Isotopic and geochemical investigation of unit 10 from the Eastern Layered Series of the Rhum Intrusion, Northwest Scotland

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Abstract
Sr and Nd isotopic compositions together with whole rock Sr and Nd abundances and olivine compositions are presented for cumulates from unit 10 of the Eastern Layered Series of the Rhum intrusion, Northwest Scotland.The results show an Nd–Sr isotopic correlation consistent with contamination by high 87Sr/86Sr, low 143Nd/144Nd crust. There is a strong correlation between the degree of contamination, Sr and Nd whole rock abundance and Fe enrichment in cumulus olivine. The allivalites are the most contaminated, while the basal peridotites are uncontaminated. This suggests that the cumulates crystallized from a primitive uncontaminated magma and the allivalites from an evolved contaminated magma. Subsequently, movement of contaminated feldspathic intercumulus liquid has perturbed the isotopic, trace element and olivine composition of the upper peridotites.