New approach to quantification of metamorphism using ultra-small and small angle neutron scattering

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dc.contributor.authorAnovitz, LMen_AU
dc.contributor.authorLynn, GWen_AU
dc.contributor.authorCole, DRen_AU
dc.contributor.authorRother, Gen_AU
dc.contributor.authorAllard, LFen_AU
dc.contributor.authorHamilton, WAen_AU
dc.contributor.authorPorcar, Len_AU
dc.contributor.authorKim, MHen_AU
dc.date.accessioned2010-01-21T05:42:49Zen_AU
dc.date.accessioned2010-04-30T05:05:15Zen_AU
dc.date.available2010-01-21T05:42:49Zen_AU
dc.date.available2010-04-30T05:05:15Zen_AU
dc.date.issued2009-12-15en_AU
dc.date.statistics2009-12-15en_AU
dc.description.abstractIn this paper we report the results of a study using small angle and ultra-small angle neutron scattering techniques (SANS and USANS) to examine the evolution of carbonates during contact metamorphism. Data were obtained from samples collected along two transects in the metamorphosed Hueco limestone at the Marble Canyon, Texas, contact aureole. These samples were collected from the igneous contact out to similar to 1700 m. Scattering curves obtained from these samples show mass fractal behavior at low scattering vectors, and surface fractal behavior at high scattering vectors. Significant changes are observed in the surface and mass fractal dimensions as well as the correlation lengths (pore and grain sizes), surface area to volume ratio and surface Gibbs Free energy as a function of distance, including regions of the aureole outside the range of classic metamorphic petrology. A change from mass-fractal to non-fractal behavior is observed at larger scales near the outer boundary of the aureole that implies significant reorganization of pore distributions early in the metamorphic history. Surface fractal results suggest significant smoothing of grain boundaries, coupled with changes in pore sizes. A section of the scattering Curve with a slope less than -4 appears Lit low-Q in metamorphosed samples, which is not present in unmetamorphosed samples. A strong spike in the surface area to volume ratio is observed in rocks near the mapped metamorphic limit, which is associated with reaction of small amounts of organic material to graphite. It may also represent an increase in pore Volume or permeability, suggesting that a high permeability zone forms at the boundary of the aureole and moves outwards as metamorphism progresses. Neutron scattering data also correlate well with transmission electron microscopic (TEM) observations, which show formation of micro- and nanopores and microfractures during metamorphism. The scattering data are, however, quantifiable for a bulk rock in a manner that is difficult to achieve using high-resolution imaging (e.g. TEM). Thus, neutron scattering techniques provide a new approach to the analysis and study of metamorphism. © 2009, Elsevier Ltd.en_AU
dc.identifier.citationAnovitz, L. M., Lynn, G. W., Cole, D. R., Rother, G., Allard, L. F., Hamilton, W. A., Porcar, L., & Kim, M. H. (2009). New approach to quantification of metamorphism using ultra-small and small angle neutron scattering. Geochimica Et Cosmochimica Acta, 73(24), 7303-7324. doi:10.1016/j.gca.2009.07.040en_AU
dc.identifier.govdoc1343en_AU
dc.identifier.issn0016-7037en_AU
dc.identifier.issue24en_AU
dc.identifier.journaltitleGeochimica Et Cosmochimica Actaen_AU
dc.identifier.pagination7303-7324en_AU
dc.identifier.urihttp://dx.doi.org/10.1016/j.gca.2009.07.040en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/2734en_AU
dc.identifier.volume73en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectMetamorphismen_AU
dc.subjectSmall angle scatteringen_AU
dc.subjectCarbonatesen_AU
dc.subjectLimestoneen_AU
dc.subjectTransmission electron microscopyen_AU
dc.subjectGrain boundariesen_AU
dc.titleNew approach to quantification of metamorphism using ultra-small and small angle neutron scatteringen_AU
dc.typeJournal Articleen_AU
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