Nureddin M. Saadi

Integration of DEM, ETM+, Geologic, and Magnetic Data for Geological Investigations in the Jifara Plain, Libya

We used an integrated approach to constrain the geological structure of the Jifara Plain in northwest Libya. The analysis of surface data, including a digital elevation model (DEM), Landsat Enhanced Thematic Mapper Plus images, and geologic maps, was combined with subsurface data, including well logs and magnetic data. The DEM data were used for the identification of geological lineaments in the study area. The interpretation and analysis of the lineaments indicate that the Jifara Plain is controlled by three main fault systems, trending northwest-southeast, east-west, and northeast-southwest. The three trends represent the remnants of reactivated structures that formed under the stress regimes generated during the tectonic evolution of North Africa. The magnetic data reveal three northwest- and northeast-trending sedimentary basins in the study area. The depth of the basement inside the main basin ranges from 1 to 5 km. The results indicate that the Jifara Basin is shallower than the surrounding basins. The integration of the results reflects different periods of tectonic activity in the Jifara Plain and the adjacent Jabal Nafusah.

Assessing image processing techniques for geological mapping: A case study in Eljufra, Libya

Various image processing techniques were experimented with in this study to evaluate their efficiency for geological mapping in the Eljufra area of northwest Libya. Remote sensing data including multi-spectral optical Landsat Enhanced Thematic Mapper (ETM+), Synthetic Aperture Radar (ERS-2 SAR) and Digital Elevation Models (DEMs) extracted from the Shuttle Radar Topography Mission (SRTM) data were used to trace different lithological units as well as extracting geological lineaments in the study area. The study area is located in an arid environment mostly devoid of any vegetation. Most lithological and structural units are distinguishable based on their topographic form and spectral properties. Fusion of ETM+ and ERS-2 images was experimented with to further identify lithological units. Shaded relief techniques were implemented to enhance terrain perspective views and to extract geological lineaments. The results discriminated different rock units and modified formation boundaries and revealed new geological lineaments. Nine rock units were identified and plotted in the new geological map defined by the new boundaries. The dominant lineaments tend to run in the NNW-SSE and NNE-SSW directions. Analysis and interpretation of the lineaments provided information about the tectonic evolution of the study area.

Integrating potential fields with remote sensing data for geological investigations in the Eljufra area of Libya

In this study, we successfully integrated geological data, potential field data, and remote sensing data with the aim of investigating and improving our knowledge of the structural setting of the Eljufra area, northwestern Libya. SPOT-5 panchromatic band and digital elevation models (DEM) were used to construct surface shaded maps, and gravity and aeromagnetic surveys were used to provide information on subsurface structures and the nature of intrusive bodies. The results revealed that the prevailing trend of lineaments is NNW-SSE and NNE-SSW. A Bouguer anomaly map revealed that horst and graben blocks occur inside the large graben. An analytic signal method was applied to the aeromagnetic data to estimate locations and the minimum depths to the contact. A comparison of gravity and magnetic data provided information on hydrothermally altered basalt and sediment density. An anticlinal structure was detected in the western part of the study area. The effects of faults on basalt rocks indicated geological time for volcanic activity.

Integrating data from remote sensing, geology and gravity for geological investigation in the Tarhunah area, Northwest Libya

Abstract The present work deals with the integration of remote-sensing, surface-geology and gravity-survey data to improve the structural knowledge of the Tarhunah area, northwest Libya. Geological information and remote-sensing data provided information about the surface structure. A gravity survey was conducted to decipher the subsurface structure. The results revealed that a basin having a width of 39 to 48 km trends NE. A two-dimensional (2-D) schematic model shows that the basin gradually deepens toward the southwest. Faults determined from a horizontal gradient, tilt derivative, and Euler deconvolution show a depth range of 2.5 to 7.5 km. The integration and interpretation of the results indicate that volcanic activity was related to the tectonic activity of an anticlinal structure called the Jabal Uplift.

