Red Sea gravity - comparing satellite-derived with shipboard and structural patterns

What is it about?

Free-air gravity anomalies derived from satellite altimeter measurements by Sandwell et al. (their version 18) are compared with data from shipboard gravimeters. Standard deviations between the two data types are ~5 to 6 mGal, though importantly show coherent structures that are due to systematic errors that remained in version 18. Despite these errors, the field reveals lineaments crossing the Red Sea that in places correspond with known structures on African-Arabian shield. Lineaments in the central Red Sea form a pattern much like that of spreading segments on a slow spreading ridge. They have slightly different orientations on either side of the ridge suggesting that they have been migrating to the north. This sense of migration, away from the Afar mantle plume, is typical of that seen at mid-ocean ridges near plumes. Overall, the gravity field supports a continental-type crust in the central Red Sea rather than hyper-extended continental crust.

Featured Image

Photo by Jeff Sheldon on Unsplash

Photo by Jeff Sheldon on Unsplash

Why is it important?

The free air gravity anomaly differences with shipboard data suggest that the precision of version 18 was worse than in the open oceans or in some other closed seas that have been studied in this way. The segmentation pattern revealed by the gravity field helps to address the question of whether oceanic or hyperextended continental crust surrounds the deeps in the Red Sea, supporting the former.