3D Numerical Inversion of gravity data from marine surveys and satellite. Application to an Antarctic area

The gravity modelling of the oceanic crust of the central zone of Drake Passage in the Shackleton Fracture zone (Antarctica) is presented as an example of application of a 3D numerical inversion of gravity data. The methods used are discussed. The treated data are from the survey carried out by the Spanish R/V Hesprerides and the data base of the "Global Gravity Grid and Global Sea Floor Topography (GGSFT) (Sandwell & Smith, 1997). The limitations of the Spectral Factor Method (Spector & Grant, 1970) are discussed and analyzed. The Spectral Factor Method allows us to separate the contribution of the different sources to the gravity anomaly. In particular, in the case of marine and satellite data, which we used, we consider the negative effect in the radial spectrum of the indiscriminate combination of data of diverse origin. We also discuss the inversion method employed, which is based on Parker (1973), and the utilization of the water plate correction (WPC) applied to the Free Air anomaly to obtain the Total anomaly. This anomaly is the point of departure of the inversion process.