Development of a Palaeovalley complex on a late Ordovician glaciated margin in NW Saudi Arabia
- Author(s)
- S. Tofaif, D. P. Le Heron, J. Melvin
- Abstract
Late Ordovician glacial deposits are of great importance in North Africa and the Middle East as a result of their significance as reservoirs for hydrocarbons and groundwater. The sedimentary record of this glaciations inNWSaudi Arabia (the Sarah Formation) is generally preserved in meridionally oriented palaeovalleys cut beneath northward-flowing ice sheets. In the Tabuk region of NW Saudi Arabia, an apparently intersecting complex of north-south- and east-west-oriented palaeovalleys occurs in the Alwizam area. Field relationships show two generations of palaeovalley incision, suggesting that the north-south-oriented palaeovalley was cut subglacially, filled, subsequently deformed and then cross-cut by the east-west-oriented palaeovalley. Abundant facetted and striated quartzite clasts occur at the base of each palaeovalley, testifying to a subglacial origin. Detailed examination of the north-south-oriented palaeovalley shows it to be well-defined with symmetrical sides. Its fill is composed of nine lithofacies grouped into four facies associations. About 80% of the fill consists of three sandstone facies: a parallel-bedded massive sandstone, a stacked scoured sandstone and a massive sandstone. Centimetre-scale extensional faults developed in soft sediments are commonly found throughout the stratigraphy, along with a glacially striated surface seen mid-way through the succession. These features provide evidence for direct ice contact, synglacial fill, and consequent reworking, cannibalization and deformation by the fluctuating ice margin.
- Organisation(s)
- Department of Geology
- External organisation(s)
- Reservoir Characterization Department, Saudi Aramco
- Pages
- 81-107
- No. of pages
- 27
- DOI
- https://doi.org/10.1144/SP475.8
- Publication date
- 01-2019
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105121 Sedimentology
- ASJC Scopus subject areas
- Water Science and Technology, Ocean Engineering, Geology
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/d22880b8-1d60-4f44-b998-1f0e7ac763f5