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dc.contributor.authorVargas-Meleza, L.
dc.contributor.authorHealy, D.
dc.contributor.authorAlsop, G.I.
dc.contributor.authorTimms, Nicholas Eric
dc.identifier.citationVargas-Meleza, L. and Healy, D. and Alsop, G.I. and Timms, N.E. 2015. Exploring the relative contribution of mineralogy and CPO to the seismic velocity anisotropy of evaporites. Journal of Structural Geology. 70: pp. 39-55.

We present the influence of mineralogy and microstructure on the seismic velocity anisotropy ofevaporites. Bulk elastic properties and seismic velocities are calculated for a suite of 20 natural evaporate samples, which consist mainly of halite, anhydrite, and gypsum. They exhibit strong fabrics as a result of tectonic and diagenetic processes. Sample mineralogy and crystallographic preferred orientation (CPO) were obtained with the electron backscatter diffraction (EBSD) technique and the data used for seismic velocity calculations. Bulk seismic properties for polymineralic evaporites were evaluated with a rock recipe approach. Ultrasonic velocity measurements were also taken on cube shaped samples to assess the contribution of grain-scale shape preferred orientation (SPO) to the total seismic anisotropy. The sample results suggest that CPO is responsible for a significant fraction of the bulk seismic properties, in agreement with observations from previous studies. Results from the rock recipe indicate that increasing modal proportion of anhydrite grains can lead to a greater seismic anisotropy of a halite-dominated rock.Conversely, it can lead to a smaller seismic anisotropy degree of a gypsum-dominated rock until anestimated threshold proportion after which anisotropy increases again. The difference between thepredicted anisotropy due to CPO and the anisotropy measured with ultrasonic velocities is attributed to the SPO and grain boundary effects in these evaporites.

dc.publisherPergamon-Elsevier Science Ltd.
dc.titleExploring the relative contribution of mineralogy and CPO to the seismic velocity anisotropy of evaporites
dc.typeJournal Article
dcterms.source.titleJournal of Structural Geology

NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Structural Geology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Structural Geology, Vol. 70 (2015). DOI: 10.1016/ j.jsg.2014.11.001

curtin.departmentDepartment of Applied Geology
curtin.accessStatusOpen access

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