C. Hans Nelson¹, Carlota Escutia², David Twichell³, Chris Goldfinger⁴, Marc DeBatist⁵, William R. Bryant⁶

(1) Department of Oceanography, Texas A & M University, College Station, TX
(2) Ocean Drilling Program, Texas A & M University, College Station, TX
(3) U.S. Geological Survey, MA
(4) College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR
(5) University of Gent, Belgium
(6) Texas A&M University, College Station, TX

ABSTRACT: Case histories of modern depositional systems that link shallow to deep-water sedimentary environments

The importance of a variety of shallow water controls on deep-water systems can be shown in several modern turbidite systems that have been studied with multibeam bathymetry, sidescan sonar, seismic profiles, and piston cores. In Lake Baikal, Russia and Wilkes Land, Antarctica, the effect of glacial sources results in unusual fan morphology together with backstepping lobe and channel infilling history as the glaciers recede. In Bryant Canyon during isotopic stage 6 of the Pleistocene, Mississippi deltaic sources fed a slope pathway of fill and spill intraslope turbidite basins that led to Bryant Fan on the deep basin floor of the Gulf of Mexico. Post-depositional salt withdrawal tectonics since then have resulted in canyon and basin infilling by mass transport deposits. On the Ebro continental margin, Messinian dessication of the Mediterranean Sea resulted in a subareal drainage system that extended to the deep-basin floor. During the Pleistocene these subareal valleys were reoccupied as canyon and turbidite channel pathways that drained turbidites into Valencia Valley and aborted distal lobe development in the Ebro turbidite systems. Southwest Ebro shelf currents have resulted in an 80 km asymmetric progradation of the slope wedge and development of turbidite systems progressively southwestward during the Pleistocene. Generation of synchronous seismo-turbidites, in a variety of tributary canyons along the 1000 km Cascadia subduction zone USA during the late Quaternary, has resulted in deep-sea channels, submarine fans, base of slope aprons, and complexes of plunge pools, sediment waves, channels and distal lobes.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado