Evolution of upper crustal faulting assisted by magmatic volatile release during early-stage continental rift development in the East African Rift

摘要: During the development of continental rifts, strain accommodation shifts from border faults to intra-rift faults. This transition represents a critical process in evolution rift basins East African Rift, resulting focusing and, ultimately, breakup. An analysis fault and fluid systems younger than 7 Ma Natron Magadi (Kenya-Tanzania border) reveals as complex interaction between plate flexure, magma emplacement, magmatic volatile release. Rift basin was investigated by analyzing systems, lava chronology, geochemistry spring systems. Results show that extensional 3 is primarily accommodated along fault, whereas results reveal fault–dominated accommodation. The into system also occurred without oblique-style rifting, observed Ethiopia, hanging-wall flexure can account for only minor portion faulting central axis (∼12% or less). Instead, areas high upper crustal coincide with presence hydrothermal springs exhibit carbon isotopes N2-He-Ar abundances indicating mixing mantle-derived (magmatic) fluids air saturated water. By comparing distribution fault-related zones release basins, we present conceptual model early-stage rifting. In first m.y., accommodate majority regional extension (1.24–1.78 mm yr–1 at slip rate ranging 1.93–3.56 yr–1), significant (38%–96%) driven hanging wall. Fluids released bodies ascend then outward nearby forming flexing By there reduction amount (0.40–0.66 0.62 1.32 population (1.34–1.60 an accompanying center. toward center concomitant wall provides previously unrecognized mechanism may help weaken crust assist dominated We conclude flow within plays important role weakening lithosphere prior establishment segments.