Understanding the location of the subsurface heat sources is crucial for efficient geothermal resource exploration and exploitation. This study aimed to investigate the faults and the depth to heat sources for a geoth...Understanding the location of the subsurface heat sources is crucial for efficient geothermal resource exploration and exploitation. This study aimed to investigate the faults and the depth to heat sources for a geothermal system in Magadi, southern Rift Valley, through the integration of gravity mapping, 3D Euler deconvolution, and spectral analysis. Gravity mapping is a powerful geophysical method widely used to infer subsurface density variations, which are indicative of geological structures and volcanic intrusions that can be potential heat sources. The Volcano-Tectonic and Fluvial-Deltaic Sedimentation process of the Kenyan rift which encompasses the Magadi basin are responsible for geomorphic and geologic processes in the area. Alkali lava sheets of Magadi plateau trachytes covered with lacustrine sediments characterize 80% of the area. Deeper is the Tanzanian craton basement, overlain by Pliocene to Miocene volcanic and sedimentary rocks. A gravity survey with a data density of 2.375 stations/km<sup>2</sup> produced high-resolution anomaly and total horizontal derivative maps showing gravity highs between −180 mGals to −174 mGals along the eastern zone of the study area. A buried major fault trending N-S was delineated in the mid-upper region of the area by Euler solutions at an average depth of 350 meters. Deeper features associated with possible volcanic dykes and sills gave Euler depth ranges of 0.7 km to 2.2 km. Radial average spectral analysis showed depth to the top of shallow and deep features at 2.4694 km and 5.827 km respectively. The correlation between gravity anomalies, geological structures, and present hot springs supports the hypothesis that volcanic processes have played a significant role in the development of the geothermal system in the study area.展开更多
The Hercynian massif of the central Jebilet (Morocco) is characterized by the outcrop of many gossans with great economic importance. This work focuses on interpreting gravity data of Benslimane gossan, located about ...The Hercynian massif of the central Jebilet (Morocco) is characterized by the outcrop of many gossans with great economic importance. This work focuses on interpreting gravity data of Benslimane gossan, located about thirty kilometres to the North-West of Marrakech. The residual gravity map of the study area highlights several anomalies which coincide with the mining and geological contexts. Applying edge detection methods, for example, tilt angle derivative (TDR), the total horizontal derivative of the tilt angle derivative (HDR_TDR) and the 3D Euler deconvolution, allowed us to estimate the depth of the Benslimane deposit. As a result, the average depth of the ore deposit was estimated to exceed 200 m. The results are promising, and the processing methods must be applied to the other gossan in the Jebilet massif for further exploration studies.展开更多
To decipher both shallow and deeper structural features that may control the emplacement of Kimberlite/Lamproite bodies in basement-exposed and covered areas, a detailed gravity survey was conducted on the northern ba...To decipher both shallow and deeper structural features that may control the emplacement of Kimberlite/Lamproite bodies in basement-exposed and covered areas, a detailed gravity survey was conducted on the northern bank of the Krishna River in the Kollarpur region of the Proterozoic Cuddapah Basin, within the Eastern Dharwar Craton. The study revealed an overall basement disposition dipping from south to north, controlled by a set of parallel E-W and NW-SE trending faults. In the northeastern part of the study area, the high-gravity zone corresponds to high-density source rocks at both shallow and deeper levels within the granite-gneissic basement. The residual gravity map highlights the disposition of high-density shallow source bodies as elliptical highs, located at Narlapur, Kalwakole, and Yelur in the eastern part. These residual gravity highs correspond to enclaves of amphibolite schist and BIF bands within granite-gneissic rocks. In the covered region of the southern part, the overall gravity low zone indicates the distribution of sediments with a thickness of about 1 km. Several NW-SE, N-S, NE-SW, and E-W structural features were delineated from the gravity survey. A major E-W gravity gradient along the northern margin of the Cuddapah and Kurnool groups of sediments is interpreted as a deep-rooted boundary fault. Parallel to this boundary fault, two NW-SE gravity gradients were identified in the northern and central parts within the Archean granite-gneissic basement rocks. Depth extensions of these major structures exceed 1 km. The N-S and NE-SW structures, although shorter in strike length, intersect with the major NW-SE and E-W structures. Some of these intersection zones correspond to known Kimberlite/Lamproite occurrences in both covered and basement-exposed areas. Based on these findings, potential loci for Kimberlite/Lamproite exploration have been delineated along the northern bank of the Krishna River in the Kollarpur region.展开更多
