THE MIDDLE AND LATE PLEISTOCENE EVOLUTION OF THE BEAR-ISLAND TROUGH MOUTH FAN

The evolution of a submarine fan, the Bear Island Trough Mouth Fan, is outlined using high-resolution seismic data. Fight seismic units are identified. The identified units comprise sediments of Middle and Late Pleistocene age. They were probably deposited during eight glacial ad vances of the Barents Sea Ice Sheet to the shelf break. The units are dominated by a chaotic seismic signature on the upper fan and a mounde d seismic facies further downslope. The mounded signature is inferred to reflect large submarine debris flow deposits, probably generated by oversteepening of the upper slope. Unlike many other passive margin f ans, glacigenic sediments derived from an ice sheet at the shelf break were the primary sediment input. During interstadials and interglacia ls the sedimentation rate was reduced markedly. Three large sliding ev ents also influenced the Middle and Late Pleistocene fan growth.