{"title":"磁位反演和电位场建模对绘制阿尔及利亚霍加尔中部 Gour Oumelalen 深部地质结构图的贡献","authors":"Abdelghafour Boukar , Mohammed Djeddi , Mohamed Hamoudi , Abderrezak Bouzid","doi":"10.1016/j.jafrearsci.2024.105398","DOIUrl":null,"url":null,"abstract":"<div><p>The Gour Oumelalen area is situated in the northern part of the Egere-Aleksod terrane (Central Hoggar, South of Algeria). This area is one of the best preserved Palaeoproterozoic and Archaean zones in Central Hoggar. The aim of this study based on a survey of 33 Magnetotelluric (MT) soundings, aeromagnetics and gravity data, is to investigate the crustal structure and its architecture beneath this area.</p><p>As the first stage, we have determined dimensionality of the regional electric conductivity structure. For this purpose, we have used the impedance and phase tensor approaches. Our results suggest that the underling regional conductivity structure is complex. In the central part it presents a 3D geometry, and beyond, it is mainly 2D; with a strike direction oriented in the North-South direction. Thus, the MT data were inverted using the Occam's inversion algorithm (v.3); which is a powerful tool to modeling and inverting the 2-D MT data. The obtained geo-eletric models, show clearly a high resistive upper crust with a resistivity up to 1000 Ω m; overlies a conductive lower crust with a resistivity approximately less then 100 Ω m. Although, our resulting cross-sections confirm the major Precambrian faults, especially the Ounan shear zone, which is characterized by a high conductivity anomaly.</p><p>At the second stage, using the joint modeling of gravity and magnetic data, we have characterized the different geological units. Although, our modeling reveals that the thicknesse of the upper crust is deeping toward the East, from 16 to 25 km. The Moho depth reaches an average value of 40 Km. Moreover, in the centre of the survey area, the Moho depth decreases and becomes equal to 20 Km. This uplifting of the upper mantle may corresponds to the high magnetic anomaly of the Tisseliline pluton. It seems also related to the magmatic intrusion along the Ounan Shear Zone.</p></div>","PeriodicalId":14874,"journal":{"name":"Journal of African Earth Sciences","volume":"219 ","pages":"Article 105398"},"PeriodicalIF":2.2000,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Contribution of Magnetotelluric inversion and potential field modeling to map the Gour Oumelalen deep geological Structure, Central Hoggar, Algeria\",\"authors\":\"Abdelghafour Boukar , Mohammed Djeddi , Mohamed Hamoudi , Abderrezak Bouzid\",\"doi\":\"10.1016/j.jafrearsci.2024.105398\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The Gour Oumelalen area is situated in the northern part of the Egere-Aleksod terrane (Central Hoggar, South of Algeria). This area is one of the best preserved Palaeoproterozoic and Archaean zones in Central Hoggar. The aim of this study based on a survey of 33 Magnetotelluric (MT) soundings, aeromagnetics and gravity data, is to investigate the crustal structure and its architecture beneath this area.</p><p>As the first stage, we have determined dimensionality of the regional electric conductivity structure. For this purpose, we have used the impedance and phase tensor approaches. Our results suggest that the underling regional conductivity structure is complex. In the central part it presents a 3D geometry, and beyond, it is mainly 2D; with a strike direction oriented in the North-South direction. Thus, the MT data were inverted using the Occam's inversion algorithm (v.3); which is a powerful tool to modeling and inverting the 2-D MT data. The obtained geo-eletric models, show clearly a high resistive upper crust with a resistivity up to 1000 Ω m; overlies a conductive lower crust with a resistivity approximately less then 100 Ω m. Although, our resulting cross-sections confirm the major Precambrian faults, especially the Ounan shear zone, which is characterized by a high conductivity anomaly.</p><p>At the second stage, using the joint modeling of gravity and magnetic data, we have characterized the different geological units. Although, our modeling reveals that the thicknesse of the upper crust is deeping toward the East, from 16 to 25 km. The Moho depth reaches an average value of 40 Km. Moreover, in the centre of the survey area, the Moho depth decreases and becomes equal to 20 Km. This uplifting of the upper mantle may corresponds to the high magnetic anomaly of the Tisseliline pluton. It seems also related to the magmatic intrusion along the Ounan Shear Zone.</p></div>\",\"PeriodicalId\":14874,\"journal\":{\"name\":\"Journal of African Earth Sciences\",\"volume\":\"219 \",\"pages\":\"Article 105398\"},\"PeriodicalIF\":2.2000,\"publicationDate\":\"2024-08-28\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of African Earth Sciences\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S1464343X24002310\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of African Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1464343X24002310","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Contribution of Magnetotelluric inversion and potential field modeling to map the Gour Oumelalen deep geological Structure, Central Hoggar, Algeria
The Gour Oumelalen area is situated in the northern part of the Egere-Aleksod terrane (Central Hoggar, South of Algeria). This area is one of the best preserved Palaeoproterozoic and Archaean zones in Central Hoggar. The aim of this study based on a survey of 33 Magnetotelluric (MT) soundings, aeromagnetics and gravity data, is to investigate the crustal structure and its architecture beneath this area.
As the first stage, we have determined dimensionality of the regional electric conductivity structure. For this purpose, we have used the impedance and phase tensor approaches. Our results suggest that the underling regional conductivity structure is complex. In the central part it presents a 3D geometry, and beyond, it is mainly 2D; with a strike direction oriented in the North-South direction. Thus, the MT data were inverted using the Occam's inversion algorithm (v.3); which is a powerful tool to modeling and inverting the 2-D MT data. The obtained geo-eletric models, show clearly a high resistive upper crust with a resistivity up to 1000 Ω m; overlies a conductive lower crust with a resistivity approximately less then 100 Ω m. Although, our resulting cross-sections confirm the major Precambrian faults, especially the Ounan shear zone, which is characterized by a high conductivity anomaly.
At the second stage, using the joint modeling of gravity and magnetic data, we have characterized the different geological units. Although, our modeling reveals that the thicknesse of the upper crust is deeping toward the East, from 16 to 25 km. The Moho depth reaches an average value of 40 Km. Moreover, in the centre of the survey area, the Moho depth decreases and becomes equal to 20 Km. This uplifting of the upper mantle may corresponds to the high magnetic anomaly of the Tisseliline pluton. It seems also related to the magmatic intrusion along the Ounan Shear Zone.
期刊介绍:
The Journal of African Earth Sciences sees itself as the prime geological journal for all aspects of the Earth Sciences about the African plate. Papers dealing with peripheral areas are welcome if they demonstrate a tight link with Africa.
The Journal publishes high quality, peer-reviewed scientific papers. It is devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be considered. Papers must have international appeal and should present work of more regional than local significance and dealing with well identified and justified scientific questions. Specialised technical papers, analytical or exploration reports must be avoided. Papers on applied geology should preferably be linked to such core disciplines and must be addressed to a more general geoscientific audience.