207-13 Lithospheric Structure of the Chad Lineament: Evidence for a Suture Zone

Session: Honoring the Late Professor Mohamed Abdelsalam: Outstanding Researcher, Generous Colleague, Legendary Mentor, and Ambassador for the Geosciences In Africa

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Abstract:

The Saharan Metacraton underwent metacratonization during the Neoproterozoic. From the former Saharan craton, the Chad cratonic remnant is among the preserved blocks. To the east of the Chad craton, a transcontinental, arcuate-shaped lineament separates the Chad cratonic entity from the Ouaddai Massif. The Bouguer gravity anomaly maps from the World Gravity Model (WGM-2012) and EIGEN-6C4 both reveal this anomalous gravity high associated with the Chad Lineament. Additionally, the Bouguer gravity anomaly map shows a relatively higher gravity response (>60 mGal) over the Chad Craton compared to the Ouaddai Massif, which averages <40 mGal. Preliminary results from joint forward modeling of elevation, geoid, and Bouguer gravity anomalies, followed by integrated geophysical-petrological modeling of the lithosphere using LitMod 2.0, indicate Moho shallowing beneath the Chad Craton along with a relatively thicker upper crust—signifying the structural accommodation geometry of the Chad Basin. The model also reveals progressive thickening of both the upper and lower crust east of the Chad Lineament. The upper crust beneath the Chad Lineament shows distinct thickening as it transitions toward the Ouaddai Massif across the lineament. At the lithospheric scale, modelled shear wave velocity (Vs) also show variation beneath the Chad Craton and Ouaddai Massif, compared to the Chad Lineament. These preliminary results suggest that the Chad Lineament is possibly a suture zone along which the Chad Craton and the Ouaddai Massif terranes were assembled.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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