bluuebunny/crossref_metadata_2025 huggingface dataset:
Deformational and metamorphic history of Moinian and Lewisian rocks between Strathconon and Glen Affric
Authors: Tobisch O. T. , Fleuty M. J. , Merh S. S. , Mukhopadhyay D. , Ramsay J. G.
Published: January 2010

Synopsis

Seven distinct sets of fold structures have been recognised within 450 square kilometres of Moinian and Lewisian rocks. The earliest structures are only locally preserved, and are deformed by major folds which originally had approximately NE.–SW. axial traces and very variable axial directions. The formation of these folds was associated with high-grade Barrovian metamorphism and with the development of major slides. A pair of large N.–S. folds subsequently deformed this major fold pattern, apparently under conditions of fairly low metamorphic grade.

High-grade metamorphism persisted or was re-established in part of the region during the formation of later structures oblique to the dominant regional trend. Subsequently a widespread set of folds whose style and orientation vary with varying metamorphic grade was superposed. In the area of higher grade these have approximately NE.–SW. axial traces, but their attitude in rocks of lower grade is more variable. Formation of another locally-developed set intervened between this widespread folding and the development of the last structures, which are mainly small NE.–SW. folds formed under low-grade conditions. Possible correlations with events in other parts of the Northern Highlands are discussed.
Drift stratigraphy and buried morphology beneath the Forth at Rosyth
Authors: Sissons J. B. , Rhind D. W.
Published: January 2010

Synopsis

During work under contract to the Institute of Geological Sciences, over 500 old bore records have become available for a small area at Rosyth, the majority relating to the area below low water mark. They show that till and patchy fluvioglacial deposits are covered by fine late-glacial marine sediments whose maximal recorded thickness exceeds 60 m. In the western parts of the area a glacial readvance or halt stage is indicated particularly by ‘boulder clay’ inter-bedded with the late-glacial marine sediments. Sea-level when glacier ice last extended into the Rosyth area was about 35 m above present. Later in late-glacial times the sea fell below its present level and marine sediments deposited earlier were extensively planated, the coarser (ice-rafted) constituents of these sediments and the coarser constituents of the interbedded ‘boulder clay’ (where present) being left as a layer of stones and boulders sloping gently seawards. This coarse stratum now lies beneath a layer of silt and shells. The drift sequence in the Rosyth area can be correlated with that at Bo’ness and Grangemouth, enabling the gradient of the shoreline limiting the main period of late-glacial marine erosion to be provisionally calculated as between 0.20 and 0.25 m/km.
The Loch na Creitheach volcanic vent, Isle of Skye
Authors: Jassim S. Z. , Gass I. G.
Published: January 2010

Synopsis

In time and space the Loch na Creitheach vent is intermediate between the Cuillin gabbro and the Red Hills granite, being bounded to the south and west by gabbro and to the north and east by younger granites of the Red Hills. Within the vent a sequence of 450 m consists of pyroclastic debris ‘interbedded’ with large, concordant slabs of gabbro. Field evidence indicates that the pyroclastic debris, which ranges from agglomerate to fine-grained, well-bedded tuff, was deposited in a sub-aerial environment. Petrographic, mineralogical and chemical data indicate that the gabbro slabs were originally part of the Cuillin mass. It is suggested that the gabbro slabs were detached from the walls of the volcanic vent by a process involving rock fluidisation by gas-streaming. Once detached the slabs collapsed into the volcanic depression, a process that was repeated at least ten times.
Comparative grain-boundary studies of some basic and ultrabasic granulites, nodules and cumulates
Authors: Vernon R. H.
Published: January 2010

Synopsis

Average interfacial angles and their standard deviations for single-phase aggregates involving calcic plagioclase and clinopyroxene in basic Lewisian granulites occurring near Scourie, Sutherland, are similar to those in granulites occurring near Broken Hill, Australia. However, the Scourie rocks suggest that the relative proportions and/or grain-size of phases present may affect interfacial angles in two-phase aggregates. The micro-structures indicate that the Scourie granulites have undergone extensive grain adjustment in the solid state, no evidence of residual igneous micro-structures having been observed. The compositions of olivine and orthopyroxene in ultramafic granulites can be reconciled with this suggestion.

