Hydrohalite formation in frozen clay brines

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dc.contributor.authorGates, Wen_AU
dc.contributor.authorBordallo, HNen_AU
dc.contributor.authorFerhervari, Aen_AU
dc.contributor.authorKlapproth, Aen_AU
dc.contributor.authorAcikel, Aen_AU
dc.contributor.authorBouazza, Aen_AU
dc.contributor.authorAldridge, LPen_AU
dc.contributor.authorIles, GNen_AU
dc.contributor.authorMole, RAen_AU
dc.date.accessioned2023-05-04T05:40:04Zen_AU
dc.date.available2023-05-04T05:40:04Zen_AU
dc.date.issued2020-11-11en_AU
dc.date.statistics2023-04-21en_AU
dc.descriptionAlice Klapproth's name is not spelt correctly in the program. The citation shows this misspelling as this is what is presented in the co-authors list.en_AU
dc.description.abstractHydrated forms of cryosalts in frozen brines play important roles in the polar landscape and troposphere of Earth [1], and their melting [2] is implicated in recurring slope lineae (RSL) in Antarctica’s McMurdo Dry Valley [3] and equator-facing, mid-latitude (42ºN-52ºS) slopes of Mars [4]. Observation of the widespread occurrence of clay minerals and salts on the Martian surface [5] indicates that saline groundwater [6] may still be present on Mars. The surface of Mars ranges in temperature from 293 K on the equator at noon to 120 K at the poles and mobility of sub-surface water ice will depend on the local temperature and the mobility of confined water in the crustal clays. We applied quasielastic neutron scattering using the backscattering spectrometer EMU (Australian Nuclear Science and Technology Organisation) at 1 μeE resolution, to the system: sodium montmorillonite – 5M NaCl (Na-Mt-NaCl and calcium montmorillonite – 5M CaCl2 (Ca-Mt-CaCl2); to establish boundary conditions influencing the dynamics of confined water. Results from elastic fixed window (EFW) data indicate a substantial increase in the mean square displacement of hydrogen (H) in the brine conditions at all temperatures above 100K, indicating enhanced mobility of water in the presence of brines. A phase transition was observed in Na-Mt-NaCl at 255K (on heating) indicating the presence of the cryosalt hydrohalite (NaCl·2H2O), but no phase transition was observed in Ca-Mt-CaCl2. In addition, quasielastic neutron scattering (QENS) spectra highlighted that water in the Ca-Mt-CaCl2 system was strongly confined at room temperature. Recently [6] hydrohalite was observed to form in frozen gels of Na-Mt brines, but not in Ca-Mt brines. They considered that textural differences in the two forms allowed the gel pores of the Na-Mt to retain liquid saline pore water to well below the freezing point of pure water. Based on our analysis, water is restricted to rotational mobility in the Na-Mt-NaCl below 255K, but presents more translational mobility above 255K. These findings largely support those of Yesilbas [7] in the importance of pore structure in controlling cryosalt formation, and further implicate their role in associated phenomena such as RSL.en_AU
dc.identifier.citationGates, W., Bordallo, H. N., Ferhervari, A., Klaproth, A., Acikel, A., Bouazza, A., Aldridge, L., Iles, G. N., & Mole, R. (2020). Hydrohalite formation in frozen clay brines. Paper presented to the ANBUG-AINSE Neutron Scattering Symposium, AANSS 2020, Virtual Meeting, 11th - 13th November 2020. (pp. 38). Retrieved from: https://events01.synchrotron.org.au/event/125/attachments/725/1149/AANSS_Abstract_Booklet_Complete_-_1_Page_Reduced.pdfen_AU
dc.identifier.conferenceenddate13 November 2020en_AU
dc.identifier.conferencenameANBUG-AINSE Neutron Scattering Symposium, AANSS 2020en_AU
dc.identifier.conferenceplaceVirtual Meetingen_AU
dc.identifier.conferencestartdate11 November 2020en_AU
dc.identifier.pagination38en_AU
dc.identifier.urihttps://events01.synchrotron.org.au/event/125/contributions/3734/contribution.pdfen_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/14976en_AU
dc.language.isoenen_AU
dc.publisherAustralian Institute of Nuclear Science and Engineering (AINSE)en_AU
dc.subjectHydrogenationen_AU
dc.subjectTroposphereen_AU
dc.subjectMeltingen_AU
dc.subjectAntarcticaen_AU
dc.subjectEquatoren_AU
dc.subjectSurfacesen_AU
dc.subjectWateren_AU
dc.subjectMineralsen_AU
dc.subjectEarth planeten_AU
dc.subjectMars planeten_AU
dc.subjectIceen_AU
dc.titleHydrohalite formation in frozen clay brinesen_AU
dc.typeConference Abstracten_AU
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