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Ameghiniana 2009
Impact of storms on Pliocene benthic foraminiferal assemblages of southwestern SpainKeywords: benthic foraminifera, storms, lower pliocene, sw spain. Abstract: 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.
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