Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province

Abstract Two subvertical gabbroic dikes with widths of ~ 350 m (East-Muren) and ≥ 500 (West-Muren) crosscut continental flood basalts in the Antarctic extension 180 Ma Karoo large igneous province (LIP) Vestfjella, western Dronning Maud Land. The exhibit unusual geochemical profiles; most significantly, initial (at Ma) ε Nd values increase from dike interiors towards hornfelsed wallrock (from − 15.3 to 7.8 East-Muren more gradually 9.0 5.5 West-Muren). In this study, we utilize models partial melting energy-constrained assimilation‒fractional crystallization deciphering magmatic evolution their contact aureoles. modeling indicates that both acquired distinctly negative recorded by central parts varying degrees assimilation Archean crust at depth. This first phase deep contamination was followed a second event or close emplacement level is related interaction magmas basalts. These belong distinct LIP magma type having 2.1 + 2.5, which provides stark contrast composition parental (− for East-Muren, West-Muren) previously contaminated crust. For distal hornfelses represent partially melted proximal zones hybrids such residues differentiated melts intrusion; were likely transported away currently exposed conduit before magma–wallrock sealed further prevented. contrast, West-Muren, basalt increasing presently rocks roof Our study shows primitive release enough sensible latent heat melt potentially assimilate wallrocks multiple stages. multi-stage difficult detect general, especially if associated show broad compositional similarity intruding magmas. Notably, trace element isotopic heterogeneity can be homogenized processes (basaltic cannibalism). If similar work larger scales, they may affect influence generation of, example, massif-type anorthosites “ghost plagioclase” signature.