Petrological and geochemical study of basalts and dolerites in East Antarctica, the formation of which is explained by the Karoo plume impact on the Queen Maud Land, revealed the presence of high-magnesium magmas, Fe-rich and depleted in incompatible elements, among the geochemically diverse magmas. Such high-Mg ferropicrites are scarce in other plume-related igneous provinces and their genesis is related to melting of a peculiar pyroxenite mantle source. These rocks were found only in the Ahlmannryggen and Vestfjella massifs in Antarctica and in the Letabo province in South Africa, correspond to the central part of the plume and likely the earliest eruptions. The studied dolerites are close to the parental melts. They have a relatively smoothed lithophile element pattern (from Th to Er), the lowered content of most compatible elements (Y, Yb, Lu), as well as the low ²⁰⁶Pb/²⁰⁴Pb = 17.33–17.37 and moderately radiogenic neodymium composition with ¹⁴³Nd/¹⁴⁴Nd from 0.51249 to 0.51259, which indicate a relatively old age of the pyroxenite component. All high-Ti basalts related to the Karoo–Maud plume point to the presence of this component in their compositions, but its proportion could significantly vary.