Radiolarite ages in Alpine-Mediterranean ophiolites: Constraints on the oceanic spreading and the Tethys-Atlantic connection

Abstract

Research Article| January 01, 2001 Radiolarite ages in Alpine-Mediterranean ophiolites: Constraints on the oceanic spreading and the Tethys-Atlantic connection Markus Bill; Markus Bill 1Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Search for other works by this author on: GSW Google Scholar Luis O'Dogherty; Luis O'Dogherty 2Facultad de Ciencias del Mar, Universidad de Cádiz, 11510 Puerto Real, Spain Search for other works by this author on: GSW Google Scholar Jean Guex; Jean Guex 3Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Search for other works by this author on: GSW Google Scholar Peter O. Baumgartner; Peter O. Baumgartner 3Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Search for other works by this author on: GSW Google Scholar Henri Masson Henri Masson 3Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Search for other works by this author on: GSW Google Scholar Author and Article Information Markus Bill 1Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Luis O'Dogherty 2Facultad de Ciencias del Mar, Universidad de Cádiz, 11510 Puerto Real, Spain Jean Guex 3Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Peter O. Baumgartner 3Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Henri Masson 3Institut de Géologie et Paléontologie, Université de Lausanne, BFSH-2, CH-1015 Lausanne, Switzerland Publisher: Geological Society of America Received: 10 May 1999 Revision Received: 05 Jan 2000 Accepted: 08 Feb 2000 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2001) 113 (1): 129–143. https://doi.org/10.1130/0016-7606(2001)113<0129:RAIAMO>2.0.CO;2 Article history Received: 10 May 1999 Revision Received: 05 Jan 2000 Accepted: 08 Feb 2000 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 Markus Bill, Luis O'Dogherty, Jean Guex, Peter O. Baumgartner, Henri Masson; Radiolarite ages in Alpine-Mediterranean ophiolites: Constraints on the oceanic spreading and the Tethys-Atlantic connection. GSA Bulletin 2001;; 113 (1): 129–143. doi: https://doi.org/10.1130/0016-7606(2001)113<0129:RAIAMO>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 history of continental breakup and oceanic spreading of the Alpine Tethys is defined by a revision of isotopic and biochronologic ages of 65 stratigraphic sections located in the Alps, Apennines, Betic Cordillera, Rif, and central Atlantic and a reinterpretation of the stratigraphic sequences of surpraophiolitic radiolarites. The biochronology of radiolarites is revised by using the deterministic approach known as the unitary association method.During the early Bajocian (unitary association zone, UAZ 3) radiolarite sedimentation began at the continental margin. Biochronologic ages determined in the lowermost radiolarites in basinal sequences of Tethyan margins are synchronous and mark a regional change in sedimentation regime in the Alpine Tethys. The onset of oceanic spreading of the Alpine Tethys is dated by isotopic methods as Bajocian, and is consistent with the timing of the structural evolution of the continental margins. The earliest fragments of Tethyan oceanic crust are characterized by the associations of ophiolites with deep-sea sediments, and coarse reworked sediments including platform and continental basement fragments. The earliest ophiolites also show geochemical affinities with synrift and transitional mid-oceanic-ridge basalts. The oldest radiolarites on oceanic crust are so far dated as Bathonian (UAZ 6) and are located in the Gets nappe (western Alps), in the Balagne nappe (Corsica), and in the central Atlantic (Deep Sea Drilling Project [DSDP] Site 534A). The oldest remnants of Alpine Tethyan crust have been identified in weakly metamorphosed cover nappes that occupy an external tectonic position in the Alpine orogenic belts, as compared to the main ophiolitic sutures. Thus, the older relics of oceanic lithosphere were the first to be accreted and transported onto the foreland during the collision.Siliceous sedimentation during the early Bajocian is correlated with westward deep-water circulation in the Alpine Tethys related to the opening of deep seaways between Laurasia and Gondwana. In the central Atlantic no radiolarites, but thin radiolarian-rich layers, were deposited during the earliest Bathonian (UAZ 6). The similarity between radiolarian faunal assemblages and ages in the Northern Alps, Gets nappe, Betic Cordillera, and Site 534 (DSDP Leg 76) suggest a Middle Jurassic connection between the Alpine Tethys and central Atlantic. Biochronologic and isotopic ages currently indicate that oceanic spreading of the Alpine Tethys began during the Bajocian and continued until the Kimmeridgian. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.