Experiments on phosphate-silicate liquid immiscibility with potential links to iron oxide apatite and nelsonite deposits

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dc.contributor.authorLledo, Haroldo L.
dc.contributor.authorNaslund, H. Richard
dc.contributor.authorJenkins, David M.
dc.date2020
dc.date.accessioned2021-04-30T16:40:40Z
dc.date.available2021-04-30T16:40:40Z
dc.description.abstractThe formation of phosphorus-iron oxide (P-Fe) immiscible melts and their possible connection to the genesis of Kiruna-type and Nelsonite deposits was experimentally investigated by adding phosphoric acid (H3PO4), water, and sulfur, to andesite at 100-450 MPa, 500-900 degrees C, at the NiNiO and magnetite-hematite fO(2) buffers using internally heated gas vessels. The addition of up to 8.02 wt% of H3PO4 to the andesite causes crystallization of apatite. At higher concentrations of H3PO4 whitlockite crystallizes, and at concentrations above similar to 11.4% H3PO4 (at 800 degrees C, 385 MPa) an immiscible P-Fe melt forms. Adding sulfur at low fO(2) (NiNiO) causes an additional immiscible Fe-S melt to form. Increasing the fO(2) to the hematite-magnetite buffer causes the sulfur-rich melt to shift in composition to a Ca-S-O melt, and the coexisting P-Fe melt to incorporate large amounts of SO4. Immiscible P-Fe melts can form at temperatures above 1100 degrees C down to 600 degrees C (at 400 MPa). Mass balance calculations show that some experimentally produced P-Fe rich immiscible liquids may result in mineral assemblages similar to those found at some Kiruna-type deposits, such as actinolite-rich dikes, and apatite-rich veins. Depending on the geological conditions and the composition the fractionation of a P-Fe melt may result in the formation of nelsonites at high pressures, high temperatures, and low fO(2) or Kiruna-type deposits at lower temperatures and higher fO(2).
dc.identifier.citationCONTRIBUTIONS TO MINERALOGY AND PETROLOGY,Vol.175,,2020
dc.identifier.doi10.1007/s00410-020-01751-8
dc.identifier.urihttp://repositoriodigital.uct.cl/handle/10925/3252
dc.language.isoen
dc.publisherSPRINGER
dc.sourceCONTRIBUTIONS TO MINERALOGY AND PETROLOGY
dc.subject.englishMagnetite
dc.subject.englishApatite
dc.subject.englishImmiscible
dc.subject.englishPhosphorus
dc.subject.englishKiruna
dc.subject.englishIron
dc.titleExperiments on phosphate-silicate liquid immiscibility with potential links to iron oxide apatite and nelsonite deposits
dc.typeArticle
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uct.indizacionSCI
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