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dc.contributor.authorMenegon, Luca
dc.contributor.authorFusseis, F
dc.contributor.authorStunitz, H
dc.contributor.authorXiao, X
dc.date.accessioned2017-01-12T10:46:43Z
dc.date.available2017-01-12T10:46:43Z
dc.date.issued2015-03-01
dc.identifier.issn0091-7613
dc.identifier.issn1943-2682
dc.identifier.urihttp://hdl.handle.net/10026.1/8235
dc.description.abstract

Shear zones channelize fluid flow in Earth’s crust. However, little is known about deep crustal fluid migration and how fluids are channelized and distributed in a deforming lower crustal shear zone. This study investigates the deformation mechanisms, fluid-rock interaction, and development of porosity in a monzonite ultramylonite from Lofoten, northern Norway. The rock was deformed and transformed into an ultramylonite under lower crustal conditions (temperature = 700–730 °C, pressure = 0.65–0.8 GPa). The ultramylonite consists of feldspathic layers and domains of amphibole + quartz + calcite, which result from hydration reactions of magmatic clinopyroxene. The average grain size in both domains is <25 μm. Microstructural observations and electron backscatter diffraction analysis are consistent with diffusion creep as the dominant deformation mechanism in both domains. Festoons of isolated quartz grains define C′-type bands in feldspathic layers. These quartz grains do not show a crystallographic preferred orientation. The alignment of quartz grains is parallel to the preferred elongation of pores in the ultramylonites, as evidenced from synchrotron X-ray microtomography. Such C′-type bands are interpreted as creep cavitation bands resulting from diffusion creep deformation associated with grain boundary sliding. Mass-balance calculation indicates a 2% volume increase during the protolith-ultramylonite transformation, which is consistent with synkinematic formation of creep cavities producing dilatancy. Thus, this study presents evidence that creep cavitation bands may control deep crustal porosity and fluid flow. Nucleation of new phases in creep cavitation bands inhibits grain growth and enhances the activity of grain size–sensitive creep, thereby stabilizing strain localization in the polymineralic ultramylonites.

dc.format.extent227-230
dc.languageen
dc.language.isoen
dc.publisherGeological Society of America
dc.titleCreep cavitation bands control porosity and fluid flow in lower crustal shear zones
dc.typejournal-article
dc.typeJournal Article
plymouth.author-urlhttps://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000352096700011&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=11bb513d99f797142bcfeffcc58ea008
plymouth.issue3
plymouth.volume43
plymouth.publication-statusPublished
plymouth.journalGeology
dc.identifier.doi10.1130/G36307.1
plymouth.organisational-group/Plymouth
plymouth.organisational-group/Plymouth/Faculty of Science and Engineering
plymouth.organisational-group/Plymouth/REF 2021 Researchers by UoA
plymouth.organisational-group/Plymouth/REF 2021 Researchers by UoA/UoA07 Earth Systems and Environmental Sciences
dcterms.dateAccepted2014-12-12
dc.rights.embargodate2016-03-01
dc.identifier.eissn1943-2682
dc.rights.embargoperiod12 months
rioxxterms.versionofrecord10.1130/G36307.1
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/under-embargo-all-rights-reserved
rioxxterms.licenseref.startdate2015-03-01
rioxxterms.typeJournal Article/Review


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