[ Interprétation des données gravimétriques et contribution à l’étude structurale du bloc Bilma (Bassin de Termit, Niger oriental) ]
Abdourhmane Halidou Amadou1, Ismaël Ibrahim Cissé2, and Adji Ousmane Gambo3
1 Laboratoire Systèmes Intelligents Géoressources et Energies Renouvelables, Faculté des Sciences et Techniques, Université Sidi Mohamed Ben Abdallah, Fès, Morocco
2 Ministère du Pétrole, Niamey, Niger
3 Ministère du Pétrole, Niamey, Niger
Original language: French
Copyright © 2024 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The present study aims to improve knowledge of the structure of the Bilma block based on the interpretation of gravity anomaly maps. Three filtering methods were applied: upward continuation, horizontal gradient and Euler deconvolution. The analysis of the residual anomaly map upwarded allowed us to understand the behavior of gravity anomalies at the different applied altitudes. The negative anomalies thus resist to the various continuations, unlike the positive ones anomalies. The horizontal gradient method also allowed us to identify and highlight gravity lineaments that may be associated with faults already recognized by geological and geophysical studies. Those faults are responsible for the structuration of the Bilma block and are organized into three families of directions: NW-SE, NNW-SSE and NE-SW, with a prevalence of the NW-SE direction. Finally, the estimated depths by using Euler deconvolution calculations exceed 3 km for the deepest density sources and they are less than 1 km for the shallower ones sources.
Author Keywords: Bilma block, density, lineaments, structure.
Abdourhmane Halidou Amadou1, Ismaël Ibrahim Cissé2, and Adji Ousmane Gambo3
1 Laboratoire Systèmes Intelligents Géoressources et Energies Renouvelables, Faculté des Sciences et Techniques, Université Sidi Mohamed Ben Abdallah, Fès, Morocco
2 Ministère du Pétrole, Niamey, Niger
3 Ministère du Pétrole, Niamey, Niger
Original language: French
Copyright © 2024 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The present study aims to improve knowledge of the structure of the Bilma block based on the interpretation of gravity anomaly maps. Three filtering methods were applied: upward continuation, horizontal gradient and Euler deconvolution. The analysis of the residual anomaly map upwarded allowed us to understand the behavior of gravity anomalies at the different applied altitudes. The negative anomalies thus resist to the various continuations, unlike the positive ones anomalies. The horizontal gradient method also allowed us to identify and highlight gravity lineaments that may be associated with faults already recognized by geological and geophysical studies. Those faults are responsible for the structuration of the Bilma block and are organized into three families of directions: NW-SE, NNW-SSE and NE-SW, with a prevalence of the NW-SE direction. Finally, the estimated depths by using Euler deconvolution calculations exceed 3 km for the deepest density sources and they are less than 1 km for the shallower ones sources.
Author Keywords: Bilma block, density, lineaments, structure.
Abstract: (french)
La présente étude a pour objectif d’améliorer la connaissance de la structure du bloc Bilma en se basant sur l’interprétation des cartes d’anomalies gravimétriques. Trois méthodes de filtrage ont été appliquées: le prolongement vers le haut, le gradient horizontal et le calcul de la déconvolution d’Euler. L’analyse de la carte d’anomalie résiduelle prolongée vers le haut nous a permis de comprendre le comportement des anomalies gravimétriques aux différentes altitudes appliquées. Nous y retenons que les anomalies négatives résistent aux différents prolongements contrairement aux anomalies positives. La méthode du gradient horizontal nous a permis également d’identifier et de mettre en évidence des linéaments gravimétriques qui peuvent être associés à des failles déjà reconnues par les études géologiques et géophysiques. Ces failles sont responsables de la structuration du bloc Bilma et sont organisées en trois familles de directions NW-SE, NNW-SSE et NE-SW, avec une dominance de la direction NW-SE. Enfin, les profondeurs estimées par le calcul de la déconvolution d’Euler dépassent 3 km pour les sources de densité les plus profondes et moins de 1 km pour les sources moins profondes.
Author Keywords: bloc Bilma, densité, linéaments, structure.
