- Chapter contents
- Abstract
- Introduction
- Methods
- Results
- Acknowledgments
- References
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Figures - PDF file
doi:10.2204/iodp.proc.341.203.2017
Introduction
Site U1419, drilled during Integrated Ocean Drilling Program (IODP) Expedition 341, is located on the upper continental slope in the northern Gulf of Alaska (Fig. F1) (see the “Site U1419” chapter [Jaeger et al., 2014b]). Previous results from the site reveal a high-resolution, heterolithic, deglacial–modern sedimentary record (Davies et al., 2011; Addison et al., 2012). The drilling objectives of Site U1419 were to extend this record of glacial dynamics and paleoceanography into the late Pleistocene. The primary objectives were to constrain the timing of modern to late Pleistocene glacial events of the northwestern Cordilleran ice sheet. The secondary objectives were to document the influence of North Pacific sea-surface temperatures as a control on the regional glacial dynamics and to address the dynamics of productivity and intermediate water circulation on hypoxia in the region.
Previous work done at this site revealed the link between the varied sedimentary lithofacies and the water column and glacimarine processes. Diamicts accumulated from the deglacial (~17.5 ka) through to ~14.8 ka, after which warming coincident with the Bølling Interstate of northern Europe and Greenland resulted in a lithofacies transition to laminated mud (Davies et al., 2011). Periods of enhanced water column productivity and bottom water hypoxia between 10.7 and 14.8 ka are recognized by this laminated facies (Addison et al., 2012). The Holocene period of accumulation consists of massive bioturbated mud (Davies et al., 2011).
The periodic correspondence of the Gulf of Alaska paleoclimate with events in the North Atlantic suggests that strata accumulating at Site U1419 prior to the deglacial could contain stadial and interstadial periods with varied productivity and glacigenic sedimentation (Praetorius and Mix, 2014). Lithofacies and sediment composition are expected to follow these potential changes. To create a high spatial resolution elemental data set to capture these changes, scanning X-ray fluorescence (XRF) analyses were performed on core sections within the stratigraphically continuous spliced composite record (see the “Site U1419” chapter [Jaeger et al., 2014b]). Elements of interest were those commonly used to identify changes in lithofacies and paleoproductivity (Rothwell and Croudace, 2015). In this report, we present the raw count data for all measured elements of interest. The data are available for all measured sections as CSV files in XRF in “Supplementary material.” Downcore and box and whisker plots of all elements are provided in DOWNHOLE and BOXPLOTS in “Supplementary material.”