Olivine aggregates in some ultramafic nodules enclosed in basaltic rocks and olivine and plagioclase aggregates in some layered adcumulates have interfacial angles similar to those of granulites and have polygonal grains with curved boundaries. Available evidence suggests that adcumulates have undergone at least some adjustment of grain shapes in the solid state.
Magnetised rocks within the Lewisian of Western Scotland and under the Southern Uplands
Authors: Powell D. W.
Published: January 2010

Synopsis

An extensive aeromagnetic anomaly over part of the Southern Uplands is considered to be part of a more regional pattern, showing some connection with Lower Palaeozoic structure but arising from magnetic rocks within the underlying Precambrian. The depth to this basement estimated from its apparent magnetic relationship to the Fleet granite is consistent with one based upon a comparison with an anomaly over Islay due to magnetised Lewisian rocks. The anomaly pattern over the Lewisian in Sutherland is explained in terms of blocks of pyroxene granulite within less strongly magnetised gneisses. West from Islay a different pattern is due to some combination of effects from magnetisation contrasts within the Lewisian and structural relief of its surface. These may not be independent of each other.
The ammonites of the Bukowskii Subzone of the Oxfordian of Skye
Authors: Turner Judith A.
Published: January 2010

Synopsis

The ammonite fauna of the Bukowskii Subzone of the Cordatum Zone consists of large numbers of relatively few species of cardioceratids and aspidoceratids. The fauna of this zone in the Staffin Shales can be correlated with that of the Bukowskii subzone of the English succession, although in Skye
Cardioceras
(
Korythoceras
)
korys
is abundant and
Vertebriceras
is rare. The following ammonites are described and figured:
Cardioceras
(
Scarburgiceras
) aff.
bukowskii, C
. (
S
.)
alphacordatum, C
. (
K
.)
korys, C
. sp.,
Peltoceras
(
Peltomorphites
)
hoplophorus, P
. (
Para-wedekindia
)
arduennense
and
Euaspidoceras
sp.
Observations on Lewisian Chronology
Authors: Park R. G.
Published: January 2010

Synopsis

Evidence relating to the chronology of the Lewisian is reviewed in five categories in the light of recent differing interpretations.

(1)
Metamorphic and migmatitic episodes
—the restriction of the term
Scourian
to a time period is urged. ‘
Badcallian’
is proposed for the early Scourian (c. 2600 m.y.) episode,
Inverian
being well established as the late Scourian (c. 2200 m.y.) episode. The sub-division of the Laxfordian (? 1800–1400 m.y.) is discussed—the younger dates (
c
. 1100 m.y.) may refer to a younger orogeny.

(2)
Scourie dyke suite
—although four tectonically separable suites have been proposed, the evidence is consistent with a single suite.

(3)
Structural episodes and sequences
—unjustified correlation has led to over-elaborate structural chronology.

(4)
Gairloch–Loch Maree sediments
—evidence points to a post-Badcallian pre-Inverian age but the existence of large areas of gneisses of this age is doubted.

(5)
Other basic and ultrabasic intrusions
—chronological implications are discussed.

Finally it is argued that since the major tectonic re-orientation of the Lewisian seems to have occurred in the
Inverian
, there is a case for placing an orogenic break
within
the Scourian.
Chemical variability in some Moine rocks of Lochailort, Inverness-shire
Authors: Steveson B. G.
Published: January 2010

Synopsis

The chemical variability of some Moine metasedimentary rocks in Inverness-shire is examined, in an area near Lochailort where one pelitic band crops out in two different metamorphic zones. It is found that the high and low grade pelites have a similar composition and that possible within-outcrop variability is obscured by a variance due to the methods of analysis.
An analysis of the flight of the Cretaceous pterodactyl
Pteranodon ingens
(March)
Authors: Heptonstall W. B.
Published: January 2010

