1. LATE NEOGENE AND QUATERNARY SEDIMENTATION ON THE CONTINENTAL SLOPE AND UPPER RISE OFFSHORE SOUTHEAST GREENLAND: INTERPLAY OF CONTOUR AND TURBIDITY PROCESSES1Lene Clausen2 |
Three seismic sequences have been identified within the late Neogene and Quaternary deep-sea sedimentary succession on the continental slope and rise in the Irminger Basin offshore southeast Greenland. They are bounded at the base by unconformities of middle Pliocene, early Pliocene, and (?) late Miocene ages, respectively. The sequences form large, elongate drifts on the seafloor, oriented almost perpendicular to the continental rise. The seismic facies of the two youngest sequences suggest mixed deposition both from contour and turbidity currents off the then glaciated shelf. Inter-drift channel-levée complexes recognized within the youngest sequence (middle Pliocene–Pleistocene) were deposited from turbidity currents. The major turbidity channels, originating at the base of the continental slope, are prolongations of transverse shelf trough/trough-mouth fan systems. A moat zone separates the elongate drifts from the continental slope. The depth stratum of the modern southward-flowing deep-sea contour-currents correlates with the position of this moat zone. It is concluded that the Labrador Sea Water Current has played a far more important role in sculpturing the continental slope and rise than earlier recognized. Mixed depositional systems as described in this paper might prove to be a widespread feature at high-latitude glaciated margins. |
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