Publication Date:
2001-01-01
Description:
The rocks of the Kalahari Craton in central western Mozambique have crystallization ages of between c. 2300 and 3400 Ma and comprise dominantly granite-greenstones, peraluminous two-mica granites, subordinate younger mafic and granitic intrusions of uncertain age and cover sedimentary rocks. The rocks of the Mozambique Belt comprise c. 1100 Ma intrusive granitoids as well as mafic intrusives and supracrustal migmatite gneisses of uncertain age. The boundary zone between and including these two crustal provinces is characterized by a strong N-S penetrative planar and migmatitic fabric. Sparse kinematic indicators suggest a sinistral sense of displacement along this shear zone. The metamorphic gradient increases from west to east from low grade on the Kalahari Craton to high-grade in the east, characterized by two generations of anatectic migmatization. 40Ar/39Ar thermochronology on mica suggests that the Kalahari Craton lithologies have experienced heating above at least c. 300{degrees}C during the c. 1100 Ma Grenville age orogeny and again at c. 530 Ma during the Pan-African Orogeny, possibly related to the collisional amalgamation of East and West Gondwana. The Mozambique Belt lithologies record a c. 550 Ma thermal overprint with the lithologies in the vicinity of the N-S shear zone recording thermal reactivation at c. 470 Ma. Comparisons of the new data with that from western Dronning Maud Land, which was adjacent to the study area prior to Gondwana fragmentation, yield many similarities.
