Quartz- Porphyry Dolerite in A Selected Part of Southern Benue Trough, Nigeria

The dolerites in some parts of southern Benue Trough were studied petrographically. The results show that most of the dolerites in the Anambra and Afikpo basins are olivine dolerites except Umuchieze LokpaUkwu that host mostly quartz porphyry dolerites. The thin section results show that the dolerite rocks in Umuchieze LokpaUkwu has mineral paragenesis of plagioclase feldspar+quartz +pyroxene + biotite + hornblende + and hematite. The pore spaces and fractures in the rocks are healed by the infilling of quartz.  The porphyritic texture of the dolerite in the study area show variable temperatures of the crystallized magma that formed the dolerite. The sharp contacts of the dolerites and the host rocks could play roles in the alteration of the crystallizing magma. Hydrothermal interaction, contamination and assimilation played major roles in the evolutionary processes of the magma that formed the quartz-porphyry dolerite. Key word: Quartz, Dolerites, Benue Trough, Magma DOI: 10.7176/JEES/10-2-09 Publication date: February 29th 202