Weathering-driven porosity generation in altered oceanic peridotites

Simple item page
dc.contributor.authorPujatti, Simone
dc.contributor.authorPlümper, Oliver
dc.contributor.authorTutolo, Benjamin M.
dc.date.accessioned2023-01-30T22:30:03Z
dc.date.available2023-01-30T22:30:03Z
dc.date.issued2023-01
dc.descriptionTomographic study of pore networks in serpentinized peridotite, where pore structures are characterized from the nanometer to the micrometer scale. Pores are localized at grain boundaries of olivine with no secondary mineralization, which we suggest formed formed due to olivine dissolution during low-temperature seafloor weathering. The resulting elemental fluxes are exported from the subseafloor to seawater.en_US
dc.description.abstractUltramafic rocks exposed at slow and ultra-slow spreading mid-ocean ridges represent a significant and extremely reactive portion of the oceanic lithosphere. Thus, mechanistic understanding of the processes by which seawater infiltrates into and reacts with these rocks is essential for constraining their contribution to the chemistry of the oceans and the coupled carbonate-silicate cycle. Recent observations indicate that nanoscale processes contribute to seawater-driven alteration of ultramafic rocks, but conventional petrographic and tomographic observations of the associated physical features are challenging to link to these nanoscale features. Moreover, multiple generations and varying conditions of fluid infiltration often obscure the relative roles of higher-temperature serpentinization, where reactions are mostly isochemical, and lower-temperature weathering reactions, where observations suggest the release of massive amounts of magnesium. Here we bridge these scales and investigate the specific role of weathering processes in dissolution-driven porosity generation by integrating focused ion beam scanning electron microscopy nanotomography and micro-computed X-ray tomography imaging of the pore structures preserved in drill cores of serpentinized oceanic peridotites. Relict olivine crystals in all imaged samples contain abundant etch pits, and those in the higher-resolution FIB-SEM imagery show the presence of channel-like dissolution structures. The pore channels preferentially affect olivine along grain boundaries and show anisotropic distribution likely controlled by crystallographic features. The pores formed via olivine dissolution are interpreted to result from dissolution of serpentinized peridotite at conditions where serpentine and carbonate precipitation are kinetically inhibited, i.e., at weathering conditions. Importantly, the calculated connectivity of the imaged pore structures increases as the scale of investigation increases, suggesting that weathering-driven olivine dissolution facilitates further seawater infiltration and olivine dissolution, a positive feedback that can sustain continued magnesium extraction until the rocks are ultimately cut off from seawater circulation via sedimentation. Thus, while much attention has been directed towards constraining geochemical fluxes from the higher-temperature alteration of ultramafic rocks, our results support literature studies suggesting that mineral dissolution, and hence elemental fluxes, are significant at the lower temperatures of seafloor weathering. Our data thus provide mechanistic evidence of the physical process contributing to the observed elemental loss from weathered oceanic peridotites.en_US
dc.description.grantingagencyNatural Sciences and Engineering Research Council (NSERC)en_US
dc.identifier.citationPujatti, S., Plümper, O., & Tutolo, B. M. (2023). Weathering-driven porosity generation in altered oceanic peridotites. Earth and Planetary Science Letters, 604, 118006. https://doi.org/10.1016/j.epsl.2023.118006en_US
dc.identifier.doi10.1016/j.epsl.2023.118006en_US
dc.identifier.grantnumberRGPIN-2018-03800en_US
dc.identifier.urihttp://hdl.handle.net/1880/115788
dc.identifier.urihttps://dx.doi.org/10.11575/PRISM/40693
dc.language.isoengen_US
dc.publisherElsevieren_US
dc.publisher.departmentGeoscienceen_US
dc.publisher.facultyScienceen_US
dc.publisher.hasversionacceptedVersionen_US
dc.publisher.institutionUniversity of Calgaryen_US
dc.publisher.institutionUtrecht Universityen_US
dc.publisher.policyhttps://www.elsevier.com/about/policies/sharingen_US
dc.rightsUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0en_US
dc.subjectseafloor weatheringen_US
dc.subjectolivine dissolutionen_US
dc.subjectdissolution channelen_US
dc.subjectporosity generationen_US
dc.subjectelemental fluxen_US
dc.titleWeathering-driven porosity generation in altered oceanic peridotitesen_US
dc.typejournal articleen_US
ucalgary.item.requestcopytrueen_US
ucalgary.scholar.levelGraduateen_US
ucalgary.scholar.levelFacultyen_US
ucalgary.scholar.levelAssociate Professor from Utrecht Universityen_US
Files
Original bundle
Now showing 1 - 2 of 2
Thumbnail Image
Name:
PujattietalMS+Figures+Tables.docx
Size:
2.31 MB
Format:
Microsoft Word
Description:
Main article + figures + tables
Download
Thumbnail Image
Name:
PujattietalMS+Figures+Tables.pdf
Size:
2.82 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.92 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Science Research & Publications