LA‐ICP‐MS Pb isotope test of meteorite provenance: A terrestrial origin for Lovina. (15th May 2020)

• Record Type: Journal Article
• Authors: Charles, Christopher R. J.; McCausland, Phil J. A.; Davis, Donald W.
• Is Part Of: Meteoritics & planetary science. Volume 55:Number 5(2020)
• Page Start: 1093
• Page End: 1102
• Publication Date: 2020-05-15
• Subjects: Meteorites -- Periodicals; Planetology -- Periodicals; 523.4
• DOI: 10.1111/maps.13492
• Languages: English
• ISSNs: 1086-9379

Abstract

Abstract: Lovina, classified as an ungrouped ataxite, is controversial and its identity as a meteorite has been questioned. In this work, we use Pb isotopes on targeted troilite nodules in Lovina as a test of its antiquity and provenance. Although precise ages cannot be obtained, LA‐ICP‐MS offers a rapid, straightforward procedure to establish the source of lead, whether ancient (meteoritic) or modern (terrestrial). For nine pristine, unweathered nodules in Lovina, we find a lead isotopic composition of: 206 Pb/ 208 Pb = 0.492 ± 0.003 (2σ, MSWD 0.79; 95%) and 207 Pb/ 206 Pb = 0.852 ± 0.003 (2σ, MSWD 1.09; 95%) with no detectable uranium. All lead compositions of the troilite fall in the range expected for modern environmental and mantle lead and are distinctly different from the primordial Canyon Diablo Troilite (CDT) composition of ancient meteoritic troilite. Although the origin of Lovina remains unknown, we conclude that lead in the Lovina troilite is unsupported by U decay and originated from a terrestrial source.