11, 92, 2020.

Steinberger, B., E. Bredow, S. Lebedev, A. Schaeffer, T. H. Torsvik. Widespread volcanism in the Greenland-North Atlantic region explained by the Iceland plume. Nature Geoscience, 12, 61–68, 2019.