Characterizing Eastern North American Mantle Using Re-Os

University Of Maryland, College Park, College Park MD

Investigators

Abstract

Minarik EAR-0229995 Mantle xenoliths and ophiolites (preserved oceanic lithosphere) from eastern North America will be studied with the purpose of constraining the evolution of mantle lithosphere from the Archean through the Mesozoic Atlantic rifting. These two different suites sample different mantle regions and will return complementary information on the evolution of the subcontinental lithospheric mantle, and the convecting athenospheric mantle which gives rise to oceanic lithosphere. The first goal of this work is to characterize a set of mantle xenoliths found in lamprophyre dikes and kimberlites in upstate New York, Vermont, and Quebec. These xenoliths hold information about the evolution of the mantle under eastern North America from the Archean to the Cretaceous. The second goal will be to determine the Re-Os systematics of chromites from tectonically emplaced ophiolites spanning the length of the Appalachians. These ophiolites all crystallized and were emplaced within a short period of time during the Ordovician. This sample set will allow an evaluation of the heterogeneity of the convecting mantle with respect to osmium isotopes, and of the possible role of subducting slab-derived osmium during the formation of supra-subduction zone ocean lithosphere. Undergraduate student researchers will perform much of the work outlined in this proposal as part of independent research or senior thesis projects. The major contributions of this study will be a better understanding of the processes of creation of lithosphere during mountain-building events.