Synopsis

The strength of the humerus of
P. ingens
has been calculated and it is shown to have been capable of supporting a weight of 49 kg. An estimate of the average weight of mature individuals of this species has been made and the figure of 22.7 kg suggests that the humerus had a safety factor of about 4.3 in level gliding flight. This was sufficient to enable the animal to bank to an angle of 75° and allowed a minimum horizontal turning circle of radius 11.4 metres. The relationship between flying speed and sinking speed has been computed and a comparison made between the performance of this pterosaur and published data on fulmars and a typical man-made glider. It is shown from a calculation of the volume of muscle required for hovering flight that because of the inertia of the wings,
P. ingens
was unable to take to the air without the assistance of a prevailing wind. The supraoccipital crest is shown to have been adapted for controlling yawing movements while reducing the torque on the neck muscles.
Pteranodon
was well suited to thermal soaring.
The age of the granitic injection complex of Harris, Outer Hebrides
Authors: van Breemen O. , Aftalion Margaret , Pidgeon R. T.
Published: January 2010

Synopsis

The age of the granitic injection complex of Harris has been determined from an eight point Rb-Sr whole-rock isochron to be 1750 ± 34 m.y. An independent determination of the age of the complex of 1715 ±
20
10
m.y. was found from U-Pb measurements on eight zircon size fractions from two of the granite samples. These ages, from two independent methods, are the same within the uncertainties. The results confirm the Laxfordian age of the injection complex and establish a minimum age for the main Laxfordian metamorphism in the region. The variation in the initial Sr
87
/Sr
86
ratios of the whole rocks suggests that the granite intrusions were derived from an inhomogeneous source or sources. The Rb-Sr mineral ages are inconsistent and mineral data-points do not plot on the whole-rock isochron, indicating that the minerals have been open systems to the movement of Rb-Sr isotopes at some time after the emplacement of the granites.
Petrography and correlation of sandstones in the New Red Sandstone (Permo-Triassic) of Arran
Authors: Lovell J. P. B.
Published: January 2010

Synopsis

Petrographic data on the lithic sandstones in the New Red Sandstone of Arran are presented. Fibrous chert (agate) appears to be confined to a belt of outcrop running across the island from east to west. It is suggested that the base of the agate-bearing rocks may represent the nearest approach to a time plane in a succession in which correlation is otherwise both broad and uncertain.
A preliminary seismic survey adjacent to the Rashiehill borehole near Slamannan, Stirlingshire
Authors: Hall Jeremy
Published: January 2010

Synopsis

A brief seismic reflection survey, adjacent to the site of the Rashiehill borehole, Slamannan, indicates a thickness of 1,550 ft (470 m) of Lower Carboniferous lavas which rapidly thin eastwards, as, to a lesser extent, do the overlying sediments.
Dalradian Palaeocurrents from the Jura Quartzite
Authors: Anderton R.
Published: January 2010

Synopsis

The results of 212 cross-bedding measurements from the islands of Jura and Scarba, Argyll, indicate northward flowing palaeocurrents.
A model for the Lower Palaeozoic evolution of the southern margin of the early Caledonides of Scotland and Ireland
Authors: Dewey J. F.
Published: January 2010

