Late Quaternary high-resolution seismic stratigraphy and core-based paleoenvironmental reconstructions in Ona Basin, southwestern Scotia Sea (Antarctica)

• Published in: Marine Geology
• Main Authors: López-Quirós, Adrián, Lobo, Francisco J., Duffy, Meghan, Leventer, Amy, Evangelinos, Dimitris, Escutia, Carlota, Bohoyo, Fernando
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Antarctica; Deglaciation; Diatom assemblage; Late Quaternary; LGM; Scotia Sea; Seismic stratigraphy; Antarctic; Antarctic Peninsula; Drake Passage; Ona Basin; Southern Ocean; Weddell; Weddell Sea; Antarc*
• Online Access: https://pure.au.dk/portal/da/publications/late-quaternary-highresolution-seismic-stratigraphy-and-corebased-paleoenvironmental-reconstructions-in-ona-basin-southwestern-scotia-sea-antarctica(e19b34bf-b45a-41dc-9191-5fa884dcf384).html; https://doi.org/10.1016/j.margeo.2021.106565; https://pure.au.dk/ws/files/285202900/1_s2.0_S002532272100147X_main.pdf; http://www.scopus.com/inward/record.url?scp=85110457065&partnerID=8YFLogxK

The variability of sedimentation patterns and processes driven by late Quaternary glacial-interglacial paleoclimatic and paleoceanographic changes are investigated in Ona Basin, southwestern Scotia Sea. The interest of this area lies in the fact that the nearby Antarctic Peninsula has recorded extreme climatic variability, and the Drake Passage-Scotia Sea oceanic domain is influenced by two major Southern Ocean water masses, the eastward-flowing Antarctic Circumpolar Current (ACC) and the westward-flowing Weddell Sea Deep Water (WSDW). These goals are achieved through the examination of a grid of very high-resolution sub-bottom profiles and two gravity cores collected in Ona Basin. Multi-proxy data derived from the gravity cores include 14 C-derived ages, descriptions of sedimentary units and diatom assemblages, and continuous logging of physical properties and micro-XRF core scanning. The sub-surface seismic stratigraphy is composed of four seismic units (U4 to U1) with a dominant sub-parallel configuration, with local occurrence of wavy facies and intercalations of transparent seismic facies. Additionally, four sedimentary units were recognized through sediment core analysis from bottom to top: Unit IV is composed of slightly bioturbated diatom-rich mud and silty mud with sparse ice-rafted debris (IRDs); Unit III is composed of gravelly silty to sandy mud with large amounts of IRDs; Unit II mostly contains bioturbated diatomaceous mud; and Unit I is composed of diatom-rich silty to sandy mud. The highest diatom abundances are found in Unit II, whereas highly variable abundances are found in Unit IV. The most common diatoms are Fragilariopsis kerguelensis and Chaetoceros subg. Hyalochaete. Overall, these characteristics document a change in the depositional style from terrigenous during the Last Glacial Maximum (LGM) to hemipelagic sedimentation during the deglaciation. The high-resolution seismic stratigraphy analysis reveals significant fluctuations in the regional bottom-current patterns during the late ...