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High-resolution sediment records from the climatically sensitive Svalbard margin are crucial for reconstructing ice sheet dynamics and ocean–ice sheet interactions during past warm periods. In the boreal summer of 2024, International Ocean Discovery Program (IODP) Expedition 403 collected new sedimentary records from the eastern Fram Strait. Here, we present X-ray fluorescence (XRF) scanning data for the uppermost ~85 m at Site U1618, which was drilled on the eastern Vestnesa Ridge near the continental margin of Svalbard. XRF data, complemented by shipboard magnetic susceptibility and natural gamma radiation records, are used here to improve our understanding of sediment geochemical variability and evaluate stratigraphic variations in elements widely used in proxies of marine productivity, terrigenous sediment input, and authigenic alteration.
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This content will become publicly available on April 7, 2027
Data report: sedimentary X-ray fluorescence scanning of International Ocean Discovery Program Expedition 374 Site U1521, Ross Sea, Antarctica
International Ocean Discovery Program (IODP) Expedition 374 drilled Site U1521 (75°41.0′S, 179°40.3′W; 562 m water depth) on the middle to outer continental shelf in the Pennell Basin, Ross Sea (Figure F1), to test hypotheses related to Neogene evolution of the West Antarctic Ice Sheet, particularly in the Miocene (McKay et al., 2019a). Site U1521 was drilled to a total depth of 650.1 meters below seafloor (mbsf) and recovered 411.5 m (63% recovery) of Lower Miocene to Pleistocene sediments. The sedimentary sequence includes seven lithostratigraphic units (McKay et al., 2019b) containing diamictites, mudstones, diatom-rich mudstones, and diatomites that provide insight into past depositional environments (Marschalek et al., 2021; Pérez et al., 2022; McKay et al., 2024). X-ray fluorescence (XRF) core scanning of Site U1521 sediments provides semiquantitative data useful for further characterizing sedimentary units, as well as for paleoceanographic and terrigenous provenance studies (e.g., Grützner et al., 2003; Monien et al., 2012; Cook et al., 2013; Patterson et al., 2014; Croudace and Rothwell, 2015; Bertram et al., 2018; Penkrot et al., 2018; Wilson et al., 2018; Jimenez-Espejo et al., 2020). Here, we report XRF data from Site U1521. Raw XRF counts are influenced by sediment density and atomic weight (e.g., Tjallingii et al., 2007; Lyle et al., 2012; Kasuya et al., 2023) such that elements with higher atomic weights (e.g., Fe and Ba) emit higher energy X-rays compared to elements with lower atomic weights (e.g., Al and Si), resulting in attenuation of signals for elements with lower atomic weights (Tjallingii et al., 2007). To account for these effects, XRF data were (1) scaled to the median elemental concentrations of sediment collected from Site U1521, which were measured shipboard using inductively coupled plasma–optical emission spectroscopy (ICP-OES) to transform peak areas to weight percents and (2) normalized to eliminate variations caused by changes in sediment density, porosity, and cracking (Lyle et al., 2012). Normalized median-scaled (NMSc) XRF data are plotted against shipboard lithology and natural gamma radiation (NGR), which reflects relative amounts of fine-grained terrigenous sediment (clays) (Figure F2) (McKay et al., 2019b; Blum, 1997).
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- PAR ID:
- 10675977
- Publisher / Repository:
- International Ocean Discovery Program
- Date Published:
- Volume:
- 374
- Issue:
- 204
- ISSN:
- 2377-3189
- ISBN:
- 978-1-954252-67-7
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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International Ocean Discovery Program (IODP) Expedition 374 drilled Site U1521 on the outer shelf of the Ross Sea, Antarctica. Site U1521 is composed of seven lithostratigraphic units consisting of diamictites, mudstones, and diatomites. We present low to moderate resolution records of bulk sediment-derived total organic carbon (TOC), total nitrogen (TN), and carbon and nitrogen isotopes (δ13Corg and δ15N, respectively) from the uppermost ~300 m of Site U1521. Measured TOC values range 0.39–1.55 wt%, and TN values range 0.03–0.14 wt%. δ13Corg values range −28‰ to −22‰, and δ15N ranges 2‰–8‰. Generally, geochemical trends correspond with lithologic variations at Site U1521. Diamictites contain lower %TOC, %TN, and δ13Corg and higher δ15N and TOC/TN ratios. In contrast, diatom-bearing/-rich mudstones contain higher and more variable %TOC, %TN, and δ13Corg and lower and more variable δ15N and TOC/TN. These general trends indicate that organic matter sources shifted as depositional environments changed during the Miocene and Pliocene.more » « less
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