Synopsis

Consideration of the stratigraphical and structural development of the relationship between the early and late Caledonides lends some support to the view that the early Caledonides of Scotland and Ireland lay on a leading plate edge above a northward-dipping descending plate. An early Ordovician trench just north of the Longford/Down Massif and Southern Uplands was the probable site of consumption of an oceanic plate which carried Ordovician/Silurian spilite-argillite-chert-turbidite sequences. The Highland Zone of high temperature metamorphism and gabbroic and granitic intrusion probably lay above a zone of calc-alkaline magma ascent, generated by partial fusion of the crust of a descending plate at depths over 100 km. During Ordovician and early Silurian times the Midland Valley was a southward, oceanward, thickening sedimentary wedge built on deformed Dalradian terrain in the north and on upthrust wedges of early Ordovician oceanic crust and mantle (Ballantrae Complex) in the south. At this time flysch wedges were built out southwards into the ocean and, beginning in late Upper Llandovery times, were progressively deformed to produce a growing land area (Cockburnland). By early Devonian times the sediments of the oceanic region were strongly deformed, forming the lands of the late Caledonides, and the Midland Valley was a graben receiving high rank metamorphic detritus from the Highlands and low rank metamorphic detritus from the Southern Uplands. Ophiolite complexes throughout the Appalachian/Caledonian Orogen are dominantly of early Ordovician age. By analogy with Tethyan ophiolite complexes and the processes involved in the genesis of marginal basins behind, and within, island arc complexes, the Appalachian/Caledonian ophiolites are considered to have originated by sea-floor spreading behind and within Ordovician island-arc complexes.
The earliest Caledonian structures in the Moine thrust belt
Authors: Soper N. J.
Published: January 2010

Synopsis

Evidence is presented which indicates that the earliest Caledonian structures in the Moine thrust belt at Loch Eriboll (a) post-date the Arenig and (b) antedate a suite of minor intrusions which, it is suggested, are associated with the Carn Chuinneag complex (530 ± 10 m.y.). Mylonitization of both basement and cover rocks took place at this stage, a result of major tectonic transport to the north-west.
The Late Laxfordian granite-migmatite complex of western Harris, Outer Hebrides
Authors: Myers J. S.
Published: January 2010

Synopsis

The Late Laxfordian history of Harris and south-western Lewis is described, on the basis of a primary field survey. The principal event recorded is the development of a complex of granite bodies and migmatites in an older gneiss complex. This migmatite complex has the form of a broad crescentic dome, elongated north-south, of which only the upper portion is exposed. It is younger than most of the fold structures of the region and appears to have developed by the irregular intrusion of potash-rich granite accompanied by local homogenization and granitization of the banded gneisses. The complex is fringed by distinct sheets of granite which are orientated sub-parallel to its roof. The episode of granite intrusion and migmatization was followed by the intrusion of potash-rich pegmatite veins into sub-vertical, east-west trending fissures. The granite-migmatites appear to be similar to the more extensive Svecofennid migmatite complexes of southern Finland. They are late-kinematic in the nomenclature of Eskola (1932) and thus differ from the better known Caledonian granites of Scotland which are chiefly syn-kinematic and post-kinematic.
Periglacial phenomena on the Island of Rhum in the Inner Hebrides
Authors: Ryder R. H. , McCann S. B.
Published: January 2010

Synopsis

The mountain areas of Rhum, developed in Tertiary volcanic rocks, exhibit various landforms and deposits of periglacial origin, the most important of which were formed by cold climate geomorphological processes during the later stages of the Late-glacial period. Blockfields were developed in the west, in well jointed granophyre; in the east there are frost shattered tors, an altiplanation terrace, and huge screes were initiated below all the steeper higher peaks. Contemporary processes continue to produce screes and induce solifluction and the development of small scale patterned ground.
Relationship between metamorphism and migmatization in the northern part of the Moine Nappe
Authors: Soper N. J. , Brown P. E.
Published: January 2010

Synopsis

It is shown that in northern Scotland there is a regional decrease in metamorphic grade westwards from the migmatites of central Sutherland towards the Moine thrust belt. Regional structural and microfabric evidence demonstrate that migmatization was coeval with the climax of regional metamorphism. The migmatites have a sheet-like form and overlie unmigmatized rocks. Thermal surfaces in the unmigmatized rocks are geometrically related to the base of the migmatite sheet and are inverted. It is concluded that the heat source immediately responsible for the thermal structure lay in the migmatites themselves.
Strain-rates, folding and cleavage
Authors: Cheeney R. F.
Published: January 2010

