Integrated biochronology of the pliocene deposits of the Estepona basin (Málaga, S Spain). Palaeobiogeographic and palaeoceanographic implications

Resumen

In the Estepona basin (Málaga, S Spain), the richest and the most diverse Pliocene sites of marine invertebrates (mostly molluscs) of the Mediterranean are found. Most of the species described up until now (~95% out of 892 identified species) occur at the Parque Antena and the Velerín Area (Velerín, Velerín-Carretera and Velerín-Antena) sites. Although molluscs are very well known, the age of these important sites is still controversial. In this paper, a biochronological study of these sites based on an integrated study of the microfossil (calcareous nannoplankton and planktonic foraminifers) and macrofossil (molluscs) assemblages is presented.

The Parque Antena and Velerín-Carretera sites can be attributed to the late Zanclean (uppermost part of the early Pliocene) based on the presence of Globorotalia margaritae, Gr. puncticulata and Gr. group crassaformis (including Gr. crassaformis s.s.). Nannoplankton assemblages agree with this age, and can be attributed to the CN11b biozone of Okada & Bukry (1980) due to the presence of small Gephyrocapsa, Sphenolithus abies and Reticulofenestra pseudoumbilica. At the Velerín-Antena section, the bioindicators of the early Pliocene Gr. margaritae, Sphenolithus abies and Reticulofenestra pseudoumbilica are absent.

The molluscs found in the studied sites correlate with the Mediterranean Pliocene Molluscan Unit 1 of Raffi & Monegatti (1993) (MPMU1).

Finally, the coexistence of Gr. margaritae and Gr. group crassaformis in the Mediterranean domain is described for the first time.