Extensional detachment faulting in the evolution of a Tethys passive continental margin, Eastern Alps, Switzerland

Abstract

Research Article| September 01, 1990 Extensional detachment faulting in the evolution of a Tethys passive continental margin, Eastern Alps, Switzerland NIKOLAUS FROITZHEIM; NIKOLAUS FROITZHEIM 1Geologisches Institut, ETH-Zentrum, CH-8092 Zürich, Switzerland Search for other works by this author on: GSW Google Scholar GREGOR P. EBERLI GREGOR P. EBERLI 1Geologisches Institut, ETH-Zentrum, CH-8092 Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Author and Article Information NIKOLAUS FROITZHEIM 1Geologisches Institut, ETH-Zentrum, CH-8092 Zürich, Switzerland GREGOR P. EBERLI 1Geologisches Institut, ETH-Zentrum, CH-8092 Zürich, Switzerland Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1990) 102 (9): 1297–1308. https://doi.org/10.1130/0016-7606(1990)102<1297:EDFITE>2.3.CO;2 Article history 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 NIKOLAUS FROITZHEIM, GREGOR P. EBERLI; Extensional detachment faulting in the evolution of a Tethys passive continental margin, Eastern Alps, Switzerland. GSA Bulletin 1990;; 102 (9): 1297–1308. doi: https://doi.org/10.1130/0016-7606(1990)102<1297:EDFITE>2.3.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 Austroalpine nappes of Switzerland represent an exhumed and tectonically imbricated segment of the passive continental margin of the Jurassic Tethys. Within one of these nappes (Err nappe), part of an upper-crustal, extensional detachment is preserved, indicating that the thinning of the crust was achieved by non-uniform extension. The Mesozoic age of the detachment is shown by comparison between its associated cataclasites and identical cataclasites that are found as redeposited components in Middle(?) Jurassic sedimentary breccias. This low-angle detachment within the basement was kinematically linked to synsedimentary high-angle normal faults at the surface.The area of the Err nappe belongs, in terms of Jurassic paleogeography, to the most distal part of the continental margin, where both low- and high-angle normal faults dipped oceanward (that is, west to northwest in present-day coordinates). In the more proximal part of the margin, however, the high-angle normal faults dipped eastward toward the continent. Ammonite stratigraphy within the sediment prisms adjacent to the faults gives evidence for an Early Jurassic age of the faulting in the proximal part of the margin, whereas in the distal part, faulting occurred during latest Early to Middle Jurassic time. We therefore propose that the Jurassic extension of the crust, which finally led to the opening of the Piemont-Ligurian ocean, was achieved by two fault systems, which differ in geometry, fault orientation, and age. These fault systems were composed of a basal low-angle detachment with high-angle normal faults above.The orientation of the older, eastward-dipping detachment was prone for reactivation during early Alpine crustal shortening. The present-day thrust contact between the two major tectonic units of the area, the Lower Austroalpine and the Central Austroalpine nappe complex, therefore might correspond to an eastward-dipping, Jurassic low-angle normal fault. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.