Sedimentary basins of the Ross Sea, Antarctica

Abstract

Seismic refraction and variable angle reflection measurements made using sonobuoys at 48 sites in the Ross Sea have been interpreted to define seismic velocity-depth structure of the deep sedimerttary basins underlying the Ross Sea. Three major basins exist in the region and the data show distinctly different seismic velocity-depth functions for each. In the east the continental shelf is underlain by a basin containing up to 4 km of sediments which show a simple linear increase in velocity with depth. This basin is considered to have formed partially in response to loading by glacial sediments since the Oligocene. A major trough of sediments, also up to 4 km deep, underlies the western part of central Ross Sea. The velocity-depth functions consist of several (usually 3) segments with linear velocity increase with depth, with the gradient of the segments increasing with depth. The trough is aligned approximately north-south and is considered to have been: formed by a failed crustal rift in the Late Cretaceous or early Tertiary. The third sediment basin is a trough running along the eastern side of the Transantarctic Mountains from McMurdo Sound to Coulman Island. About 3 km of sediments occur in this trough and show a distinct layered velocity structure. The trough has formed in association with the uplift of the Transantarctic Mountains, possibly as a result of compressive lithospheric -motion.

Shear‐wave velocities under the Transantarctic Mountains and terror rift from surface wave inversion

“…[Cooper et al, 1991]); the Victoria Land basin (VLB), the Central trough and the Eastern basin [Davey et al, 1982]. Seismic data indicate that the basins are infilled with up to 14 km of sediment [Davey et al, 1982], and are underlain by rifted continental crust [Cooper et al, 1987;Trehu et al, 1989], with crustal thicknesses between 17 and 25 km.…”

“…[Cooper et al, 1991]); the Victoria Land basin (VLB), the Central trough and the Eastern basin [Davey et al, 1982]. Seismic data indicate that the basins are infilled with up to 14 km of sediment [Davey et al, 1982], and are underlain by rifted continental crust [Cooper et al, 1987;Trehu et al, 1989], with crustal thicknesses between 17 and 25 km. Present-day rifting is thought to be represented by the Terror Rift, a 70 km wide axial rift zone [Cooper et al, 1987] which lies on the western side of the VLB, 50-100 km east of the TAM Front in the western Ross Sea (Fig.l).…”

Gravity, Geoid, Isostasy and Moho Depth in the Ross Sea, Antarctica

“…A dextral offset of Moho contours occurs across these lineations in the northern sector of the Ross Sea. These lineations curve from W-SW E-NE to E-W along 73.5°S and 73°S, in the N-E Ross sea nearly coincident with gravity trends observed by Davey (1994).…”

Deep crustal structure of the Adare and Northern Basins, Ross Sea, Antarctica, from sonobuoy data

“…In the southern Ross Sea, sonobuoys revealed a range of velocity gradients similar to those found in sedimentary rocks further north (Cochrane et al, 1995;Davey et al, 1983Davey et al, , 1982; Ross Sea sedimentary rock velocities are systematically faster than those found at similar depths in the Gulf of Alaska (e.g., Bruns and Carlson, 1987) and the Gulf of Mexico (e.g., Gardner et al, 1974). This is interpreted as the result of compaction of Ross Sea sediments due to past loading by a grounded ice sheet (Cochrane et al, 1995).…”