Tectonic and magmatic segmentation interlinkage in the central main Ethiopian rift

Abstract

The Main Ethiopian Rift (MER) presents a spectrum of rift sector evolution from embryonic continental rifting in the south to incipient oceanic spreading in the north. The central sector of the MER (CMER) remains relatively immature, characterized by strain accommodation through border faults, axial magmatic segments, and off-rift magmatic zones. However, understanding of the tectonic and magmatic segmentation within this sector is relatively incomplete. This study investigates the CMER at a crustal scale, utilizing gravity data to analyze the nature of tectonic segmentation (TS). While previous studies only considered the Aluto-Gedemsa magmatic segment (MS) within the CMER, our work maps three distinct MS for the first time: Tullu Moye-Gedemsa-MS, Aluto-MS, and Corbetti-Shalla-MS, based on subsurface imaging using gravity data. We find that the distribution of surface faults correlates with subsurface magmatic intrusion zones within the Tullu Moye-Gedemsa and Boseti-Kone MS, indicating a clear interlinkage between tectonic and magmatic segmentation and suggesting the TS stage of the region. In contrast, the absence of such association in the Corbetti-Shalla and Aluto-MS regions suggests that the southern section of the CMER may not be in a stage of TS.