Field and isotopic evidence for a <i>c.</i> 750 Ma tectonothermal event in Moine rocks in the Central Highland region of the Scottish Caledonides

Piasecki, M. A. J.; Breemen, O. van

doi:10.1017/s0263593300010105

Cited by 77 publications

(17 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Powell et al (1983) reported Rb-Sr muscovite ages of 746-776 Ma, whereas U-Pb dating of monazite from the same pegmatite has given a considerably older age of 827 AE 2 Ma (Rogers et al 1998). In addition, Piasecki & van Breemen (1983) reported c. 750 Ma Rb-Sr ages on muscovite books from pegmatitic segregations in shear zones from a number of localities in the Central Highlands, and in the western Moine at Kinloch Hourn.…”

Section: Moine Pegmatitesmentioning

confidence: 99%

“…This criticism was countered by Bluck (2000), who, referring to the unpublished work of Hyslop, pointed out that large muscovites from the Moine similar to those that have yielded c. 750 Ma ages (i.e. Piasecki & van Breemen 1983) contain inclusions of regional metamorphic garnet that have a similar chemistry and growth history to the Morar examples.…”

Section: Regional Metamorphic Patternmentioning

confidence: 99%

“…The D 1 and D 2 structures, the main regional metamorphic event in the Moine, and the major, early, displacement on the Sgurr Beag Thrust are all of Neoproterozoic age and together constitute a major episode of crustal thickening. This orogenic event was accompanied by the widespread development of c. 750 Ma micas in shear zones, including the Sgurr Beag Thrust at Kinloch Hourn (Piasecki & van Breemen 1983). It was followed by the intrusion of a suite of microdiorite dykes.…”

Section: Neoproterozoic Orogeny (Knoydartian)mentioning

confidence: 99%

“…1), where pioneering radiometric dating in the 1960s appeared to demonstrate the presence of a Precambrian orogeny at .700 Ma (Giletti et al 1961;Long & Lambert 1963), overprinted by a much younger Caledonian orogenic event. This model was considerably refined during the 1980s (Piasecki & van Breemen 1983;Barr et al 1985Barr et al , 1986Roberts et al 1987), but more recent work has led to an apparently irreconcilable difference of opinion between those who support this hypothesis (Bluck et al 1997;Vance et al 1998;Bluck 2000Bluck , 2001, and those who contend that all of the regionally important structural and metamorphic events that have affected the Moine are of early Ordovician (c. 470 Ma) age (Soper & England 1995;Soper & Harris 1997;Soper et al 1999;Dalziel & Soper 2001).…”

mentioning

confidence: 99%

See 3 more Smart Citations

Late Precambrian U–Pb titanite age for peak regional metamorphism and deformation (Knoydartian orogeny) in the western Moine, Scotland

Tanner

Evans²

2003

JGS

View full text Add to dashboard Cite

There has been controversy over the number and timing of orogenies in the Precambrian Moine block in the Scottish Caledonides since the earliest radiometric dating in the 1960s. This work challenges a recent hypothesis, that this sector of the Laurentian margin was subjected to continuous crustal extension between .900 and 470 Ma. U-Pb dating (thermal ionization mass spectrometry) of titanite from a calcsilicate pod in the Moine (Morar Group) of the western Highlands gives an age of 737 AE 5 Ma. The titanite grew from Fe-Ti-bearing detrital minerals during the main progressive, syn-D 2 , amphibolite-facies (sillimanite zone) regional metamorphism, thus demonstrating that a Neoproterozoic contractional tectonothermal event (Knoydartian orogeny) affected the Moine block following the rift-related emplacement of the West Highland granite gneiss at 873 Ma. We conclude that the Sgurr Beag Thrust, a major tectonic break separating the Morar and Glenfinnan groups of the Moine, is mainly of Neoproterozoic, not Caledonian, age. The early tectonothermal event was succeeded by the Grampian Phase (Caledonian orogeny) at 460-470 Ma.

show abstract

Section: Moine Pegmatitesmentioning

confidence: 99%

Section: Regional Metamorphic Patternmentioning

confidence: 99%

Section: Neoproterozoic Orogeny (Knoydartian)mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Late Precambrian U–Pb titanite age for peak regional metamorphism and deformation (Knoydartian orogeny) in the western Moine, Scotland

Tanner

Evans²

2003

JGS

View full text Add to dashboard Cite

show abstract

“…In an insightful study, Piasecki and van Breemen (1983) recognised correctly that Rb-Sr dating of large books of muscovite, even when subjected to an amphibolite facies Caledonian event, preserved evidence of their crystallisation more than 700 Ma ago. This can be explained by the positive correlation of grain size with closure temperature (Dodson 1973); very large muscovite books several centimetres in diameter may retain their radiogenic Sr to upper amphibolite facies temperatures.…”

Section: Metamorphic and Isotopic Effects During Lower Temperature Rementioning

confidence: 99%

The response of mineral chronometers to metamorphism and deformation in orogenic belts

Parrish

2001

View full text Add to dashboard Cite

Mineral chronometers, especially accessory minerals using the U-Pb decay system, can reveal important information regarding the environmental conditions and duration of metamorphic-deformation events during the re-working of older rocks. Minerals such as zircon can newly grow during amphibolite facies or granulite facies events, providing direct ages of metamorphism. Pre-existing minerals like monazite, allanite, and titanite can preserve a component of their original age in spite of upper amphibolite facies re-working and very thorough recrystallisation of the rock fabric during mylonite development. The degree of incomplete Pb loss can be used to deduce, at least semi-quantitatively, the temperature and duration of the subsequent event. In well-studied examples, the relative retentivity of Pb is highly predictable, and this helps place strong constraints on relative closure temperatures, even when laboratory experimental data are lacking or inconclusive. A number of examples are presented from a wide variety of geological environments to illustrate the response of U-Pb isotope systematics within accessory minerals superimposed deformation, metamorphism and/or mineral growth.2

show abstract

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

et al. 2000

View full text Add to dashboard Cite

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.

show abstract

Field and isotopic evidence for a c. 750 Ma tectonothermal event in Moine rocks in the Central Highland region of the Scottish Caledonides

Cited by 77 publications

References 52 publications

Late Precambrian U–Pb titanite age for peak regional metamorphism and deformation (Knoydartian orogeny) in the western Moine, Scotland

Late Precambrian U–Pb titanite age for peak regional metamorphism and deformation (Knoydartian orogeny) in the western Moine, Scotland

The response of mineral chronometers to metamorphism and deformation in orogenic belts

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

Contact Info

Product

Resources

About