The aim of the present study is to investigate the crust and upper mantle of the central northern part of Egypt, using Bouguer gravity
data. To achieve this aim, the gravity data have been subjected to modeling and interpretation. Analysis of the gravity data includes
regional-residual separation technique utilizing the least-squares polynomial. Moreover, depth determination to the basement surface for
the gravity anomalies is applied using the spectral analysis technique. The gravity data were integrated with the available geological well
data and geophysical information to build up two-dimensional (2-D) crustal geologic models taken along the S - N direction across the
study area. Consequently, three depth maps for the basement surface, Conrad and Moho discontinuities are constructed. These maps and
models enable us to conclude that, 1) The densities of the rock units in the investigated area are; 2.1, 2.5, 2.7, 2.93 and 3.3 gr/cm3 for the
upper and lower sedimentary cover, upper crust (granitic layer) and lower crust (basaltic layer), and upper mantle, respectively. 2) The
basement surface ranges between 1 km in the southwestern pat and 10 km in the northeastern part, the Conrad discontinuity occurs at a
depth varies from 13.5 to 25 km from north to south, and the Mohorovicic discontinuity ranges approximately between 20 at the northern
area and 35 km at the southern one. Euler deconvolution technique is applied to locate the step-faults and to determine their depths.
Finally, a structural tectonic map was constructed using the available analytical data. It shows that, the area is affected by a large number
of normal faults trending in an ENE trend intersected by a NNW trend forming uplifted and down-lifted blocks with step-faulted blocks in
parts. |
