1. Enriched Grenvillian lithospheric mantle as a consequence of longlived subduction beneath Laurentia.
- Author
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Chiarenzelli, Jeff, Marian Lupulescu, Cousens, Brian, Thern, Eric, Coffin, Lindsay, and Regan, Sean
- Subjects
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ULTRABASIC rocks , *COSMIC abundances , *EARTH'S mantle , *OROGENIC belts , *ZIRCON , *ANORTHOSITE , *SUBDUCTION zones - Abstract
Geochemical and Nd isotopic data from mafic and newly discovered ultramafic rocks in the Adirondack Lowlands suggest widespread enrichment of the lithospheric mantle under the Grenville Province. Incompatible element abundances and previously published Hf T DM(zircon) (depleted mantle model age) and Nd TDM ages from rocks of the anorthosite-mangeritecharnockitegranite suite in the Adirondack Highlands document similar enrichment in the lower crust and its strong infl uence on subsequent magmatic events throughout the OntarioQuebec-Adirondack segment of the Grenville Province. Likely the consequence of long-lived (ca. 1.4-1.2 Ga) northwest-directed subduction along the southeast edge of Laurentia (previously proposed Andean margin), this enrichment is similar to that associated with the vast (>240,000 km2) ultrapotassic province of the western Churchill Province. Enrichment of the lithospheric mantle beneath orogenic belts is a predictable and important differentiation process that has operated on Earth for at least the past 3 b.y. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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