TY - JOUR
T1 - Eclogite-Facies Mineral Inclusions in Clinozoisite from Paleozoic Blueschist, Central Chugoku Mountains, Southwest Japan
T2 - Evidence of Regional Eclogite-Facies Metamorphism
AU - Tsujimori, T.
AU - Liou, J. G.
N1 - Funding Information:
We dedicate this paper to W. G. Ernst who was the first to propose an eastern extension of the Chinese UHP belt to southwest Japan. This research was supported financially in part by a JSPS Research Fellowship for Young Scientists (1998–1999, 2001–2003), and a JSPS Research Fellowship for Research Abroad (2004–) of the first author. Preparation of this manuscript was supported by NSF EAR-0003355. The first author thanks to A. Ishiwatari for discussions during his stay at Kanazawa University (1994–2000).
PY - 2005/3
Y1 - 2005/3
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 (M 1) and subsequent blueschist-facies overprinting (M 2). Moreover, low-P amphibolite-facies minerals (M 0) 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 (M 1) and subsequent blueschist-facies overprinting (M 2). Moreover, low-P amphibolite-facies minerals (M 0) 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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U2 - 10.2747/0020-6814.47.3.215
DO - 10.2747/0020-6814.47.3.215
M3 - Article
AN - SCOPUS:15844411676
SN - 0020-6814
VL - 47
SP - 215
EP - 232
JO - International Geology Review
JF - International Geology Review
IS - 3
ER -