Synopsis

Some already-published equations relating to theoretical models can be manipulated so as to provide some indication of the absolute time scale of folding events. It would appear that very large folds with axial plane cleavage could be generated in a very short period of geological time.
Terminal features of the Creran Glacier of Loch Lomond Readvance age in western Benderloch, Argyll, and their significance in the late-glacial history of the Loch Linnhe area
Authors: Peacock J. D.
Published: January 2010

Synopsis

From a reinterpretation of drift deposits it is inferred that the glacier of Loch Lomond Readvance age which extended along Loch Creran crossed part of western Benderloch. Outwash deposits formerly believed to have been laid down pro-glacially at the greatest extent of the readvance ice are now thought to lie within the area covered by such ice. Following the readvance, the terminal part of the glacier stagnated while ice further back supplied material for deposition as outwash. A similar history can be inferred for other contemporary glaciers in the area, and is thought to be due to the occurrence of a restriction to glacier flow a short distance behind the maximum position reached by the readvance ice.
The mode of origin of some late diagenetic sandstone concretions from the Scottish Carboniferous
Authors: Deegan C. E.
Published: January 2010

Synopsis

Field observations and textural analysis suggest that the carbonate concretions in the fluviatile Wall Hill Sandstones of southern Scotland are late diagenetic in origin since the carbonate of the concretions has clearly replaced a secondary silica cement in the enclosing sandstones.

Carbonate crystallization seems to be mainly dependent on pH conditions and the problem of producing localized areas of varying pH within a sediment is discussed. Decaying organic material can produce local variations of pH and thus promote localized carbonate crystallization but this is considered an unlikely explanation in the present case. A possible mode of concretion formation is advanced involving fluctuation in pH around the threshold value necessary for carbonate crystallization which governs the number of nuclei of crystallization formed.
Palaeoecology of post-glacial beaches in East Lothian
Authors: Smith Shelagh M.
Published: January 2010

Synopsis

Molluscan assemblages, not previously described in detail, from raised beaches in the Aberlady and Gosford Bay areas indicate that several facies are present: rocky shoreline deposits formed at high-water mark; sandy shore facies from a little lower in the shore zone; a sandspit and various intertidal and estuarine deposits. In addition there are fossil life assemblages of
Ostrea edulis
and
Cerastoderma edule.
The raised beaches are correlated on the evidence of their depositional facies combined with their present height O.D., from which have been determined the relative heights of high-water marks at the times of their formation. The older life assemblages and the highest shoreline (8–9 m O.D.) have thus been grouped together and by means of C14 dating found to be about 5500 years old, corresponding with the age of the main post-glacial marine transgression in the Firth of Forth area.
Pumice on postglacial strandlines and in prehistoric sites in the British Isles
Authors: Binns Richard E.
Published: January 2010

Synopsis

Pumice can be used to correlate postglacial strandlines in the British Isles. Pumice found in many archaeological sites, for example the Outer Hebrides and Orkney, was probably obtained from nearby postglacial strandlines.
Geology and the museum
Authors: Waterston C. D.
Published: January 2010

Synopsis

A brief historical review of geology and museums in Edinburgh is given to illustrate the opinion that until the Second World War the growth and function of geological museums reflected the state of the science which they have been active in promoting. The place of museums in the Earth sciences should now be reassessed in view of the revolution in techniques, manpower and thought patterns which has taken place since the war. It is concluded that museums will continue to provide three important services to geological science: acquisition and conservation of reference collections; publication of data provided by research based on these collections; and the promotion of a greater public understanding of the work of geologists through exhibition and museum educational services.
Corophium
burrows as environmental indicators of Quaternary estuarine sediments of Tayside
Authors: Buller Antony T. , McManus John
Published: January 2010

Synopsis

The postglacial Brackmont Sands of St. Michaels, Fife, contain considerable numbers of small tubes which cut across a horizontally bedded sequence. The tubes closely resemble those constructed by the amphipod crustacean
Corophium volutator
in the Recent upper estuarine mud flats of the Tay. The environment of deposition of the Brackmont Sands has been variously attributed to fluviatile and marine origin. On the basis of comparative textural properties and burrow morphology it is suggested that the sediments are estuarine.
Dating events in the Metamorphic Caledonides: impressions of the symposium held in Edinburgh, September 1971
Authors: Dunning F. W.
Published: January 2010

