Sedimentary response of the Po Basin to Mid-Late Pleistocene glacio-eustatic oscillations

The Middle and Late Pleistocene were characterized by high-amplitude climate and sea-level oscillations that deeply influenced the evolution of alluvial and coastal systems worldwide. Through the correlation of 43 cores and 168 well data, with the aid of pollen, meiofauna, 14 C, ESR and IRSL data, this work provides a detailed reconstruction of the Middle Pleistocene to Holocene stratigraphy of the Po Basin and explores the sedimentary response of the Po-Adriatic alluvial-coastal system to glacio-eustatic oscillations and other concomitant forcing factors. The Middle Pleistocene to Holocene sedimentary succession of the Po Basin is composed of alluvial, paralic, coastal and shallow-marine facies associations arranged in an overall shallowing-upward trend. This general trend is punctuated by the rhythmical alternation of progradationally stacked coastal wedges with thick alluvial deposits. At landward locations, where the coastal facies wedge out, the depositional cyclicity records alternating paralic and alluvial facies associations. The overall shallowing-upward trend documents the longer-term, progressive filling of the basin driven by high sediment supply which overcame the rate of creation of accommodation induced by subsidence. The cyclic arrangement of facies, paralleled by rhythmical changes in vegetation, reflects Milankovitch-scale, glacio-eustatic oscillations in the 100 ka band. Increasing subsidence towards the sea and the activity of selected sectors of the buried Apennine thrust front, might have enhanced the seaward migration of coastal wedges. This study provides clues on the sedimentary response of a low-gradient coastal system to dramatic climatic and eustatic changes. The model of basin evolution presented here may help predict the environmental modifications of coastal areas in near future scenarios of climate and sea-level change.