Geophysical measurements for subsurface mapping and groundwater exploration at the central part of the Sinai peninsula, Egypt

Abstract EN

-Characterization of a deep aquifer is the main target of the research work presented here.

The study area is located in the central part of Sinai, an extremely arid region in Egypt.

Different geophysical methods, including resistivity, gravity, and magnetic, were applied in the study area for groundwater exploration.

Fifteen vertical electrical soundings were measured with current electrode spacing ranging from AB = 10 m to AB= 6000 m, in order to detect the deep aquifer in the study area.

The resistivity 1D models were used to construct a geoelectrical cross-section to define the subsurface stratigraphy units, including the water-bearing aquifer.

The geoelectrical cross-sections showed that the upper part of the subsurface consists of four geoelectric units.

The deep aquifer is lodged by the last unit constituted of Nubian sandstone (Lower Cretaceous deposits).

The depth of the top of the Nubian sandstone ranges between 300 and 1000 m.

The resistivity of the aquifer varies between 60 and 400 ohm-m, indicating the existence of good quality water.

Gravity and ground magnetic (total magnetic field) measurements were made at one hundred and fifty stations.

The combined interpretation of the magnetic and gravity data allowed the determination of the depth of the surface of the granitic basement and the depth of the Conrad surface.

The results of the modeling indicate that the basement lies between 1500 and 3150 m depth and that the Conrad surface (interface between the granitic and basaltic layer) is ranging from 7130 to 8780 m.

Structural elements (mostly normal faults) NW-SE, N–S and NE–SW oriented, have been detected.

These structures are associated with vertical movements that might have controlled the sedimentation of the uppermost geological formations.