Synopsis

The symposium comprised seventeen contributions on the following subjects: palaeontological evidence for the age of the Dalradian, the Ordovician of western Ireland and other formations relevant to the dating of events (2 papers); the sequence of tectonothermal events in parts of the Moine Thrust Belt and the Moine Nappe (4 papers); deformation rates (1 paper); isotope ages and their relation to events in the Moinian and Dalradian areas (4 papers); early events in the Scandinavian Caledonides and their isotope dating (3 papers); and wider geotectonic aspects, including a plate tectonics synthesis (1 paper), a comparison of Newfoundland and Ireland (1 paper), and new palaeomagnetic evidence for the location of the main continental masses in the Palaeozoic (1 paper).

The symposium failed to settle the question of the significance of the Precambrian isotope ages obtained from various parts of the Moine outcrop. Several new Precambrian ages were put forward to augment those already published, but at the same time further geological evidence was adduced to show that the earliest tectonic structures in the Moinian were post-Arenig.

Evidence was presented to show that Dalradian sedimentation in Scotland and Ireland north of the Highland Boundary Fault lasted from perhaps 700 m.y. ago (top of the Lower Dalradian = 660 m.y.) through the Cambrian into the Lower Ordovician (Arenig or Llanvirn). The main folding and metamorphism of the Dalradian north of the Highland Boundary Fault occurred around 500–505 m.y. ago. In western Ireland south of the Highland Boundary Fault, Dalradian sedimentation ceased before the Arenig and the main polyphase folding and metamorphism occurred about 520 m.y. ago. The younger D
3
dedformation phase in the Scottish Dalradian may be about 460 m.y. old and possibly equivalent to the pre-Silurian deformation of the Ordovician of western Ireland.

It now seems probable that early Caledonian folding in the Scandinavian Caledonides is confined to the North Cape and Bergen regions and may be about 530 m.y. old. Elsewhere in Scandinavia the main Caledonian folding is of Upper Silurian date; K-Ar ages around 435 m.y. are reported in the Trondheim area. The Varanger Tillite is 660 m.y. old.

Palaeomagnetic evidence was put forward which demonstrated the existence of a vast Hercynian ocean which closed around the beginning of the Carboniferous, but there is no evidence for a Caledonian ocean between the presently exposed forelands in Britain that could have been wider than 2000 km.
Microcline porphyroblasts in the Moinian rocks of the Western Highlands
Authors: Smith D. I. , Harris A. L.
Published: January 2010

Synopsis

In the Moinian rocks of western Inverness-shire microcline porphyroblasts are widely developed in the pelitic and semipelitic schists outside the zone of regional migmatisation. Field evidence and textural relationships indicate that microcline crystallised in segregations prior to the formation of the local F2 folds and also as post-F2 porphyroblasts. Both types were rotated by F3 folds. Associated mineral assemblages show that the porphyroblasts were stable in the lower amphibolite or greenschist/amphibolite transition facies of regional metamorphism. A contrast is drawn between such potash-rich (garnet-) biotite-bearing pelites which are widespread in the Moinian, and potash-deficient Dalradian pelites which, according to other workers, commonly lack biotite.
The structural development of the Lewisian rocks on the north shore of Loch Torridon, Ross-shire.
Authors: Cresswell D.
Published: January 2010

Synopsis

Nine phases of deformation, D1–D9, are recognised in the Lewisian complex of Torridon. D1–D5 pre-date the Scourie dykes and are thus of Scourian age, whilst D6–D9 post-date the dykes and belong to the Laxfordian.

