Coeval hindward- and forward-imbricating thrusting in the south-central Pyrenees, Spain: Timing and rates of shortening and deposition

Research Article| January 01, 1992 Coeval hindward- and forward-imbricating thrusting in the south-central Pyrenees, Spain: Timing and rates of shortening and deposition DOUGLAS W. BURBANK; DOUGLAS W. BURBANK 1Department of Geological Sciences, University of Southern California, Los Angeles, California 90089 Search for other works by this author on: GSW Google Scholar JAUME VERGÉS; JAUME VERGÉS 2Servei Geològic de Catalunya, Avenida Parallel 71, 08015 Barcelona, Spain Search for other works by this author on: GSW Google Scholar J. ANTON MUNOZ; J. ANTON MUNOZ 3Departament de Geologia Dinàmica, Universitat de Barcelona, Zona Universitaria de Pedralbes, 08071 Barcelona, Spain Search for other works by this author on: GSW Google Scholar PETER BENTHAM PETER BENTHAM 1Department of Geological Sciences, University of Southern California, Los Angeles, California 90089 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1992) 104 (1): 3–17. https://doi.org/10.1130/0016-7606(1992)104<0003:CHAFIT>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 DOUGLAS W. BURBANK, JAUME VERGÉS, J. ANTON MUNOZ, PETER BENTHAM; Coeval hindward- and forward-imbricating thrusting in the south-central Pyrenees, Spain: Timing and rates of shortening and deposition. GSA Bulletin 1992;; 104 (1): 3–17. doi: https://doi.org/10.1130/0016-7606(1992)104<0003:CHAFIT>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 Clear demonstrations of detailed sequences of thrust development are rare, particularly with respect to hindward-imbricating successions. Similarly, well-constrained chronologies of the timing of multiple thrust motions and associated rates of shortening are also uncommon. Along the eastern oblique ramp of the South-Central Unit (SCU) of the Pyrenees, well-exposed structural geometries and crosscutting stratigraphic packages unambiguously illustrate a sequence of break-back thrusts that developed synchronously with the growth of an adjacent duplex. The break-back sequence includes both the Sierras Marginales and Montsec thrusts: structures defining two of the major east-west partitions within the SCU. Balanced, sequentially restored structural cross sections indicate that a minimum of 7.5 km of shortening occurred within the imbricate stack. An additional 9 km of contraction was accommodated by the duplex, prior to translation of the duplex and imbricate stack to the south along a detachment within upper Eocene evaporites. Magnetic polarity stratigraphies have been used to calibrate these late Eocene to Oligocene episodes of deformation. These temporal data indicate that Sierras Marginales thrusting began in the study area ∼39.8 Ma and that the Montsec thrust ceased movement ∼36.2 Ma, yielding a mean rate of shortening of 2.1 mm/yr. Coeval shortening within the duplex was ∼2.5 mm/yr, and subsequent translation across the footwall ramp occurred at ∼2.5-4 mm/yr. Despite the partitioning of shortening into distinctively different styles of deformation, the mean rate of contraction remained steady over ∼4 m.y. These new chronologies indicate that the locus of large-scale thrusting did not progress systematically toward the foreland, but shifted episodically within the SCU, such that, during the late Eocene shortening, the Sierras Marginales thrust was active both prior to and south of the Montsec thrust. 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.