Geochronology and geochemical evolution of Carboniferous volcanism in Scotland’s Midland Valley: Insights from Arthur’s Seat

This project set out to temporally constrain Carboniferous (ca. 359-299 Ma) volcanic, magmatic, and interbedded sedimentary basins which host the important Midland Valley coal seams. We are interrogating rates of eruption and temporal variations in the magma source geochemistry to link these to palaeoclimate variability as recorded by these classic sedimentary successions.Rifting of the Midland Valley, Scotland and synchronous short-lived volcanism (ca. 30 Myr) [7] is associated with the eruption of mildly alkaline olivine basalts and associated intrusive rocks (e.g. micro-gabbro, phonolite). Remnants of this volcanism are exposed across the Midland Valley, including the world-famous geological site, Arthur’s Seat, Edinburgh. Arthur’s Seat is a classic example of a volcanic cross section with approximately nineteen lava layers and numerous vents exposed and characterised [1, 6]. Previous mapping efforts established a stratigraphy for this Site of Special Scientific Interest (SSSI) landmark, constrained by interbedded palynological zones. This has since been succeeded by direct radio-isotopic dating including K-Ar and 40Ar/39Ar geochronological techniques [2, 3, 4]. The most recent published ages constrained the eruption and emplacement of the Arthur’s Seat volcano with a precision ranging between 0.18-1.40% [5, 6].New high precision (