THE APPLICATION OF A SUBTIDAL FORAMINIFERA-BASED TRANSFER FUNCTION TO RECONSTRUCT HOLOCENE PALEOBATHYMETRY OF THE PO DELTA, NORTHERN ADRIATIC SEA

Abstract

This study evaluates the potential of a foraminifera-based transfer function to reconstruct the Holocene paleobathymetric evolution of the Po Delta area (northern Adriatic Sea). The Northern Adriatic Transfer Function (NATF) is based upon the largest modern Adriatic database existing in the literature (Jorissen, 1988). The performance of the NATF suggests a strong relationship between observed and foraminifera-predicted water depths (r2jack = 0.95) with relatively precise reconstructions (RMSEP = ~5 m) within the depth range of 8 to 100 m. We applied the NATF to a fossil marine succession in 40-meter-long core from the southern part of the modern Po Delta. The transfer function produced a shallowing-upward trend of paleowater depths from about 30 to 10 m within the interval of 5500-400 cal yr BP. The deepest reconstructed water depths (>18 m) are from the inner shelf deposits at the base of the marine succession (~29–27 m core depths). The transition to a prodelta setting at 4700 cal yr BP is associated with oscillations in water-depth reconstructions and should be treated with caution because of the unstable and complex paleoenvironmental conditions. Thereafter, from core depths of ~27 to 15m, shallower paleowater depths(<18 m) characterize the prodeltaic succession that was deposited as the Po Delta system developed. The shallowest paleowater depths (11–8 m) characterize the uppermost deposits, in line with the shallowing-upward, progradational trend. These results suggest that subtidal foraminifera-based transfer functions can be useful tools in reconstructing the paleobathymetric history of subsurface deposits in modern deltaic systems.