Associated Facies
As mentioned, alluvial fans form a common associated facies at the proximal end of braided stream deposits. At its distal termination, the modern braided river grades into a diversity of environments, including meandering alluvial plains, and various arid or semiarid coastal depositional regimes. In the case of the latter, association with evaporitic facies – either ephemeral playa lakes, eolian dunes, or the dry coastal environment of the wadi-sabkha, the best developed today in parts of northern Africa along the Persian Gulf.
(Figure 1, Schematic cross section through the Trucial Coast of Oman, showing transition from alluvial fan to coastal marine environments.
Braided stream/wadi facies would occur between the fan and dune facies.) The wadi fluvial plain, largely braided, is determined by a short period of seasonal discharge that creates short-lived streams and extreme flooding, which subsequently dries up completely. The wadi passes into the highly evaporitic, transitional marine sabkha, which largely consists of dolomitized carbonates, algal mats, and gypsum/anhydrite mush deposited in an arid salt marsh (Selley 1978).
