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Article: Newly discovered youngest UHT metamorphism on Earth, Western Sulawesi, Indonesia

TitleNewly discovered youngest UHT metamorphism on Earth, Western Sulawesi, Indonesia
Authors
Issue Date2023
Citation
Geoscience Frontiers, 2023, v. 14, p. 101500 How to Cite?
AbstractUltrahigh-temperature (UHT) metamorphism represents an extreme crustal thermal event with peak conditions exceeding 900 °C at 7–13 kbar. In the modern-style plate tectonic system, records of the UHT metamorphism are relatively rare due to the secular cooling of Earth. In the Palu region of Western Sulawesi, we newly discovered a series of HT-UHT metamorphic rocks including amphibolite, granulite, eclogites and gneiss. Of them, two granulite samples (18CS14-2, 18CS14-4) with high garnet content (>50 mol%) are chosen for petrographic observation, phase equilibrium modelling, and zircon U-Pb dating. These rocks are characterized by a relic M1 assemblage of Grt + Ky + Bt + Rt and a M2 assemblage of Grt + Sil + Pl + Spl + Crd ± Qtz + Ilm + melt. Phase equilibrium modelling based on effective bulk compositions yields UHT conditions of 7.2–8.5 kbar/940–1080 °C (18CS14-2) and 7.0–7.3 kbar/1000–1040 °C (18CS14-4). U-Pb analysis reveals two generations of metamorphic zircon with evolving REE content that is intimately related to garnet growth and decomposition. Zircon age of 36–5.3 Ma is ascribed to syn- to post-M1 metamorphism, whereas the young zircon age of 5.1–3.8 Ma is linked to syn- and post-M2 stage. The UHT metamorphism was probably the consequence of the upwelling of asthenospheric mantle triggered by post-collisional delamination of lithosphere in the Miocene-Pliocene (ca. 5 Ma). It could represent the youngest known UHT metamorphism on Earth.
Persistent Identifierhttp://hdl.handle.net/10722/323582
ISSN
2023 Impact Factor: 8.5
2023 SCImago Journal Rankings: 1.734
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorHsia, J-
dc.contributor.authorZhang, J-
dc.contributor.authorZhao, G-
dc.contributor.authorQian, J.H.-
dc.contributor.authorLiu, J-
dc.contributor.authorSun, M-
dc.contributor.authorYin, C.Q.-
dc.contributor.authorGao, P.-
dc.contributor.authorXian, W-
dc.contributor.authorGuo, M-
dc.date.accessioned2023-01-08T07:08:46Z-
dc.date.available2023-01-08T07:08:46Z-
dc.date.issued2023-
dc.identifier.citationGeoscience Frontiers, 2023, v. 14, p. 101500-
dc.identifier.issn1674-9871-
dc.identifier.urihttp://hdl.handle.net/10722/323582-
dc.description.abstractUltrahigh-temperature (UHT) metamorphism represents an extreme crustal thermal event with peak conditions exceeding 900 °C at 7–13 kbar. In the modern-style plate tectonic system, records of the UHT metamorphism are relatively rare due to the secular cooling of Earth. In the Palu region of Western Sulawesi, we newly discovered a series of HT-UHT metamorphic rocks including amphibolite, granulite, eclogites and gneiss. Of them, two granulite samples (18CS14-2, 18CS14-4) with high garnet content (>50 mol%) are chosen for petrographic observation, phase equilibrium modelling, and zircon U-Pb dating. These rocks are characterized by a relic M1 assemblage of Grt + Ky + Bt + Rt and a M2 assemblage of Grt + Sil + Pl + Spl + Crd ± Qtz + Ilm + melt. Phase equilibrium modelling based on effective bulk compositions yields UHT conditions of 7.2–8.5 kbar/940–1080 °C (18CS14-2) and 7.0–7.3 kbar/1000–1040 °C (18CS14-4). U-Pb analysis reveals two generations of metamorphic zircon with evolving REE content that is intimately related to garnet growth and decomposition. Zircon age of 36–5.3 Ma is ascribed to syn- to post-M1 metamorphism, whereas the young zircon age of 5.1–3.8 Ma is linked to syn- and post-M2 stage. The UHT metamorphism was probably the consequence of the upwelling of asthenospheric mantle triggered by post-collisional delamination of lithosphere in the Miocene-Pliocene (ca. 5 Ma). It could represent the youngest known UHT metamorphism on Earth.-
dc.languageeng-
dc.relation.ispartofGeoscience Frontiers-
dc.titleNewly discovered youngest UHT metamorphism on Earth, Western Sulawesi, Indonesia-
dc.typeArticle-
dc.identifier.emailZhao, G: gzhao@hku.hk-
dc.identifier.emailSun, M: minsun@hku.hk-
dc.identifier.authorityZhao, G=rp00842-
dc.identifier.authoritySun, M=rp00780-
dc.identifier.doi10.1016/j.gsf.2022.101500-
dc.identifier.scopuseid_2-s2.0-85141525622-
dc.identifier.hkuros343185-
dc.identifier.volume14-
dc.identifier.spage101500-
dc.identifier.epage101500-
dc.identifier.isiWOS:000903595800007-

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