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GEOREF RECORD

Craton formation in late Archean subduction zones revealed by first Greenland eclogites

Sebastian Tappe, Katie A. Smart, D. Graham Pearson, Agnete Steenfelt and Antonio Simonetti
Craton formation in late Archean subduction zones revealed by first Greenland eclogites
Geology (Boulder) (December 2011) 39 (12): 1103-1106

Abstract

It is now well established that the early continental crust was formed by melting of basaltic lithologies such as amphibolite and eclogite. However, considerable uncertainty surrounds the geologic environment in which melting took place. Commonly invoked options range between melting at the underside of oceanic plateaus above mantle plumes or melting of oceanic lithosphere during shallow subduction. Distinguishing between these scenarios has important implications for the early evolution of continents. We use the first eclogites discovered from the North Atlantic craton (NAC) to constrain the formation of the deep root to this continent. Late Archean eclogite xenoliths (2.7 + or - 0.3 Ga) from a kimberlite in West Greenland are broadly coeval with a major regional episode of tonalite-trondhjemite-granodiorite (TTG) magmatism. Major and trace element systematics of the eclogites reveal a highly refractory character that is mirrored by NAC peridotites. Moreover, the refractory eclogites define a complementary relationship to the Late Archean TTG granitoids from the NAC, and their elevated garnet delta (super 18) O values along with negative Eu anomalies suggest seafloor-altered oceanic crust as the most viable eclogite protolith. These results from Greenland provide strong support for a model in which early continental crust grew by melting of basaltic slabs in subduction zones, where tectonic stacking of down-going oceanic lithosphere provided the mechanism that coupled formation of cratonic crust and mantle.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 39
Serial Issue: 12
Title: Craton formation in late Archean subduction zones revealed by first Greenland eclogites
Affiliation: University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada
Pages: 1103-1106
Published: 201112
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2012-007707
Categories: StratigraphySolid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2011332
Illustration Description: illus. incl. geol. sketch map
N63°30'00" - N64°30'00", W51°00'00" - W49°30'00"
Secondary Affiliation: Geological Survey of Denmark and Greenland, DNK, Denmark
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201204
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