engleski

The role of the Paleogene Adriatic carbonate platform in spatial distribution of alveolinids

Sediments of the Paleogene Adriatic carbonate platform, a distinctive paleogeographic unit, are today exposed along the eastern Adriatic coast for a distance of 800 km and a width of 100 - 130 km. The large number of identified alveolinid species (69) from the Early Ypresian (Ilerdian) to the Bartonian record the dynamics of their evolution, with emphasis on the following: 1) great species diversity and great abundance in the middle Ilerdian (SBZ 7 - 8) followed by a sharp decline in occurrences at the Ilerdian/Cuisian transition ; 2) a diversity boom in the late Ypresian (late Cuisian. SBZ 11 - 12) and 3) an abrupt decrease in species numbers after the early Lutetian. This pattern shows relationship between abundance and diversity and global sea-level changes in TA and AP events. The “two peaks” model in alveolinid occurrence is present also in the “Mediterranean assemblage” in the Pyrenees and within the middle Cuisian assemblages of various Mediterranean areas. Based on studies of numerous stratigraphic sections from the Paleogene Adriatic carbonate platform, biosedimentary zones (BioZ 2, BioZ 3.1, BioZ 3.2 and BioZ 4) were determined, and each zone is characterized by specific alveolinid associations. These zones are distributed as belts stretching from NE Italy (Friuli region) to Montenegro. Alveolinid associations served as a base for a paleogeographic map of the Paleogene Adriatic carbonate platform from the Thanetian to the Priabonian.

alveolina; Paleogene Adriatic carbonate platform; Tethys; Cretaceous/Paleocene - Priabonian; paleogeography

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