Facies model of a mixed clastic–carbonate, wave‐dominated open‐coast tidal flat (Tithonian–Berriasian, north‐east Spain)

Detailed logging and analysis of the facies architecture of the upper Tithonian to middle Berriasian Aguilar del Alfambra Formation (Galve sub-basin, north-east Spain) have made it possible to characterize a wide variety of clastic, mixed clastic–carbonate and carbonate facies, which were deposited in coastal mudflats to shallow subtidal areas of an open-coast tidal flat. The sedimentary model proposed improves what is known about mixed coastal systems, both concerning facies and sedimentary processes. This sedimentary system was located in an embayed, non-protected area of a wide C-shaped coast that was seasonally dominated by wave storms. Clastic and mixed clastic–carbonate muds accumulated in poorly-drained to well-drained, marine-influenced coastal mudflat areas, with local fluvial sandstones (tide-influenced fluvial channels and sheet-flood deposits) and conglomerate tsunami deposits. Carbonate-dominated tidal flat areas were the loci of deposition of fenestral-laminated carbonate muds and grainy (peloidal) sediments with hummocky cross-stratification. Laterally, the tidal flat was clastic-dominated and characterized by heterolithic sediments with hummocky cross-stratification and local tidal sandy bars. Peloidal and heterolithic sediments with hummocky cross-stratification are the key facies for interpreting the wave (storm) dominance in the tidal flat. Subsidence and high rates of sedimentation controlled the rapid burial of the storm features and thus preserved them from reworking by fair-weather waves and tides. This article is protected by copyright. All rights reserved.