Langone, A, Zanetti, A, Daczko, NR et al. (3 more authors) (2018) Zircon U‐Pb Dating of a Lower Crustal Shear Zone: A Case Study From the Northern Sector of the Ivrea‐Verbano Zone (Val Cannobina, Italy). Tectonics, 37 (1). pp. 322-342. ISSN 0278-7407
Abstract
A geochronological study was performed on zircon grains from a middle‐lower crustal shear zone exposed in the northern sector of the Ivrea‐Verbano Zone (Southern Alps, Italy) for the first time. The shear zone developed at the boundary between mafic rocks of the External Gabbro unit and ultramafic rocks of the Amphibole Peridotite unit. It is ~10–20 m wide, can be followed along a NE strike for several kilometers, and consists of an anastomosing network of mylonites and ultramylonites. Zircon grains were studied in thin sections and as separates from three representative outcrops along the shear zone. Zircon grains are more abundant in the shear zone compared to wall rocks and are generally equant, rounded to subrounded with dimensions up to 500 μm. U‐Pb data are mainly discordant, and the apparent ²⁰⁶Pb/²³⁸U dates show a large variation from Permian to Jurassic. Isotopic data, combined with microstructural, morphological, and internal features of zircon, reveal an inherited age component and suggest partial zircon recrystallization under high‐temperature conditions during Late Triassic to Early Jurassic. High‐temperature deformation in the shear zone, at lower crustal levels, was coeval with amphibolite to greenschist facies mylonitic deformation at upper crustal levels and is inferred to be related to Mesozoic rifting processes at the Adriatic margin.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | ©2018. American Geophysical Union. All Rights Reserved. This is the peer reviewed version of the following article: Langone, A, Zanetti, A, Daczko, NR et al. (3 more authors) (2018) Zircon U‐Pb Dating of a Lower Crustal Shear Zone: A Case Study From the Northern Sector of the Ivrea‐Verbano Zone (Val Cannobina, Italy). Tectonics, 37 (1). pp. 322-342. which has been published in final form at https://doi.org/10.1002/2017TC004638 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. |
Keywords: | HT shear zone; zircon U‐Pb dating; zircon geochemistry; external gabbro unit; Ivrea‐Verbano; zone; Mesozoic rifting |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 19 Sep 2018 10:24 |
Last Modified: | 19 Sep 2018 12:46 |
Status: | Published |
Publisher: | AGU |
Identification Number: | 10.1002/2017TC004638 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:135925 |