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Bio- and lithofacies of modern sediments in Knight and Bute inlets, British Columbia

Charles T. Schafer, F. E. Cole and J. P. M. Syvitski
Bio- and lithofacies of modern sediments in Knight and Bute inlets, British Columbia
Palaios (April 1989) 4 (2): 107-126


The high sedimentation rates that occur in fjords make them an ideal setting for studying sediment transfer from proximal first cycle sources. These environments, and their associated sediment transport processes, are good analogues to some small hydrocarbon-bearing basins. Knight and Bute Inlets, on Canada's west coast, are fjords that display textural facies of recent sediments and distributions of benthonic foraminifera, thecamoebians and clay-size minerals that reflect freshwater discharge, bottom-water renewal and sediment gravity flow processes. In Knight and Bute, a fjord head prodelta mud facies shaped by fluvial depositional processes is defined by unimodal (5-6) sediments and by low-diversity arenaceous foraminifera assemblages that include a large proportion of displaced freshwater thecamoebian specimens. A comparatively distal basinal mud facies reflects a flocculation process that gives rise to a unimodal (8) sediment. The clay-size fraction of this basinal facies is enriched in quartz and feldspar compared to the prodelta mud. Arenaceous foraminifera predominate in upper and middle fjord basinal mud facies environments but are replaced by calcareous types near fjord mouths because of the seasonal incursion of marine water from the continental shelf. The prodelta mud and basinal mud facies interfinger with a gravity flow and overspill transition facies. The grain size distributions of the transition facies includes types having 1.5 or 4-6 modes that reflect a combination of fluvial, hemipelagic, and gravity flow processes. Channels cut by the downslope transport of coarse sediment as cohesionless mass flows "focus" deposition in distal basins. Inherent in this process is sediment bypassing and the passive transport of large numbers of thecamoebians to distal prodelta marine environments. Sediment on sills near the mouth of Knight and Bute Inlets are reworked morainal deposits facies that are presently being modified by tidal currents that also serve to concentrate indigenous calcareous foraminifera populations into foraminiferal lag deposits.

ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 4
Serial Issue: 2
Title: Bio- and lithofacies of modern sediments in Knight and Bute inlets, British Columbia
Affiliation: Bedford Inst. Oceanogr., Geol. Surv. Can., Dartmouth, NS, Canada
Pages: 107-126
Published: 198904
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 29
Accession Number: 1989-071263
Categories: Oceanography
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch maps
N48°25'00" - N60°00'00", W139°00'00" - W114°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 1989
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