Holford et al. Post-Caledonian exhumation of northwest Scotland 1 Multiple post-Caledonian exhumation episodes across northwest Scotland revealed by 2 apatite fission track analysis 3 4 Simon P. Holford1, Paul F. Green2, Richard R. Hillis1, John R. Underhill3, Martyn S. Stoker4 5 & Ian R. Duddy2 6 7 1Australian School of Petroleum, Centre for Tectonics, Resources and Exploration (TRaX), University of Adelaide, SA 5005, Australia 8 (
[email protected]) 9 2Geotrack International Pty Ltd, 37 Melville Road, Brunswick West, Victoria 3055, Australia 10 3School of Geosciences, The University of Edinburgh, Grant Institute of Earth Science, The King’s Buildings, West Mains Road, Edinburgh 11 EH9 3JW, United Kingdom 12 4British Geological Survey, Murchison House, West Mains Road, Edinburgh EH9 3LA, United Kingdom 13 14 Abstract 15 The post Caledonian exhumation history of northwest Scotland is a controversial issue, with 16 some studies advocating largely continual emergence while others suggest dominantly early 17 Palaeogene plume-driven exhumation. AFTA data in samples of Precambrian basement and 18 Permian-Cretaceous sediments from onshore and onshore reveal multiple phases of post- 19 Caledonian cooling, viz: Triassic (beginning 245-225 Ma), Cretaceous (140-130 Ma; 110-90 20 Ma) and Cenozoic (65-60 Ma; 40-25 Ma; 15-10 Ma), all of which are interpreted at least in 21 part as recording exhumation. Basement and sedimentary cover rocks display similar thermal 22 histories, emphasising the regional nature of these episodes and implying that sedimentary 23 outliers represent the remnants of previously more extensive sequences. Significant 24 thicknesses of Jurassic rocks may once have covered northwest Scotland.