Evolution of the northern Somali basement: New constraints from zircon ages

Abstract:

The northern Somali crystalline basement (NSB) consists of seven major rock complexes, five of which are mainly metasedimentary sequences with some meta-igneous intercalations, while two are plutonic complexes. Using the single grain evaporation method, the authors have dated zircons of six samples from three of these complexes exposed in the Hargheisa-Sheikh-Burao area, the western part of the NSB. The single zircon ages confirm that the western NSB is not a juvenile Pan-African terrain, but a composite basement consisting of pre-Pan-African Proterozoic crust ranging in age between ∼1400 and ∼1820 Ma. This was affected by granitoid magmatism and associated tectono-thermal events at ∼840, ∼800-760 and ∼720 Ma, respectively, at the same time when, farther north in the Arabian-Nubian shield, subduction-related magmatism led to the formation of intra-oceanic island arcs and marginal basins. Pre-Pan-African Archaean to Proterozoic rocks similar in age to the western NSB also occur in eastern Ethopia and the two regions may be part of the same continental terrane, sandwiched in between juvenile domains farther west in Ethiopia and farther east in northern Somalia.

Año de publicación:

1996

Keywords:

Fuente:

scopus