The Composition and Origin of the Amphibolite’s in Kumunu, North Central Nigeria
Abstract:
The study area is bounded by latitudes 10o 00' 00" N to 10o 20' 00" N and longitudes 6o 15' 00" E to 6o 30' 00" E in Tegina Sheets 142 SE and part of 142 NE. Three samples of amphibolite’s were analyzed for major element oxides using (ICM-MS). The mineral phases of the amphibolite’s examined contains: diopside + hornblende, hornblende + garnet, hornblende, hornblende + biotite. The rocks are characteristic of amphibolite facies metamorphism. Al, Ti, Sc, Zr, Y, Ta, Hf, Nb and heavy REE were the elements less redistributed by the metamorphism or alteration in the studied area. The amphibolite’s from Kumunu are similar to the low-k tholeiites affinity, typical of the early stages of development of recent island arc. The geochemical peculiarities of the amphibolites and associated rocks in the study area suggest an origin in a tectonic setting similar to modern volcanic arcs environment. Some of the geochemical features of the amphibolites can be explained through the involvement of a component of subducted sediment in the source region. This suggests that the amphibolites are derived from sedimentary rocks. lt is suggested that the evolution of the rocks is related subduction that occurred during the Pan-African event.
