Distribution of recent benthonic foraminifera near Sable Island, Nova Scotia

Abstract

Sable Island is a 38 km long feature that is situated near the outer margin of the Scotian Shelf between George's Bank and the Laurentian Channel. Grab samples of the predominantly sandy substrate that surrounds the island's offshore areas were collected from water depths of 0 to ~55 m.Textural data indicate that winnowing processes are comparatively intense in offshore areas, especially on the north side of the island. A higher frequency of samples containing more than 2% clay-size particles occurs in an area lying off the southeastern coast of the island. The clay suggests that a pre-Recent source of fines is there or that wave energy conditions are somewhat reduced at this locality.Cluster analysis of foraminiferal percentage data defines several foraminiferal thanatotopes. The largest one is dominated by Eggerella advena, with large percentages of Elphidium and Trochammina. The second largest thanatotope is distinguished by its comparatively high porportion of miliolid species and by the highest mean percentage of E. advena.The offshore shelf environment around Sable Island appears to represent an area where several regional assemblage zones overlap. The factors controlling local assemblage distribution patterns in the shelf environment surrounding the island do not appear to be related directly to ambient water-mass characteristics. However, the occurrences of assemblages that include a large proportion of the lower estuarine – nearshore species E. advena may indicate the existence of an influx of groundwater from the island's aquifers to the surficial layer of offshore sediments.Foraminiferal barren zones are apparently related to resuspension and transport of tests to zones of reduced wave energy and to long-term effects of abrasion on the total indigenous thanatocoenoses.