Constraints on the lithospheric structure beneath the North Pyrenean fault from teleseismic observations

Abstract

Research Article| February 01, 1992 Constraints on the lithospheric structure beneath the North Pyrenean fault from teleseismic observations G. Poupinet; G. Poupinet 1Observatoire de Grenoble, BP 53X, 38041 Grenoble, France Search for other works by this author on: GSW Google Scholar A. Souriau; A. Souriau 2Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France Search for other works by this author on: GSW Google Scholar M. Vadell; M. Vadell 2Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France Search for other works by this author on: GSW Google Scholar J. D. Njike-Kassala J. D. Njike-Kassala 2Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France Search for other works by this author on: GSW Google Scholar Author and Article Information G. Poupinet 1Observatoire de Grenoble, BP 53X, 38041 Grenoble, France A. Souriau 2Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France M. Vadell 2Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France J. D. Njike-Kassala 2Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (2): 157–160. https://doi.org/10.1130/0091-7613(1992)020<0157:COTLSB>2.3.CO;2 Article history First Online: 02 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 G. Poupinet, A. Souriau, M. Vadell, J. D. Njike-Kassala; Constraints on the lithospheric structure beneath the North Pyrenean fault from teleseismic observations. Geology 1992;; 20 (2): 157–160. doi: https://doi.org/10.1130/0091-7613(1992)020<0157:COTLSB>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 SocietyGeology Search Advanced Search Abstract The Pyrenean range is bordered to the north by the North Pyrenean fault, which represents the boundary between the European and the Iberian plates. Reflection profiles have shown that the Moho is vertically offset by 15 km at the latitude of the fault. In order to determine the structure beneath the crust, we have recorded teleseismic events on seismic stations deployed on both sides of the fault. Large P-wave traveltime residual variations are observed over a very short distance. The residuals given by the rays coming from the south are close to those predicted from the known Moho offset (southern stations are 0.5 s later). They rule out a stacking of the Iberian and European crusts underneath the North Pyrenean zone, as postulated in some models. In contrast, rays coming from the north give residual variations opposite to those expected from the known crustal structure (southern stations are as much as 0.9 s earlier). The simplest model fitting the data introduces an abrupt change in lithospheric thickness about 30 km north of the North Pyrenean fault; i.e., the southern lithosphere is about 60-70 km thicker than the northern lithosphere. The P- wave residual variations as a function of incidence angle suggest the existence of an anisotropy; a low-velocity vertical axis is in the vicinity of the fault. This simple structure can be explained by the collision of a thick Iberian plate with a thinned Aquitaine plate margin, a collision involving the imbrication of the crusts and a small decoupling of the lithosphere at the base of the Iberian Moho. 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.