麻豆传媒

Approximately 1000 surface and subsurface samples were used to determine the marsh and estuarine foraminiferal distributions in four marsh-estuarine areas in Nova Scotia: Chezzetcook Inlet, Chebogue Harbour, Wallace Basin, and Summerville marsh.

Several assemblage zones could be recognized in the estuarine environment of Chezzetcook Inlet, however these zones were not accurate indicators of sea level. Detailed sampling in Chezzetcook revealed that marsh foraminiferal distributions demonstrated strong vertical zonation with respect to mean sea level and closely paralleled marsh floral zonation. These distributions could accurately relocate former sea levels to within + 5 cm. Seasonal variations had little effect on total populations and they probably did not cause serious errors when interpreting subsurface foraminiferal assemblages.

Less detailed sampling of marsh areas in the other three study localities indicated that the same relationships observed in Chezzetcook occurred in these areas as well. Examination of detailed data from southern California and less detailed data from other parts of the world suggest that marsh foraminiferal assemblages generally can be used as accurate sea level indicators.

Subsurface borings in Chezzetcook, Chebogue, and Wallace are interpreted from recent foraminiferal data. Accurate determinations of former sea levels using marsh foraminiferal assemblages indicate that Chebogue is experiencing less relative rise now than in the past. The opposite is true for Chezzetcook where relative sea level rise has apparently increased in the last 2000 years. Wallace is experiencing a relatively low apparent sea level rise. The collapsing of the "peripheral bulge" following deglaciation is proposed as the mechanism causing these differential relative sea level rises.

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Pages: 254
Supervisor: Franco Medioli