Rebesco et al. (1998) proposed a general depositional model that relates sediment drift evolution on the Antarctic Peninsula Pacific-margin continental rise to glacial processes on the continental shelf. In their model, terrigenous sediment was directly delivered to the rise and contributed to the construction of large sediment drifts when grounded ice extended to the shelf edge. In this scenario, large volumes of fluidized sediment by-passed the margin at the mouth of ice streams (i.e., fast flowing ice), whereas prograding slopes were constructed on those portions of the shelf margin between major ice streams. This model relies heavily on the modern geomorphology of the margin. In contrast, an evaluation of the subsurface stratigraphy suggested that there may have been significant lateral shifts of ice-stream locations and associated trough-mouth-fan depositional systems through time (Bart and Anderson, 1995). New seismic data was acquired along the strike of the Antarctic Peninsula shelf during the 2002 season aboard the NBP R/VIB. Detailed mapping and regional correlations confirm that slope progradation between the modern troughs was indeed associated with large ice streams. Moreover, the new mapping results presented here illustrate that the last several glacial cycles did not produce significant slope progradation anywhere along the margin. This signifies a major change in the stratal-stacking pattern on the outer continental shelf. Correlation with age control at ODP Leg 178 shelf sites 1097 and 1103 indicates that the shift from progradation to aggradation occurred at approximately 5 Ma (Pliocene).

West: -74.0000 East: -66.0000 North: -64.0000 South: -66.3000

Expedition: 178

Site: 178-1097

Site: 178-1103

Includes appendices; accessed on Sep. 19, 2006

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=2007-034730 (c.f. for more detailed metadata)

Data download: application/pdf

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