The northern volcanic terrane includes the Harare (Salisbury), Mount Darwin, Chipuriro (Sipo-lilo), Midlands (Silobela and Que Que), Chegutu (Gatoma), Bubi, Bulawayo, and parts of the Fila-busi and Gwanda greenstone belts. These contain a lower volcanic series overlain by a calc-alkaline suite of basalts, andesites, dacites, and rhyolites. Pyro-clastic, tuffaceous, and volcaniclastic horizons are common. Also common are iron formations, and other sedimentary rocks including slates, phyllites, and conglomerate. In the Bulawayo-Silobela area (Mulangwane Range), the top of the upper volca-nics include a series of porphyritic and amgdaloidal andesitic and dacitic agglomerate and other pyroclas-tic rocks.
u-Pb ages from felsic volcanics of the northern volcanic belt include 2.696, 2.698, 2.683, 2.702, and 2.697 billion years. Isotopic data from the Harare-Shamva greenstone belt and surrounding granitoids suggest that the greenstones evolved on older continental crust between 2.715 and 2.672 billion years ago. The age of deformation is constrained by a 2.667 billion-year-old syn-tectonic gneiss, a 2.664 billion-year-old late syn-tectonic intrusion, and 2.659 billion-year-old shear zone-related gold mineralization. Other posttectonic granitoids yielded U-Pb zircon ages of 2.649, 2.618, and 26.01 billion years. Isotopic data for the felsic volcanics suggest that the felsic magmas were derived from a melt extracted from the mantle 200 million years before volcanism and saw considerable interaction between these melts and older crustal material.
Was this article helpful?
Preparing for Armageddon, Natural Disasters, Nuclear Strikes, the Zombie Apocalypse, and Every Other Threat to Human Life on Earth. Most of us have thought about how we would handle various types of scenarios that could signal the end of the world. There are plenty of movies on the subject, psychological papers, and even survivalists that are part of reality TV shows. Perhaps you have had dreams about being one of the few left and what you would do in order to survive.