Highly silicic Paleocene-Eocene ignimbrite deposits, and mafic lavas at Kilchrist and Belig, Isle of Skye, NW Scotland, form part of a ~800m thick extensive caldera fill which largely fringes the Eastern Red Hills on Skye. Magma was supplied to the growing caldera via the Moine-related Kishorn Thrust fault, and ponded against pre-existing Paleocene rocks of the Cuillin and Western Red Hills Centres. Silicic magma reservoirs which fed the Kilchrist Caldera were frequently replenished with basic magma. Such replenishment triggered eruptions. Later eruptions typically deposited extremely coarse ignimbrites, demonstrating catastrophic collapse of the caldera. Collapse was followed by caldera resurgence and formation of the
Eastern Red Hills Granite Centre.
Within the caldera sequence, ignimbrites at Kilchrist have been dated at 56.15 Ma. This date is precisely coincident with the Paleocene-Eocene Thermal Maximum (PETM). We suggest that the North Atlantic atmospheric temperature increases during the PETM were intimately linked to consumption of surrounding dolostone country rock by the Kilchrist caldera. We calculate such consumption released between ~5.32 - 8.52 Gt of CO2 into the Paleocene atmosphere. Our study provides the first unequivocal evidence of large-scale eruptions within the North Atlantic Igneous Province on the PETM.
Simon Drake is a research associate (and former associate lecturer) at
Birkbeck College, University of London and was recently appointed
North Downs Way Ambassador leading Geo walks on the North Downs
Way and advising re Geopark status. Previously, Simon was part of the
Metropolitan Police working on the Diplomatic Protection Group at
Downing Street during the Major and Blair Premierships.