Clinopyroxene trace element compositions of cumulate mafic rocks and basalts from the Hercynian Moroccan Central Meseta: Petrogenetic implications

In the Fourhal foreland basin, in the north-eastern part of the Marrocan Central Meseta, mafic series are represented by basalts interbedded with Early Namurian turbidites and by numerous mafic sills, including the Marziqallal sill detailed here. The study of the trace element compositions of the clinopyroxenes, a ubiquitous mineral in the gabbroic sill and basalts, indicate that these two formations are derived from a similar parental magma. This magma evolved following a general fractional crystallization process involving the cumulation of clinopyroxene, then of ilmenite, occurring within the sill and having a leading role in the composition of the associated basalts. Calculated parental melts inferred from clinopyroxene analyses from the various cumulative units of the sill have trace element patterns similar to the one found for the basaltic flows. These patterns are compatible with magma and clinopyroxene compositions from a subduction-related geotectonic setting.