麻豆传媒

B. Sc. Honours Thesis

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Two piston cores, 78-005-112 and 77-002-15, from the Inner Scotian Shelf off the South Shore of Nova Scotia provide the basis for a micropaleontological study of the paleoceanographic trends. The study of benthonic foraminifera provides an accurate determination of paleoenvironments because certain species are restricted to narrow ranges of physical and chemical parameters.

The basal unit of core 78-005-112, with an Elphidium excavatum f. clavata - Cassidulina reniforme faunal assemblage, represents a "warm" ice margin fauna. A barren zone, which overlies the basal faunal assemblage, may signify a rapid change in environment with rapid deposition. A decrease in the ice margin fauna suggests latest glacial or early post-glacial conditions. An assemblage with the co-dominant species of Islandiella teretis and Globobulimina auriculata represents the mid-Holocene hypsithermal. The agglutinated foraminifera of the surface assemblage have statistically related to Inner Labrador Current water. The Holocene paleoceanography is similar to that reported for offshore basins.

The faunal assemblage of the basalt unit of core 77-002-15 represents a shallow, warmer water type of ice margin. An overlying sequence barren of fauna may be related to increased sedimentation rates or lower pH conditions. This event is followed by restricted bay fauna which gradually changes to an open bay assemblage, without Eggerella advena. The fauna of the surface assemblage suggests nearshore conditions, with the addition of some shelf fauna. A radiocarbon date of 14,000 + 200 BP was obtained from the base of the core (400-425 cm). The significance of this date lies in its age and its position relative to sea level. It has been suggested that sea level was 110 m lower than present at 14,000 BP. However, the marine fauna indicates that sea level could not have been 100 m lower at 14,000 BP.

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Pages: 73
Supervisors: David Scott

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