Organic and inorganic proxies, and concentration of diatoms from surface sediment PS97/ Sterols preserved in surface sediments PS97/ Diatoms of surface sediments PS97

• Main Authors: Cárdenas, Paola, Lange, Carina B, Vernet, Maria, Esper, Oliver, Srain, Benjamin, Vorrath, Maria-Elena, Ehrhardt, Sophie, Müller, Juliane, Kuhn, Gerhard, Arz, Helge Wolfgang, Lembke-Jene, Lester, Lamy, Frank
• Format: Dataset
• Language: English
• Published: PANGAEA 2021
• Subjects: diatoms; Drake Passage; organic carbon; Photosynthetic pigments; sterols; surface sediments; Antarctic; The Antarctic; Antarctic Peninsula; South Shetland Islands; Bransfield Strait; Antarc*
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.927026; https://doi.org/10.1594/PANGAEA.927026

The Antarctic Circumpolar Current is the world's largest current system connecting all major ocean basins of the global ocean. Its flow, driven by strong westerly winds, is constricted to its narrowest extent in the Drake Passage, located between South America and the Antarctic Peninsula. Due to the remoteness of the area, harsh weather conditions and strong bottom currents, sediment recovery is difficult and data coverage is still inadequate. Here, we report on the composition of 51 surface sediments collected during the R/V Polarstern PS97 expedition (February-April 2016) across the western and central Drake Passage, from the Chilean/Argentinian continental margin to the South Shetland Islands and the Bransfield Strait (water depth: ∼100-4000 m). We studied microfossils (diatoms), bulk sediment composition and geochemical proxies (biogenic opal, organic carbon, calcium carbonate, carbon and nitrogen stable isotopes, sterols and photosynthetic pigments), and evaluated how they respond to, and reflect oceanic domains and polar to subpolar frontal systems in this region. Our multi-proxy approach shows a strong relationship between the composition of surface sediments and ocean productivity, terrigenous input, intensity of ocean currents, and ice proximity, clearly differentiating among 4 biogeographical zones. The Subantarctic Zone was characterized by warmer-water diatoms, high carbonate (>45%) and low organic carbon contents (avg. 0.26%), as well as low concentrations of pigments (avg. 1.75 μg/g) and sterols (avg. 0.90 μg/g). A general N-S transition from carbonate-rich to opal-rich sediment was observed at Drake Passage sites of the Polar Front and Permanently Open Ocean Zone. These sites were characterized by low organic carbon content (0.22%), high relative abundances of heavily silicified diatoms (≥60% Fragilariopsis kerguelensis), and abundant foraminifera at shallower stations. Approaching the Antarctic Peninsula in the Transitional Zone, an increase in the concentrations of pigments and sterols (avg. ...