The Palaeogene Eskdalemuir dyke, Scotland: long-distance lateral transport of rhyolitic magma in a mixed-magma intrusion

摘要: The Palaeogene Eskdalemuir dyke, part of the Mull dyke swarm in Southern Uplands Scotland, is ∼60 km long and up to 40 m thick. Its southern tip 230 from inferred source on Mull. composite, with tholeiitic basaltic margins a vitreous central facies ranging andesite composition. Plagioclase pyroxene phenocrysts matrix crystals show unusually large compositional ranges complex textural relationships. Whole-rock major trace-element abundances linear variations against MgO content, consistent rocks having formed by mixing basalt rhyolite magmas. can be closely matched centre. mafic silicic magmas were intruded compositionally zoned chamber beneath Mull, perhaps during collapse Centre 1 caldera. lower-viscosity magma was emplaced before, but lubricated lateral propagation of, magma, which mixed partially solidified basalt, proportion increasing towards represents an unusual, unique, example being >200 its source. supposed correlative north Fault, Dalraith-Linburn not comagmatic it.