CGRG Bibliography of Canadian Geomorphology
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Author : Enkin, R.J.; Dallimore, A.; and Baker, J.
Date : 2007.
Title : A combined 14C, varve count and paleomagnetic secular variation age model for Effingham Inlet, Vancouver Island, B.C.
Publication : CANQUA Ottawa 2007. Canadian Quaternary Association Conference, June 4-8, 2007. Carleton University, Ottawa, Ontario, Canada.
Issue :
Page(s) :
Abstract
Annually laminated sediments raised from the anoxic Effingham Inlet, Vancouver Island, B.C., record oceanographic, climatic and tectonic conditions. By matching varve thickness patterns between cores, we have produced a continuous record from modern times, collected in freeze cores, down to the Late Pleistocene, collected in piston cores including the 41 m MD02-2494 Calypso core. We combine over 50 14C dates with paleomagnetic secular variation correlations and varve counts to produce a well-constrained and reliable age model. Holocene sediments consist of three main facies: laminated muds, homogenites, and seismites or debris flow units. The depositions rate in the laminated muds can be measured directly from the varve thicknesses. Sedimentological and physical properties observations, combined with the oceanographic model for their formation, indicate that the deposition rate of the homogenites are similar to the laminated muds. The seismites and debris flow units, which are distinguished from the homogenites using sedimentological and physical properties observations, are deposited almost instantaneously. The dispersion of age constraints around a linear age model for the Holocene sediments is significantly reduced when the major seismites are subtracted from the depth. Seismites in the Effingham Inlet record which can be positively correlated to Cascadia subduction earthquakes observed in offshore turbidites are more reliably dated than can be done with marine 14C measurements.
Bibliography of Canadian Geomorphology