Active subsurface structures at Fayoum- Cairo district, Northern Western Desert, Egypt, as deduced from magnetic data

Abstract

In the present work, we present a reconnaissance study to elucidate and delineate
the subsurface structures and tectonics of the area between Dahshour and El Fayoum
province using available magnetic data; including land magnetic survey and aeromagnetic
data. The study area has been selected due to its active tectonic situation. The magnetic
data have been analyzed to provide new information about the tectonic setting and subsurface
structures of the study area. A detailed land magnetic survey has been carried
out for the total component of geomagnetic field using two Proton magnetometers, one
of them as a local reading base station placed in the middle part of the area, while the
second was used for measuring the total intensity of the different points in a mesh-like
configuration. The necessary corrections for the measured magnetic data have been carried
out. The total land intensity and aeromagnetic maps have been reduced to the north
magnetic pole. Moreover, wave number filtering technique has been carried out on the
magnetic data utilizing three types of filters with varying wavelengths. The application
of these tools on magnetic data discriminated the variable sources of specific depth ranges
for the residual and regional anomalies, as well as those limited to a certain depth interval.
It was found that the main tectonic trends taken the directions NE–SW, NW–SE
and E–W. Three basement cross-sections have been generated using the 2-D modeling
to support the interpreted structures and give idea about the configuration of subsurface
basement shape. Depth estimations have been conducted by application of the Power
spectrum, analytical signal and 2-D modeling techniques. The results indicate that the
average calculated depth ranges between 1.8 km to 3.5 km, while the depth to volcanic
intrusions ranges between 0.20 km and 0.30 km.