The stratigraphy and structure of the southern Monadhliath Mountains between Loch Killin and upper Glen Roy

Haselock, P. J.; Winchester, J. A.; Whittles, K. H.

doi:10.1144/sjg18040275

Cited by 28 publications

(6 citation statements)

References 12 publications

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“…2), also k n o w n as the Grampian Division or 'Younger Moine', was included in the Dalradian by Harris et al (1978) although this has not met with general acceptance (e.g. Thomas 1980, Haselock et al 1982. Very little is known about the depositional environments of the Grampian Group, but there are significant lithological and geochemical contrasts between it and the Dalradian.…”

Section: Appin Groupmentioning

confidence: 99%

Sedimentation and tectonics in the Scottish Dalradian

Anderton

1985

SJG

119

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Synopsis Sedimentological research on the Scottish Dalradian has progressed from the recognition of sedimentary structures in the 1930s, via the identification of sedimentary facies from the 1950s onwards, to the integration, in the 1970s, of sedimentological data with that from studies of stratigraphy, tectonics and volcanism. This has now led to an understanding of the pre-orogenic evolution of the Dalradian terrane in terms of progressive lithospheric stretching associated with the break-up of the Proterozoic Supercontinent. The Appin and Argyll Groups were deposited on the NW side of a late Precambrian marine gulf which developed over a complex zone of crustal thinning between the Laurentian and Baltic parts of the Super-continent. As extension accelerated, subsidence rates increased and the Dalradian area of the gulf evolved from a relatively shallow shelf into a series of turbidite basins. Thinning of the lithosphere gave rise, in Argyll Group times, to locally intense igneous activity. Subsequently, complete continental rupture along the gulf axis led to the birth of the Iapetus Ocean. By Southern Highland Group times the Dalradian terrane had become part of the new, thermally-subsiding, Laurentian continental margin. One can envisage the geometry and facies variations of many horizons within the Dalradian in terms of a pattern of numerous fault blocks defined by listric normal faults, dipping SE towards the site of continental rupture, and NW–SE trending transfer faults, which divided the gulf and subsequent margin into a series of compartments. It was movements on these faults that largely controlled Dalradian stratigraphic evolution. For example, pulses of rapid stretching, and consequent fault activity, produced basin-deepening sequences which mark the base of the Easdale and Crinan Subgroups.

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Section: Appin Groupmentioning

confidence: 99%

Sedimentation and tectonics in the Scottish Dalradian

Anderton

1985

SJG

119

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“…Overlying the Erris Complex in the northern Mullet Peninsula are psammites of the Erris Group, represented locally by the Doonamoo Formation, consisting typically of biotite-quartzplagioclase schist, and thought to be a stratigraphic equivalent of the Grampian Division Moine which crops out extensively in the Central Highlands of Scotland (Piasecki, 1980;Haselock, Winchester & Whittles, 1982). Like the Grampian Division, Erris Group rocks pass stratigraphically into the lowest Dalradian rocks.…”

Section: Geological Settingmentioning

confidence: 99%

Element mobility associated with syn‐metamorphic shear zones near Scotchport, NW Mayo, Ireland

Winchester¹,

Max²

1984

Journal Metamorphic Geology

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Three major blastomylonitic synmetamorphic (epidote amphibolite to mid amphibolite facies) shear zones are seen on the NW coast of the Mullet Peninsula in NW Mayo. These shear zones occur at the contacts of major structural units and in an imbricated slice where rocks of the Erris Complex are deformed and chemically modified. Chemical changes associated with individual shear zones have been deduced by comparing the compositions of various gneisses both within and adjacent to the shear zones. Compositional changes are different in theconstituent rock-types within each unit and many elements normally considered immobile have been selectively mobilized within the shear zones. Little evidence of wholesale metasomatic introduction of components into these shear zones was found to accompany the selective mobilization.

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“…Perhaps such features as the thick pebbly schists recently found in the upper part of the Grampian division at Garva Bridge and in the Corrieyairack region ( Fig. 3; see Haselock et al 1982), and along the SE margin of the Great Glen fault (Parson 1979), could relate to the c. 750 Ma disturbances at depth.…”

Section: Early Palaeozoic Agesmentioning

confidence: 88%

“…3), the rocks of the pelitic-semipelitic belts within the psammites of the Moine assemblage, even where migmatised, have been referred to previously as the "Monadhliath Schists": this follows Anderson's (1956) correlations with the Monadhliath Schists of the type area near Glen Roy (Fig. 1), which he considered to represent the lateral equivalents of the Leven Schists of the Dalradian Appin Group (but see Haselock & Winchester 1981;Haselock et al 1982). The psammites of this region were thought to correspond with the Eilde Flags, the stratigraphically highest psammites of the Moine assemblage in the type area (Anderson 1956).…”

Section: Laggan Inliermentioning

confidence: 99%

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

Piasecki

Breemen

1983

Transactions of the Royal Society of Edinburgh: Earth Sciences

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Evidence is presented for a late Proterozoic, tectonothermal event which affected the rocks of the Moine assemblage in the Central Highland region of the Scottish Caledonides c. 750 Ma ago. This is about 200 Ma before the early Palaeozoic Grampian orogeny, whose effects are superimposed on the Moine rocks as well as dominating the tectonism in the Dalradian Supergroup.Field and isotopic studies are integrated in zones of ductile thrusting (sliding) which are typified by belts of tectonic schists with related swarms of quartz and muscovite-bearing pegmatite veins. Of particular significance is a ductile thrust (the Grampian slide) which separates deeper crustal rocks (the Central Highland division), interpreted as showing the imprint of the Grenville orogeny, from shallower rocks (the Grampian division) representing a supracrustal assemblage formed between the Grenville and the c. 750 Ma events.The Grampian slide is the structurally highest member of a system of related, previously unrecorded slides affecting the Central Highland division. New structural, petrographic and Rb-Sr isotopic data, obtained largely from a recently recognised inlier of the Central Highland division at Laggan, bear out that the quartz and pegmatite veins are segregations formed during ductile shearing under amphibolite facies conditions. Muscovites from these veins yield ages between 780 and 730 Ma, and a regression analysis of tectonic schists and the muscovites gives an age of 740 ± 40 Ma. These data substantiate our previous hypothesis that the deeper-seated Moine rocks were affected by a distinct orogenic event at 750 ± 30 Ma.In the Northern Highlands, similar vein swarms are related to the Sgurr Beag slide and to belts of previously unrecorded tectonic schists in the Glenfinnan division of the Moine assemblage. A new, 755 ± 8 Ma age obtained from such a tectonic schist at Kinloch Hourn, combined with previous, similar age data from lensoid pegmatites, imply that the c. 750 Ma event may have also affected the Morar and Glenfinnan divisions.

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The stratigraphy and structure of the southern Monadhliath Mountains between Loch Killin and upper Glen Roy

Cited by 28 publications

References 12 publications

Sedimentation and tectonics in the Scottish Dalradian

Sedimentation and tectonics in the Scottish Dalradian

Element mobility associated with syn‐metamorphic shear zones near Scotchport, NW Mayo, Ireland

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

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