Deep Sea Depositional Systems of the Thyrrenian Basin

Fabiano Gamberi and Michael Marani
ISMAR-CNR-GEOLOGIA MARINA BOLOGNA, Bologna, Italy

We review, on the basis of newly acquired multibeam and seismic reflection lines, the present-day morphosedimentary features and the character and distribution of depositional systems within the Tyrrhenian Sea and their relationship with the recent geological evolution of the area consisting of distinct, eastward migrating episodes of extensional tectonics and backarc basin opening. Numerous intraslope basins are located along the rifted margins that surround the two abyssal plains of Vavilov and Marsili, where extensional tectonics has progressed up to back-arc basin formation. Due to the variability in age and style of the tectonics that have shaped the margins and of the present-day geodynamic setting of the adjacent emerged areas, contrasting sedimentary processes are active and are responsible for distinct depositional environments in the different intraslope basins.

We will show examples of destructional slope sectors characterized by large mass-wasting complexes or focused erosion along canyon systems as compared with prograding slope wedges consisting of channel-levee deposits. The variations in the depositional elements of the different intraslope basins, consisting either of small fans with circular or elongated planform and dimensions up to 15 km, or of sedimentary pathway bypassing to deeper levels will be highlighted and the morphology and sedimentary regime of the resulting slope valleys discussed. Finally, the factors that control the development of the depositional systems in a single key intraslope basin, where constructional and destructional slope sectors coexist, will be analyzed.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005