The petrology and geochemistry of dykes of the Lizard Ophiolite Complex, Cornwall

Abstract

Dykes from the coastal section of the Lizard ophiolite, SW England, have been analysed for both major and trace elements. The dykes vary from fresh olivine dolerites to lower amphibolite grade metadolerites. All are basaltic and tholeiitic and possess broadly oceanic characteristics. Three magma groupings can be defined geochemically on the basis of trace element contents, particularly rare earth elements and P/Y ratios. These magma groupings are thought to have been generated by differing degrees of partial melting and from differing source rocks. Each group is thought to have undergone fractional crystallization. The spatial and suggested temporal separation of these groups supports a pulsatory magma chamber model for the spreading centre at which the Lizard ophiolite developed.