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GEOREF RECORD

Petrology and geochemistry of lunar granite 12032,366-19 and implications for lunar granite petrogenesis

Stephen M. Seddio, Bradley L. Jolliff, Randy L. Korotev and Ryan A. Zeigler
Petrology and geochemistry of lunar granite 12032,366-19 and implications for lunar granite petrogenesis
American Mineralogist (October 2013) 98 (10): 1697-1713

Abstract

Apollo 12 sample 12032,366-19 is a 21.3 mg granite fragment that is distinct from any other lunar granite or felsite. It is composed of barian K-feldspar, quartz, sodic plagioclase, hedenbergite, fayalite, and ilmenite, with trace amounts of zirconolite, baddeleyite, apatite, and merrillite. The texture of 12032,366-19 is largely a micrographic intergrowth predominantly of K-feldspar and quartz and, to a lesser extent, plagioclase and quartz. Hedenbergite, fayalite, and ilmenite are present in minor but significant quantities--6.0, 3.1, and 1.7 wt%, respectively--and are scattered throughout the feldspar-quartz intergrowths. Trace amounts of Zr-bearing phases are found including zirconolite (0.6 wt%) and baddeleyite (0.04 wt%). Incompatible trace-element concentrations are high in 12032,366-19, particularly the high-field-strength elements, e.g., Zr, Sm, and Th (1500, 25, and 61 mu g/g, respectively). The chondrite-normalized, rare-earth-element concentrations form a "V-pattern" that is characteristic of other lunar granitic material. By modeling 12032,366-19 as a derivative from a KREEP-like parent melt, the composition and mineral assemblage can be obtained by extended fractional crystallization combined with separation of the low-density minerals plus trapped melt components prior to final solidification. However, this model cannot quantitatively account for the relatively sodic composition of the plagioclase (An (sub 34-50) ) and requires that the starting melt has Na (sub 2) O of 1.2-1.4 wt%, which is higher than most KREEP compositions. Formation of this assemblage by silicate-liquid immiscibility is neither required nor indicated by petrogenetic modeling.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 98
Serial Issue: 10
Title: Petrology and geochemistry of lunar granite 12032,366-19 and implications for lunar granite petrogenesis
Affiliation: Washington University, Department of Earth and Planetary Sciences, St. Louis, MO, United States
Pages: 1697-1713
Published: 201310
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 80
Accession Number: 2013-084916
Categories: Igneous and metamorphic petrologyExtraterrestrial geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables
Secondary Affiliation: NASA, Johnson Space Center, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201350
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