Join Scripps Oceanography for the first of two lectures by 2021 Robert L. and Betty P. Cody Award in Ocean Sciences recipient Laurie Reisberg of the Université de Lorraine.
Reisberg's presentation, "Clues to the Formation of the Subcontinental Lithosphere,” will take place Wednesday, May 4 at 3:00 p.m. at the Scripps Seaside Forum.
Description: The origin of the subcontinental lithosphere in non-cratonic regions remains poorly understood. This lithosphere, represented by mantle xenoliths carried by alkali basalts and by orogenic lherzolites, is considerably more fertile than that underlying the cratons. It is also on average more fertile than the mantle domains represented by abyssal peridotites. The fertile nature of the non-cratonic lithosphere is often attributed to refertilization processes acting on harzburgitic protoliths. Osmium isotope compositions are often strongly correlated with major element abundances in non-cratonic peridotites. Modeling of these correlations shows that refertilization of these rocks must have been an ancient process, occurring soon after or even concomitantly with the original melt extraction event that led to the production of depleted harzburgites. More recent refertilization is excluded, except on very local scales. Moreover, all of the non-cratonic suites showing correlations between Os isotopes and fertility indices (~20 localities) have Os model ages indicating that profound melting occurred in the early to mid Proterozoic Era. Such correlations are highly unlikely to form in the the mantle wedge overlying subduction zones. As continental crust is generally thought to form in convergent margins, this raises questions concerning the relationship between crustal rocks and the underlying mantle lithosphere.
Reisburg will also deliver a public lecture, “The Oman Ophiolite: A Window into the Oceanic Mantle," Thursday, May 5 at 3 p.m. at the Scripps Seaside Forum. Details on that event here.