The middle Neoproterozoic (717 Ma) Mount Harper Volcanic Complex (MHVC) is a calc-alkaline magmatic suite developed within a rift system on the northwestern margin of Laurentia. Based on its low Al2O3, Na2O, and TiO2 contents, the primary melt was derived from a harzburgitic source, was most likely picritic in composition, and required mantle potential temperatures above those recognized for the ambient mantle. Constraints on mantle melting place the mantle at ~6 km, a depth that would require significant crustal attenuation.
Although the volcanic rocks at Mount Harper are the same age as the Franklin Large Igneous Province, the geochemical trends are distinct. Apart from their age, the only plausible link would be to consider the MHVC as the product of a partial melt at the margin of a dispersed mantle plume.
