MORPHOSTRUCTURE, GROWTH-PATTERNS, AND TECTONIC CONTROL OF THE RHONE AND NILE DEEP-SEA FANS - A COMPARISON

The Rhone and the Nile rivers shape the sediment distribution of the L igurian and the Levantine basins in the Mediterranean Sea, respectivel y. Both rivers cut huge canyons in their bed rock during the Messinian desiccation of the Mediterranean, and the subsequent early Pliocene m arine transgression reached far inland both in France and in Egypt, Th e sediment supply of both rivers was affected by climatic variations d uring the Pleistocene, but whereas glacial periods were associated wit h reduced water flow in the Rhone, they can be correlated with enhance d flow of the Nile. The sediment distribution and accumulation pattern s of both rivers built large deltas on their continental shelves durin g high sea level stands. During low-stands both rivers flowed as far a s the shelf edge, and transported their sedimentary load through the c ontinental slopes directly to their deep-sea fans. The patterns of sed iment distribution and accumulation in the marine basins of the Liguri an and the Levantine seas were affected also by Pliocene-Quaternary te ctonic activity and halokinetic offsets that led to sediment instabili ty. The present hydrographic and sedimentological regimes of both rive rs do not represent their natural potential due to artificial interfer ence. The principal economic significance of the deepsea fan accumulat ion process is the transportation of medium- and coarse-grained sedime nts into the deep-marine basin. Considering the effect of these sedime nts on stratal permeabilities and hydrocarbon potential, the presented comparative overview emphasizes recent and subrecent sedimentological aspects that are critical to petroleum exploration in active and exti nct deep-sea depositional environments.