Basement Topography and Sediment Thickness Beneath Antarctica's Ross Ice Shelf

Abstract

The southern sector of Antarctica's Ross Embayment beneath the Ross Ice Shelf (RIS; area ∼480,000 km 2 ) is poorly resolved because the region is not accessible to conventional seismic or geophysical surveying. Rock exposures on land suggest that Ross Ice Shelf (RIS) crust consists of early Paleozoic post-orogenic sediments, intruded in places by mid-Paleozoic and Cretaceous granitoids (Goodge, 2020;Luyendyk et al., 2003). Following the onset of extension in the mid-Cretaceous, grabens formed and filled with terrestrial and marine deposits, continuing into the Cenozoic (e.g., Coenen et al., 2019;Sorlien et al., 2007), as the Ross Embayment underwent thermal subsidence (Karner et al., 2005;Wilson & Luyendyk, 2009). The physiography of this region then responded to the onset of glaciation in the Oligocene (Paxman et al., 2019), coinciding with localized extension in the western Ross Sea until 11 Ma (Granot & Dyment, 2018). The Oligocene-early-Miocene paleo-landscape of the Ross Sea sector was revealed by marine seismic data (e.g., Brancolini et al., 1995;Pérez et al., 2021) and offshore drilling that penetrated crystalline basement (DSDP Site 270; Ford & Barrett, 1975) (Figure 1). Recognition of the role of elevated topography in Oligocene formation of the Antarctic Ice Sheet (DeConto & Pollard, 2003;Wilson et al., 2013) and the likely influence of subglacial topography upon ice sheet processes during some climate states (Austermann et al., 2015;Colleoni et al., 2018) motivated our effort to determine basement topography beneath the RIS.

Antarctic Sedimentary Basins and Their Influence on Ice‐Sheet Dynamics

“…Upper Oligocene to Lower Miocene strata (RSS-2) are preserved in the major basins of the Ross Sea, but are thin to absent on the basement highs (Pérez et al, 2021). These sediments are interpreted to be deposited in (Davey et al, 2021;Lindeque, Gohl, Wobbe, & Uenzelmann-Neben, 2016;Pérez et al, 2021;Sauli et al, 2021;Studinger et al, 2001;Tankersley et al, 2022;D. S. Wilson et al, 2012;T.…”

“…Also important are faults and stratigraphy, which provide critical controls on fluid flow within the basins. Consequently, these dictate the hydrogeological response to changing glacial load and so advective heat transport to the ice‐sheet bed (Tankersley et al., 2022). The sensitivity of gravity and magnetic data to internal basin structure may be limited by density and magnetization contrasts between sedimentary rocks which are relatively low in comparison to the contrast with the basement and other features such as intrusions and volcanic rocks.…”

“…Figure 6 shows several models of sedimentary basin thickness, including models derived from gravity (Haeger & Kaban, 2019), interpolation of seismic data (Baranov et al., 2021), passive seismic models (Zhou et al., 2022), magnetic depth to basement tied to seismic‐reflection data (Tankersley et al., 2022) and marine seismic‐reflection data (Hochmuth et al., 2020; Lindeque, Gohl, Wobbe, & Uenzelmann‐Neben, 2016; Straume et al., 2019). While there is some commonality between these models, there are also many differences and only the seismic‐reflection models show strong consistency with each other.…”

“…On the continental shelf, ice shelves and perennial sea ice limit access to both marine and terrestrial techniques. Sedimentary basins are important not just for the understanding of Antarctic geology, but also because they provide key boundary conditions for glacial processes, with major impacts on the dynamics of the overlying ice sheet (Bell et al., 1998; Gooch et al., 2016; Kulessa et al., 2019; Li et al., 2022; Person et al., 2012; Siegert et al., 2018; Studinger et al., 2001; Tankersley et al., 2022; Zhang et al., 2018).…”

“…(a) shows the location of the three profiles A, B, and C (see also Figure 3) at latitudes of 82.5°S, 77.5°S, show the profile data for profiles A, B, and C respectively including in the upper panel the basin likelihood model of. The lower panel shows bed topography(Morlighem, 2020) and base-of-basin elevation for several basin thickness model(Baranov et al, 2021;Haeger & Kaban, 2019;Hochmuth et al, 2020;Lindeque, Gohl, Wobbe, & Uenzelmann-Neben, 2016;Straume et al, 2019;Tankersley et al, 2022;Zhou et al, 2022). SPB, South Pole Basin; WSB, Wilkes Subglacial Basin; VH, Vostok Highlands; TAH, Terre Adelie Highlands; TAM, Transantarctic Mountains; EWM, Ellsworth Whitmore Mountains; PM, Pensacola Mountains; RSH, Recovery Subglacial Highlands; GSM, Gamburtsev Subglacial Mountains; ASB, Aurora Subglacial Basin; MBL, Marie Byrd Land; LV, Lake Vostok; BI, Berkner Island; CL, Coats Land; FSH, Fuji Subglacial Highland; SPCM, Southern Prince Charles Mountains; VSB, Vincennes Subglacial Basin; IB, Iselin Bank; TI, Thurston Island; PL, Palmer Land; JS, Jutulstraumen; WRT, West Ragnhild Trough; AIS, Amery Ice Shelf.…”