Crust Architecture of the Eastern Mediterranean Region: Results from GIADA Project

Abstract:

The observations of the gravitational field can be profitably exploited in the search of natural resources as hydrocarbons and minerals. Two main applications based on gravity data can be envisage: the so-called gravity inversion and gravity interpretation. The former consists in deriving the 3D density distribution of a given volume, while the latter consists in the analysis of the gravitational field in order to improve the geological interpretation of an area. Both these aspects have been investigated in the GIADA (Gravity for lIthosphere Architecture Determination and Analysis) project funded by ESA in the framework of the BASS (Business Applications-Space Solutions) initiative. In details a set of algorithms based on the Bayesian Paradigm have been developed to firstly classify and then invert the gravitational field. The results are an improved map of geological provinces (here defined as provinces homogeneous from the mass density point of view) and a 3D density distribution of the investigated volume.

The developed algorithms have been applied to study the Eastern Mediterranean area (from 16.5°E to 36.5°E and from 31°N to 37°N, see image). The a-priori knowledge, consisting in the main geological horizons of the area (i.e. bathymetry, plioquaternary sediments, messinian salt, sediments, crystalline crust, upper mantle, lithosphere-asthenosphere boundary) are taken from freely available data. The accuracies of each layer have also been evaluated. Moreover, we suppose different average densities and density variability for each layer. On the basis of these assumptions and of an a-pirori map of geological provinces, we firstly used second derivatives of the gravitational potential to refine the map of geological provinces and, after that, we perform a full 3d inversion modifying both the geometries and the densities in order to fit the observed gravity field and the constraints given by the accuracy of the initial model.

The results are an improved map of geological provinces and a full 3D crustal model (expressed in terms of depths of the major discontinuities and in terms of 3D density variations) of the Eastern Mediterranean.