International Journal of Earth Sciences

, Volume 104, Issue 3, pp 753–773 | Cite as

Syn-rift unconformities punctuating the lower–middle Cambrian transition in the Atlas Rift, Morocco

  • J. Javier Álvaro
  • Hassan Ezzouhairi
  • Sébastien Clausen
  • M. Luisa Ribeiro
  • Rita Solá
Original Paper
  • 210 Downloads

Abstract

The Cambrian Tamdroust and Bab n’Ali Volcanic Complexes represent two magmatic episodes developed in the latest Ediacaran–Cambrian Atlas Rift of Morocco. Their rifting pulses were accompanied by accumulation of volcanosedimentary edifices (dominated by effusive lava flows in the former and explosive acidic aprons in the latter) associated with active tilting and uplift. Sealing of their peneplaned horst-and-graben palaeotopographies led to the onset of distinct onlapping geometries and angular discordances capping eroded basements ranging from the Ediacaran Ouarzazate Supergroup to the Cambrian Asrir Formation. Previous interpretations of these discordances as pull-apart or compressive events are revised here and reinterpreted in an extensional (rifting) context associated with active volcanism. The record of erosive unconformities, stratigraphic gaps, condensed beds and onlapping patterns across the traditional “lower–middle Cambrian” (or Cambrian Series 2–3) transition of the Atlas Rift must be taken into consideration for global chronostratigraphic correlation based on their trilobite content.

Keywords

Tholeiitic volcanism Uplift Angular discordance Palaeorelief Condensation Gondwana 

Notes

Acknowledgments

The authors thank field support by Nouredine Ait Ayad, Abdelmounim Charif (El Jadida), Xavier Legrain (Lille), Julie Dewit and Robin Honlet (Leuven), and constructive manuscript reviews by Ulf Linnemann and Gregory Walsh. Agreement for using Google Earth images was yielded by Google Brand Permissions. Financial support for this work was provided by project CGL2013–48877 from Spanish MINECO and EU–FEDER.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • J. Javier Álvaro
    • 1
  • Hassan Ezzouhairi
    • 2
  • Sébastien Clausen
    • 3
  • M. Luisa Ribeiro
    • 4
  • Rita Solá
    • 4
  1. 1.Centro de Astrobiología (INTA/CSIC)Torrejón de ArdozSpain
  2. 2.Département de GéologieUniversité Chouaib DoukkaliEl JadidaMorocco
  3. 3.Département de GéosciencesUniversité de Lille IVilleneuve d’AscqFrance
  4. 4.Laboratório Nacional de Energia e Geologia (LNEG)AmadoraPortugal

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