Crustal structure of Precambrian terranes in the southern African subcontinent with implications for secular variation in crustal genesis

摘要: SUMMARY New estimates of crustal thickness, Poisson’s ratio and shear wave velocity have been obtained for 39 stations in Angola, Botswana, the Democratic Republic Congo, Malawi, Mozambique, Namibia, Rwanda, Tanzania Zambia by modellingP-wave receiver functions using H–κ stacking method jointly inverting with Rayleigh-wave phase group velocities. These estimates, combined similar results from previous studies, examined secular trends Precambrian structure within southern African subcontinent. In both Archean Proterozoic terranes we find Moho depths [38–39 ± 3k mSD (standard deviation)], (0.26 0.01 SD), mean (3.7 0.1 km s −1 amounts heterogeneity thickness mafic lower crust, as defined velocities ≥4.0 . addition, amount variability these parameters is each individual age grouping between groupings. Thus, provide little evidence variation structure, including Meso- Neoarchean crust. This finding suggests that (1) continental has generated processes since Mesoarchean or (2) plate tectonic reworked modified crust through time, erasing variations resulting genesis.