Ten-million-year history of a thrust sheet

Abstract

Research Article| December 01, 1996 Ten-million-year history of a thrust sheet Andrew J. Meigs; Andrew J. Meigs 1Department of Earth Sciences, University of Southern California, Los Angeles, California 90089-0740 Search for other works by this author on: GSW Google Scholar Jaume Vergés; Jaume Vergés 2Departamento de Geologia Dinàmica, Geofísica i Paleontologia, Universidad de Barcelona, 08071 Barcelona, Spain Search for other works by this author on: GSW Google Scholar Douglas W. Burbank Douglas W. Burbank 1Department of Earth Sciences, University of Southern California, Los Angeles, California 90089-0740 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1996) 108 (12): 1608–1625. https://doi.org/10.1130/0016-7606(1996)108<1608:TMYHOA>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Andrew J. Meigs, Jaume Vergés, Douglas W. Burbank; Ten-million-year history of a thrust sheet. GSA Bulletin 1996;; 108 (12): 1608–1625. doi: https://doi.org/10.1130/0016-7606(1996)108<1608:TMYHOA>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 final, deformed state of a fold-and-thrust belt may be reached by an infinite number of kinematic paths. Two end-member kinematic paths are due to continuous or discontinuous rates of deformation.We have used a new magnetostratigraphic section from the Spanish Pyrenees to calibrate the emplacement history, over ≈10 m.y., of a major thrust sheet (the Sierras Marginales thrust sheet) and the deformation of both its hanging wall and footwall. Six time windows from before 36.5 Ma until after 24.7 Ma were recognized on the basis of structural and stratigraphic relationships between syntectonic strata and major structures. Footwall deformation of the Sierras Marginales thrust sheet occurred continuously on a detachment within the foreland-basin sequence (4.5 km net shortening; shortening rates steadily increased from 0.14 to 1.5 mm/yr with time). Although the detachments at the base of the foreland and the detachment at the base of the Sierras Marginales thrust sheet were active coevally, the rate of displacement on the Sierras Marginales detachment decayed with time and shows considerable variability.Emplacement of the thrust sheet may be divided into three distinct periods: a rapid 13.8 km translation from 37.0 to 36.5 Ma (27.6 mm/yr), a gradual climb of the toe of the thrust sheet up a 4.3-km-long ramp across the foreland-basin succession from 36.5 to 32.0 Ma (0.95 mm/yr), and a final 8.9 km translation from 32.0 to 29.5 Ma (3.56 mm/yr). Internal deformation of the thrust sheet occurred only after it reached its present position at some time before 29.5 Ma. Shortening rates steadily decreased from 0.6 mm/yr between 29.5 and 27.8 Ma to 0.26 mm/yr from 27.8 until after 24.7 Ma. Only ≈1 km of shortening accumulated during each of the two periods; the last shortening localized on the most northerly thrust in the study area.Folding and subsequent faulting above the detachment beneath the foreland suggest that slip was transmitted to its tip point continuously throughout the deformation. In contrast, translation followed by internal deformation on the hinterland side of the toe of the Sierras Marginales thrust sheet indicates a successive deactivation of the southern parts of the detachment with time. Rate of deformation on both detachments was discontinuous and shows substantial variability about the mean. In general, the spatial and temporal pattern of deformation was distributed and continuous. In detail, however, shortening was spatially and temporally discontinuous above each detachment, and structures related to each one display distinctly different deformational patterns, rates, and styles. 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.