The Late Tortonian-Early Messinian Foraminiferal Record Of The Abad Member (Turre Formation), Sorbas Basin, Almería, South-East Spain

The Late Tortonian-Early Messinian Abad Member in the Sorbas Basin, south-east Spain contains abundant foraminifera. Planktonic foraminifera have been used to reconstruct the environmental conditions that developed within the basin. Benthonic foraminifera reveal a detailed picture of the palaeoenvironment. After an initial deepening episode, from upper epibathyal ( c . 200 m) depths to lower epibathyal ( c . 1000 m) depths, the basin progressively shallowed to shelf depths ( c . 100 m); this palaeobathymetric reconstruction thus describes an initial rapid transgressive episode, a highstand and a regressive phase; the basin water mass became progressively warmer, and yet there was no significant increase in salinity or oxygen level in the water mass. The lack of any microfossil evidence to support an increase in the salinity levels towards the top of the Abad Member indicates a rapid environmental switch from normal marine conditions during the deposition of the Abad Member to hypersaline conditions during deposition of the overlying Yesares Member and precipitation of great thicknesses of gypsum. This research illustrates the necessity for high resolution sampling, approximate to the standard interval (10 feet: c . 3 metres) used in industrial boreholes, for Mediterranean Late Miocene stratigraphies, and indicates that all previous palaeoenvironmental studies on the Sorbas Basin have had inadequate sampling regimes which do not represent the evolving environmental conditions of the Abad Member.