Recent volcano-tectonic activity of the Ririba rift and the evolution of rifting in South Ethiopia

Abstract

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Active Deformation Constraints on the Nubia‐Somalia Plate Boundary Through Heterogenous Lithosphere of the Turkana Depression

“…Our synthesis argues against the interpretation of Franceschini et al. (2020) that eruptive centers east of Lake Turkana reactivate inherited Precambrian and Mesozoic crustal structures: the deeper mantle melt zones instead appear to drive the location of magmatism.…”

“…RS and GA are the Red Sea and Gulf of Aden, respectively. (b) Zone of linkage between the MER and ER showing the Turkana Depression with Mesozoic‐Paleogene and Oligocene‐Recent faults and basins in purple and black, respectively (after Corti et al., 2019; Davidson, 1983; Ebinger et al., 2000; Schofield et al., 2021; Franceschini et al., 2020; Morley, 2020). Four sub‐parallel rift strands from southwest to northeast: Turkwel‐Lokichar (LK) rift, Suguta‐Lake Turkana‐Omo‐Usno rift, Kino Sogo (KSFB)‐Chew Bahir (CHB)‐Weyto (WYT) rift and Ririba‐Segen‐Chamo rift.…”

Large-to Local-Scale Control of Pre-Existing Structures on Continental Rifting: Examples From the Main Ethiopian Rift, East Africa

“…In the Ririba rift, at the southern termination of the MER, the Quaternary volcanic fields are aligned in a NE-SW direction and show no apparent relationship with the N-Strending Pliocene boundary faults of the rift (Figure 10) therefore indicating that these structures do not exert a control on the pathways of magma ascent. This volcanism aligns parallel with regional, NE-SW/NNE-SSW-trending pre-existing lineaments (such as the Buluk Fault Zone in Figure 10) suggesting that the distribution of volcanic centres may have been controlled by these major deep inherited structures (e.g., Vétel and Le Gall, 2006;Corti et al, 2019;Franceschini et al, 2020). Magma ascent along these pre-existing structures may have been caused by abandonment of the Ririba rift and consequent deactivation of the main rift faults, and a stress re-organization due to gradients in crustal thickness (Franceschini et al, 2020).…”

“…This volcanism aligns parallel with regional, NE-SW/NNE-SSW-trending pre-existing lineaments (such as the Buluk Fault Zone in Figure 10) suggesting that the distribution of volcanic centres may have been controlled by these major deep inherited structures (e.g., Vétel and Le Gall, 2006;Corti et al, 2019;Franceschini et al, 2020). Magma ascent along these pre-existing structures may have been caused by abandonment of the Ririba rift and consequent deactivation of the main rift faults, and a stress re-organization due to gradients in crustal thickness (Franceschini et al, 2020). This resulted in buoyancy forces causing a local stress field with maximum horizontal stress orthogonal to the Turkana depression, enabling the uprising and emplacement of magma along NE-SW pre-existing structures.…”

“…This resulted in buoyancy forces causing a local stress field with maximum horizontal stress orthogonal to the Turkana depression, enabling the uprising and emplacement of magma along NE-SW pre-existing structures. At a more local scale, the distribution of vents and their preferential directions of elongation (within individual volcanic fields) suggest a second-order control by inherited basement fabrics (Franceschini et al, 2020), as documented by the above-mentioned angular networks of minor normal faults observed in the area. Overall, the Ririba example supports that major, lithospheric-scale inherited structures may represent zones of crustal weakness that magma can exploit during its ascent, controlling the volcanic spatial and temporal evolution, volcanic morphology, magma volume, and eruptive dynamics (e.g., Le Corvec et al, 2013;Wadge et al, 2016).…”