SPECTRAL ANALYSIS OF GRAVITY DATA IN TUNISIA

The crust structure of Tunisia under the Tell and Atlas Mountains are only known in general terms. Only one widely spaced seismic refraction profile has been recorded and the results were difficult to interpret due to poor signals. Gravity data have proven to be the most useful as a number of studies have shown that the Mesozoic and Paleozoic sediments vary greatly in thickness under these ranges plus the depth to the mantle gently increases toward the south. In order to increase our knowledge of the crustal density structure and the properties of the crust, we have conducted an analysis of gravity data by determining a spectral analysis of three profiles across the Tell Mountains and three profiles across the Atlas Mountains. In addition, calculations of coherency between the Bouguer gravity anomalies and topography, and the admittance between these two parameters will be made along each profile in order to determine the nature of the loads producing the observed gravity anomalies. Preliminary spectra results indicate that there are at least three major density interfaces along each profile with the deepest beneath the Tell Mountains being the crust/mantle boundary between 20-25 kilometers in depth.