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First application of titanium-in-zircon thermometry to ultrahigh-temperature metamorphism

J. A. Baldwin, M. Brown and M. D. Schmitz
First application of titanium-in-zircon thermometry to ultrahigh-temperature metamorphism
Geology (Boulder) (April 2007) 35 (4): 295-298

Abstract

Titanium-in-zircon thermometry has been applied to evaluate the temperatures of metamorphism for two ultrahigh-temperature (UHT) granulite localities, the Neoproterozoic Anapolis-Itaucu Complex in central Brazil, and lower crustal xenoliths from the Neo-archean Kaapvaal craton in South Africa. UHT metamorphism in the Anapolis-Itaucu Complex occurred ca. 640 Ma. Ti-in-zircon thermometry on metamorphic zircon yields temperatures of 965-811 degrees C; a population of late zircon that formed from ilmenite and rutile breakdown records temperatures of approximately 780 degrees C. Maximum temperatures are less than those inferred from quantitative phase equilibria modeling. Based on textural setting (inclusions in peak phases and as matrix grains), these zircons likely record growth during the pro-grade and/or postpeak evolution. In contrast, the Kaapvaal xenoliths record two phases of zircon growth: during UHT metamorphism at 2720-2715 Ma, followed by growth during isobaric cooling in kyanite-bearing leucosomes ca. 2690 Ma. Temperatures recorded by the two phases of growth are 1024-878 degrees C and 936-839 degrees C, respectively, suggesting that zircon growth occurred during UHT conditions and continued throughout the postpeak evolution over a 200 degrees C interval. These examples demonstrate that the Ti-in-zircon thermometer is a powerful new tool with the potential to determine crystallization temperatures of zircon during granulite facies metamorphism, throughout the prograde to postpeak evolution of such terranes.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 35
Serial Issue: 4
Title: First application of titanium-in-zircon thermometry to ultrahigh-temperature metamorphism
Affiliation: University of Montana, Department of Geosciences, Missoula, MT, United States
Pages: 295-298
Published: 200704
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 14
Accession Number: 2007-037411
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2007073
Illustration Description: illus. incl. geol. sketch maps
S16°00'00" - S16°00'00", W50°00'00" - W50°00'00"
S27°30'00" - S27°00'00", E27°00'00" - E27°30'00"
Secondary Affiliation: University of Maryland, USA, United StatesBoise State University, USA, United States
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: 200720
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