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1

Structural Investigations of Afghanistan Deduced from Remote Sensing and Potential Field Data

Saibi H., Azizi M., Mogren S.

Acta Geophysica

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2016

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Vol. 64, no. 4

978--1003

EN

This study integrates potential gravity and magnetic field data with remotely sensed images and geological data in an effort to understand the subsurface major geological structures in Afghanistan. Integrated analysis of Landsat SRTM data was applied for extraction of geological lineaments. The potential field data were analyzed using gradient interpretation techniques, such as analytic signal (AS), tilt derivative (TDR), horizontal gradient of the tilt derivative (HG-TDR), Euler Deconvolution (ED) and power spectrum methods, and results were correlated with known geological structures. The analysis of remote sensing data and potential field data reveals the regional geological structural characteristics of Afghanistan. The power spectrum analysis of magnetic and gravity data suggests shallow basement rocks at around 1 to 1.5 km depth. The results of TDR of potential field data are in agreement with the location of the major regional fault structures and also the location of the basins and swells, except in the Helmand region (SW Afghanistan) where many high potential field anomalies are observed and attributed to batholiths and near-surface volcanic rocks intrusions. A high-resolution airborne geophysical survey in the data sparse region of eastern Afghanistan is recommended in order to have a complete image of the potential field anomalies.

2

3D Gravity Inversion using Tikhonov Regularization

Toushmalani R., Saibi H.

Acta Geophysica

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2015

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Vol. 63, no. 4

1044--1065

EN

Subsalt exploration for oil and gas is attractive in regions where 3D seismic depth-migration to recover the geometry of a salt base is difficult. Additional information to reduce the ambiguity in seismic images would be beneficial. Gravity data often serve these purposes in the petroleum industry. In this paper, the authors present an algorithm for a gravity inversion based on Tikhonov regularization and an automatically regularized solution process. They examined the 3D Euler deconvolution to extract the best anomaly source depth as a priori information to invert the gravity data and provided a synthetic example. Finally, they applied the gravity inversion to recently obtained gravity data from the Bandar Charak (Hormozgan, Iran) to identify its subsurface density structure. Their model showed the 3D shape of salt dome in this region.

3

Analysis and interpretation of gravity data from the Aluto-Langano geothermal field of Ethiopia

Saibi H., Aboud E., Ehara S.

Acta Geophysica

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2012

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Vol. 60, no. 2

318-336

EN

The Aluto-Langano geothermal field is located in the central southern portion of Ethiopia within the Ethiopian Rift Valley. The gravity of the area was surveyed in an attempt to delineate the subsurface structure and to better understand the relationship between the geothermal systems and the subsurface structure. The gravity data were analyzed using integrated gradient interpretation techniques, such as the Horizontal Gradient (HG), Source Edge Detection (SED), and Euler Deconvolution (ED) methods. These techniques detected many faults that were compared with the mapped faults in the surface geology. The results of the present study will lead to an improved understanding of the geothermal system in the study area and aid the future geothermal exploration of the area.