The N.-S. to NE.-SW. S3 foliation which is dominant in the north of the area has been affected by NW.-SE. large-scale (F3A) and subsequent small-scale (F4) folds and related axial-planar foliation (S4). S4 was originally regarded as Laxfordian by Sutton (
in
Sutton and Watson 1951), but has been assigned here to the late Scourian or Inverian. In D5 both large and small scale F5 folds were produced with SE.-plunging axes, affecting sub-horizontal belts of S4. L5 is co-axial with L4.

The earliest Laxfordian structure S6 is usually parallel or sub-parallel to dyke margins. In D7 were formed F7 folds, S7 axial-planar foliation and L7 lineation which increase in intensity towards the south. S7 is co-planar with S4 and S6, and L7 is co-axial with L4. The D8 structures are restricted to narrow NW.-SE. belts in which F8 small-scale folds and L8 lineations were formed. The last penetrative structure is the S9 mylonite banding affecting certain NW.-SE. belts and is co-planar with S4 and S7.

Correlations are made with other areas in the southern Laxfordian belt.
A revision of the stratigraphic succession of the East Mainland of Shetland.
Authors: Flinn Derek , May F. , Roberts John L. , Treagus J. E.
Published: January 2010

Synopsis

The succession of metamorphic rocks in the eastern part of the Mainland of Shetland is briefly described. Four main divisions are recognised. These rocks are compared in terms of lithology and sedimentary structures with the Moine and
Dalradian rocks of Scotland
. The westernmost division of the Shetland succession is correlated with the Moine while the other three divisions are considered to be Dalradian.
Rate of sedimentation in the North Esk Reservoir, Midlothian
Authors: Lovell J. P. B. , Ledger D. C. , Davies I. M. , Tipper J. C.
Published: January 2010

Synopsis

Measurements made on the floor of the temporarily drained North Esk Reservoir indicate that
c
. 6 × 10
4
m
3
(wet volume) of sediment has been deposited there since 1850. This corresponds to an estimated minimum average rate of erosion in the catchment area of 10
−2
m/10
3
years.
Miospores of Triassic age and organic-walled microplankton from the Auchenhew Beds, south-east Arran
Authors: Warrington G.
Published: January 2010

Synopsis

Miospores indicative of a late Early or early Middle Triassic (late Scythian or Anisian) age have been obtained from the lower part of the Auchenhew Beds (upper lithostratigraphical unit of the ‘New Red Sandstone’ sequence) of Arran. Organic-walled microplankton, occurring with the miospores, may indicate that the depositional environment of the Auchenhew Beds was marine or in connection with a marine source.
Potassium-Argon ages for minerals from the Ross of Mull, Argyllshire, Scotland
Authors: Beckinsale R. D. , Obradovich J. D.
Published: January 2010

Synopsis

Sixteen K-Ar ages for samples of biotite and amphibole from the Ross of Mull and analytical data for the standards Bern 4M and W1 are presented. Ages determined for biotite and amphibole samples from the Caledonian pluton average 423 ± 4 m.y. and 416 ± 4 m.y. respectively. Field observations combined with gravity data indicate that this intrusion was guided by the Moine thrust plane. These ages therefore provide a minimum age for the Moine thrust and their concordance is interpreted in relation to the retentivity of the dated amphiboles to
40
Ar inferred from electron microprobe analyses of their composition. A biotite sample from a minette dyke cutting the pluton yielded an age of 406 ± 10 m.y., whereas two samples of amphibole from a fourchite dyke in the Moine country rock yielded early Permian ages of 276 ± 7 m.y. and 274 ± 8 m.y.
The age of the Cuttie's Hillock Sandstone (Permo-Triassic) of the Elgin area
Authors: Walker A. D.
Published: January 2010

Synopsis

The Cuttie's Hillock Sandstone is of non–marine origin and caps hills of Upper Old Red Sandstone. It is thus stratigraphically isolated and has to be dated by comparing its fossil reptiles with allied forms from Permo–Triassic sequences elsewhere, particularly Russia and South Africa, on the bases of presumed phylogeny and degree of specialization. Its age lies within the range late Permian to early Triassic, the evidence tending to favour the latter alternative, that is, equivalent to a position low in the Lystrosaurus Zone of South Africa.
Precambrian sediments of western Islay
Authors: Stewart A. D. , Hackman B. D.
Published: January 2010

