Mass transport deposits on the southwestern Newfoundland slope

Abstract

Sediment mass failure is a major process during Cenozoic development of the southwestern Grand Banks of Newfoundland margin. Recently acquired seafloor multibeam and seismic reflection data provide evidence of stacked and regionally extensive mass transport deposits (MTDs) since the middle-late Miocene. MTDs with volumes between 30 and 150 km3 lie between the top of a Cretaceous Unconformity and mid-Pliestocene and MTDs with volumes less than 1 km3 are recognized since the mid Pleistocene. Seaward dipping faults at the base of the mid Miocene MTD suggest zones of weakness and increase the susceptibility to failure. Sediment stability is also reduced by ongoing shallow salt deformation. These factors and sealevel lowering are key ingredients leading to sediment failure during the mid Miocene to Middle Pleiocene. During the Pleistocene, high sedimentation rates following glaciations may have generated underconsolidated sediment profiles with interbedded sandy horizons, explaining more frequent and smaller MTD sizes in the Plio-Pleistocene section. Although these factors "precondition" the sediment column to mass failure, seismicity, such as occurred in 1929, is likely the ultimate triggering mechanism. © Springer Science + Business Media B.V. 2010.