Petrography of Pan African Migmatite around Liman Katagum, Bauchi North East Nigeria

Abstract

The study area Liman Katagum lies within latitudes 10°00'00" N and 10°30'00" N and longitudes 9°30'00" E and 10°30'00" E which is part of sheet 149 Bauchi SW covering a total area of 42 km2. Based on field relationship and petrography, the area is underlined predominantly by migmatites of different texture such as restite, stromatic metatexite, banded orthogneisses metatexite, melanocratic diatexite, mesocratic diatexite, and leucocratic diatexite. Restite composed of a predominance of mafic minerals because these are harder to melt. Typical minerals are amphibole, biotite, pyroxene, ilmenite or other iron oxides and some plagioclase feldspar. The stromatic migmatites bands of leucosome that are oriented parallel to the major plane of anisotropy in the palaeosome, which are typically compositional layering or a solid-state foliation. It is evident that the individual leucosome bands have melanosome on both sides, while the stromatic type shows evidence of pytgmatic fold and crenulation cleavage. The diatexite migmatite is dominated by pervasive neosome and display a granitic appearance with abundant schlieren. Pre-partial-melting structures are absent from the neosome, and commonly replaced by syn-anatectic flow structures or isotropic neosome. The melt-depleted remains of protolith layers (biotite schlieren) stand out as dark alignment within the diatexites.

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