40Ar/39Ar thermochronology of the Ethiopian and Yemeni basements: reheating related to the Afar plume?

摘要: Abstract In order to constrain the timing of mantle plume-related basement uplift and discuss active or passive mechanisms continental rifting in Afar triple junction area, a 40 Ar/ 39 Ar thermochronological study has been carried out on Panafrican Ethiopia Yemen. Muscovites, biotites K-feldspars from granitoids high-grade metamorphic samples have analysed using furnace step heating procedure. K-feldspar thermal histories numerically modelled, according multi-domain diffusion theory. The cooling ages range 462 Ma 679 Ma for 495 Ma 796 Ma rocks, which suggests that magmatic episodes belong same thermotectonic event. A gradual younging north south is consistent with assumption collision began Southern Ethiopia. Age gradients recorded by reflect loss are most likely related Cenozoic reheating basement. estimated mean temperature over last 50 Ma between 138°C 177°C at 2 km below surface, minimum gradient 69–88°C/km. anomaly expected heat conduction plume, magma underplating melting lower crust, advection transfer through crust. However, due limited exhumation, it was not possible any uplift. This thermochronology generally unsuited monitor denudation crust an extensional setting. Furthermore, highlights some effects flood basalts may can lead inconsistencies mica age data.