Stratigraphy and sedimentology of the Hofuf Formation in the State of Qatar in relation to the tectonic evolution of the East Arabian Block

Abstract

Well-exposed, fine-grained to pebbly coarse-grained fluvial sandstones of Late Miocene to Pleistocene age crop out in the south-central and south-western parts of Qatar. These sandstones belong to the Hofuf Formation and were deposited largely in stream channels along Wadi As-Sahba over a distance of 450 kms. The graben structure of Wadi As-Sahba reflects a strike-slip motion that took place in the Plio-Quaternary. The evolution of the Hofuf Formation is related to the tectonic evolution of the East Arabian Block in Neogene time. The sandstones comprise three distinct facies: clast-supported conglomerate, coarse-grained sandstone, and fine-grained sandstone. Sandstone compositions show a uniform framework composition dominated by monocrystalline quartz and feldspar with less abundant polycrystalline quartz, calcite, micas and igneous, metamorphic and sedimentary rock fragments. Quartz was derived mostly from plutonic source rocks. The heavy-mineral assemblage is characterized by abundant unstable minerals, particularly hornblende and pyroxene. The pebbles are granitic, metamorphic and sedimentary rocks derived from the Arabian platform. Modal compositions of the sandstones indicate a transitional provenance that ranges from continental to a craton interior and recycled orogen.