Mediterranean planktonic foraminiferal faunas during the last glacial cycle

This paper highlights the planktonic foraminiferal abundance variations dur ing the last glacial cycle from six new cores along a roughly west-east tra nsect in the Mediterranean Sea, together with results from previous studies . Multivariate statistical analysis describes a first significant axis that indicates a general sea surface temperature (SST) gradient from west to ea st. As expected lower SST values are recorded in glacial times but the east ern and western basins seem to have reacted differently to glacial conditio ns. The western basin shows a SST decrease from the Alboran Sea to the cent ral Mediterranean, whereas the eastern basin records a west to east increas e that is similar to the present-day eastern Mediterranean gradient. These new results show that: (1) few almost basin-wide faunal trends may be recog nised, but these are interrupted by local anomalies with opposing trends; a nd (2) major abundance variations are distinctly diachronous in some specie s and virtually synchronous in others. The implication is that over the gla cial-interglacial timescale concerned, biostratigraphy should only be used on a local rather than basin-wide scale, unless it is supported by other in dependent dating methods. (C) 1999 Elsevier Science B.V. All rights reserve d.