Abstract

GONZALEZ-REGALADO, María Luz et al. Impact of storms on Pliocene benthic foraminiferal assemblages of southwestern Spain. Ameghiniana [online]. 2009, vol.46, n.2, pp.345-360. ISSN 1851-8044.

Lithostratigraphical and faunal analyses of five Pliocene sections located in the southwestern Guadalquivir Basin (S Spain) permit reveal three main facies, which represent shallow marine fairweather conditions (FA-1), storm events (FA-2) and littoral/fluvial environments (FA-3). The vertical disposition of these facies indicates a regressive sequence. The statistical study of foraminiferal populations revealed five infralittoral and circalittoral assemblages. Vertical and horizontal variations among these assemblages, the P/B ratio and four diversity indices, together with the mollusc distributions, suggest the presence of a shallow marine palaeoenvironment in this area in the Lower Pliocene, with an increasing depth towards the southwestern. The main effects from storm events on the foraminiferal faunas are a slightly decrease of individuals and species, and a marked drop in the P/B ratio. The poststorm conditions are characterized by: a) a higher number of individuals; b) a progressive increase in the P/B ratio and c) small increases in the remaining indices.

Keywords : Benthic foraminifera; Storms; Lower Pliocene; SW Spain.