Pleistocene Turbidites of the Canada Abyssal Plain of the Arctic Ocean

Abstract

ABSTRACT Turbidites comprise about 27% of the cored sediments in the northeast and southeast parts of the Canada Abyssal Plain but only 2.5% of the cores from the north central part of the Canada Abyssal Plain. Turbidites have not been identified in cores from other areas of the Arctic Ocean. The most common sedimentary structures in the Canada Abyssal Plain turbidites are plane-parallel laminated Bouma B or D units, ripple cross-laminated Bouma C units, massive Bouma A units, and load deformation structures. The bulk of the deposits are composed of silt-sized particles. The sand-sized fractions are mostly well-sorted very fine sands. The turbidite sand-sized fractions are composed dominantly of quartz, chert, and detrital calcite. The mineralogy of the turbidites is very homogenous but does not identify a particular dominant source area. An averaged sedimentation rate of 83 mm/l,000 years can be calculated for part of the Canada Abyssal Plain based on a C14 age date of 700 ± 100 years BP for Foraminifera found in a brown lutite layer in 34 cores. The higher concentration of turbidites in the northeast and southeast parts of the Canada Abyssal Plain indicates that the Canadian Archipelago was the most likely source area for the deposits. The turbidity current flows possibly originated as a result of seismic shocks, or due to oversteepening of slopes because of high sedimentation rates, or as a result of lowered sea level during major periods of deglaciation.