U–Pb zircon constraints on obduction initiation of the Unst Ophiolite: an oceanic core complex in the Scottish Caledonides? Q. G. Crowley R. A. Strachan 10.6084/m9.figshare.3453911.v1 https://geolsoc.figshare.com/articles/dataset/U_Pb_zircon_constraints_on_obduction_initiation_of_the_Unst_Ophiolite_an_oceanic_core_complex_in_the_Scottish_Caledonides_/3453911 <p>The Unst Ophiolite is the best exposed of a chain of early Ordovician ophiolites in the Scottish Caledonides and is widely regarded as having formed in a supra-subduction zone setting within the Iapetus Ocean. Reinterpretation of sheeted dykes suggests that it formed as an oceanic core complex, presumably during subduction roll-back immediately prior to obduction onto the Laurentian margin. A new U–Pb zircon age of 484 ± 4 Ma for development of the metamorphic sole places a lower limit on the timing of obduction, which was subsequently followed by regional-scale crustal thickening and Barrovian metamorphism during the Grampian orogenic event. </p> 2016-06-21 11:45:47 Scottish Caledonides oceanic core Grampian orogenic event Unst Ophiolite obduction zircon Geology