Geological applications potential of DEM, ETM+, and gravity data in arid and semi-arid regions with special reference to south Western Desert, Egypt

The study area comprises the southeastern part of the Western Desert of Egypt. The aims of the present study are to delineate the major surface and subsurface structures and to evaluate tectonic framework of the study area. Surface studies of the present work are based mainly on data from two different types of remote sensing systems: 15 cloud-free Landsat Enhanced Thematic Mapper Plus (ETM+) images and Shuttle Radar Topography Mission (SRTM) DEM data. The remote sensing data were used to recognize and extract geological lineaments by calculating and interpreting DEM derivatives, including shaded relief maps, slope maps, and traverse profiles. A Bouguer anomaly map (scale 1:500,000) was used to delineate a detailed picture of the subsurface structure in the study area. The analysis of surface data, including SRTM DEM and ETM+, was combined with subsurface data, including Bouguer anomaly map, and gave new insight into the tectonic and structure patterns of the study area.

Lineaments extraction and analysis in Eljufra area, Libya

Several image processing techniques have been separately and simultaneously applied to data obtained from Landsat ETM+, ERS-2 SAR, and Digital Elevation Models (DEM) to evaluate the performance of different satellite sensors for extracting and mapping geological lineaments in the Eljufra area of northwest Libya. Herein, hundreds of new lineaments in various trends have been identified in comparison to previous results obtained from geological maps. Visible and near infrared color composite of Landsat ETM+ overlaid on shaded relief maps enhanced the ability of extracting and mapping geological lineaments. Analysis and interpretation of the extracted lineaments provided information about the tectonic evolution of the investigated area. A gravity survey was performed to explore the subsurface structure of the study area. Euler deconvolution was applied to the gravity data to estimate the depths and locations of gravity source anomalies. A comparison of results obtained from remote sensing and gravity data indicates that the origin of most lineaments is structural.

Integrating remote sensing and magnetic data for structural geology investigation in pegmatite areas in eastern Afghanistan

Abstract This study used an integrated approach to investigate pegmatite areas in eastern Afghanistan. The analysis of surface data, including a digital elevation model (DEM), and Landsat Enhanced Thematic Mapper Plus (ETM+) images, was combined with airborne magnetic data to better understand three-dimensional geology in the area. The ETM+ and DEM data were used to map geological structures at the surface, which indicate that the area consists of two main fault systems that trend NNE and E-W. The two trends represent the remnants of reactivated structures that formed under the stress regimes generated during the tectonic evolution of eastern Afghanistan. Magnetic data indicate an NE-SW trending basin. A two-dimensional schematic model shows that the basin gradually deepens toward the SW with depths to the magnetic basement ranging between 2 and 11.5 km. The integration of the results gave new insight into the tectonic evolution and structure patterns near the pegmatites area.

Investigating Structural and Tectonic Evolution of Central Afghanistan Using Remote Sensing and Gravity Data

This study used an integrated approach to investigate geological structure and tectonic evolution in Central Afghanistan. Several image processing techniques have been separately and simultaneously applied to data obtained from Landsat Enhanced Thematic Mapper Plus (ETM+) and Digital Elevation Models (DEM) to constrain the geological structure of the study area. Satellite images were combined with Gravity data to better understand 3D geology in the area. Analysis and interpretation of the extracted lineaments indicate that the Central Afghanistan area is controlled by two main fault systems, trending NE and EW. The two trends represent the remnants of reactivated structures that formed under the stress regimes generated during the tectonic evolution of Central Afghanistan. Gravity data indicate a NE trending basin. A two- dimensional (2D) schematic model shows that the basin deepens in the central area and gradually shallows towards the edges. The integration of the results gave insight into the tectonic evolution of the Central Afghanistan area and the adjacent areas.

Geothermal studies in oilfield districts of Eastern Margin of the Gulf of Suez, Egypt

Abstract Results of geothermal studies carried out at 149 onshore oil wells have been used in evaluation of temperature gradient and heat flow values of the eastern shore of the Gulf of Suez. The investigations included temperature logs in boreholes, calculation of amplitude temperature, geothermal gradients and heat flow. The results obtained indicate that geothermal gradient values are in the ranges of 0.02–0.044 °C/m and regionally averaged mean heat flow values are found to fall in the interval of 45–120 mW/m2. Temperature gradients and heat flow values change from low values eastward to high values toward the axial of Gulf of Suez rift. The result of this research work has been highly successful in identifying new geothermal resources eastward of the Gulf of Suez. Additionally, this study shows that the areas with relatively higher temperature gradients have lower oil window, mature earlier, than those with low gradient values. Thus, high temperature gradients cause to expedite the formation of oil at relatively shallow depths and narrow oil windows. On the other hand, low temperature gradient makes the oil window to be quite broad when locate at high depths.