Drivers of Continental Margin Growth. Examples from the Quaternary Adriatic Basin

Abstract

The growth of continental margins typically results in the development of large-scale sedimentary units with sigmoidal-shaped profiles, termed clinothems. Clinothems occur at a variety of spatial and temporal scales, are recognized from shelfal to basin regions and represent one of the fundamental building blocks of prograding successions. This Ph.D. thesis is based on four datasets from different case histories along an hypothetical sediment routing system of the Adriatic continental margin. The main goal of this Ph.D. thesis is to investigate how the interaction of allogenic and autogenic processes impacts on river morphodynamics and drives clinothems development and growth, and ultimately the formation of modern continental margins. The first case history is a portion of the Po River upstream the Isola Serafini dam. This area may be considered as a natural laboratory where investigate and quantify the impact of the backwater effect on river morphodynamics. The second case history is the Mid Adriatic Deep during the Last Glacial Maximum, where a 350m thick succession developped in a very short-time window. This area allows to investigate the internal architecture, geometric relation and facies distribution of a lowstand delta. The third case history, offshore the Gargano Promontory, offers the possibility to investigate how genetically-related coastal and subaqueous progradations, i.e. a compound delta, may develop at sub-millennial time scale. The fourth case history, the southern Adriatic Basin, gives opportunity to investigate the impact of the oceanographic regime on sediment transport, where, far from direct sediment feeding sources, lateral advection and current deposition became the dominant mechanism of margin progradation. Working on the Adriatic Quaternary succession it was possible to document the effect of a paramount control on margin feed and progradation, to discriminate short-lived phases of extremely rapid deposition during the margin construction, and to document the importance of oceanographic processes on margin growth.