A new and efficient three-dimensional implicit hybrid scheme for Euler equations is presented. The basic scheme is the coupling of the Jameson and Turkel's LU decompositions and Prof. Zhang Hanxin'sNND concept...A new and efficient three-dimensional implicit hybrid scheme for Euler equations is presented. The basic scheme is the coupling of the Jameson and Turkel's LU decompositions and Prof. Zhang Hanxin'sNND concept. The improved LU decompositions are applied to discretize the implicit part of the Euler Equations and Zhang's modified flux function to calculate the right hand side operators of the hybrid scheme. Numerical calculations were made of supersonic inlet flows with mired eXternal-internal compressions. Some of the computed results were compared with available wind tunnel data.展开更多
文摘Understanding the location of the subsurface heat sources is crucial for efficient geothermal resource exploration and exploitation. This study aimed to investigate the faults and the depth to heat sources for a geothermal system in Magadi, southern Rift Valley, through the integration of gravity mapping, 3D Euler deconvolution, and spectral analysis. Gravity mapping is a powerful geophysical method widely used to infer subsurface density variations, which are indicative of geological structures and volcanic intrusions that can be potential heat sources. The Volcano-Tectonic and Fluvial-Deltaic Sedimentation process of the Kenyan rift which encompasses the Magadi basin are responsible for geomorphic and geologic processes in the area. Alkali lava sheets of Magadi plateau trachytes covered with lacustrine sediments characterize 80% of the area. Deeper is the Tanzanian craton basement, overlain by Pliocene to Miocene volcanic and sedimentary rocks. A gravity survey with a data density of 2.375 stations/km<sup>2</sup> produced high-resolution anomaly and total horizontal derivative maps showing gravity highs between −180 mGals to −174 mGals along the eastern zone of the study area. A buried major fault trending N-S was delineated in the mid-upper region of the area by Euler solutions at an average depth of 350 meters. Deeper features associated with possible volcanic dykes and sills gave Euler depth ranges of 0.7 km to 2.2 km. Radial average spectral analysis showed depth to the top of shallow and deep features at 2.4694 km and 5.827 km respectively. The correlation between gravity anomalies, geological structures, and present hot springs supports the hypothesis that volcanic processes have played a significant role in the development of the geothermal system in the study area.
文摘The Hercynian massif of the central Jebilet (Morocco) is characterized by the outcrop of many gossans with great economic importance. This work focuses on interpreting gravity data of Benslimane gossan, located about thirty kilometres to the North-West of Marrakech. The residual gravity map of the study area highlights several anomalies which coincide with the mining and geological contexts. Applying edge detection methods, for example, tilt angle derivative (TDR), the total horizontal derivative of the tilt angle derivative (HDR_TDR) and the 3D Euler deconvolution, allowed us to estimate the depth of the Benslimane deposit. As a result, the average depth of the ore deposit was estimated to exceed 200 m. The results are promising, and the processing methods must be applied to the other gossan in the Jebilet massif for further exploration studies.
文摘To decipher both shallow and deeper structural features that may control the emplacement of Kimberlite/Lamproite bodies in basement-exposed and covered areas, a detailed gravity survey was conducted on the northern bank of the Krishna River in the Kollarpur region of the Proterozoic Cuddapah Basin, within the Eastern Dharwar Craton. The study revealed an overall basement disposition dipping from south to north, controlled by a set of parallel E-W and NW-SE trending faults. In the northeastern part of the study area, the high-gravity zone corresponds to high-density source rocks at both shallow and deeper levels within the granite-gneissic basement. The residual gravity map highlights the disposition of high-density shallow source bodies as elliptical highs, located at Narlapur, Kalwakole, and Yelur in the eastern part. These residual gravity highs correspond to enclaves of amphibolite schist and BIF bands within granite-gneissic rocks. In the covered region of the southern part, the overall gravity low zone indicates the distribution of sediments with a thickness of about 1 km. Several NW-SE, N-S, NE-SW, and E-W structural features were delineated from the gravity survey. A major E-W gravity gradient along the northern margin of the Cuddapah and Kurnool groups of sediments is interpreted as a deep-rooted boundary fault. Parallel to this boundary fault, two NW-SE gravity gradients were identified in the northern and central parts within the Archean granite-gneissic basement rocks. Depth extensions of these major structures exceed 1 km. The N-S and NE-SW structures, although shorter in strike length, intersect with the major NW-SE and E-W structures. Some of these intersection zones correspond to known Kimberlite/Lamproite occurrences in both covered and basement-exposed areas. Based on these findings, potential loci for Kimberlite/Lamproite exploration have been delineated along the northern bank of the Krishna River in the Kollarpur region.
文摘A new and efficient three-dimensional implicit hybrid scheme for Euler equations is presented. The basic scheme is the coupling of the Jameson and Turkel's LU decompositions and Prof. Zhang Hanxin'sNND concept. The improved LU decompositions are applied to discretize the implicit part of the Euler Equations and Zhang's modified flux function to calculate the right hand side operators of the hybrid scheme. Numerical calculations were made of supersonic inlet flows with mired eXternal-internal compressions. Some of the computed results were compared with available wind tunnel data.
