Trough cross-bedded rhodolith limestones in the Atlantic-linked Ronda Basin (Messinian, Southern Spain)

Rhodolith limestones occur in the upper part of Miocene infill Ronda Basin southern Spain. This basin was an embayment at margin Atlantic-linked Guadalquivir Basin, foreland Betic Cordillera. Messinian rhodolith crop out mesa Roman settlement Acinipo. They mostly consist trough cross-bedded rudstones, which change basinward to large-scale planar turn pass laterally and flat-bedded bryozoan rudstones. Rhodoliths rudstones are generally broken, exhibiting several phases breakage restarted growth coralline algae. Many rhodoliths also show asymmetrical growth. The rudstone matrix is a packstone with fragments algae, bryozoans, calcitic bivalves, echinoids, foraminifers. Large lithoclasts from basement, heavily bored by common rudstone, especially most massive type. characteristics sedimentary structures suggest that accumulated submarine dunes moved storm surges littoral wedge western side small bay (the Ruinas de Acinipo bay) Basin. Large-scale algal formed foresets progradation below storm-wave base. dominance Lithophyllaceae Hapalidiales, scarce representatives Corallinaceae assemblages, reflects basins opened Atlantic Ocean.