Neogene Development of the Terror Rift, Western Ross Sea, Antarctica

Abstract

The Terror Rift, which is located in the southwestern sector of the Ross Sea (Antarctica), is a narrow and deep basin that extends for 350 km, between Ross Island and Cape Washington, within the broader Victoria Land Basin (VLB; Figure 1). The Terror Rift is ∼75 km-wide and includes the 25-35 km-wide faulted Discovery Graben; it is flanked on the eastern side by the 25-40 km-wide volcanically intruded Lee Arch (Cooper et al., 1987a). Southward continuation of the Terror Rift for an additional 300 km beneath the Ross Ice Shelf is suggested by airborne gravity and magnetic data (Tankersley et al., 2018). Inversion of the gravity data reveals a deep, narrow sedimentary basin, with a left stepover (jog to the east looking south) near Ross Island (Jordan et al., 2020; Tinto et al., 2019). The Terror Rift is one of the youngest parts of the West Antarctic Rift System (WARS), which is a Mesozoic-Cenozoic continental rift system that extends along a strike for 3,200 km from the Weddell Sea to the Ross Sea. The WARS extensional area includes the crustal block assemblage of West Antarctica and the rift shoulder on the border of the East Antarctic craton. During the Late Cretaceous and Paleogene WARS phases within the Ross Sea, part of the Ross Embayment, the E-W stretching of continental crust resulted in several hundred kilometers of extension (e.g., D. S. Wilson & Luyendyk, 2009). The subsidence related to this crustal thinning produced four main broad N-S basins (e.g., Victoria Land Basin, connected to Northern

Flexural Subsidence Around Ross Island, West Antarctica

“…Continued extension in the Terror Rift since the end of the Miocene Period might also have weakened the lithosphere over time, either as a result of lithospheric thinning or by faulting. Faulting in the Terror Rift has been ongoing since at least middle Miocene time (Fielding et al., 2008; Sauli et al., 2021; Wenman et al., 2020). This continued faulting may have progressively weakened the lithosphere beneath Ross Island, such that it behaved as a continuous plate prior to the end of the Pliocene Period (when Mt.…”

“…The seismic stratigraphy of the areas north, southeast, and west of Ross Island is well studied (Cooper et al., 1995; Fielding, 2018; Fielding et al., 2008; Horgan et al., 2005; Sauli et al., 2021; Wenman et al., 2020). Fielding et al.…”

Volcanic features in the Victoria Land Basin of Antarctica and implications of Cenozoic structures

“…The international waterdepth grid map resolution of the Southern Ocean can be up to 500 m × 500 m. According to the waterdepth grid map in the northern VLB, the Drygalski Basin has been affected by multistage glaciation and developed a groove with a near NNE trend and a water depth of more than 1000 m. The high terrain-Crary Bank is located partly in the VLB basin and partly in Culman High, where the shallowest water depth reaches 250 m (Kooyman et al, 2020). Based on previous studies, this table focuses on refining the stratigraphic age of the 32nd CHINARE (Hall et al, 2007;Hansaraj, 2008;Sauli et al, 2021).…”

“…The hole bottom may correspond to the RSU4a interface (Brancolini et al, 1995), and the strata below the RSU4a interface are described according to the boreholes from ANDRILL. (Fielding et al, 2008;Sauli et al, 2021). The oldest stratigraphic interface RSU6 (~29 Ma) in the study area crops out only in the Drygalski Basin (Fig.…”

“…Its internal multistage fault extension and rifting provide channels for volcanic intrusions and eruptions. At present, there have been studies on the structural characteristics of the southern Terror Rift (Blocher, 2017;Fielding, 2018;Hall et al, 2007;Henrys et al, 2008;Sauli et al, 2021), but the northern Terror Rift is severely eroded by multiple glaciers and lacks seismic and multibeam data.…”