Author	Turon, J.-L. and Londeix, L.
Year	1988
Journal	Bull. C.R.E.P. Elf-Aquitaine vol.12, no.1 pp.313-344 pl.7Bull. C.R.E.P. Elf-Aquitaine vol.12, no.1
Title	Dinoflagellate assemblages In the western Mediterranean (Alboran Sea) Evidence of the evolution of palaeoenvironments since the last glacial maximum.

Abstract Turon, J.-L. and Londeix, L., 1988; Dinoflagellate assemblages In the western Mediterranean (Alboran Sea) Evidence of the evolution of palaeoenvironments since the last glacial maximum . Bull. C.R.E.P. Eolf-Aquitaine vol.12, no.1 pp.314-344 pl.7 (in French) Palynological analyses from three cores collected in the Alboran Sea show the qualitative and quantitative evolution of dinocysts in a time span covering the last 18 000 years This evolution is replaced in the oxygen-isotope climatostratigraphy (delta 18 0) which is recorded on the same cores. From the interpretation of analytical data, this period can be described as a succession of several stages. which are interpreted as important climatic and hydrologic changes. The first Deglaciation phase (Termination IA) and the Younger Dryas (11 000-10 000 years BP) correspond to optimal development of Nematosphaeropsls labyrinthea. within an association in which Bngantedlnlum slmplex + B. canacoense and Operculodinium centrocarpum are predominant species. The occurrence of Spiniferites elongatus and Bitectatodinium teplkiense is well marked only dunng Terminatlon IA. Interpretations of palynological data support the existence of cool-temperate highly productive environments while high Artemisla + Ephedra pollen frequencies reveal arid conditions on the neighbouring continent during the first Deglaciation phase and Younger Dryas period These local environmental data are related to an intensification of the Mediterranean outflow in the Atlantic Ocean linked to a global increase of deep water formation in the north of the western Mediterranean Basin As early as the beginning of Holocene, and to a lesser degree during Bolling/Allerod period (13 000-11 000 years BP). the development of warm-temperate species (Spmifentes mlrabills + S. hyperacanthus and Impagidmlum aculeatum) shows the improvement of warmer conditions in the Alboran Sea These two stages are characterized by low absolute frequencies, revealing a marked decrease of the phytoplanktonlc productivity This observation supports the existence of more stratified water masses inducing a decreasing churning up of nutrients in subsuperficial waters This local evolution is controlled by hydrodynamlc changes in the Western basin (weaker production of deep waters more sluggish bottom circulation and less importance of Mediterranean/Atlantic exchanges on the Gibraltar Sill). The highest decrease in fertility is recorded at ca 7 000 years BP near the Early/Late Holocene boundary which corresponds to the sharp increase of the / aculeatum curve These particular conditions appear to be synchronous with the Holocene climatic optimum (occurrence of the tropical species Ipatulum and lstrialatum) and could have been reinforced by the drastic reduction in Levantine intermediate waters formation during the sapropel deposition in eastern Mediterranean Basins. The now prevailing conditions were settled during the Late Holocene with the noticeable development of Spiniferites mirabilis and S hyperacanthus as dominant species in the upper levels of the three sequences.