ABSTRACT

The South Georgia Basin is the southernmost and largest of the East Coast Newark Series rift basins. However, it does not exhibit the typical asymmetric half graben or paired half graben structure of the other Newark Series basins. Rather, the South Georgia Basin is a series of synrift grabens with intervening structural highs.

An integrated study utilizing LandSat, gravity, magnetic and seismic data was completed to further understand the structural complexity of the basement structure and its relationship to the overlying rift graben. The findings are:

1. The pre-existing basement fabric is different from the other Newark Series basins due to its Gondwana underpinnings.
2. Rift basin geometry is controlled by pre-existing zones of weakness in the basement fabric.
3. Rift basin depths range from -1,250 m (-4,100 feet) to -6,100 m (-20,000 feet).
4. Synrift and postrift sediment thicknesses range from 335 m (1,100 feet) to 4,270 m (14,000 feet), respectively.
5. Evidence of structural inversion and diabase intrusives associated with rifting and with post-rifting tectonic events are seen on seismic data.
6. The central basin, where the rift fill is thickest [>1525 m (5,000 ft)], covers an area of 12,140 square kilometers (three million acres).