New constraints for the timing of the Alpine metamorphism in the internal ophiolitic nappes from the Western Alps as inferred from fission-track data
| Autor: | Joelle Carpena, Bruno Lombardo, Ugo Pognante |
|---|---|
| Přispěvatelé: | Centre des Faibles Radioactivités, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Scienze della Terra [Torino], Università degli studi di Torino = University of Turin (UNITO) |
| Jazyk: | angličtina |
| Rok vydání: | 1986 |
| Předmět: |
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean
Atmosphere Greenschist Geochemistry Metamorphism Ophiolite Fission track dating Nappe Paleontology Geophysics Alpine orogeny Eclogite [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces environment Geology ComputingMilieux_MISCELLANEOUS Earth-Surface Processes Zircon |
| Zdroj: | Tectonophysics Tectonophysics, 1986, 127 (1-2), pp.117-127. ⟨10.1016/0040-1951(86)90082-X⟩ |
| ISSN: | 0040-1951 1879-3266 |
| DOI: | 10.1016/0040-1951(86)90082-X⟩ |
| Popis: | Fission track ages performed on zircons from different units of the internal ophiolites of the Western Alps lie between 135 ± 8 Ma and 90 ± 8 Ma. These data imply that the Piemonte Nappe consists of different ophiolitic nappes which followed distinctive pressure-temperature-time ( P - T - t ) paths during the Alpine orogeny: 1. (1) The zircon fission track clock of the internal (i.e. eastern) ophiolitic units has been significantly reset during the Cretaceous eo-Alpine eclogitic metamorphism, in contrast with zircon from external (i.e. western) units. 2. (2) These internal ophiolites, situated south of Val d'Aoste, have not been heated above 250°C since Late Cretaceous times. This means that the post-eclogitic greenschist stage (350°–450°C) which occurred in the studied samples, should be of Cretaceous age, that is, much older than the Lepontine stage. The duration of this post-eclogitic greenschist stage appears to have been variable according to the unit considered. 3. (3) The Lepontine stage occurred 35–40 Ma ago (Late Eocene-Early Oligocene), only locally resetting the apatite fission-track clock. |
| Databáze: | OpenAIRE |
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