The Devonian fluvial to lacustrine sedimentary rocks of Shetland (“Old Red Sandstone”) host a series of volcanic and intrusive rocks that has the potential to accurately constrain the stratigraphy of the Mid Devonian both locally in Shetland (Marshall 2000) and in the wider Orcadian Basin, as well as potentially providing important new constraints on the relatively poorly defined Mid-Devonian timescale. Both the extrusive and intrusive magmatism are attributed to transtensional tectonics (Lancaster et al. 2017) and may correlate with well-dated volcanic events in the Orkney Islands further south (Bjerga 2017; Svebo 2018).
Precise age data on the Mid-Devonian volcanic and intrusive rocks may provide important chronostratigraphic constraints to the Mid-Devonian timescale, will aid in regional correlations, as well as contribute to our general understanding of volcanic activity related to strike-slip systems and melt-producing processes associated with transtensional tectonics.
This thesis will be based on fieldwork, including logging of volcanic sequences and sampling for geochronology and geochemistry, as well as geochronological analyses in the Goldschmidt Lab at UiO.
References
- Bjerga, A. D. (2017). The Caledonian tectonomagmatic evolution of the Orkney Islands, Scotland.
- Lancaster, P. J., Strachan, R. A., Bullen, D., Fowler, M., Jaramillo, M., & Saldarriaga, A. M. (2017). U–Pb zircon geochronology and geodynamic significance of ‘Newer Granite’plutons in Shetland, northernmost Scottish Caledonides. Journal of the Geological Society, 174(3), 486-497.
- Marshall, J. E. A. (2000). Devonian (Givetian) miospores from the Walls Group, Shetland.
- Svebo, J. R. (2018). High precision U/Pb dating of the Hoy Volcanic Member and its implications.