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The U-Th-Pb, Sm-Nd, and Ar-Ar isotopic systematics of lunar meteorite Yamato-793169U-Th-Pb, Sm-Nd, and (Ar-40)-(Ar-39) isotopic studies were performed on Yamato (Y)-793169, an unbrecciated diabasic lunar meteorite whose chemical composition is close to low Ti(LT) and very low-Ti (VLT) mare basalts. The isotopic data indicate that the meteorite was formed earlier than 3.9 Ga from a source with low U/Pb and high Sm/Nd and was distributed by a thermal event at 751 Ma. due to the small sample size (104 mg), a plagioclase crystal and glass grains were handpicked for Ar analysis, leaving four fractions for the U-Th-Pb and Sm-Nd studies; a fine-grained fraction (less than 63 microns; Fine) and three medium-grained fractions (63-150 microns). Medium-grained fractions were divided by density; a heavy fraction (rho greater than 3.3) consisting mainly of pyroxene (PX1), a lighter fraction (rho less than 2.8) consisting of plagioclase (PL), and a middle density fraction (predominantly pyroxene; PX2). The fractions were washed with acetone and alcohol, and then leached in 0.01 HBr and 0.1N HBr in order to remove any terrestrial Pb contamination. Analysis of the HBr leaches revealed that this meteorite was heavily contaminated with terrestrial Pb during its residence in Antarctic ice.
Document ID
Document Type
Conference Paper
Torigoye, Noriko (Geological Survey Denver, CO, United States)
Misawa, Keji (Geological Survey Denver, CO, United States)
Dalrymple, G. Brent (Geological Survey Menlo Park, CA., United States)
Tatsumoto, Mitsunobu (Geological Survey Denver, CO, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z
Subject Category
Distribution Limits
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19940015909Analytic PrimaryWorkshop on the Martian Northern Plains: Sedimentological, Periglacial, and Paleoclimatic Evolution19940016163Analytic PrimaryTwenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z