ICHNOLOGY OF HOLOCENE GLACIOMARINE SEDIMENTS: MAKTAK, CORONATION AND NORTH PANGNIRTUNG FJORDS, BAFFIN ISLAND, CANADA
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North Pangnirtung, Coronation and Maktak fjords are situated on Cumberland Peninsula, Baffin Island, Canada, having a common freshwater source related to the melting of the Penny Ice Cap. Bottom photographs and Holocene core samples analysed for this Thesis were acquired during the 1982 Sedimentology of Arctic Fjords Experiment (S.A.F.E.) cruise of the CSS Hudson and were reinterpreted from an ichnological point of view. Bottom photographs were examined to identify epifaunal and infaunal organisms and their associated trails or burrows exposed on the substrate surface. Locomotion and resting traces produced by echinoderms and gastropods, as well as a variety of burrows produced by infaunal organisms, were observed. These biogenic structures were then compared to biogenic structures revealed through x-radiograph images and direct observations from Lehigh cores. Intermediate- and deep-tier structures were observed in the ichnofabric of the glaciomarine sediments. Extensive bioturbation by the shallow-tier epibenthic tracemakers, most notably ophiuroid echinoderms (brittlestars), destroyed much of the primary sedimentary fabric resulting in homogenous silty clay sediments. The dominant deep-tier structure consists of an open burrow three-dimensional boxwork which allows for oxygen penetration into the sediment through the burrow walls at depths below the redox zone. Potential tracemakers for these deep-tier structures are likely polychaetes, particularly capitellids. Sandy event beds, associated with mass wasting of delta front and fjord sidewall sediments, are mostly unaffected by bioturbation. Sedimentation rates during these events were high and re-establishment of the three-dimensional burrow boxwork occurred quickly as normal conditions of suspension fall-out resumed. Deep-tier structures are not observed in sandy intervals indicating that the tracemaker preferred finer-grained sediments. The three-dimensional burrow boxwork occurs pervasively in the cores, though the intensity of bioturbation is greater in cores distal to the fjord head.
DegreeMaster of Science (M.Sc.)
SupervisorMangano, Gabriela; Aitken, Alec
Copyright DateMarch 2012