Miocene temperate carbonates in the Agua Amarga Basin (Almería, SE Spain)

Abstract

The Agua Amarga Basin is a small Neo gene Mediterranean basin in the volcanic area of Cabo de Gata (Almería, SE Spain). The Miocene infill of the basin is made up of two units of Tortonian temperate carbonates separated by the youngest volcanic rocks in the area. These temperate carbonate units are unconformably overlain by Messinian reefs and locally brecciated, oolitic/stromatolitic limestones. The lower Tortonian temperate carbonate unit consists of fan-delta volcaniclastics and bryomol calcarenites/calcirudites. These sediments, arranged in a subsequence, were deposited in coastal palaeonviroments around small emerged reliefs. Volcanic rocks 8.1-8.7 Ma-old cut, engulf and overlie these lower carbonates. The upper Tortonian-lower Messinian temperate carbonate unit consists of four subunits: a) debris-flow conglomerates and trough cross-bedded, bryomol calcarenites/calcirudites; b) a bioclastic and volcaniclastic breccia; c) bryomol calcarenites/calcirudites; and d) calcarenites/calcisiltites. The first three subunits represent the Lowstand Systems Tract and the expansive fine-grained sediments of the fourth subunit the Transgressive Systems Tract of a sequence interrupted by a tectonic pulse. Higher orders of cyclity can be recognised within this sequence. The palaeogeography of the upper temperate carbonate unit, with facies belts trending N80E from a northern palaeocoast, was probably controlled by the strike-slip Carboneras fault system.