Eclogite-facies mineral inclusions in clinozoisite from Paleozoic blueschist, central Chugoku Mountains, southwest Japan: Evidence of regional eclogite-facies metamorphism

T. Tsujimori, J. G. Liou

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16 Citations (Scopus)

Abstract

An eclogite-facies assemblage garnet + omphacite + rutile + glaucophane + quartz occurs as inclusions in clinozoisite porphyroblasts in a high-grade blueschist block in the Paleozoic Osayama serpentinite mélange of the Chugoku Mountains, southwest Japan. Textual relations, and parageneses and compositions of minerals, indicate that the high-grade block experienced peak eclogite-facies metamorphism (M1) and subsequent blueschist-facies overprinting (M2). Moreover, low-P amphibolite-facies minerals (M0) that may represent remnants of pre-subduction conditions are locally preserved in the protolith. Omphacite + adjacent garnet inclusion pairs in clinozoisite give a minimum P = 1.1-1.3 GPa at T = ∼480-550°C. Many petrologic similarities between the Osayama eclogite and the Hida Mountains eclogite provide evidence for a regional eclogite-facies metamorphism in Paleozoic terranes of southwest Japan. Considering available petrotectonic information regarding eastern Asia, we suggest two alternative models: (1) Japanese Paleozoic eclogites may represent "Pacific-type" subduction prior to collision between the Sino-Korean and Yangtze blocks, which occurred on both western and eastern sides of the Qinling-Dabie-Sulu belt; or (2) Japanese Paleozoic eclogites may represent part of a Paleozoic "Pacific-type" subduction chain, which is continuous from the China-Russia border through Japan southward to North Korea.

Original languageEnglish
Pages (from-to)215-232
Number of pages18
JournalInternational Geology Review
Volume47
Issue number3
Publication statusPublished - Mar 2005
Externally publishedYes

Fingerprint

clinozoisite
blueschist
eclogite
metamorphism
Paleozoic
mountain
mineral
omphacite
subduction
garnet
blueschist facies
glaucophane
porphyroblast
overprinting
serpentinite
paragenesis
rutile
protolith
amphibolite facies
terrane

ASJC Scopus subject areas

  • Geology

Cite this

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title = "Eclogite-facies mineral inclusions in clinozoisite from Paleozoic blueschist, central Chugoku Mountains, southwest Japan: Evidence of regional eclogite-facies metamorphism",
abstract = "An eclogite-facies assemblage garnet + omphacite + rutile + glaucophane + quartz occurs as inclusions in clinozoisite porphyroblasts in a high-grade blueschist block in the Paleozoic Osayama serpentinite m{\'e}lange of the Chugoku Mountains, southwest Japan. Textual relations, and parageneses and compositions of minerals, indicate that the high-grade block experienced peak eclogite-facies metamorphism (M1) and subsequent blueschist-facies overprinting (M2). Moreover, low-P amphibolite-facies minerals (M0) that may represent remnants of pre-subduction conditions are locally preserved in the protolith. Omphacite + adjacent garnet inclusion pairs in clinozoisite give a minimum P = 1.1-1.3 GPa at T = ∼480-550°C. Many petrologic similarities between the Osayama eclogite and the Hida Mountains eclogite provide evidence for a regional eclogite-facies metamorphism in Paleozoic terranes of southwest Japan. Considering available petrotectonic information regarding eastern Asia, we suggest two alternative models: (1) Japanese Paleozoic eclogites may represent {"}Pacific-type{"} subduction prior to collision between the Sino-Korean and Yangtze blocks, which occurred on both western and eastern sides of the Qinling-Dabie-Sulu belt; or (2) Japanese Paleozoic eclogites may represent part of a Paleozoic {"}Pacific-type{"} subduction chain, which is continuous from the China-Russia border through Japan southward to North Korea.",
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AU - Liou, J. G.

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N2 - An eclogite-facies assemblage garnet + omphacite + rutile + glaucophane + quartz occurs as inclusions in clinozoisite porphyroblasts in a high-grade blueschist block in the Paleozoic Osayama serpentinite mélange of the Chugoku Mountains, southwest Japan. Textual relations, and parageneses and compositions of minerals, indicate that the high-grade block experienced peak eclogite-facies metamorphism (M1) and subsequent blueschist-facies overprinting (M2). Moreover, low-P amphibolite-facies minerals (M0) that may represent remnants of pre-subduction conditions are locally preserved in the protolith. Omphacite + adjacent garnet inclusion pairs in clinozoisite give a minimum P = 1.1-1.3 GPa at T = ∼480-550°C. Many petrologic similarities between the Osayama eclogite and the Hida Mountains eclogite provide evidence for a regional eclogite-facies metamorphism in Paleozoic terranes of southwest Japan. Considering available petrotectonic information regarding eastern Asia, we suggest two alternative models: (1) Japanese Paleozoic eclogites may represent "Pacific-type" subduction prior to collision between the Sino-Korean and Yangtze blocks, which occurred on both western and eastern sides of the Qinling-Dabie-Sulu belt; or (2) Japanese Paleozoic eclogites may represent part of a Paleozoic "Pacific-type" subduction chain, which is continuous from the China-Russia border through Japan southward to North Korea.

AB - An eclogite-facies assemblage garnet + omphacite + rutile + glaucophane + quartz occurs as inclusions in clinozoisite porphyroblasts in a high-grade blueschist block in the Paleozoic Osayama serpentinite mélange of the Chugoku Mountains, southwest Japan. Textual relations, and parageneses and compositions of minerals, indicate that the high-grade block experienced peak eclogite-facies metamorphism (M1) and subsequent blueschist-facies overprinting (M2). Moreover, low-P amphibolite-facies minerals (M0) that may represent remnants of pre-subduction conditions are locally preserved in the protolith. Omphacite + adjacent garnet inclusion pairs in clinozoisite give a minimum P = 1.1-1.3 GPa at T = ∼480-550°C. Many petrologic similarities between the Osayama eclogite and the Hida Mountains eclogite provide evidence for a regional eclogite-facies metamorphism in Paleozoic terranes of southwest Japan. Considering available petrotectonic information regarding eastern Asia, we suggest two alternative models: (1) Japanese Paleozoic eclogites may represent "Pacific-type" subduction prior to collision between the Sino-Korean and Yangtze blocks, which occurred on both western and eastern sides of the Qinling-Dabie-Sulu belt; or (2) Japanese Paleozoic eclogites may represent part of a Paleozoic "Pacific-type" subduction chain, which is continuous from the China-Russia border through Japan southward to North Korea.

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