In February 1984, the U. S. Geological Survey conducted geophysical and geologic investigations of the Ross Sea Shelf and outer continental margin of Antarctica aboard the research vessel S. P. Lee. The geophysical data included 24-channel seismic-reflection, high-resolution seismic-reflection, sonobuoy seismic, gravity, magnetic-gradiometer, bathymetry, and heat-flow measurements. Sea-floor samples were collected for geologic and geochemical studies, using 3-m gravity corer, box corer, and rock dredge.

Principal survey areas were along the southern and western Ross Shelf, near Cape Adare and Islin Bank, and along the central outer continental margin. These areas lie adjacent to those covered by earlier multichannel-seismic-reflection surveys made by France, West Germany, and Japan.

Three north-south-trending sedimentary basins, containing as much as 5 km (16,404 ft) of Cenozoic sediment, lie beneath the Ross Sea Shelf and extend seaward beyond the continental shelf edge. These basins are separated by basement ridges and are bounded on the west by the Transantarctic mountains and on the east by mountain ranges of Marie Byrd Land. Seismic stratigraphy, crustal-thickness measurements, and rock samples from the Ross Sea region indicate that the three basins may have formed initially by crustal rifting during the middle and Late Cretaceous time and have subsequently filled with early Tertiary(?) as well as Oligocene and younger glacial marine sediment. Sedimentary thicknesses, heat-flow values, and geochemical analyses indicate that some parts of the Ross Sea Shelf m y have favorable conditions for the generation of hydrocarbons.

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