The Pejo fault system: An example of multiple tectonic activity in the Italian Eastern Alps

Abstract

Research Article| May 01, 2003 The Pejo fault system: An example of multiple tectonic activity in the Italian Eastern Alps Giulio Viola; Giulio Viola 1Department of Geological Sciences, University of Cape Town, 7701 Rondebosch, South Africa Search for other works by this author on: GSW Google Scholar Neil S. Mancktelow; Neil S. Mancktelow 2Department of Earth Sciences, ETH, Sonneggstrasse 5, 8092 Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Diane Seward; Diane Seward 2Department of Earth Sciences, ETH, Sonneggstrasse 5, 8092 Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Andreas Meier; Andreas Meier 2Department of Earth Sciences, ETH, Sonneggstrasse 5, 8092 Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Silvana Martin Silvana Martin 3Dipartimento di Scienze Chimiche, Fisiche e Matematiche, Università dell'Insubria, via Valleggio 11, 22100 Como, Italy Search for other works by this author on: GSW Google Scholar Author and Article Information Giulio Viola 1Department of Geological Sciences, University of Cape Town, 7701 Rondebosch, South Africa Neil S. Mancktelow 2Department of Earth Sciences, ETH, Sonneggstrasse 5, 8092 Zürich, Switzerland Diane Seward 2Department of Earth Sciences, ETH, Sonneggstrasse 5, 8092 Zürich, Switzerland Andreas Meier 2Department of Earth Sciences, ETH, Sonneggstrasse 5, 8092 Zürich, Switzerland Silvana Martin 3Dipartimento di Scienze Chimiche, Fisiche e Matematiche, Università dell'Insubria, via Valleggio 11, 22100 Como, Italy Publisher: Geological Society of America Received: 13 Dec 2001 Revision Received: 16 Oct 2002 Accepted: 04 Nov 2002 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2003) 115 (5): 515–532. https://doi.org/10.1130/0016-7606(2003)115<0515:TPFSAE>2.0.CO;2 Article history Received: 13 Dec 2001 Revision Received: 16 Oct 2002 Accepted: 04 Nov 2002 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Giulio Viola, Neil S. Mancktelow, Diane Seward, Andreas Meier, Silvana Martin; The Pejo fault system: An example of multiple tectonic activity in the Italian Eastern Alps. GSA Bulletin 2003;; 115 (5): 515–532. doi: https://doi.org/10.1130/0016-7606(2003)115<0515:TPFSAE>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Pejo fault in the Italian Eastern Alps is a major sinistral transtensional fault. It marks the boundary between basement units displaying contrasting thermal histories, with Alpine (i.e., Mesozoic–Cenozoic) cooling ages preserved in the footwall juxtaposed against Variscan (i.e., Carboniferous– Permian) age in the hanging wall. Structural investigations, together with fission-track analysis, confirm a Late Cretaceous age for the Pejo fault, which excludes any direct kinematic contribution of the Pejo fault to the late Oligocene–Neogene evolution of the central-eastern segment of the Periadriatic fault. However, our results establish the importance of a major early Oligocene north-south to north-northwest–south-southeast shortening phase in the Central-Eastern Alps, which resulted in the development of new reverse shear zones, in the reactivation of the Pejo fault with a reverse motion, and in regionally important folding. The Pejo mylonites are folded on a kilometer scale around an east-northeast–trending axis. Field observations and fission-track analysis suggest a post-Oligocene age for the folding phase. Apatite fission-track data in the Pejo valley area reveal the base of a fossil apatite partial annealing zone exhumed to the surface. This finding argues for >4 km of exhumation since the Miocene, which was related to a major pulse of exhumation that began at ca. 15 Ma. This study suggests that the simple distinction between largely pre-Alpine fabrics of Variscan age in the hanging wall of the Pejo fault (Tonale nappe) and Alpine fabrics (Cretaceous) in the footwall (Campo-Ortler nappe) is not universally valid. Alpine overprinting is confined to the mylonitic shear zone itself. Deeper into the footwall, pre-Alpine structures are still well preserved. Earlier maps and interpretations based on a clear distinction between Tonale and Campo should be viewed with caution. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.