01970nas a2200193   4500000000100000008004100001260004900042100001400091700001400105700001700119700001200136700001600148700001900164700001300183245009000196856003400286300001200320520144400332       2002                            d  bThe Royal Society of New ZealandaWellington1 aC. Pudsey1 aJohn Howe1 aPeter Morris1 aD. Gunn1 aJ.A. Gamble1 aD.N.B. Skinner1 aS. Henry00aProcesses on sediment drifts from 3.5 kHz data, Antarctic Peninsula continental rise.  uhttp://nora.nerc.ac.uk/14171/  a345-3503 aOn the continental rise west of the Antarctic Peninsula, large sediment drifts preserve a hihg-resolution record of Neogene glaciation, We present a new map of acoustic facies on the continental rise, derived from 3.5 kHz profiles. Most drifts have steep sides to the southeast (towards the base of the slope) and southwest (towards the channels which separate each drift). The gentle slopes of the drifts (to northeast, and merging with the abyssal plain to the northwest) contain laterally continuous sub-bottom reflectors. Convergence of reflectors to the northwest shows the sediments thin offshore, confirmed by core studies; strike lines show negligible thickness change acress the drifts, except within a few kilometres of the channels. It is likely that deposition from meltwater plumes and slope-derived turbidity currents pevailed over deposition from channelised turbidity currents. Small areas of sediment waves occur on two drifts. Evidence for small-scale mass wasting includes normal faults and slump blocks on the steep sides of all the the drifts, and one drift contains a number of small, locally derived debris flows. Both 3.5 kHz profiles and cores show evidence for a change in sedimentation style at c. 3300 m water depth, with intermittent bottom-current winnowing above this depth. Sedimentation rates from ODP Leg 178 show the acoustic penetration depth of some 50 m represents the last 0.5-1.0 m.y. of deposition.