Document Type
Article
Publication Date
8-1-2018
Publication Title
Journal of Structural Geology
Abstract
In the Caledonides of northern Scotland temperatures of metamorphism (Tm) and deformation (Td) progressively increase structurally up section in the Moine thrust sheet at the foreland edge of the Scandian (mid Silurian) orogenic wedge. However, the thermal history of the structurally overlying, more hinterland positioned thrust sheets is less well known. This study focuses on determining Td and Tm for both the central/upper part of the Moine thrust sheet and the lower part of the overlying Sgurr Beag thrust sheets in the middle of the Northern Highlands Terrane. Preserved microstructures and quartz c-axis fabric opening angles in the Moine and Sgurr Beag thrust sheets imply Td of 460 °C to 605 °C ± 50 °C. Thermobarometry and pseudosection-based P-T constraints, indicate Tm of ∼550–680 °C at 4.8–7.2 kbar in the Moine thrust sheet and Tm of ∼620 °C at 5.6–7.7 kbar in the Sgurr Beag thrust sheet. Together, Td and Tm in the Moine and Sgurr Beag thrust sheets indicate that deformation continued after peak metamorphic conditions in the Sgurr Beag thrust sheet. Monazite and xenotime petrochronology show that Tm, and possibly Td, record Precambrian metamorphism. Peak metamorphism is associated with the Knoydartian orogenic event (840-720 Ma), with possible reworking during Scandian thrusting (430-425 Ma).
Keywords
Deformation temperatures, Monazite and xenotime petrochronology, Northern Scotland, Quartz fabrics, Thermobarometry
Volume
113
First Page
10
Last Page
32
DOI
10.1016/j.jsg.2018.05.002
ISSN
01918141
Recommended Citation
Mazza, Sarah E.; Mako, Calvin; Law, Richard D.; Caddick, Mark J.; Krabbendam, Maarten; and Cottle, John, "Thermobarometry of the Moine and Sgurr Beag Thrust Sheets, Northern Scotland" (2018). Geosciences: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/geo_facpubs/112
Comments
Peer reviewed accepted manuscript.