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Kwon S, Samuel VO, Song Y, Kim SW, Park SI, Jang Y, Santosh M. Eclogite resembling metamorphic disequilibrium assemblage formed through fluid-induced metasomatic reactions. Sci Rep 2020; 10:19869. [PMID: 33199786 PMCID: PMC7670418 DOI: 10.1038/s41598-020-76999-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/05/2020] [Indexed: 11/28/2022] Open
Abstract
Equilibrium omphacite-garnet-bearing mafic rocks have been classified as eclogites, either pristine or retrogressed, that were formed at great depths in the lithosphere. Here we report a unique natural example of eclogite resembling assemblage in disequilibrium formed through fluid-induced metasomatic reactions under the amphibolite to granulite facies. Primarily, the amphibolized protolith experienced a garnet-amphibolite facies metamorphism at ~ 500–700 °C and ~ 0.8–1 GPa. Subsequently, CO2 fluid induced fracturing and dissolution-reprecipitation reactions occurred at peak metamorphic conditions of ~ 700 °C and ~ 1 GPa. Occasional omphacite-albite assemblage, which gradually replace diopside-oligoclase symplectite adjacent to albite veins along fractures, indicates fluid-induced coupled dissolution-reprecipitation disequilibrium reactions. Here the albite-omphacite assemblage is in local equilibrium at least on 1 mm length scale, during cooling, below ~ 600 ºC and ~ 1 GPa, within the amphibolite facies conditions. The results from this study clearly suggest that disequilibrium garnet-omphacite assemblage in mafic rocks could be formed by crustal reworking processes below granulite facies conditions, and their textural equilibrium is an important criterion while defining eclogite facies.
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Affiliation(s)
- Sanghoon Kwon
- Department of Earth System Sciences, Yonsei University, Seoul, 03722, Republic of Korea
| | - Vinod O Samuel
- Department of Earth System Sciences, Yonsei University, Seoul, 03722, Republic of Korea.
| | - Yungoo Song
- Department of Earth System Sciences, Yonsei University, Seoul, 03722, Republic of Korea
| | - Sung Won Kim
- Geology Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, 34132, Republic of Korea
| | - Seung-Ik Park
- Department of Geology, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Yirang Jang
- Department of Earth and Environmental Sciences, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - M Santosh
- School of Earth Sciences and Resources, China University of Geosciences Beijing, 29 Xueyuan Road, Beijing, 100083, China.,Department of Earth Sciences, University of Adelaide, Adelaide, SA, Australia
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