Antarctica’s continental margins pose an unknown submarine landslide-generated tsunami risk to Southern Hemisphere populations and infrastructure. Understanding the factors driving slope failure is essential to assessing future geohazards. Here, we present a multidisciplinary study of a major submarine landslide complex along the eastern Ross Sea continental slope (Antarctica) that identifies preconditioning factors and failure mechanisms. Weak layers, identified beneath three submarine landslides, consist of distinct packages of interbedded Miocene- to Pliocene-age diatom oozes and glaciomarine diamicts. The observed lithological differences, which arise from glacial to interglacial variations in biological productivity, ice proximity, and ocean circulation, caused changes in sediment deposition that inherently preconditioned slope failure. These recurrent Antarctic submarine landslides were likely triggered by seismicity associated with glacioisostatic readjustment, leading to failure within the preconditioned weak layers. Ongoing climate warming and ice retreat may increase regional glacioisostatic seismicity, triggering Antarctic submarine landslides.
<p>The repeated proximity of West Antarctic Ice Sheet (WAIS) ice to the Ross Sea continental shelf break has been inferred to directly influence sedimentary processes occurring on the continental slope. Sediment delivery to the shelf edge by grounded ice sheets during past glacials may have influenced turbidity current and debris flow activity, thus the records of these processes can be used to study the past history of the WAIS. However, the continental slope record may also be affected by density-driven or geostrophic oceanic bottom currents, therefore additionally providing an archive on their history and interplay with depositional mechanisms that are driven by ice sheets. Here, we investigate the upper 120.94m of one sediment core (length: 208.58mbsf) from Hole U1525A collected by International Ocean Discovery Program (IODP) Expedition 374 in 2018. Hole U1525A is located on the south-western levee of the Hillary Canyon (Ross Sea, Antarctica) and the depositional lobe of the nearby trough-mouth fan. Using core descriptions, grain size analysis, and physical properties datasets, we develop a lithofacies scheme that allows construction of a detailed depositional model and environmental history of past ice sheet-ocean interaction at the eastern Ross Sea continental shelf break/slope for the past 2.4 Ma. The earliest Pleistocene interval (2.4-1.35 Ma) is interpreted as a largely hemipelagic environment dominated by ice-rafting and reworking/deposition by relatively persistent bottom current activity. Microfossil barren, finely interlaminated sediments are interpreted as contourites deposited under the presence of multi-year sea-ice. During the latter part of the early Pleistocene (1.35-0.8 Ma), bottom current activity was weaker and turbiditic processes more common, likely related to the increased proximity of grounded ice at the shelf edge. Much of the fine-grained sediments were probably deposited via gravitational settlement from turbid plumes, and a sustained nepheloid layer. The thickest interval of turbidite interlamination occurs after ~1 Ma, following the onset of the &#8220;Mid-Pleistocene Transition&#8221; (MPT), interpreted as a time when most terrestrial ice sheets increased in size and glacial periods were longer and more extreme. Sedimentation in the mid-late Pleistocene (< ~0.8 Ma) was dominated by glacigenic debris flow deposition, as the trough mouth fan that dominates the eastern Ross Sea continental shelf prograded and expanded over the site. More frequent and longer-lasting fully-extended glacial conditions allowed the continued progradation of the trough-mouth fan across the core site. These findings will help to improve estimations of WAIS ice extent in future Ross Sea shelf-based modelling studies, and provide a basis for more detailed analysis of the formation and growth of the WAIS under distinct oceanographic conditions.</p>
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.