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dc.contributor.authorLi, Xianwei
dc.contributor.authorWhite, Richard William
dc.contributor.authorWei, Chunjing
dc.identifier.citationLi , X , White , R W & Wei , C 2019 , ' Can we extract ultrahigh-temperature conditions from Fe-rich metapelites? An example from the Khondalite Belt, North China Craton ' , Lithos , vol. 328-329 , pp. 228-243 .
dc.identifier.otherRIS: urn:E3CE624E291C21F1485F80BE3389E78C
dc.identifier.otherORCID: /0000-0002-5270-3985/work/59953737
dc.descriptionThis work was financially supported by the National Natural Science Foundation of China (Grant Numbers 41430207 and 41172055) and China Scholarship Council.en
dc.description.abstractIn this study, garnet–sillimanite gneisses at Hongshaba in the eastern segment of the Khondalite Belt, North China Craton (NCC) are interpreted to have experienced ultrahigh-temperature (UHT) metamorphism (980–1040 °C) followed by post-Tmax cooling at pressures of 8–9 kbar to the solidus (810–830 °C), consistent with rare sapphirine-bearing assemblages in surrounding regions. This interpretation is mainly based on the combination of P–T fields and garnet Xgr (=Ca/(Ca + Mg + Fe2+)) isopleths on the pseudosection of three garnet–sillimanite gneiss samples. Spinel tends to be enclosed in the outer margins of garnet, commonly closely associated with quartz. We interpret this to reflect the partial break down of garnet along the prograde path during heating with decompression followed by new garnet growth during cooling along an overall clockwise P–T evolution. Although Fe-rich UHT metapelites tend to contain neither diagnostic mineral assemblages nor orthopyroxene from which to extract T via Al-in-orthopyroxene thermometry, isopleths of Ca in garnet may aid in retrieving UHT conditions from these compositions. This is attributed to Ca diffusion in garnet being much slower than Fe and Mg diffusion, leading to little change in Ca contents during post-Tmax cooling. LA-ICP-MS U-Pb dating of metamorphic zircon in one garnet–sillimanite gneiss sample yields a mean 207Pb/206Pb age of ca. 1.91 Ga, which is interpreted to record the timing of cooling of the UHT rocks to the solidus. This UHT metamorphism is interpreted to have been generated by mantle-derived magma during a tectonic extension from ca. 1.95 to 1.92 Ga within a post-orogenic setting.
dc.subjectKhondalite Belten
dc.subjectNorth China Cratonen
dc.subjectPhase equilibrium modellingen
dc.subjectUltrahigh-temperature metamorphismen
dc.subjectZircon geochronologyen
dc.subjectGE Environmental Sciencesen
dc.titleCan we extract ultrahigh-temperature conditions from Fe-rich metapelites? An example from the Khondalite Belt, North China Cratonen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Earth & Environmental Sciencesen
dc.description.statusPeer revieweden

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