Marsh foraminifera in the Bay of Fundy: modern distribution and application to sea-level determinations

Authors

  • D. A. Smith Centre for Marine Geology, Dalhousie University, Halifax, N.S. B3H 3J5
  • D. B. Scott Centre for Marine Geology, Dalhousie University, Halifax, N.S. B3H 3J5
  • F. S. Medioli Centre for Marine Geology, Dalhousie University, Halifax, N.S. B3H 3J5

DOI:

https://doi.org/10.4138/1581

Abstract

Although marsh foraminiferal zonations are comparatively well known for most of Atlantic Canada, data from the vertically expanded marsh zones in the Bay of Fundy are insufficient for marsh foraminiferal zonations that can be used to accurately determine former sea levels. In this paper we present data from two well-documented surface transects that illustrate vertical ranges of marsh foraminifera in the Bay of Fundy. Trochammina inflata characterizes the highest margin with a zone la of 20cm vertical range. Tiphotrocha comprimata together with T. inflata comprise zone lb (vertical range 75cm) while Miliammina fusca and other low marsh species characterize zone II faunas (vertical range 450cm). As in Atlantic marshes the fauna nearest the higher high water level produces the best accuracy for relocating former sea levels while low marsh (zone II) is not a good indicator. Using marsh foraminiferal zonations and the tidal amplicication curve developed in earlier work, it is now possible to accurately determine former sea levels in the Bay of Fundy, at least for the last 4000 years. RÉSUMÉ Même si L’on connait assez bien la zonation des foraminifères de marais pour la plus grande partie de la côte atlantique du Canada, le manque de données sur le dévelopment vertical des zones de marais nous empèche d'établir avec exactitude les niveaux marins passés. Dans cet article, nous présentons des données provenant de deux traverses bien documentées, qui illustrent les étendues verticales des fora-miniféres de marais dans la Baie de Fundy. Trochammlna inflata charactérise la limite supérieure par une zone la d'une étendue verticale de 20cm. Tiphotrocha comprimata ainsi que T. inflata embrassent la zone lb (étendue verticale de 75cm) cependant que Miliammina fusca et d'autres espèces de basmarais charactérisent les faunes de la zone II (fitendue verticale de 450cm). Comme dans les marais at I antiques, la faune ia plus près du plus haut niveau de marée haute procure la meilleure exactitude pour situer les niveaux marins antérieurs alors que la zone de bas-marais (zone II) n'est pas un bon indice. L'utilization des zonations de foraminifères de marais et de la courbe d'amplification de marée développée lors de travaux antérieurs permet done de déterminer avec exactitude, à tout le moins pour les derniers 4000 ans, les niveaux marins passés dans le Baie de Fundy. [Traduit par le journal]

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Published

1984-12-12

How to Cite

Smith, D. A., Scott, D. B., & Medioli, F. S. (1984). Marsh foraminifera in the Bay of Fundy: modern distribution and application to sea-level determinations. Atlantic Geoscience, 20(3). https://doi.org/10.4138/1581

Issue

Vol. 20 No. 3 (1984)

Section

Articles

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