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Hadean origins of Paleoarchean continental crust in the central Wyoming Province

C. D. Frost, J. F. McLaughlin, B. R. Frost, C. Mark Fanning, S. M. Swapp, S. C. Kruckenberg and J. Gonzalez
Hadean origins of Paleoarchean continental crust in the central Wyoming Province
Geological Society of America Bulletin (September 2016) 129 (3-4): 259-280


The scarce remnants of Earth's earliest history make it challenging to describe the crust-forming processes that operated during that time, and all evidence that survived subsequent tectonism and recycling deserves to be studied closely. We present geologic, petrologic, geochemical, and isotopic descriptions of Paleoarchean gneisses in the central Wyoming Province. We identify two groups of gneisses: a bimodal suite of amphibolite and tonalite-trondhjemite-granodiorite (TTG) layered gneisses (3385-3450 Ma), and a suite of massive trondhjemite and granite gneisses (3300-3330 Ma). Here, 3.82 Ga inherited zircon components are present in several samples. Negative bulk rock initial epsilon (sub Nd) values also indicate that older crust was involved. Oxygen isotopic compositions of zircon mainly fall within the range of mantle zircon delta (super 18) O values, but several analyses extend up to approximately 6.5 ppm. Initial Hf isotopic compositions of 3.82 Ga zircon are negative and require derivation from Hadean crustal sources. Our data reveal the record of a 3.82 Ga differentiation event during which Hadean crust was partially melted, and zircon crystallized from those melts. Hadean crust must have persisted in the central Wyoming Province until 3.45-3.37 Ga, when mafic crust partially melted to form the TTG layered gneisses, which also incorporated the 3.82 Ga zircons. Subsequent intracrustal recycling at 3.33-3.30 Ga produced calc-alkalic granites. The central Wyoming Province provides a significant addition to the sparse record of Hadean crust being magmatically reworked to form the abundant quartzofeldspathic gneisses common in Archean terrains worldwide, which effectively transformed Earth's evolving continental crust from mafic to felsic in composition.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 129
Serial Issue: 3-4
Title: Hadean origins of Paleoarchean continental crust in the central Wyoming Province
Affiliation: University of Wyoming, Department of Geology and Geophysics, Laramie, WY, United States
Pages: 259-280
Published: 20160927
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 81
Accession Number: 2016-090436
Categories: Igneous and metamorphic petrologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2016297
Illustration Description: illus. incl. 3 tables, geol. sketch map
N42°30'00" - N43°00'00", W108°00'00" - W107°00'00"
Secondary Affiliation: Australian National University, AUS, Australia
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: 201644
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