ABSTRACT: Foraminiferal distribution in the Seymour Belize Inlet Complex, British Columbia: Implications for Holocene paleoceanographic reconstruction.

CGRG Bibliography of Canadian Geomorphology
Search Results

Author :

Date :

Title :

Publication :

Issue :

Page(s) :

Abstract

The Holocene distribution of agglutinated foraminifera and freshwater thecamoebians was reconstructed from two piston cores collected from glacier-carved Frederick and Alison sounds in the Seymour-Belize Inlet Complex (SBIC), British Columbia coast. The sedimentary record archived in these late Holocene cores was characterized by unevenly distributed massive and laminated intervals interrupted by occasional slumps and turbidites.In the Frederick Sound core, the faunal assemblages are overwhelmingly dominated by the foraminiferal species Eggerella advena. In the Alison Sound core, thecamoebians as a group are more abundant than any individual foraminiferal species. Cluster analysis identified the presence of four foraminiferal/thecamoebian biofacies; Eggerella advena Biofacies, Eggerella advena-Recurvoides turbinatus-Spiroplectammina biformis Biofacies, Thecamoebian spp. Biofacies and the Eggerella-advena-Thecamoebian spp. Biofacies. In both cores, these biofacies are characterized by a low Shannon Diversity Index (SDI) (0.064-1.55) indicating that the foraminifera lived in an unfavourable habitat. The predominance of low-oxygen tolerant agglutinated foraminifera and absence of calcareous fauna indicate that oxygen was the main environmental stresser, which exhibited considerable control on the late Holocene foraminiferal distribution in the SBIC. Abundant organic matter in the core sediments provide additional evidence of the low oxygen conditions that precluded most organisms that might have utilized this rich food resource. The presence of varying proportions of freshwater thecamoebians throughout the cores is a result of soil erosion from the adjacent nearby shore in these narrow fjords and subsequent reworking of the nearshore sediments into deep water.A moderate upcore increase in the abundances of the glaciomarine indicator species Spiroplectammina biformis, Recurvoides turbinatus, Portatrochammina bipolaris and Cribrostomoides jeffreysii within the Eggerella advena-Recurvoides turbinatus-Spiroplectammina biformis Biofacies and Eggerella-advena-Thecamoebian spp. Biofacies suggests a subtle shift to cooler bottom water conditions in the late Holocene. Development of these relatively cold bottom water conditions seems to have been coeval throughout the SBIC becoming established at ~2,860 cal yr BP in both the Frederick Sound and Alison Sound cores,

Bibliography of Canadian Geomorphology