Unveiling the lithosphere below Northeast Africa: Insights from 3-D electrical resistivity models and joint inversion

Hossam Marzouk, Tarek Arafa-Hamed, Michael Becken, Matthew J. Comeau

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Abstract

The tectonic evolution of Northeast Africa, particularly the interaction between the Saharan Metacraton and the Arabian-Nubian Shield in Egypt, remains poorly understood due to the lack of deeply-penetrating geophysical data that can shed light on lithospheric structures. We present magnetotelluric data along a 700 km profile that was acquired to reveal the lithosphere's composition, thickness, and thermal state, thereby contributing to a better understanding of the tectonic evolution in the region.

The generated 3-D electrical resistivity model illustrates the resistivity distribution along the tectonic boundaries. The Nile Valley region, characterized by significant sedimentary deposits, shows a complex resistivity pattern. The upper crust is highly conductive, consistent with thick sedimentary layers, while deeper sections reveal heterogeneous resistivity indicative of tectonic reactivation and sedimentary basin evolution. The Saharan Metacraton shows as a massive resistive feature interlocated with a more conductive feature revealing the location of the cratonic remnants that still hold some of the cratonic signature. The electrical signature of the Arabian Nubian Shield shows a resistive upper crust corresponding to the predominantly crystalline and igneous rocks, such as granitoids and gneisses, which form the bulk of the shield.

Magnetic and gravity data were combined with the electrical resistivity model in a joint inversion approach to enhance the accuracy and confidence in the interpretations by cross-verifying the findings from multiple sources. The magnetotelluric survey across Northeast Africa, integrating joint inversion with magnetic and gravity data, has provided detailed insights into the lithospheric structures, revealing complex resistivity patterns indicative of tectonic reactivation and sedimentary basin evolution.
Original languageEnglish
Number of pages1
Publication statusPublished - 2024
Event26th International Electromagnetic Induction Workshop 2024 - B-Con Plaza, Beppu, Japan
Duration: 7 Sept 202413 Sept 2024
https://www.emiw.org/emiw2024/

Conference

Conference26th International Electromagnetic Induction Workshop 2024
Abbreviated titleEMIW2024
Country/TerritoryJapan
CityBeppu
Period7/09/2413/09/24
Internet address

Keywords

  • Magnetotelluric
  • Resistivity
  • Inversion
  • Arabian Nubian Shield
  • Saharan Metacraton

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