TY - JOUR
T1 - Episodic and long-lasting Paleozoic felsic magmatism in the pre-Alpine basement of the Suretta nappe (eastern Swiss Alps)
AU - Scheiber, T.
AU - Berndt, J.
AU - Heredia, B.D.
AU - Mezger, K.
AU - Pfiffner, O.A.
N1 - Funding Information:
Acknowledgments The authors thank Ivan Mercolli and Deta Gasser for fruitful discussion and Wolf-Christian Dullo for the careful editorial handling of the manuscript. The constructive reviews of Tom Andersen and Ryszard Kryza greatly improved the paper. This project was funded by the Swiss National Science Foundation (Grant no. 200020–122143).
PY - 2013/11
Y1 - 2013/11
N2 - The Suretta nappe of eastern Switzerland contains a series of meta-igneous rocks, with the Rofna Porphyry Complex (RPC) being the most prominent member. We present LA-ICP-MS U–Pb zircon data from 12 samples representing a broad spectrum of meta-igneous rocks within the Suretta nappe, in order to unravel the pre-Alpine magmatic history of this basement unit. Fine-grained porphyries and coarse-grained augengneisses from the RPC give crystallization ages between 284 and 271 Ma, which either represent distinct magma pulses or long-lasting magmatic activity in a complex magma chamber. There is also evidence for an earlier Variscan magmatic event at ~320–310 Ma. Mylonites at the base of the Suretta nappe are probably derived from either the RPC augengneisses or another unknown Carboniferous–Permian magmatic protolith with a crystallization age between 320 and 290 Ma. Two polymetamorphic orthogneisses from the southern Suretta nappe yield crystallization ages of ~490 Ma. Inherited zircon cores are mainly of late Neoproterozoic age, with minor Neo- to Paleoproterozoic sources. We interpret the Suretta nappe as mainly representing a Gondwana-derived crustal unit, which was subsequently intruded by minor Cambrian–Ordovician and major Carboniferous–Permian magmatic rocks. Finally, the Suretta nappe was thrust into its present position during the Alpine orogeny, which hardly affected the U–Pb system in zircon.
AB - The Suretta nappe of eastern Switzerland contains a series of meta-igneous rocks, with the Rofna Porphyry Complex (RPC) being the most prominent member. We present LA-ICP-MS U–Pb zircon data from 12 samples representing a broad spectrum of meta-igneous rocks within the Suretta nappe, in order to unravel the pre-Alpine magmatic history of this basement unit. Fine-grained porphyries and coarse-grained augengneisses from the RPC give crystallization ages between 284 and 271 Ma, which either represent distinct magma pulses or long-lasting magmatic activity in a complex magma chamber. There is also evidence for an earlier Variscan magmatic event at ~320–310 Ma. Mylonites at the base of the Suretta nappe are probably derived from either the RPC augengneisses or another unknown Carboniferous–Permian magmatic protolith with a crystallization age between 320 and 290 Ma. Two polymetamorphic orthogneisses from the southern Suretta nappe yield crystallization ages of ~490 Ma. Inherited zircon cores are mainly of late Neoproterozoic age, with minor Neo- to Paleoproterozoic sources. We interpret the Suretta nappe as mainly representing a Gondwana-derived crustal unit, which was subsequently intruded by minor Cambrian–Ordovician and major Carboniferous–Permian magmatic rocks. Finally, the Suretta nappe was thrust into its present position during the Alpine orogeny, which hardly affected the U–Pb system in zircon.
KW - Geochronology
KW - LA-ICP-MS
KW - Rofna Porphyry Complex
KW - Suretta nappe
KW - Zircon
UR - http://www.scopus.com/inward/record.url?scp=84885923004&partnerID=8YFLogxK
U2 - 10.1007/s00531-013-0926-0
DO - 10.1007/s00531-013-0926-0
M3 - Article
SN - 1437-3254
VL - 102
SP - 2097
EP - 2115
JO - International Journal of Earth Sciences
JF - International Journal of Earth Sciences
IS - 8
ER -