The Mesozoic and Cenozoic depositional, structural, and tectonic evolution of the Ross Sea, Antarctica

Many first order questions have not been answered regarding the timing and magnitude of tectonic events in the Ross Sea. New geophysical data collected across the Ross Sea were used to investigate the structural framework and tectonic history of the region. Outstanding questions include: (1) What is the timing and magnitude of tectonic events in the Ross Sea?, (2) What is the subsidence history of the Ross Sea, (3) What does the sedimentary infill tell about the tectonic history of the Ross Sea?; New mutlichannel seismic reflection data, collected in front of the Ross Ice Shelf, shows that Oligocene sediments can be correlated between the Ross Sea basins. Below the Oligocene sediment are two synrift packages that are interpreted across the Ross Sea. The synrift sediments suggest two phases of Ross Sea extension and have not been sampled. Extension most likely occurred in the Cretaceous, resulting in crustal thinning of the region. A second extension phase probably occurred in the Tertiary and was associated with seafloor spreading of the Adare Trough north of the Ross Sea. Potential drill sites designed to target pre-Oligocene synrift strata have been selected along the Ross Ice Shelf front and plan on using the ice shelf as the drilling platform.; Subsidence modeling indicates that Cretaceous extension, followed by Tertiary extension can explain the observed Ross Sea subsidence. Crustal models constrained by subsidence results indicate the Ross Sea was a region of thickened, elevated crust, significantly above sea level prior to Cretaceous rifting. Cretaceous extension thinned the crust to the present-day thickness of the Ross Sea basement highs. Further extension in the Tertiary thinned localized regions of the Ross Sea resulting in the formation of the present-day basins. All extension was completed by 30 Ma as constrained by the stratigraphic record. Thermal subsidence resulted in accommodation space for the deposition of Oligocene and younger sediments. The Transantarctic Mountains may be a high remnant piece of the pre-extension Ross Sea lithosphere that was not extended by either the Cretaceous or Tertiary rifting events.