Climatic influences on sediment deposition and turbidite frequency in the Nitinat Fan, British Columbia

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doi: 10.1016/j.margeo.2009.03.002
Author(s): Knudson, K. P.; Hendy, I. L.
Author Affiliation(s): Primary:
University of Michigan, Department of Geological Sciences, Ann Arbor, MI, United States
Volume Title: Marine Geology
Source: Marine Geology, 262(1-4), p.29-38. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 49 refs.; illus., incl. sects., sketch map
Summary: Continental margins in regions influenced by temperate ice sheets experience climate-dependent changes in sedimentary processes. A new stratigraphy is presented for Ocean Drilling Program Hole 888B, from the Nitinat Fan, on the Vancouver Margin, in which we examine the relationship between fluctuations in glacial-sourced sediment delivered to the continental shelf and turbidite character and frequency. Glacial/interglacial episodes are determined based on: (1) core lithology, where sandy/coarse-grained sediment and fine-grained clay/silty clay represents glacial and interglacial intervals, respectively; (2) δ18O of planktonic foraminifera G. bulloides, in which higher values indicate warmer sea surface temperatures and lower global ice volume; (3) magnetic susceptibility, in which higher values indicate coarser grain sizes deposited during glacials; and (4) ratios of sinistral N. pachyderma to dextral N. incompta, in which higher proportions of N. pachyderma are a sign of cooler sea surface temperatures. Finally, using radiocarbon 14C dates, specific Marine Isotope Stages (MIS) within the top 240 m of core are assigned: MIS 2-4 (2-118 mbsf), MIS 5 (118-157 mbsf), and MIS 6 (213-240 mbsf). Using this chronology, sedimentation rates for the Nitinat Fan were greater (187 cm/kyr) during glacial MIS 2-4 than interglacial MIS 5 (69 cm/kyr). Additionally, during glacial MIS 2-4 thicker turbidites (upwards of ≈150 cm) were deposited relatively frequently (≈75 year periodicity) compared with those from MIS 5, which are relatively thin (up to 27 cm) and deposited more rarely (≈130 year periodicity). These results indicate that turbidite frequency and thickness are linked to climate through ice sheet extent, since transport of glacimarine sediment to the continental slope promotes turbidity currents that are responsible for the most significant amount of offshore sedimentation. This study shows that geological processes influencing turbidite deposition can fluctuate over time and may not necessarily be represented by ongoing processes within the modern depositional setting. Abstract Copyright (2009) Elsevier, B.V.
Year of Publication: 2009
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Absolute age; British Columbia; C-14; Canada; Carbon; Cascadia Basin; Cenozoic; Climate effects; Continental margin sedimentation; Cordilleran ice sheet; Cycles; Dates; East Pacific; Foraminifera; Glacial environment; Glacial extent; Glacial geology; Glaciomarine environment; Globigerina; Globigerina bulloides; Globigerinacea; Globigerinidae; Grain size; Ice sheets; Interglacial environment; Invertebrata; Isotope ratios; Isotopes; Leg 146; Magnetic susceptibility; Marine environment; Marine sediments; Microfossils; Neogloboquadrina; Neogloboquadrina pachyderma; Nitinat Fan; North Pacific; Northeast Pacific; O-18/O-16; ODP Site 888; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Protista; Quaternary; Radioactive isotopes; Rotaliina; Sediment transport; Sedimentation; Sedimentation rates; Sediments; Stable isotopes; Submarine fans; Turbidite; Vancouver Island; Western Canada
Coordinates: N480959 N481001 W1263943 W1263948
Record ID: 2009070060
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands