LITHOLOGICAL DELINEATION OF ROCKS AROUND BALI SHEET 255 NE AND ENVIRONS TARABA STATE, NORTHEASTERN NIGERIA

Abstract

A study was carried out to evaluate the lithology and delineate rock units in Bali and Environs. Hand specimen and petrographic studies of sampled rocks allowed for the identification of the rock types and describing their geologic history. Four lithological units comprising of gneiss, granites, metasediments and pegmatite were identified and delineated. Petrophysical analysis reveals quartz, feldspars, biotite, and hornblende as the main rock-forming minerals in the granites and ortho-gneisses. Modal composition of the ortho-gneisses shows a range between 30-35% plagioclase feldspar, 18-25% quartz, 5-15% hornblende and 5-25% biotite mica with similar composition for the granites and therefore referred to as biotite-hornblende granites. The lithologies show variable degrees of metamorphism and alterations ranging from foliations, lineation and ferricretization.  From the results of this study it was deduced that these rocks belong to the Older Granite Suites of the North-Eastern Basement Complex of Nigeria, having strong imprint of the Pan African Orogeny.