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Chemical studies of L chondrites. VI: variations with petrographic type and shock-loading among equilibrated falls

Friedrich, Jon M.; Bridges, John C.; Wang, Ming-Sheng and Lipschutz, Michael E. (2004). Chemical studies of L chondrites. VI: variations with petrographic type and shock-loading among equilibrated falls. Geochimica et Cosmochimica Acta, 68(13) pp. 2889–2904.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/j.gca.2004.01.010
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Abstract

To study compositional trends associated with open and closed system metamorphism and/or shock-induced heating of the L4-6 chondrite parent(s), we used ICPMS and RNAA to quantify 51 trace elements in 48 chemically representative fall samples. With these data, we used graphic and two multivariate statistical methods for examining evidence for compositional differences with respect to petrographic type and degree of shock loading. Comparisons of mildly shocked (S1-S3) L5 and L6 suites (9 and 8 chondrites, respectively) yield no convincing statistical evidence for a difference in trace element content. Our multivariate comparisons show a difference on a model-dependent basis, but yield indeterminate results on a model-independent basis. Compositionally, suites of strongly shocked (S4-S6) and mildly shocked L4-6 chondrites (26 and 19 samples, respectively) can be distinguished at statistically significant levels on both model-dependent and -independent bases. In the strongly shocked suite, contents of refractory lithophiles are higher, and siderophiles and volatiles are lower than those of the mildly shocked suite at moderately (p ≤ 0.05) to highly significant (p ≤ 0.01) levels. Our studies suggest that chemical differences from vaporization and loss of volatiles along with metal/silicate partitioning are present from extended cooling of shock-heated bodies produced by intermittent impacts, especially the massive impact(s) that disrupted the L chondrite parent(s) 500 Ma ago.

Item Type: Journal Article
ISSN: 0016-7037
Extra Information: Some of the symbols may not have transferred correctly into this bibliographic record.
Academic Unit/Department: Science > Physical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 5357
Depositing User: Users 6044 not found.
Date Deposited: 24 Aug 2006
Last Modified: 02 Dec 2010 19:53
URI: http://oro.open.ac.uk/id/eprint/5357
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