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

Publication Type:Journal Article
Year of Publication:2005
Authors:Aguirre, J, Cachão, M, Domènech, R, Lozano-Francisco, MC, Martinell, J, Mayoral, E, Santos, A, Vera-Peláez, JL, Da Silva, CM
Journal:Revista Española de Paleontolog{\'ıa
Volume:20
Pagination:225-244
ISSN:0213-6937
Keywords:biochronology, Parque Antena, Piacenzian, Pliocene, Spain, Velerín, Velerín-Carretera, Zanclean
Abstract:

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 identifi ed 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 microfossil assemblages are characterised by the occurrence of Gr. puncticulata and Gr. group crassaformis among foraminifers and Discoaster asymmetricus and D. tamalis among nannoplankton. This microfossil assemblage allows us to attribute this site to the lowermost Piacenzian (middle Pliocene): biozone CN12a of Okada & Bukry (1980). The molluscs found in the studied sites correlate with the Mediterranean Pliocene Molluscan Unit 1 of Raffi & Monegatti (1993) (MPMU1). This unit ranges from the base of the Zanclean (base of the early Pliocene) to the lower half of the Piacenzian (middle Pliocene; ~3 Ma). This age attribution is consistent with that inferred from microfossils. Finally, the coexistence of Gr. margaritae and Gr. group crassaformis in the Mediterranean domain is described for the fi rst time, so far. These two species coexisted during ca. 600 ka in the Atlantic Ocean, thus the coincidence of both species in the western Mediterranean can be related to the occasional invasion of inhabitants from the Atlantic by superfi cial currents through the Strait of Gibraltar.

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