Geological Society of London
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Devonian–Permian magmatic pulses in the northern Vosges Mountains (NE France): result of continuous subduction of the Rhenohercynian Ocean and Avalonian passive margin

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posted on 2016-06-21, 11:37 authored by Anne-Sophie Tabaud, Hubert Whitechurch, Philippe Rossi, Karel Schulmann, Catherine Guerrot, Alain Cocherie

Middle Devonian–Permian magmatic rocks from the northern Vosges Mountains show temporal and chemical variations which are linked to the continuous subduction of the Rhenohercynian oceanic crust and the Avalonian Devonian passive margin underneath the Saxothuringian continental crust. Major and trace elements and Sr–Nd isotopes of the northern Vosges basic to acidic magmatic rocks show that they evolved through time from: (1) Middle Devonian tholeiitic to calc-alkaline volcanic Rabodeau–Schirmeck sequence derived from partial melting of a depleted mantle, with these primary magmas having triggered anatexis of young crustal material of the Saxothuringian crust; (2) calc-alkaline Bande Médiane volcanic belt (c. 334 Ma), diorite and Hohwald granodiorite intrusion (c. 329 Ma) originated from enriched mantle contaminated and metasomatized by fluids expelled from a subduction zone; (3) high-K calc-alkaline Belmont granite (c. 318 Ma), whose chemical signature suggests magma-mixing between enriched mantle-derived melts and magmas from a young crustal source; (4) Mg–K Younger granite (c. 312 Ma) might be related to partial melting of enriched mantle which interacted with juvenile crustal material; and (5) Kagenfels S-type granite and Permian volcanic rocks generated by anatexis of meta-igneous and minor metasedimentary rocks.