Eclogite from the Kumon range,Myanmar: Petrology and tectonic implications |
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| Authors: | Masaki Enami Motohiro Tsuboi |
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| Institution: | 1. Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan 430074, China;2. Research Institute, China National Offshore Oil Corporation (CNOOC), Beijing 10027, China;3. Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;1. Escuela de Ciencias de la Tierra, Universidad Nacional Andrés Bello, Salvador Sanfuentes 2375, Santiago, Chile;2. Departamento de Geología, Universidad de Chile, Plaza Ercilla 803, Santiago, Chile;3. Research School of Earth Sciences, Australian National University, Canberra, Australia;4. Antofagasta Minerals, Apoquindo 4001, Santiago, Chile;1. Universidade de São Paulo, Instituto de Geociências, Departamento de Geoquímica e Geotectônica, Rua do Lago 562, CEP 05508-080 São Paulo, SP, Brazil;2. Departamento de Mineralogía y Petrología, Universidad de Granada, Avda. Fuentenueva SN, 18002 Granada, Spain;3. Argon Geochronology Laboratory, University of Michigan, 2534 C.C. Little Building, 1100 North University Avenue, 48109-1005 Ann Arbor, United States;4. Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Avda. de las Palmeras 4, E-18100 Armilla, Granada, Spain |
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| Abstract: | This paper presents the first report on the occurrence of eclogite from the Kumon range of the Western province in Myanmar, which is in the southeastern extension of the Himalayan orogenic belt. The eclogite is mainly composed of omphacite, garnet, hornblende/edenite/katophorite/taramite, biotite, quartz, and rutile. The garnet grains in the eclogite usually show textures of barrier reef, atoll, and table reef types, and have a wide compositional range of Alm58–70Sps1–2Prp9–16Grs14–31. Omphacite grains that occur as garnet inclusions and as isolated crystals in the matrix have similar compositions of Jd34–45 and Jd37–44, respectively. Lesser amounts of jadeitic clinopyroxene (Jd21–38), phengite, biotite, albite, and quartz occur in the lagoon of barrier reef and atoll garnet grains. The matrix omphacite is partly replaced by symplectite of sodic clinopyroxene of Jd20–29 and albite. The lower limits of the pressure/temperature during the eclogite stage, which are defined by the assemblage of garnet, omphacite (Jd40–45), and quartz, are 1.2–1.3 GPa/530–615 °C. The finding of eclogite from Myanmar suggests the possibility of a wide occurrence of high-pressure metamorphic rocks in the ophiolite zone along the southeastern extension of the Indus-Yarlung Zangbo suture in Myanmar and Indochina. |
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