This study presents a petrographic description and a classification of ordinary chondrite NWA 6514 and aims to establish the first high-precision Pb-Pb age of a single ordinary chondrite chondrule. Furthermore, the distribution of different isotopic Pb signatures among chondritic components will be investigated by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS).
This study shows that NWA 6514 can be classified as a highly unequilibrated (subtype 3.10) L or LL chondrite that has experienced moderate terrestrial weathering (W2) and a low degree of shock (S2). The LA-ICP-MS measurements suggest that radiogenic Pb signatures have been locally preserved in chondrules. However, the Pb isotopic compositions of leaches from a large chondrule obtained by thermal ionization mass spectrometry show an anomalous distribution that indicates the presence of an exotic Pb component. The best estimate for the chondrule formation age is a model age of the last leach (4566.8 ± 2.6 Myr).
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/31284 |
| Date | 12 December 2011 |
| Creators | Koeoep, Levke |
| Contributors | Davis, Donald W. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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