Extensional versus compressional settings for metamorphism: Garnet chronometry and pressure-temperature-time histories in the Moine Supergroup, northwest Scotland

Vance, Derek; Strachan, R. A.; Jones, K.A.

doi:10.1130/0091-7613(1998)026<0927:evcsfm>2.3.co;2

Cited by 124 publications

(74 citation statements)

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“…Morar Group rocks and we concur with the concept that D1 isoclinal folds were formed during a Knoydartian orogeny (see also Vance et al 1998;Rogers et al 1998). However, the exact timing and nature of events remains problematic as the Knoydartian ages appear to cluster in (at least) two phases (see Cutts et al 2010).…”

Section: Timing Of Eventssupporting

confidence: 66%

“…It has been suggested that Knoydartian tectonothermal events were related to an extensional event (Dalziel and Soper 2001). However, studies on garnet have linked Knoydartian ages with metamorphic P-T conditions consistent with crustal thickening and orogenesis (Vance et al 1998;Cutts et al 2009Cutts et al , 2010. It is likely that Knoydartian garnet growth as well as pegmatite intrusion were broadly associated with isoclinal D1 folding in…”

Section: Timing Of Eventsmentioning

confidence: 99%

“…van Breemen et al 1974;Powell et al 1983;Rogers et al 1998), U-Pb titanite ages from below the Sgurr Beag Thrust (Tanner & Evans 2003), and Sm-Nd ages from garnet (Vance et al 1998) -see Figure 1 for some localities. These ages fall into two clusters: c. 830-800 Ma and 780-740 Ma.…”

Section: Timing Of Eventsmentioning

confidence: 99%

“…Giletti, 1961;van Breemen et al 1974;Rogers et al 1998;Vance et al 1998;Tanner & Bluck 1999;Oliver 2002;Tanner & Evans 2003;Cutts et al 2010;Cawood et al in press). deformation and magmatism appears to be mainly restricted to the higher Sgurr Beag and Naver nappes (Kinny et al 1999;Cutts et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Structure and stratigraphy of the Morar Group in Knoydart, NW Highlands: implications for the history of the Moine Nappe and stratigraphic links between the Moine and Torridonian successions

Krabbendam

Leslie

Goodenough

2014

SJG

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The Caledonian Orogen in Northern Scotland comprises two major thrust nappes: the Moine and the Sgurr Beag Nappe. The Moine Nappe contains early Neoproterozoic Morar Group rocks (Moine Supergroup) and basement inliers. This paper describes the structure and stratigraphy of the Knoydart peninsula, a key area within the southern Moine Nappe. The geology of Knoydart is dominated by a thick internally coherent sequence of Morar Group rocks. This sequence is shown to be deformed by large-scale, west-vergent and west-facing Caledonian (early Palaeozoic) folds that represent D2 within the southern Moine Nappe. Subsequent D3 deformation led to refolding or tightening of F2 folds, so that the major Morar Antiform is in essence a composite F2/F3 fold. F2 and F3 folds are broadly co-axial, but F3 folds have steeper axial planes.The F2/F3 folds refold a regional-scale, originally recumbent, isoclinal F1 fold nappe of probable Knoydartian (mid-Neoproterozoic) age. The F1 fold nappe is cored by a thin sliver of basement gneiss; the lower limb comprises migmatitic Morar Group rocks, exposed in the Morar Window. The upper limb of the F1 fold nappe occupies most of Knoydart and is stratigraphically coherent and right-way-up. Within this sequence, the upper unit of the Lower Morar Psammite is barely deformed, preserving trough-cross-bedding and largescale channels in thick beds. This suggests braided river deposition, similar to the Torridon Group west of the Moine Thrust and the Morar Group in the northern part of the Moine Nappe. On the basis of lithological similarity and stratigraphic disposition, it is suggested that the lowermost part of the Morar Group in Knoydart correlates with the Neoproterozoic Sleat Group on Skye.

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Section: Timing Of Eventssupporting

confidence: 66%

Section: Timing Of Eventsmentioning

confidence: 99%

Section: Timing Of Eventsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Structure and stratigraphy of the Morar Group in Knoydart, NW Highlands: implications for the history of the Moine Nappe and stratigraphic links between the Moine and Torridonian successions

Krabbendam

Leslie

Goodenough

2014

SJG

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“…It probably relates in a general way to slightly older Knoydartian orogenic events dated between 820 and 735 Ma in the Moine Supergroup of mainland Scotland (Rogers et al 1998;Vance et al 1998;Cutts et al 2010;Cawood et al 2015) and the Laurentian-derived Sørøy Succession of northern Norway (Kirkland et al 2006(Kirkland et al , 2008. The overall tectonic significance of these orogenic events has been much debated, the most recent syntheses suggesting that they correspond to accretionary events along a proximal active margin of the Rodinia supercontinent (Cawood et al 2010(Cawood et al , 2015Kirkland et al 2011).…”

Section: Evidence For Knoydartian Deformation and Metamorphism In Normentioning

confidence: 99%

Evidence from Rb–Sr mineral ages for multiple orogenic events in the Caledonides of Shetland, Scotland

Walker

Thirlwall

Strachan

et al. 2016

JGS

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Cleaved clasts in Dalradian conglomerates: possible evidence for Neoproterozoic compressional tectonism in Scotland and Ireland?

et al. 2000

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Cleaved metasedimentary clasts are present in stratigraphically and geographically distinct conglomerates in the Argyll and Southern Highland Groups of the Neoproterozoic Dalradian succession in the SW Scottish Highlands and NW Ireland. The significance and relationships of these clasts are that: (1) they were unequivocally reworked and deposited by sedimentary processes; (2) their internal foliation is probably due to contractional deformation that pre‐dates regional Caledonian fabrics; and (3) most of the cleaved clasts are only moderately deformed psammites and pelites and thus cannot be construed as having been derived from extensional mylonites. These conclusions, coupled with the generally accepted inferences that the Dalradian succession post‐dates Grenville deformation (c. 1100–1000 Ma) and pre‐dates early Palaeozoic Caledonian deformation (c. 470 Ma) and that the lowermost exposed Dalradian rocks, the Grampian Group, are truncated by a c. 806 Ma shear zone, imply that the clasts must have been foliated during an episode of mid‐Neoproterozoic contractional deformation. The clasts may thus represent further evidence in support of the contentious c. 870–800 Ma Knoydartian orogeny and thereby further render as equivocal interpretations that the Neoproterozoic tectonostratigraphic evolution of the Scottish Highlands and NW Ireland is a record of long‐lived ‘episodic’ extensional tectonism. Copyright © 2000 John Wiley & Sons, Ltd.

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Extensional versus compressional settings for metamorphism: Garnet chronometry and pressure-temperature-time histories in the Moine Supergroup, northwest Scotland

Cited by 124 publications

References 0 publications

Structure and stratigraphy of the Morar Group in Knoydart, NW Highlands: implications for the history of the Moine Nappe and stratigraphic links between the Moine and Torridonian successions

Structure and stratigraphy of the Morar Group in Knoydart, NW Highlands: implications for the history of the Moine Nappe and stratigraphic links between the Moine and Torridonian successions

Evidence from Rb–Sr mineral ages for multiple orogenic events in the Caledonides of Shetland, Scotland

Cleaved clasts in Dalradian conglomerates: possible evidence for Neoproterozoic compressional tectonism in Scotland and Ireland?

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