Abstract
We compile existing seismic, gravity, radar and magnetic data, together with the subglacial bedrock relief from the BEDMACHINE project, to build the most detailed sediment model for Antarctica. We interpolate these data according to a tectonic map of Antarctica using a statistical kriging method. Our results reveal significant sediment accumulation in Antarctica with several types of sedimentary basins: parts of the Beacon Supergroup and more recent rifting basins. The basement relief closely resembles major geological and tectonic structures. The thickness of sediments has significant variations around the continent, and depends on the degree of crustal extension. West Antarctica has wide sedimentary basins: the Ross basin (thickness 2–6 km), the Filchner-Ronne basin (2–12 km) with continuations into East Antarctica, the Bentley Subglacial Trench and the Byrd basin (2–4 km). The deepest Filchner-Ronne basin has a complex structure with multi-layered sediments. East Antarctica is characterized by vast sedimentary basins such as the Pensacola-Pole (1–2 km), Coats Land (1–3 km), Dronning Maud Land (1–2 km), Vostok (2–7 km), Aurora (1–3 km), Astrolabe (2–4 km), Adventure (2–4 km), and Wilkes (1–4 km) basins, along with narrow deep rifts filled by sediments: JutulStraumen (1–2 km), Lambert (2–5 km), Scott, Denman, Vanderford and Totten (2–4 km) rifts. The average thickness of sediments for the whole continent is about 0.77 km. The new model, ANTASed, represents a significant improvement over CRUST 1.0 for Antarctica, and reveals new sedimentary basins. Differences between ANTASed and CRUST 1.0 reach +12/−3 km.
Highlights
Sediments represent the most heterogeneous layer of the Earth’s interior and their characteristics can mask the mantle signature in geophysical measurements
The Beacon Supergroup experienced the intrusions of magmatic sills during the Gondwana breakup, after which sedimentation in the depressions continued and ceased in Eocene-Miocene due to ice covering the continent (Whitehead et al, 2006)
The bulk of the sediments in Antarctica belongs to the Beacon Supergroup, in addition to them, there are younger Mesozoic and Cenozoic sediments
Summary
Sediments represent the most heterogeneous layer of the Earth’s interior and their characteristics can mask the mantle signature in geophysical measurements. Gravity, radar, magnetic, and subglacial relief data can be used to construct sedimentary thickness maps Sediment properties, such as their density, can be estimated using geophysical data, from which their load can be inferred as a parameter for determining isostatic balance. CRUST2.0 uses crustal types on a 2 × 2 Cartesian grid to specify sediment properties, including sediment thickness, while model CRUST1.0 uses the sediment model of Laske and Masters (1997) based on maps available at the time, including the 1985 AAPG Tectonic Map of the World assembled for Exxon (Laske et al, 2013) These global models obviously could not take into account the later maps of subglacial relief (Fretwell et al, 2013; Morlighem et al, 2020), magnetic and gravity data We resort to new gravity, radar, bedrock and magnetic data to infer information on shallow crustal structure in regions without seismic coverage These data mainly provide indirect values for sediment thickness. We believe that the sediment map for Antarctica has significantly been improved by integrating many more information sources than in earlier studies
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