Print this pageAbstract: Continental Slopes
The continental slope is defined as the zone extending from the shelf break and terminating at the continental rise where the gradient becomes less than 1:40, or where the slope is bounded by a deep-sea trench or a marginal plateau. Although the slope is commonly the steepest physiographic province of the continental margin, a single simple definition cannot be given. Its width ranges from 20 to 100 km, its upper limit at the shelf break normally starts in water depths between 100 and 200 m. The slope province can be smooth or terraced, may contain steep escarpments or intraslope basins, or can be very irregular as a result of slumping, fault scarps, or diapirs. Most slopes are cut transversely in their upper part by submarine canyons that connect to deep-sea fans which f rm constructive sediment bodies on the lower slope, rise, and parts of the abyssal plain.
Slopes are located in both active and inactive tectonic settings, and the concepts of seafloor spreading and plate tectonics are important for interpreting the evolution of the slope. Construction by sediment up- and out-building, slumping and sliding, the influence of sea-level fluctuations, and reef formation or salt tectonics result in slopes different from those provided by the action of subduction and plate accretion.
As the transition zone between the continental shelf and the deep sea, the continental slopes form an important segment of seafloor studies for scientific, economic, and political reasons. Differing tectonic and depositional histories result in a variety of sediment suites and morphology, and in some areas these factors combine to produce conditions favorable for accumulation of economic quantities of oil and gas as well as selected hard minerals.
AAPG Search and Discovery Article #90961©1978 AAPG Annual Convention and Exhibition, Oklahoma City, Oklahoma