كفاءة تقنيات تحويلات مجالات الجهد فى استشفاف الباراميترات التركيبية فى الجزء الشمالى الغربى لمصر

                                                "CHAPTER VI

SUMMARY AND CONCLUSIONS

The study area lies in the central part of the northern Western Desert of Egypt, between latitudes 29 00` & 30 30` N and longitudes 26 00` & 29 00` E.  The present study is devoted to delineate the subsurface buried bodies and to throw some lights on the major structural elements dissecting the considered area, as well as the tectonic inferences standing behind them.  In order to accomplish these targets, the potential field data of the investigated area in the form of Bouguer gravity anomaly map and total intensity magnetic map are utilized.

The qualitative interpretation of the gravity data involves first the translation of the implicated gravity belts into structural deformations.  Four low gravity trends are mutually arranged with other four high gravity trends, expressing mostly positive and negative structural belts. Moreover, the method of least square of Henderson (1966), was applied to the RTP magnetic anomaly map and Bouguer anomaly map of the studied area using first, second, third and fourth order fitted to the input magnetic and gravity data. The wavelength linear filtering was applied to the RTP magnetic anomaly map, and Bouguer anomaly map using Zurflueh method (1967), utilizing three types of filters which are:

(1)          Low-cut of the residual anomalies with short wavelengths, high frequencies.

(2)          High-cut of the regional anomalies with long wavelengths, low frequencies, and deep depths,

(3)          Band-pass of the transitional anomalies with intermediate wavelength, frequencies and depth ranges.

The trend analysis techniques (Linsser, 1967) was applied to determine the location of the tectonic lines and its trends. The technique was applied to RTP magnetic and Bouguer anomaly, filtered magnetic and gravity maps and residual magnetic and residual gravity maps which represent the shallow, intermediate and deep level respectively in order to detect the continuation of the tectonic under the sedimentary section to the basement complex. The results of such studies, proved that possible relationships of magnetic and gravity data were established. Moreover it could be stated that the study area is affected by……. . These tectonics act as a subsurface controlling factors for the studied area.

                The quantitative interpretation of the gravity and magnetic data include the construction of two dimensional modeling. The two dimensional modeling technique was applied to both the magnetic and gravity data to illustrate the geometry of the basement surface under the sedimentary cover. It shows that, the deepest part is in …….. of the studied area. These results show that the shallower depth of the dikes or faults are ranging between …. Kms. and more than….. Kms. Furthermore, the density contrast for the faults and dikes deduced from gravity and about ……gm/cm3 . Beside, the quantitative interpretation of the magnetic and gravity data includes the determination of the depths to the basement by modeling the gravity data (Kanamori and Saito, 1963), calculation of the parameters of the buried bodies using Hilbert transform (1965), estimation of the depths of the causative features (the basement complex and the related igneous intrusions) utilizing the spectral analysis (1968), and, the rapid interpretation of gravity anomalies caused by geologic contacts (Abdel Rahman, 1984).  In these techniques, the density contrast between the causative body and the surrounding rocks, the angle of dip of the fault, the depths to the upper and lower surfaces of the fault, the dip angle of the dyke, the depths of the top and bottom of the dyke, the basement depths and the density contrast along the basement surface are determined.

By similar way, the quantitative interpretation of the magnetic data involves the basement depth determination with the implicated dyke system using the methods of Durantny and Krs (1963), Hilbert transform (1965), characteristic curves (1966), spectral analysis (1968), New method for calculation of dike parameters, Sabry and M.El-Bohoty (1990), and Poorna (1985).  These depth determination methods have been applied to a set of profiles taken across the different magnetic anomalies. Also, the depths to the tops and bottoms of the dykes, their widths, dip angles, strike and the inclination of the magnetic field are defined. Moreover, the basement relief is defined through the previously mentioned methods, and the basement tectonics are detected through Linsser technique (1968)."