Ingo Klaucke¹, Neil H. Kenyon¹, John Millington¹, Michael Ivanov²
(1) Southampton Geological Centre, Southampton, United Kingdom
(2) Moscow State University

Abstract: Canyon-lobe systems on the western margin of Corsica and Sardinia, NW Mediterranean Sea

The continental margin west of Corsica and Sardinia is characterized by a narrow continental shelf and a steep continental slope with numerous, up to 800 m deep, straight canyons showing high-backscatter intensity on side-scan sonar images. The canyons are generally filled with gravelly material forming sediment waves while the canyon walls and areas outside the canyons present numerous mass-wasting deposits (mainly slumps and debris flows). In about 2500 m water depth, these canyons directly connect to depositional lobes that show low backscatter in the center with surrounding zones of alternating high- and low-backscatter intensity.

Coring of the lobes revealed the presence of sheet-like, yet laterally discontinuous and up to 3 m thick sand deposits. The lateral extent of the lobes is only a few tens of kilometers, reflecting a small source area. With the exception of the northernmost canyons, whose depositional lobes interfinger with the dominant Var lobe, the continental margin west of Corsica and Sardinia present small, sandy depositional lobes that are directly attached to slope canyons. The lobes probably present good connectivity of the sand deposits. We believe the main reasons for the canyon-lobe architecture and sandy nature of the systems are a small and steep subaerial drainage basin together with a restricted lateral extent of the system (only 150-250 km separate the source area from the depocenter).

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana