Microstructural analysis and tectonic evolution in thrust systems: examples from the Assynt region of the Moine Thrust Zone, Scotland

1990 ◽  
pp. 228-261 ◽  
Author(s):  
Robert J. Knipe
Keyword(s):  
Tectonic Evolution ◽  
Microstructural Analysis ◽  
Thrust Zone ◽  
Moine Thrust Zone

Terranes

1992 ◽  
Vol 13 (1) ◽  
pp. 1-4 ◽  
Author(s):  
B. J. Bluck ◽  
W. Gibbons ◽  
J. K. Ingham
Keyword(s):  
Hanging Wall ◽  
Fault System ◽  
Upper Proterozoic ◽  
Lower Proterozoic ◽  
Central Highland ◽  
Thrust Zone ◽  
Lower Palaeozoic ◽  
Moine Thrust Zone ◽  
Shallow Marine Sediments ◽  
Northern Highlands

AbstractThe Precambrian and Lower Palaeozoic foundations of the British Isles may be viewed as a series of suspect terranes whose exposed boundaries are prominent fault systems of various kinds, each with an unproven amount of displacement. There are indications that they accreted to their present configuration between late Precambrian and Carboniferous times. From north to south they are as follows.In northwest Scotland the Hebridean terrane (Laurentian craton in the foreland of the Caledonian Orogen) comprises an Archaean and Lower Proterozoic gneissose basement (Lewisian) overlain by an undeformed cover of Upper Proterozoic red beds and Cambrian to early mid Ordovician shallow marine sediments. The terrane is cut by the Outer Isles Thrust, a rejuvenated Proterozoic structure, and is bounded to the southeast by the Moine Thrust zone, within the hanging wall of which lies a Proterozoic metamorphic complex (Moine Supergroup) which constitutes the Northern Highlands terrane. The Moine Thrust zone represents an essentially orthogonal closure of perhaps 100 km which took place during Ordovician-Silurian times (Elliott & Johnson 1980). The Northern Highlands terrane records both Precambrian and late Ordovician to Silurian tectonometamorphic events (Dewey & Pankhurst 1970) and linkage with the Hebridean terrane is provided by slices of reworked Lewisian basement within the Moine Supergroup (Watson 1983).To the southwest of the Great Glen-Walls Boundary Fault system lies the Central Highlands (Grampian) terrane, an area dominated by the late Proterozoic Dalradian Supergroup which is underlain by a gneissic complex (Central Highland Granulites) that has been variously interpreted as either older

Cataclastic deformation of quartzite in the moine thrust zone

1986 ◽  
Vol 8 (6) ◽  
pp. 669-681 ◽  
Author(s):  
T.G Blenkinsop ◽  
E.H Rutter
Keyword(s):  
Thrust Zone ◽  
Moine Thrust Zone

scholarly journals Fault Rocks of the Moine Thrust Zone: A Guide to Their Nomenclature

1982 ◽  
Vol 4 (4) ◽  
pp. 211-221 ◽  
Author(s):  
S. White
Keyword(s):  
Shear Strain ◽  
Country Rock ◽  
Fault Zones ◽  
Fault Rocks ◽  
Fine Grained ◽  
Fine Grain ◽  
Simple Set ◽  
Thrust Zone ◽  
Moine Thrust Zone

The aim of this article is to extract from the existing literature a consistent nomenclature that can be used in the description of coherent fault rocks. The nomenclature is dealt with in this paper. Typical microstructures illustrating each is presented in a later paper (White et al ., 1982). It will be shown that a simple set of nomenclature can be extracted from the literature, so long as genetic connotations are kept to a minimum. The sequence, with increasing shear strain is country rock–protomylonite–blastomylonite–mylonite–ultramylonite if the rock has a well developed foliation; country rock–protocataclasite–cataclasite–ultracataclasite if it is without a foliation.It is emphasized that a mylonite is basically a fine-grained schist that has formed within fault zones. It is the association with faulting that distinguishes a mylonite from a fine grain schist.

Age of the Loch Borrolan complex, Assynt, and late movements along the Moine Thrust Zone

1979 ◽  
Vol 136 (4) ◽  
pp. 489-495 ◽  
Author(s):  
O. van Breemen ◽  
M. Aftalion ◽  
M. R. W. Johnson
Keyword(s):  
Thrust Zone ◽  
Moine Thrust Zone

Palaeo-stress estimates in the Moine Thrust Zone, Eriboll, Scotland

Nature ◽  
1979 ◽  
Vol 280 (5719) ◽  
pp. 222-223 ◽  
Author(s):  
S. WHITE
Keyword(s):  
Thrust Zone ◽  
Moine Thrust Zone

Relationships between distributed and localized shear in the tectonic evolution of a Caledonian fold and thrust zone, northwest Ireland

1994 ◽  
Vol 131 (1) ◽  
pp. 123-136 ◽  
Author(s):  
G. I. Alsop
Keyword(s):  
Tectonic Evolution ◽  
Large Scale ◽  
Structural Investigation ◽  
Localized Deformation ◽  
Large Magnitude ◽  
Structural Anisotropy ◽  
Transport Direction ◽  
Thrust Zone ◽  
And Migration ◽  
Orogenic Belts

AbstractBroad zones of distributed shear operating through mid-crustal regions of orogenic belts may incorporate narrow horizons of intense localized deformation culminating in discrete, large magnitude displacements. The relative importance and relationship between distributed and localized shear are influenced by a variety of factors including lithological variation, pre-existing structural anisotropy, strain rate and migration of fluids. Rigorous structural analysis of lower amphibolite facies Dalradian metasediments in northwestern Ireland demonstrates that an early (D1) discrete ductile detachment was subsequently reactivated during distributed non-coaxial D2 deformation operating in a broad zone through the structural pile. Regional shear was directed towards the southeast and resulted in the generation and translation of kilometre-scale, isoclinal, recumbent sheath folds which close and face towards the transport direction. The D1 detachment is clearly folded around the hinges of these major folds, whilst on fold limbs it was reactivated and acted as a local décollement within the zone of distributed shear. Shear criteria along the detachment indicate a southeast-directed translation of the major folds, in sympathy with regional shear. A broad zone of D3 translation operating through the nappe pile resulted in coaxial refolding of large scale F2 folds by the D3 Ballybofey Nappe producing a complex fold interference pattern. Non-coaxial D3 deformation resulted in continued reactivation of local decollements, together with the initiation of east-southeast directed oblique thrusts and partial dismemberment of D2 folds. Detailed structural investigation allows concepts of distributed and localized shear to be evaluated and models of crustal deformation to be assessed.

Dislocation surfaces in the Moine Thrust Zone, Ullapool

1989 ◽  
Vol 25 (2) ◽  
pp. 143-151
Author(s):  
Robert F. Cheeney
Keyword(s):  
Thrust Zone ◽  
Moine Thrust Zone

The thrust structures of southern Assynt, Moine thrust zone

1985 ◽  
Vol 122 (6) ◽  
pp. 595-607 ◽  
Author(s):  
M. P. Coward
Keyword(s):  
The West ◽  
Igneous Complex ◽  
Basement Rocks ◽  
Thrust Zone ◽  
Moine Thrust Zone ◽  
Extensional Structures

AbstractThe Moine thrust zone of southern Assynt forms part of the northwest margin of the Caledonide belt and has aroused controversy concerning amounts and timing of thrust displacement and sequence of thrust development. Recent mapping shows it to have been a foreland propagating thrust sequence; the uppermost ductile Moine thrust formed first, followed by sequences of imbricates, a major thrust (the Ben More thrust) and then several lower duplex zones. This sequence is clear from new observations that many of the earlier thrusts were folded and/or breached during the development of the underlying structures. A displacement of over 54 km has been estimated for the zone as a whole. An alkaline igneous complex, including the large Borrolan syenite, was intruded during the development of the thrust zone and much of it was carried some 30 km to the west-northwest onto the foreland. Late extensional structures in southern Assynt are an integral part of the Caledonide thrust sequence and probably developed from the collapse of the thrust wedge as it climbed from stronger basement rocks on to a weaker cover sequence on the foreland.

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