Facies model for a sandy ephemeral stream and clay playa complex; the Middle Devonian Trentishoe Formation of North Devon, U.K.

摘要: Sediments in the Trentishoe Formation of Middle Devonian Hangman Sandstone Group (North Devon, U.K.) provide basis a model for sandy ephemeral stream and clay playa deposition. Three types sequence are found, representing proximal, medial distal areas on an extensive alluvial plain. The Proximal consists cross-cutting channel-fill sandstones which represent deposits network low sinuosity sand bed streams. Medial comprises upwards coarsening cyclothems start with relatively distal, thinly bedded sandstone siltstone flood sheets cut by complexes silt draped single channel fill sandstones. coarsen thicken to more proximal multistorey sheet Distal sequences consist laminated mudstone sandstone, desiccation water escape features, alternating wave rippled sandstones, lakes occasionally incised high channels laterally accreting three downslope progression from passed into deposit complex turn drained playas.