Progressive fold and fabric evolution associated with regional strain gradients: a case study from across a Scandian ductile thrust nappe, Scottish Caledonides
MetadataShow full item record
Fold and fabric patterns developed within a major Caledonian thrust nappe in NW Scotland reflect a progressive increase in regional D2 strain towards the basal ductile detachment. Within the upper greenschist to lower amphibolite facies thrust sheet, the main gently east-dipping foliations and SE-plunging transport-parallel lineations maintain a broadly similar orientation over c. 600 km2. Associated main phase, thrust-related folds (F2) are widely developed, and towards the base of the thrust sheet display progressive tightening and increasing curvilinearity of fold hinges ultimately resulting in sheath folds. Secondary folds (F3) are largely restricted to high-strain zones and are interpreted as flow perturbation folds formed during non-coaxial, top-to-the-NW ductile thrusting.These features are consistent with a structural model that incorporates plane strain pure-shear flattening with a superimposed and highly variable simple shear component focused into high-strain zones. The increase in strain over a distance of 30 km across strike is similar to the increasing deformation observed when structures are traced along strike to the north, and which are apparently related to proximity to basement-cover contacts. A U?Pb zircon age of 4156 Ma obtained from a syn-D2 meta-granite confirms that regional deformation occurred during the Scandian phase of the Caledonian orogeny.
Showing items related by title, author, creator and subject.
Tectono-metamorphic evolution of a convergent back-arc: The Famatinian orogen, Sierra de Quilmes, Sierras Pampeanas, NW ArgentinaFinch, M.; Weinberg, R.; Hasalova, P.; Becchio, R.; Gabriela Fuentes, M.; Kennedy, Allen (2017)Back-arcs are hot regions of enduring weakness in the hinterland of subduction zones that are commonly sites of strain localization, forming mobile belts that, in some cases, develop into mountain belts. Their evolution ...
Quentin de Gromard, R.; Kirkland, Chris; Howard, H.; Wingate, M.; Jourdan, Fred; McInnes, Brent; Danišík, Martin; Evans, Noreen; McDonald, B.; Smithies, R. (2018)The post-Mesoproterozoic tectonometamorphic history of the Musgrave Province, central Australia, has previously been solely attributed to intracontinental compressional deformation during the 580–520 Ma Petermann Orogeny. ...
Neoarchean orogenic, magmatic and hydrothermal events in the Kalgoorlie-Kambalda area, Western Australia: constraints on gold mineralization in the Boulder Lefroy-Golden Mile fault systemMueller, A.; Hagemann, S.; McNaughton, Neal (2016)The Boulder Lefroy-Golden Mile (BLF-GMF) fault system is the most intensely mineralized structure (>2150 t Au to 2015) in the Archean Yilgarn Craton, Western Australia. The fault system links the Kalgoorlie and Kambalda ...