Magma ascent along a major terrane boundary: crustal contamination and magma mixing at the Drumadoon Intrusive Complex, Isle of Arran, Scotland

Meade, F.C., Chew, D.M., Troll, V.R., Ellam, R.M. and Page, L.M. (2009) Magma ascent along a major terrane boundary: crustal contamination and magma mixing at the Drumadoon Intrusive Complex, Isle of Arran, Scotland. Journal of Petrology, 50(12), pp. 2345-2374. (doi: 10.1093/petrology/egp081)

Abstract

The composite intrusions of Drumadoon and An Cumhann crop out on the SE coast of the Isle of Arran, Scotland and form part of the larger British and Irish Palaeogene Igneous Province, a subset of the North Atlantic Igneous Province. The intrusions (shallow-level dykes and sills) comprise a central quartz–feldspar-phyric rhyolite flanked by xenocryst-bearing basaltic andesite, with an intermediate zone of dark quartz–feldspar-phyric dacite. New geochemical data provide information on the evolution of the component magmas and their relationships with each other, as well as their interaction with the crust through which they travelled. During shallow-crustal emplacement, the end-member magmas mixed. Isotopic evidence shows that both magmas were contaminated by the crust prior to mixing; the basaltic andesite magma preserves some evidence of contamination within the lower crust, whereas the rhyolite mainly records upper-crustal contamination. The Highland Boundary Fault divides Arran into two distinct terranes, the Neoproterozoic to Early Palaeozoic Grampian Terrane to the north and the Palaeozoic Midland Valley Terrane to the south. The Drumadoon Complex lies within the Midland Valley Terrane but its isotopic signatures indicate almost exclusive involvement of Grampian Terrane crust. Therefore, although the magmas originated at depth on the northern side of the Highland Boundary Fault, they have crossed this boundary during their evolution, probably just prior to emplacement.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Meade, Dr Fiona and Ellam, Professor Rob
• Authors: Meade, F.C., Chew, D.M., Troll, V.R., Ellam, R.M., and Page, L.M.
• Subjects: Q Science > QE Geology
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre; College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Journal of Petrology
• Journal Abbr.: J. Petrol.
• ISSN: 0022-3530
• ISSN (Online): 1460-2415
• Published Online: 22 December 2009