The Grampian Orogeny: Mid‐Ordovician Arc–Continent Collision along the Laurentian Margin of Iapetus

Strachan, Rob

doi:10.1002/9781118274064.ch6

Cited by 7 publications

(5 citation statements)

References 10 publications

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“…Torsvik et al 1992aTorsvik et al , 1996; this contraction was associated with the build-up of arc and accretionary complexes (e.g. Stephens & Gee 1985Strachan 2000). Many of these complexes contain dismembered .440 Ma ophiolites (e.g.…”

Section: The Caledonidesmentioning

confidence: 98%

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Provenance and exhumation of an exotic eclogite-bearing nappe in the Caledonides: a U–Pb and Rb–Sr study of the Jæren nappe, SW Norway

Smit

Bröcker

Kooijman

et al. 2011

JGS

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The provenance and exhumation history of paragneisses that enclose the 471-458 Ma eclogites in the Caledonian Jaeren nappe, SW Norway, were constrained by performing U-Pb analysis on detrital zircon and Rb-Sr dating of mica. Zircon grains from four samples were analysed by laser ablation inductively coupled plasma mass spectrometry, providing detrital U-Pb ages between 3130 and 620 Ma. These data suggest Laurentian provenance, implying the existence of an early Caledonian (Taconian) HP fragment of Laurentian crust in the southern Scandinavian Caledonides. Several rims and recrystallized zircon patches yielded U-Pb ages averaging at 469 AE 6 Ma (2ó). These are identical to the Lu-Hf ages of the eclogites and underscore the importance of Taconian metamorphism in this part of the Caledonides. The main phengite Rb-Sr age cluster at 424.4 AE 4.6 Ma provides time constraints on the amphibolite-facies recrystallization of former high-Si phengite. Five out of seven biotite Rb-Sr ages were identical, yielding a weighted mean age of 413.6 AE 2.6 Ma. Low-Si phengite and biotite in three samples gave c. 400 Ma ages. The Rb-Sr data record the mid-crustal emplacement of the exotic Jaeren nappe and its subsequent unroofing along the western edge of Baltica during the backsliding and collapse of the Scandian orogenic front.Supplementary material: The sample locations, U-Pb isotope data and ages for zircon, and the phengite and biotite major element data are available at http://www.geolsoc.org.uk/SUP18448.

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Section: The Caledonidesmentioning

confidence: 98%

“…Many of these complexes contain dismembered .440 Ma ophiolites (e.g. Dunning & Pedersen 1988;Pedersen et al 1991;Oliver & Krogh 1995;Strachan 2000;Yoshinobu et al 2002) that represent fragments of oceanic crust formed in short-lived back-arc or marginal-basin settings (e.g. Roberts 2003).…”

Section: The Caledonidesmentioning

confidence: 99%

Provenance and exhumation of an exotic eclogite-bearing nappe in the Caledonides: a U–Pb and Rb–Sr study of the Jæren nappe, SW Norway

Smit

Bröcker

Kooijman

et al. 2011

JGS

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“…Crust beneath the Iapetus Ocean was subducted beneath Avalonia which drifted northwards towards a more northerly continent, Laurentia. The key event in the Rhynie area pre-dated the collision of Avalonia with this continent: the c. 475-460 Ma Grampian event resulted from convergence between a shallow-water carbonate shelf (the Laurentian margin; Lambert & McKerrow, 1976;Strachan et al 2003) and a volcanic arc (Dewey & Shackleton, 1984;Draut et al 2009;Strachan, 2012). The arc-Laurentia collision resulted in the overthrusting of an exotic ophiolite nappe, and deformation plus associated Barrovian metamorphism of the Moine and Dalradian Supergroups (Dewey & Shackleton, 1984;Strachan et al 2003).…”

Section: Development Of the Rhynie Basinmentioning

confidence: 99%

An introduction to the Rhynie chert

Garwood

Oliver²,

Spencer

2019

Geol. Mag.

