Episodic and long-lasting Paleozoic felsic magmatism in the pre-Alpine basement of the Suretta nappe (eastern Swiss Alps)

Scheiber, Thomas; Berndt, J; Heredia, Benjamin Dominguez; Mezger, Klaus; Pfiffner, Othmar-Adrian (2013). Episodic and long-lasting Paleozoic felsic magmatism in the pre-Alpine basement of the Suretta nappe (eastern Swiss Alps). International journal of earth sciences, 102(8), pp. 2097-2115. Springer Berlin Heidelberg 10.1007/s00531-013-0926-0

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Isotope Geology
08 Faculty of Science > Institute of Geological Sciences > Tectonics

UniBE Contributor:

Scheiber, Thomas; Mezger, Klaus and Pfiffner, Othmar-Adrian

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

1437-3254

Publisher:

Springer Berlin Heidelberg

Language:

English

Submitter:

Klaus Mezger

Date Deposited:

11 Aug 2014 10:47

Last Modified:

23 Oct 2019 03:14

Publisher DOI:

10.1007/s00531-013-0926-0

Uncontrolled Keywords:

Geochronology, Suretta nappe, Rofna Porphyry Complex, LA-ICP-MS, Zircon

BORIS DOI:

10.7892/boris.46199

URI:

https://boris.unibe.ch/id/eprint/46199

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