SEDIMENTOLOGICAL AND ICHNOLOGICAL CHARACTERIZATION OF THE LATE CARBONIFEROUS–MIDDLE PERMIAN SUCCESSION IN THE SUBSURFACE OF CENTRAL SAUDI ARABIA

• Author / Creator

  Polo Camacho, Camilo A.

• The Late Carboniferous–Middle Permian Unayzah Group is a widespread sand-rich stratigraphic unit with equivalent deposits across the subsurface of
  the Arabian Peninsula. Historically, sediment deposition for this interval in the subsurface of Saudi Arabia has been ascribed to continental settings dominated by aeolian processes. Combining ichnology, sedimentology, and palynology this study refines traditionally held views. By introducing new depositional models and sedimentary processes operating at the time of sediment deposition, we confirm the presence of shallow-marine sedimentary environments. Integration of ichnological and sedimentological observations in the Nuayyim Formation allowed the identification of marginal-marine, tidally influenced sedimentation (FA1), and shallow-marine, wave- and storm-dominated sedimentation with subordinate tidal and fluvial influence (FA2) in its basal Wudayhi Member. Colonization by bioturbating infauna exhibiting elements of an overall impoverished Skolithos and Cruziana Ichnofacies is interpreted to be related to sea level rise, with regional transgression induced by the melting of glacier ice following the Late Carboniferous to Early Permian glaciation that affected southern Gondwana.
  Following climatic amelioration and continental drift of the Arabian Plate towards a more temperate paleolatitud, sediment deposition for the overlaying Tinat Member was characterized by aeolian and marginal-marine, tidally influenced interactions in
  two facies associations (FA1 and FA2) that are conformably interbedded. Therein, FA2 reflects sedimentation in shallow-marine, tidally influenced environments and includes punctuated occurrences of bioturbated tidal flats and sheltered shallow bay
  deposits interbedded with aeolian sediments. The ichnofossil assemblage exhibits a diminutive, highly stressed mixture with structures reflecting an impoverished Skolithos Ichnofacies and Cruziana Ichnofacies. It constitutes a model for marginal marine and aeolian interactions and their resulting ichnofossil suite that can be used in similar successions in the rock record. Widespread paleosols characterize the upper part of the Tinat Member with burrowing that exhibits elements of the Scoyenia Ichnofacies. Therein, biogenic activity in the form of continental fauna and plants mark palimpsest surfaces. Progressive thermal updoming is interpreted to have occurred during the latest portion of the Unayzah Group sedimentation cycle in the Arabian Plate culminating in the regional “Pre-Khuff unconformity” at the top of this megacycle recognized in this study by biogenically-demarcated diastems. Thereby, providing an example of the utility of trace fossil analysis in genetic stratigraphy in continental settings.

• Subjects / Keywords

  • Ichnology
  • Sedimentology
  • Permian
  • Arabia

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-362x-9g35

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.