Evidence from apatite fission track analysis for the post-Devonian burial and exhumation history of the northern Highlands, Scotland

Abstract Devonian and older rock samples from outcrops in the northern Scottish Highlands have undergone protracted cooling since they reached palaeotemperatures of ∼110°C or more in the Late Palaeozoic to Early Mesozoic. The results not only suggest that the northern Highlands region has experienced kilometre-scale exhumation since the Late Palaeozoic, but also that Devonian and possibly Permo-Carboniferous sedimentation was probably more extensive than current outcrop patterns would imply. A Permian outcrop sample from the Minches Basin reached a maximum palaeotemperature of 70–90°C prior to the onset of cooling in the Early Tertiary, while data from Devonian and older samples suggest an acceleration in the rate of cooling in the Early Tertiary. The magnitude of Early Tertiary palaeotemperatures on the mainland adjacent to the Inner Moray Firth (IMF) indicate similar amounts of Tertiary exhumation to those derived from compaction analyses for the IMF. However, to the west, the magnitude of Tertiary cooling cannot be solely ascribed to exhumation and a contribution of heating due to hydrothermal effects and/or elevated heat flow associated with the Tertiary Igneous Complex may also need to be invoked.