Cambrian granitoids in pre-Alpine basement of Crete (Greece): evidence from U-Pb dating of zircon |
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| Authors: | Email author" target="_blank">Sandra?S?RomanoEmail author Wolfgang?D?rr Gernold?Zulauf |
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| Institution: | (1) Institut für Geologie und Mineralogie, Friedrich-Alexander Universität, Schlossgarten 5, 91054 Erlangen, Germany;(2) Institut für Geowissenschaften und Lithosphärenforschung, Justus-Liebig Universität, Senkenbergstr.3, 35390 Giessen, Germany;(3) Institut für Geologie und Mineralogie, Friedrich-Alexander Universität, Schlossgarten 5, 91054 Erlangen, Germany |
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| Abstract: | The pre-Alpine basement of eastern Crete consists of at least three sub complexes which show differences in age and grade of pre-Alpine metamorphism. U-Pb analyses of zircons of two orthogneisses yielded upper intercepts in the concordia diagram at 511±16 Ma (Chamezí crystalline complex) and 514±14 Ma (Myrsini crystalline complex). These values are interpreted as protolith ages of the gneisses, suggesting that parts of the basement underwent Cadomian (Pan-African) imprints at the northern margin of Gondwana. The lower intercept ages are attributed to Alpine subduction which led to high-pressure/low-temperature metamorphism (T=ca. 300 °C), brittle-ductile deformation, and hydrothermal fluid activity. Due to pervasive Alpine fluid migration, the zircons of the Chamezí crystalline complex display disturbed zonation and solution, resulting in 87% radiogenic Pb loss, Ca- and Al-gain, and Zr depletion. |
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| Keywords: | Crete Cambrian granitoids U-Pb geochronology Pb loss Fluids |
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