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DOI10.1130/B31978.1
Compressional origin of the Naxos metamorphic core complex, greece: Structure, petrography, and thermobarometry
Lamont T.N.; Searle M.P.; Waters D.J.; Roberts N.M.W.; Palin R.M.; Smye A.; Dyck B.; Gopon P.; Weller O.M.; St-Onge M.R.
发表日期2020
ISSN167606
起始页码149
结束页码197
卷号132期号:2021-01-02
英文摘要The island of Naxos, Greece, has been previously considered to represent a Cordilleran-style metamorphic core complex that formed during Cenozoic extension of the Aegean Sea. Although lithospheric extension has undoubtedly occurred in the region since 10 Ma, the geodynamic history of older, regional-scale, kyanite-and sillimanitegrade metamorphic rocks exposed within the core of the Naxos dome is controversial. Specifically, little is known about the preextensional prograde evolution and the relative timing of peak metamorphism in relation to the onset of extension. In this work, new structural mapping is presented and integrated with petrographic analyses and phase equilibrium modeling of blueschists, kyanite gneisses, and anatectic sillimanite migmatites. The kyanite-sillimanite-grade rocks within the core complex record a complex history of burial and compression and did not form under crustal extension. Deformation and metamorphism were diachronous and advanced down the structural section, resulting in the juxtaposition of several distinct tectono-stratigraphic nappes that experienced contrasting metamorphic histories. The Cycladic Blueschists attained ~14.5 kbar and 470 °C during attempted northeast-directed subduction of the continental margin. These were subsequently thrusted onto the more proximal continental margin, resulting in crustal thickening and regional metamorphism associated with kyanite-grade conditions of ~10 kbar and 600-670 °C. With continued shortening, the deepest structural levels underwent kyanite-grade hydrous melting at ~8-10 kbar and 680-750 °C, followed by isothermal decompression through the muscovite dehydration melting reaction to sillimanite-grade conditions of ~5-6 kbar and 730 °C. This decompression process was associated with top-to-the-NNE shearing along passive-roof faults that formed because of SW-directed extrusion. These shear zones predated crustal extension, because they are folded around the migmatite dome and are crosscut by leucogranites and low-angle normal faults. The migmatite dome formed at lower-pressure conditions under horizontal constriction that caused vertical boudinage and upright isoclinal folds. The switch from compression to extension occurred immediately following doming and was associated with NNE-SSW horizontal boudinage and top-to-the-NNE brittle-ductile normal faults that truncate the internal shear zones and earlier collisional features. The Naxos metamorphic core complex is interpreted to have formed via crustal thickening, regional metamorphism, and partial melting in a compressional setting, here termed the Aegean orogeny, and it was exhumed from the midcrust due to the switch from compression to extension at ca. 15 Ma. © 2019 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.
语种英语
来源期刊Bulletin of the Geological Society of America
文献类型期刊论文
条目标识符http://gcip.llas.ac.cn/handle/2XKMVOVA/184892
作者单位Department Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, United Kingdom; Geochronology and Tracers Facility, British Geological Survey, Environmental Science Centre, Nottingham, NG12 5GG, United Kingdom; Department of Geology and Geological Engineering, Colorado School of MinesCO 80401, United States; Department of Geosciences, The Pennsylvania State University, University ParkPA 16802, United States; Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada; Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom; Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada
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Lamont T.N.,Searle M.P.,Waters D.J.,et al. Compressional origin of the Naxos metamorphic core complex, greece: Structure, petrography, and thermobarometry[J],2020,132(2021-01-02).
APA Lamont T.N..,Searle M.P..,Waters D.J..,Roberts N.M.W..,Palin R.M..,...&St-Onge M.R..(2020).Compressional origin of the Naxos metamorphic core complex, greece: Structure, petrography, and thermobarometry.Bulletin of the Geological Society of America,132(2021-01-02).
MLA Lamont T.N.,et al."Compressional origin of the Naxos metamorphic core complex, greece: Structure, petrography, and thermobarometry".Bulletin of the Geological Society of America 132.2021-01-02(2020).
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