Episodes of high productivity and cooling in the early Aptian Alpine Tethys

A palynological and organic geochemical study of the early Aptian Selli uni t (oceanic anoxic event 1a) of the western Tethys provides new information about paleoceanography and documents pronounced changes in the regional cli mate pattern. It also emphasizes the role of oxic degradation of organic ma tter, even at horizons with the highest rates of organic carbon (C-org) acc umulation The absence of anoxia indicates that enhanced primary production is the main reason for these organic carbon accumulations, and variations i n preservation are related to pulses in primary production and nutrient rec ycling. Despite the high-productivity character of the Selli unit black sha les, the delta(13)C(carb) values are not marked by a positive shift, but by an interval of unchanged values. Warm climatic conditions for deposition o f the Selli unit are inferred from the presence of southern provenance poll en and low delta(18)O values. For the interval above the Selli unit, change s in the pollen spectrum and an increase in delta(18)O values reflect a hit herto undocumented late early Aptian cooler and more humid climate and/or a reorganization of the Tethyan oceanographic circulation pattern.