Sedimentary basins of the Ross Sea, Antarctica

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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.