William Souchen

A micropaleontological study was carried out on a core taken from latitude 45.8^oN in St. Annes Basin on the northern Nova Scotian Shelf. Benthonic foraminiferal assemblages were defined in terms of abundance and dominance and were used to construct late Pleistocene - Holocene paleoceanographic trends and changes in bottom watermass characteristics. The result of this study indicate that a discontinuous glacial - interglacial record is present at this site.

Late Pleistocene glaciomarine sediments in the lower part of this core are dominated by an Elphidium excavatum f. clavatum - Cassidulina reniforme assemblage. This assemblage is typical of an ice - margin environment during which there was an influx of glacial meltwater. The presence of reworked Cretaceous Foraminifera indicates that the ice front was in close proximity and was probably in contact with Tertiary - Cretaceous sediments near the basin during the peak glacial stage. The glaciomarine sediments are cut off abruptly by a thin turbidite sequence which also contains reworked Cretaceous species. The turbidite was preceded, or was proceeded, by the erosion of the latest glacial and early Holocene sediments.

Directly overlying the turbidite is an assemblage characterized by the presence of Brizalina subaenariensis and other warm water calcareous species. This assemblage occurs primarily in warmer, more saline bottom waters that occurred during a warm interval in the mid - Holocene (about 7,000 - 5,000 yrs BP) and in the warmer, more saline waters that are characteristic of basins on the Southern Scotian Shelf. The interval above this is characterized by an increase in colder water calcareous fauns and agglutinated faunas which indicate a period of cooling from the mid - Holocene to present. The presence of a mixed fauna in the surficial sediments suggests a recent slumping of sediment in this basin.

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Pages: 73
Supervisor: David Scott