The geochemistry of the Barber mafic complex, Rowan County, North Carolina

The Barber complex is a composite gabbro-metagabbro body located in the Charlotte belt in Rowan County, North Samples from both parts of the body were analyzed for major and minor oxides and trace elements using atomic absorption Carolina. spectrophotometry. Discriminant analysis indicated that the metagabbro (B1) and gabbro {B2) sample populations are geochemically distinct, although overlap between the two occurs. Normative mineralogy of the two units differ, with B2 samples falling in the quartz tholeiite field and B1 samples falling in the alkali basalt some and olivine tholeiite field. In addition, it was found that geochemistry correlates closely with mineralogy and has been strongly influenced by crystal accumulation.

Four B1 and four B2 samples exhibited a much finer-grained texture than do the majority of samples. The fine-grained B2 samples occur near the B1/B2 contact and may be chill margin samples; their compositions have probably been affected by assimilation. The significance of the fine grained B1 samples is unclear.

Based on geochemical and petrological characteristics of the two intrusions, it is concluded that B1 probably originated from a tholeiitic parental magma and B2 from a calc-alkaline parental magma intruded at a collisional plate boundary. The complex was probably This complex is petrologically and geochemically similar to one other gabbro-metagabbro complexes in the Piedmont, e.g • f the Mecklenburg complex. North Carolina, and is probably genetically related to it.