Geomorphic Evolution of Continental Terrace (Continental Shelf and Slope)

摘要: Prevailing concepts regarding the geomorphic modification of continental margin rely on theory wave base and its corollaries, namely, a wave-built terrace, topset shelf beds, steep foreset slope beds. These views are rejected because they theoretically unsound do not adequately explain form terrace as revealed by modern echo-sounding profiles. Instead, is considered to be modified various types currents that act at all depths in ocean surf action. Turbidity especially important erosion slopes transportation sediment. Consequently, clastic sediments thought accumulate any large amount except local depressions. most sedimentation take place largely either slope, forming an apron low gradient, or inside zone, near sea-level "hinter-surf" is, littoral, estuarine, lagoonal, deltaic deposits. Much variation present terraces can accounted for assuming these processes have acted different periods time--or, other words, Davisian concept youth, maturity, old age. Initially, structural. In action cuts sediment forms slope. this becomes so weight depresses underlying crust warps down adjacent shelf. This permits preservation hinter-surf deposits which prograded across age, covers entire initial it finally depositional rather than erosional environment. Partial rejuvenation epeirogenic upl ft complete orogeny may occur. Based examination profiles obtained from fathograms, around much Pacific Ocean believed youth; eastern United States, maturity; off Mackenzie Sea sector Antarctica, The Gulf Coast Texas been rejuvenated late maturity. If proposed evolution correct, some sedimentational consequences, tested field, are: (1) depth breaker formation, topography, should dominantly control sedimentation; important; (2) topographic lows, zones non-accumulation amounts sediment; (3) zone deep sea floor along slope; (4) formed ocean; (5) show no marked tendency decrease grain size seaward shelf; (6) turbidity play role transportation; (7) sedimentary strata c pping (for example, States) found beds; (8) result depression due overloading foot (9) beds neither truncated fault nor become instead end littoral facies places where algal-coral reefs grow, limestone deposition, course, takes Such also commonly provide traps collect.