Evidence of retrograde metamorphism in the El Oro Metamorphic Complex
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Abstract
The El Oro Metamorphic Complex, located in southwestern Ecuador, consists of different low- and high-grade metamorphic rocks. The evidence of retrograde metamorphism is studied through the bibliographic review, especially, of the results obtained in the El Oro Metamorphic Complex (1990-1993) as part of the Cordillera Real Project (1986-1993) and other recent papers. Evidence of retrograde metamorphism has been mentioned in the Quebrada Plata Unit from amphibolite to green schists facies and in the Raspas ophiolitic complex from eclogite to blue schists. In addition, petrographic evidence of retrograde metamorphism has been obtained in an eclogite block from La Chilca Unit. Also, retrograde metamorphism is described regarding the evolution of the metamorphic complex (Quebrada Plata Unit), the exhumation processes, associated geological structures and mineral reactions.
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References
Aspden, J. A., Bonilla, W. & Duque, P. (1995) The El Oro metamorphic complex, Ecuador: Geology and economic mineral deposits. British Geological Survey.
Feininger, T. (1978) Mapa geológico de la parte occidental de la Provincia de El Oro [1: 50, 000]. Quito: Escuela Politécnica Nacional.
Feininger, T. (1982). The metamorphic “basement” of Ecuador. Geological Society of America Bulletin, 93(1), 87. https://doi.org/10.1130/0016-7606(1982)93<87:TMBOE>2.0.CO;2
Fossen, H. & Cavalcante, G. C. G. (2017) Shear zones – A review. Earth-Science Reviews, 171, 434–455. https://doi.org/10.1016/j.earscirev.2017.05.002
Gabriele, P., Ballèvre, M., Jaillard, E. & Hernandez, J. (2003) Garnet-chloritoid-kyanite metapelites from the Raspas Complex (SW Ecuador): A key eclogite-facies assemblage. European Journal of Mineralogy, 15(6), 977–989. https://doi.org/10.1127/0935-1221/2003/0015-0977
McAleer, R. J., Bish, D. L., Kunk, M. J., Sicard, K. R., Valley, P. M., Walsh, G. J., Wathen, B. A. & Wintsch, R. P. (2017) Reaction softening by dissolution-precipitation creep in a retrograde greenschist facies ductile shear zone, New Hampshire, USA. Journal of Metamorphic Geology, 35(1), 95–119. https://doi.org/10.1111/jmg.12222
Riel, N., Guillot, S., Jaillard, E., Martelat, J.-E., Paquette, J.-L., Schwartz, S., Goncalves, P., Duclaux, G., Thebaud, N., Lanari, P., Janots, E. & Yuquilema, J. (2012) Metamorphic and geochronogical study of the Triassic El Oro metamorphic complex, Ecuador: Implications for high-temperature metamorphism in a forearc zone. Lithos, 156–159, 41–68. https://doi.org/10.1016/j.lithos.2012.10.005
Ring, U., Brandon, M. T., Willett, S. D. & Lister, G. S. (1999) Exhumation processes. Geological Society, London, Special Publications, 154(1), 1–27.
Skrzypek, E., Štípská, P., Schulmann, K., Lexa, O. & Lexová, M. (2011) Prograde and retrograde metamorphic fabrics – a key for understanding burial and exhumation in orogens (Bohemian Massif). Journal of Metamorphic Geology, 29(4), 451–472. https://doi.org/10.1111/j.1525-1314.2010.00924.x
Stenvall, C. A., Fagereng, A., Diener, J. F. A., Harris, C. & Janney, P. E. (2020) Sources and Effects of Fluids in Continental Retrograde Shear Zones: Insights from the Kuckaus Mylonite Zone, Namibia. Geofluids, 2020, 1–21. https://doi.org/10.1155/2020/3023268
Vernon, R. H. (1976) Metamorphic Processes. Reactions and Microstructure Development. Geological Magazine, 113(4), 394–394. https://doi.org/10.1017/S0016756800047737
Winter, J. D. (2014) Principles of igneous and metamorphic petrology (Pearson Education Limited). Pearson New International Edition.
Yardley, B. W. D., Rhede, D. & Heinrich, W. (2014) Rates of Retrograde Metamorphism and their Implications for the Rheology of the Crust: An Experimental Study. Journal of Petrology, 55(3), 623–641. https://doi.org/10.1093/petrology/egu001
Zhong, X., Moulas, E. & Tajcmanova, L. (2018) Tiny timekeepers witnessing high- rate exhumation processes. Scientific Reports, 8. https://doi.org/10.1038/s41598-018-20291-7