The Development of Late-Stage Continental Breakup: Seismic Reflection and Borehole Evidence from the Danakil Depression, Ethiopia

摘要: During continental breakup, the locus of strain shifts from a broad region border faulting and ductile plate stretching to narrow zone magma intrusion in young ocean basin. Recent studies volcanic rifts margins worldwide suggest this shift occurs subaerially, before onset seafloor spreading. We test hypothesis using recently acquired seismic reflection borehole data Danakil Depression, Ethiopia, unique transition between rifting Our data, located near Dallol, ~30 km northwest Erta'Ale Volcanic Segment, reveal remarkably thick (>1‐km) sequence (~100‐ka) evaporites basin bound by major (≤400‐m‐throw), east‐dipping normal fault. To generate such large amount subsidence relatively short time, we propose that upper‐crustal extension is currently dominated faulting, not magmatic intrusion. Given region's markedly thinned crust (~15‐km‐thick), relative elsewhere Afar where magma‐assisted dominates maintains crustal thickness at ~25 km, mechanical likely coupled with lower‐crust mantle lithosphere. Despite proximity voluminous lavas active evidence for igneous material upper ~2 6‐ 10‐km‐wide limited. Late‐stage was aided thermal/strain‐induced lithospheric weakening following protracted rifting. Basin formation immediately prior spreading may also explain accumulation marine‐seepage‐fed evaporite sequences akin those observed, example, along South Atlantic rifted margins.