--> Abstract: Foraminifera as Paleoceanographic Proxies of Canadian Fjords during the Last 1100 Years; #90063 (2007)

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Foraminifera as Paleoceanographic Proxies of Canadian Fjords during the Last 1100 Years

 

Vázquez Riveiros, Natalia1, R. Tim Patterson1 (1) Carleton University, Ottawa, ON

 

Foraminiferal and thecamoebian faunas from the Seymour-Belize Inlet Complex (SBIC), a fjord network situated in the mainland coast of British Columbia, were studied to asses climatic cycles and trends impacting the area through the ~ AD 900 – 2002 interval.

Through cluster analysis, ordination methods, and the use of foraminiferal-based transfer functions, a period of weak estuarine circulation due to diminished precipitation, with feeble incursions of ocean water into the basin, was recognized in the area during the Medieval Warm Episode, which occurred here between ~ AD 900 and 1495. During this time, bottom waters in the SBIC became dysoxic to anoxic and only a low diversity agglutinated foraminiferal fauna survived. Conversely, in the years between AD 1574 and 1943, a very strong estuarine circulation developed, with frequent renewals of the bottom waters by cold, oxygenated ocean currents enhanced by a strong precipitation pattern. This period is concomitant with the onset of the Little Ice Age in western Canada, which in the SBIC was characterized by higher levels of precipitation that promoted high oxygen bottom waters and the development of a diverse calcareous foraminiferal fauna. This circulation pattern continued until 1943, when conditions similar to those existing in the inlet prior to 1495 began to redevelop.

 

This study shows the potential of high-resolution foraminiferal research in the development of accurate climate chronologies. Foraminiferal-based transfer functions are established as very functional, both as a validation of previously defined clusters and as a quantitative instrument to estimate past values of environmental variables.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California