Distribution of oceanic crust in the Enderby Basin offshore East Antarctica

Abstract

Summary Seismic reflection and refraction data were collected in 2007 and 2012 to reveal the crustal fabric on a single long composite profile offshore Prydz Bay, East Antarctica. A P-wave velocity model provides insights on the crustal fabric, and a gravity-constrained density model is used to describe the crustal and mantle structure. The models show that a 230 km wide continent-ocean transition separates stretched continental from oceanic crust along our profile. While the oceanic crust close to the continent-ocean boundary is just 3.5–5 km thick, its thickness increases northwards towards the Southern Kerguelen Plateau to 12 km. This change is accompanied by thickening of a lower crustal layer with high P-wave velocities of up to 7.5 km/s, marking intrusive rocks emplaced beneath the mid-ocean ridge under increasing influence of the Kerguelen plume. Joint interpretations of our crustal model, seismic reflection data, and magnetic datasets constrain the age and extent of oceanic crust in the research area. Oceanic crust is shown to continue to around 160 km farther south than has been interpreted in previous data, with profound implications for plate kinematic models of the region. Finally, by combining our findings with a regional magnetic data compilation and regional seismic reflection data we propose a larger extent of oceanic crust in the Enderby Basin than previously known.

Reinterpretation of Marine Magnetic Anomalies in the Bay of Bengal: Implications for Plate Tectonics During the Mid‐Cretaceous

“…Altenbernd-Lang et al (2022a) used seismic refraction and gravity data along a profile south of Sri Lanka to infer the COB beyond stretched continental crust, and unusually high velocities in the upper mantle of the oceanic crust. Based on seismic reflection and refraction data off Prydz Bay, Altenbernd-Lang et al (2022b) suggested that oceanic crust begins 160 km further south than previously proposed (Figure 2b) and the Mac Robertson Coast Anomaly is not a COB but chron M4.…”

“…Based on seismic reflection and refraction data off Prydz Bay, Altenbernd‐Lang et al. (2022b) suggested that oceanic crust begins 160 km further south than previously proposed (Figure 2b) and the Mac Robertson Coast Anomaly is not a COB but chron M4.…”

“…Recent contradictions to the above results include those by Sibuet et al (2016), Jokat et al (2021), and Altenbernd-Lang et al (2022a, 2022b. Based on observed low seismic velocities, Sibuet et al (2016) proposed that the crust in the northern BOB (north of 19°N) is thinned continental crust with minor underplating, and intruded by volcanism.…”

“…(2021), and Altenbernd‐Lang et al. (2022a, 2022b). Based on observed low seismic velocities, Sibuet et al.…”