Isotopic evolution of the Lizard Complex

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Abstract
An Sm-Nd mineral isochron from an olivine gabbro yields an age of 375 ± 34 Ma (MSWD = 0.006) which represents the formation age of the Lizard Igneous Complex. Associated dolerite dyke suites have ɛ Nd375 values between +8.9 and +11.7 and record derivation from a recently trace element-enriched, but heterogeneous, source region. The petrology and Sm-Nd isotope systematics of the Lizard peridotites record the local infiltration of a magma. Significantly, the Sm-Nd isotope systematics of the ‘metasomatized’ peridotites are the same as calculated sources of the dolerite dyke suites: their sources are probably equivalent at depth. Finally, the magmatic evolution of the Lizard Complex is likened to the initial development of the Red Sea, with early trace element-enriched volcanism followed by MORB-Iike activity.