Extracting dynamic topography from river profiles and cosmogenic nuclide geochronology in the Middle Atlas and the High Plateaus of Morocco

Alvar Pastor, Julien Babault, Lewis A. Owen, Antonio Teixell, María Luisa Arboleya

Research output: Contribution to journalArticleResearchpeer-review

8 Citations (Scopus)

Abstract

© 2015 Elsevier B.V. The Moulouya river system has intensely eroded the Arhbalou, Missour, and Guercif Neogene foreland basins in northeastern Morocco, having changed from net aggradation during the Miocene-early Pliocene to net incision punctuated by alluvial fan deposition at late Pliocene or early Quaternary time. This region as a whole has experienced mantle-driven, surface uplift (dynamic topography) since the late Cenozoic, being locally affected by uplift due to crustal shortening and thickening of the Middle Atlas too. Knickpoints located along the major streams of the Moulouya fluvial network, appear on both the undeformed margins of the Missour and Guercif foreland basins (High Plateaus), as well as along the thrust mountain front of the southern Middle Atlas, where they reach heights of 800-1000m. 500-550m of the knickpoint vertical incision might be explained by long-wavelength mantle-driven dynamic surface uplift, whereas the remaining 450-500m in the southern Middle Atlas front and 200-300m in the northeastern Middle Atlas front seem to be thrust-related uplift of the Jebel Bou Naceur. Be-10 terrestrial cosmogenic nuclides have been used to date two Quaternary river terraces in the Chegg Ard valley at 62±14ka and 411±55ka. The dated terraces allow the incision rates associated with the frontal structures of the Middle Atlas to be estimated at ~0.3mmyr-1. Furthermore, these ages have served to evaluate mantle-driven regional surface uplift since the middle Pleistocene in the central Missour basin, yielding values of ~0.1-0.2mmyr-1.
Original languageEnglish
Pages (from-to)95-109
JournalTectonophysics
Volume663
DOIs
Publication statusPublished - 16 Nov 2015

Keywords

  • Active tectonics
  • Atlas Mountains
  • Cosmogenic dating
  • Dynamic topography
  • Knickpoint
  • River profile

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