Provenance, tectonic setting, paleo-weathering and paleoclimate of the Cambrian–Middle Ordovician sandstones from the Tayma region, Tabuk Basin, NW Saudi Arabia (North Gondwana): Petrographic and geochemical evidence

Abstract

In the Tayma region of northwest Saudi Arabia, the Cambro-Ordovician rock units are gaining growing attention for hydrocarbon and groundwater exploration. Nevertheless, their petrographic and geochemical characteristics have not yet been examined. Accordingly, this study aims to reconstruct the provenance of Cambrian-Middle Ordovician sandstones in the Tayma region, northwestern Saudi Arabia, along with the tectonic setting, paleo-weathering, and paleoclimatic conditions of the source area. This is achieved by the integration of both petrographic and geochemical data (major, trace, and rare-earth elements) of the studied sandstones. The sandstones are collected from the stratigraphic successions comprising the Saq Formation (the Risha and Sajir members, in particular) and the middle member of the Qassim Formation (the Kahfah member). Petrographic analysis reveals that the sandstones consist predominantly of quartz arenite, with subordinate sub-arkose arenite and micaceous quartz wacke. The integration of both petrographic and geochemical data indicates that detritus of the studied sandstones was primarily sourced from Neoproterozoic felsic igneous rocks (mainly granites) with a minor contribution from metamorphic source (mainly gneiss). These source rocks were developed in the interior of a craton, situated within a broad passive continental margin, and were intensely weathered due to prevailing warm and humid conditions. Deposition occurred in intra-cratonic basins after the Arabian-Nubian Shield (craton) stabilized following the Neoproterozoic Pan-African Orogeny, which culminated in the assembly of Gondwana. In terms of a regional perspective, findings of this study support earlier research suggesting that, during the Cambro-Ordovician period, North Africa and Arabia formed a broad, tectonically stable continental shelf along the northern margin of the Gondwana supercontinent, adjacent to the Proto-Tethys Ocean.