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The terrestrialization of life has profoundly affected the biosphere, geosphere and atmosphere, and the Geological Magazine has published key works charting the development of our understanding of this process. Integral to this understanding – and featuring in one of the Geological Magazine publications – is the Devonian Rhynie chert Konservat-Lagerstätte located in Aberdeenshire, Scotland. Here we provide a review of the work on this important early terrestrial deposit to date. We begin by highlighting contributions of note in the Geological Magazine improving understanding of terrestrialization and Palaeozoic terrestrial ecosystems. We then introduce the Rhynie chert. The review highlights its geological setting: the Caledonian context of the Rhynie Basin and its nature at the time of deposition of the cherts which host its famous fossils. There follows an introduction to the development of the half-graben in which the cherts and host sediments were deposited, the palaeoenvironment this represented and the taphonomy of the fossils themselves. We subsequently provide an overview of the mineralization and geochemistry of the deposit, and then the fossils found within the Rhynie chert. These include: six plant genera, which continue to provide significant insights into the evolution of life on land; a range of different fungi, with recent work starting to probe plant–fungus interactions; lichens, amoebae and a range of unicellular eukaryotes and prokaryotes (algae and cyanobacteria); and finally a range of both aquatic and terrestrial arthropods. Through continued study coupled with methodological advances, Rhynie fossils will continue to provide unique insights into early life on land.

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“…The geology of the Macduff area in NE Scotland forms part of the Dalradian Supergroup that is a late Pre-Cambrian to Cambrian sedimentary sequence that was subsequently deformed and variably metamorphosed during the Early-Mid Ordovician Grampian Orogeny at 475-465 Ma [39,40]. The Macduff area (UK Grid: NJ7190 6465) comprises sandstones and mudstones that originally formed deep water turbidite fans and were subsequently regionally metamorphosed to biotite facies during the Grampian Orogeny [39][40][41]. Structurally, the Macduff area is dominated by NNE-trending upright anticlines and synclines that develop at wavelengths of meters to hundreds of metres [38].…”

Section: Macduff Case Study: Algorithms Comparisonmentioning

confidence: 99%

ArcStereoNet: A New ArcGIS® Toolbox for Projection and Analysis of Meso- and Micro-Structural Data

Ortolano

D’Agostino

Pagano

et al. 2021

IJGI

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ArcStereoNet is a new ArcGIS® based toolbox for stereographic projections that we implement here using Python 2.7 programming language. The reason to develop another stereographic projection package arises from the recent use of Python as an exclusive programming language within the ArcGIS® environment. This permits a more flexible approach for the development of tools with very intuitive GUIs, and also allows the user to take full advantage of all potential GIS mapping processes. The core of this new projections toolbox is based on the capability to easily apply and compare most of the commonly used statistical methods for cluster and girdle analysis of structural data. In addition to the well-known Fisher, K-means, and Bingham data elaborations, a completely new algorithm for cluster analysis and mean vector extraction (Mean Extractor from Azimuthal Data), was developed, thereby allowing a more reliable interpretation of any possible structural data distribution. Furthermore, as in any other GIS platform, users can always precisely correlate each single projected data point with the corresponding geographical/locality position, thereby merging or subdividing groups of structural stations with a simple selection procedure. ArcStereoNet also creates rose diagrams, which may be applied not only to fault/joint planes orientation data, but also for the analysis of 2D microstructural fabric parameters. These include geometrical datasets derived from the minimum bounding approach as applied to vectorized grains in thin sections. Finally, several customization settings ensure high-quality graphic outputs of plots, that also allow easy vector graphics post-processing.

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The Grampian Orogeny: Mid‐Ordovician Arc–Continent Collision along the Laurentian Margin of Iapetus

Cited by 7 publications

References 10 publications

Provenance and exhumation of an exotic eclogite-bearing nappe in the Caledonides: a U–Pb and Rb–Sr study of the Jæren nappe, SW Norway

Provenance and exhumation of an exotic eclogite-bearing nappe in the Caledonides: a U–Pb and Rb–Sr study of the Jæren nappe, SW Norway

An introduction to the Rhynie chert

ArcStereoNet: A New ArcGIS® Toolbox for Projection and Analysis of Meso- and Micro-Structural Data

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