The Late Quaternary Transgressive Record in the Adriatic
Epicontinental Sea
Authors: Cattaneo A. , Trincardi F. 
Published: November 2010

In the Central Adriatic basin the late Quaternary Depositional Sequence comprises four systems tracts that vary greatly in thickness and internal geometry along the margin. Each of the systems tracts was deposited during distinctive portions of the relative sea-level curve that was dominated by the eustatic signal. This paper summarizes the physical-stratigraphic framework of late Quaternary TST deposits in the Central Adriatic area, based on the interpretation of a dense network of seismic profiles, sediment cores and accelerator mass spectrometer (AMS) 14C dates. The Adriatic epicontinental basin includes two contrasting shelf domains: the wide and low-gradient northern shelf and the narrower and steeper central shelf surrounding a slope basin 250 m deep. A refined stratigraphic scheme of complementary shelf and deeper water records helps to recognize the influence of past environmental change on depositional systems, internal geometry, and lateral facies changes within the late Quaternary TST

During the late Quaternary sea-level rise, between 16,000 and 5,500 years BP, several factors influenced the deposition of the TST in the Adriatic basin. Short-term climatic instability caused repeated changes in sediment flux, while the transgressive drowning and widening of this semienclosed basin permanently changed the oceanographic regime, which affected the mechanisms of shelf sediment dispersal. The late Quaternary TST consists of three distinctive units that are easily recognized through high-resolution seismic profiles, sediment cores, and multiproxy stratigraphic data. The middle TST unit is more complex compared to the underlying and overlying TST units, which were deposited during an interval of extreme climatic instability (between approximately 14,800 and 11300 calibrated years BP) and includes proximal progradational and distal mounded deposits on the shelf. The middle TST unit records a peak in sediment flux and mean grain size that suggest a significant change in supply regime

This three-fold subdivision can be extended to the late Quaternary TST in the rest of the Adriatic basin in areas where the record is essentially composed of undersupplied and physically detached barrier-lagoon-estuary systems. These transgressive systems, which either drowned in place or were partially reworked, have no offshore muddy correlative on the northern shelf. This evidence indicates a marked longshore facies partitioning between a northern area with barrier-lagoon deposits and starved shelf and a southern area with thick and complex mud-dominated shelf units. This kind of facies partitioning was established during the deposition of the middle TST and affected the upper TST and the HST as well.

Variable sediment flux and oceanographic regime affect the stratigraphic record, even during an interval of rapid accommodation-dominated cyclicity like the late Quaternary. The recognition of such factors is possible through the study of mud-dominated shelf sequences on modem margins, but it is important to consider the relevance of such factors also when interpreting ancient successions, although straightforward comparisons among modern and ancient continental-margin deposits are hampered by the different investigation techniques required and the diverse scales of observation.