Late-Middle Quaternary lithostratigraphy and sedimentation patterns on the Alpha Ridge, central Arctic Ocean: Implications for Arctic climate variability on orbital time scales

Dynamics of Manganese and Cerium Enrichments in Arctic Ocean Sediments: A Case Study From the Alpha Ridge

“…Gravity sediment core ARC3-B85D (hereafter B85D) (147.080 • W,85.140 • N; water depth: 2060 m; Figure 1) was recovered from the Alpha Ridge, western Arctic Ocean, during the Third Chinese Arctic Expedition in 2008, along with a number of cores reported earlier (Wang et al, 2018), especially close to core B85A. This study focuses on the B85D sediments down to a depth of 1.3 m estimated to correspond to the upper and part of the middle Pleistocene, as discussed below.…”

“…This study focuses on the B85D sediments down to a depth of 1.3 m estimated to correspond to the upper and part of the middle Pleistocene, as discussed below. Lithostratigraphy of core B85D is typical for deep western Arctic Ocean sediments (e.g., Wang et al, 2018, and references therein) and shows no indication of turbidites. Besides samples from core B85D, 31 surface sediment samples collected during the Sixth Chinese Arctic Expedition in 2014 from the western Arctic and adjacent Bering Sea were analyzed to complement the existing major element and REE datasets across the Arctic shelves and deep basins (Nolting et al, 1996;Viscosi-Shirley et al, 2003;Astakhov et al, 2013).…”

“…While not very accurate, this approach provides a general age constraint for the youngest sediments. Lithostatigraphy coupled with the major element contents, IRD and foraminiferal abundances were used to constrain the age of B85D sediments by correlation to neighboring cores from the Alpha Ridge with a developed age model (Wang et al, 2018).…”

“…In addition, voluminous amounts of sediments were transported to the deep basins by glacial erosion on the FIGURE 1 | Geographic setting of the study area and core locations. Core B85D (red star) is presented in this study; cores B85A, BN10, 8JPC and M03 (yellow circles) used for correlation are from Adler et al (2009); Wang et al (2013), and Wang et al (2018), respectively. Orange and blue circles indicate Fe-Mn micro-nodule samples in the deep Arctic Ocean (Winter et al, 1997;Fagel et al, 2014) and Fe-Mn nodule samples on shelves (Baturin and Dubinchuk, 2011;Kolesnik and Kolesnik, 2015), respectively; green circles for water samples at 500 m depth from the Eurasian Basin (Westerlund and Öhman, 1992).…”

“…Mn (oxyhydr)oxides, which are characteristic for brown layers, provide sorption sites for other metals, resulting in enrichments of reactive Fe, Co, Mo, Ni, and Rare Earth Elements (REEs), like Ce, which are closely related to Mn and should thus be equally sensitive to redox conditions (Moffett, 1990;Haley et al, 2004;März et al, 2011a). While the use of Mn as a proxy for interglacial conditions may be complicated by early diagenesis, application of this approach provides climatically meaningful age constraints for Quaternary sediments on orbital timescales (Jakobsson et al, 2000;Adler et al, 2009;Schreck et al, 2018;Wang et al, 2018). Insights into sedimentary Mn sources, geochemical nature, and deposition aid understanding the mechanisms of brown layer formation and their environmental meaning (März et al, 2011a;Macdonald and Gobeil, 2012;Löwemark et al, 2014;Sundby et al, 2015).…”