Geotechnical properties of fine-grained turbidite sequences: observations from the Nares Abyssal Plain

Variations in the geotechnical properties of fine-grained turbidite sequences located in the Nares Abyssal Plain appear directly related to the dominant processes controlling sediment deposition. Changes in the index properties are gradational from the turbidite bases, often containing silt beds or laminae, upwards through the chemically laminated possibly turbiditic clays and into the nonturbiditic pelagic and hemipelagic clays. The depth at which consolidation processes begin to control the distribution of geotechnical properties is unclear; however, it is apparent that depositional processes predominate to depths of 3 to 4 meters. Consolidation test results indicate that abyssal plain sediments appear normally to overconsolidated using standard soil mechanics terminology and methods. Clay fabric analyses using transmission electron microscopy show significant variations in grain size, grain type, and orientation between the turbiditic and nonturbiditic clays.