Color version of Figure 7a through d from Luyendyk et al., 2001.
7a: FreeAir gravity anomalies (FAA) over the trough and surrounding regions. Dots
show positions of median observations in 1km bins. Contour interval 5 mgal,
polar equidistant projection. 7b: Structurecontour map on probable Oligocene unconformity RSU6 between RSS2 and underlying RSS1 or basement. This map is based on seismic data (dots) and has been converted to depth using velocity analysis during multichannel processing. Bathymetry is plotted southeast of dashed line where RSS2 has been eroded and RSS1 or basement outcrops at the sea floor. Contour interval 100 meters. Locations of faults that cut the RSS1 sequences are shown. 7c: Residual FAA calculated by subtracting a forward gravity model comprising three layers: water, younger sediments, and undifferentiated older sediments plus basement (Figure 7b) from the observed FAA (Figure 7a). Model densities are 1000 kg/m cubed for water, 2000 kg/m cubed for younger sediments, and 2650 kg/m cubed for older sediments and basement.
7d: Depthtobasement model computed iteratively to satisfy the shorter wavelength
components of the residual FAA in Figure 7c. Here layer 3 of the 3layer model
(older sediments and basement) was further divided into basement with density 2850/kg/m cubed
and overlying synrifting sediments of RSS1 with a density of 2200 kg/m cubed.
The modeled basement shows northerly to northwesterlytrending highs and lows with
relief approaching one kilometer.

