Shear Modulus Dispersion in Cracked and Fluid-Saturated Quartzites: Experimental Observations and Modeling

dc.contributor.authorSchijns, Heather
dc.contributor.authorJackson, Ian
dc.contributor.authorSchmitt, Douglas
dc.date.accessioned2020-01-14T03:11:39Z
dc.date.available2020-01-14T03:11:39Z
dc.date.issued2018-04-13
dc.date.updated2022-07-31T08:16:35Z
dc.description.abstractThe effect of pore fluids on acoustic wave dispersion in rocks with low aspect ratio crack porosity is important for the interpretation of laboratory and field observations in hard rock mineral exploration environments. Here we make laboratory measurements of shear modulus dispersion at frequencies 0.01–1 Hz and at 1 MHz with different saturating fluids (dry, argon, and water saturated) in two thermally cracked quartzite samples with ~2% total porosity. Measurements are made across a range of effective pressures (10–150 MPa), with the resulting very low permeabilities of the samples varying from 1–300 × 10−21 m2. Moduli across the 0.01–1 Hz band were typically independent of frequency. The shear moduli measured at sub‐Hz frequencies are unaffected by fluid saturation, as expected for the saturated isobaric (Gassmann) regime. In marked contrast, water saturation of the cracked rocks results in very large increases in the shear moduli measured at 1 MHz and low effective pressures, indicative of saturated isolated conditions. Thus, at an effective pressure of 20 MPa, the shear moduli for the two water‐saturated quartzites increase by 74% and 98% from 1 Hz to 1 MHz. The contrast in elastic moduli between dry and water‐saturated conditions is well represented by the theoretical model developed by Walsh and others. The observed dispersion highlights the need for care in seismological application of results obtained at MHz frequencies from laboratory ultrasonic measurements.
dc.description.sponsorshipThe work was funded through NSERC Discovery grants to D. R. S. and grant DP110101830 from the Australian Research Council to I. J. and D. R. S. H. S.’s visit to Canberra was funded by the NSERC Michael Smith Foreign Study Supplement.en_AU
dc.format.mimetypeapplication/pdfen_AU
dc.identifier.citationSchijns, H., Jackson, I., & Schmitt, D. R. (2018). Shear modulus dispersion in cracked and fluid-saturated quartzites: Experimental observations and modeling. Journal of Geophysical Research: Solid Earth, 123, 2825–2840. https://doi. org/10.1002/2017JB014633
dc.identifier.issn2169-9313en_AU
dc.identifier.urihttp://hdl.handle.net/1885/197189
dc.language.isoen_AUen_AU
dc.provenancehttp://sherpa.ac.uk/romeo/issn/2169-9313/..."Publisher's version/PDF may be used 6 months after publication on an Institutional Repository or Governmental Repository only" from SHERPA/RoMEO site (as at 14.1.20)en_AU
dc.publisherWiley Blackwell
dc.relationhttp://purl.org/au-research/grants/arc/DP110101830
dc.rights© 2018 American Geophysical Union
dc.sourceJournal of Geophysical Research: Solid Earth
dc.subjectdispersion
dc.subjectseismic
dc.subjectultrasonic
dc.subjectrock physics
dc.subjectcracks
dc.subjecthard rock
dc.titleShear Modulus Dispersion in Cracked and Fluid-Saturated Quartzites: Experimental Observations and Modeling
dc.typeJournal article
dcterms.accessRightsOpen Accessen_AU
dcterms.dateAccepted2018-02-02
local.bibliographicCitation.issue4en_AU
local.bibliographicCitation.lastpage2840en_AU
local.bibliographicCitation.startpage2825en_AU
local.contributor.affiliationSchijns, Heather, University of Albertaen_AU
local.contributor.affiliationJackson, Ian, College of Science, ANUen_AU
local.contributor.affiliationSchmitt, Douglas , University of Albertaen_AU
local.contributor.authoremailu7800055@anu.edu.auen_AU
local.contributor.authoruidJackson, Ian, u7800055en_AU
local.description.notesImported from ARIESen_AU
local.identifier.absfor040407 - Seismology and Seismic Explorationen_AU
local.identifier.absseo850102 - Geothermal Explorationen_AU
local.identifier.absseo970104 - Expanding Knowledge in the Earth Sciencesen_AU
local.identifier.ariespublicationa383154xPUB10131en_AU
local.identifier.citationvolume123en_AU
local.identifier.doi10.1002/2017JB014633en_AU
local.identifier.scopusID2-s2.0-85048048575
local.identifier.thomsonIDWOS:000434133700017
local.identifier.uidSubmittedBya383154en_AU
local.publisher.urlhttps://agupubs.onlinelibrary.wiley.com/en_AU
local.type.statusPublished Versionen_AU

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