Synopsis

An upward-facing succession 2 km thick and comprising ten newly-defined formations is described. The lower half is built of well-sorted, cross-bedded arkoses with interleaved slates and phyllites (deltaic facies). The upper half is built of turbidite greywackes, becoming more distal upwards, with interleaved mudstones and phyllites. The succession is continued upwards in Oronsay and Colonsay where the turbidites revert abruptly to deltaic facies. The sediments are tentatively correlated with the Dalradian.

Three deformation phases are recognized, the second accounting for the major folds plunging gently north-east.
Basin margin deposits of the Middle Old Red Sandstone at Dirlot Caithness
Authors: Donovan R. N.
Published: January 2010

Synopsis

Complex stromatolites and tufa-coated breccias of Middle Old Red Sandstone age, overlying two inliers of Moine gneiss are described and shown to be lacustrine shore deposits in a lake of variable salinity and fluctuating water level.
Observed beach modifications, Kiloran Bay, Isle of Colonsay, Argyll
Authors: Jardine W. G.
Published: January 2010

Synopsis

Observation of marked changes in beach configuration occurring over a short time period was possible during July and August 1971 at Kiloran Bay, Isle of Colonsay, Argyll. A semi-permanent lagoon situated behind a beach bar of calcareous sand, having survived periods of both neap and spring tides accompanied by offshore winds, was transformed to a tidal lagoon by the events of a single spring flood tide accompanied by a strong onshore wind. The tidal lagoon survived for only three days, being eliminated in the course of shoreward migration of the beach bar by the action of large waves resulting from Atlantic swell.
A breccia pipe in the Dalradian series, East Kincardineshire
Authors: Porteous W. G.
Published: January 2010

Synopsis

A body of coarse breccia occurring on the east coast of Scotland, south of Aberdeen, has the form of a pipe. Brecciation took place at considerable depth, probably below a volcanic centre, and was followed by granite emplacement.
A seismic reflection survey of the Clyde Plateau Lavas in North Ayrshire and Renfrewshire
Authors: Hall Jeremy
Published: January 2010

Synopsis

Studies of surface geology and of the results of recent gravity and magnetic surveys have yielded limited information about the development of the Clyde Plateau Lavas south-west of Glasgow. Seismic reflection velocity surveys linked by continuous reflection profiles were carried out to determine the depth of the base of the lavas, the recognition of which is based on the probability of a velocity reversal below it and on correlation with borehole and surface geological evidence. Operational methods, results and interpretation of the surveys are described.

The survey was designed to discriminate between two models of the lava pile: post-extrusion folding of a fairly uniform pile and an original maximal development of the lavas along their NW.–SE. trending outcrop. The results of the survey support the latter model, with compaction dips of later sediments banked against the pile and the whole modestly accentuated by later folding. More rapid, but smaller-amplitude variations of thickness occur across NE.–SW. trending faults with long histories of repeated movement.

The survey provides further evidence of the gradual diminution of activity of NE.–SW. faults, allied to the emergence of increasingly significant NW.–SE. trending, extensional structures. The inferred change of stress during Carboniferous times is thought to be related to the initiation of Atlantic rifting.
Oblique fold axes in the Dalradian rocks of the Southwest Highlands
Authors: Roberts John L. , Sanderson David J.
Published: January 2010

Synopsis

The development of folds with axes oblique to the northwest-southeast stretching-direction during the first two stages in the deformational history of Dalradian rocks in the Southwest Highlands is considered in terms of a quantitative model recently proposed by Sanderson (1973). This model allows the distribution of fold axes within the axial planes of the folds to be related to (1) the initial variability of the individual fold axes about a mean fold axis, (2) the initial attitude of the mean fold axis relative to the stretching-direction and (3) the amount of subsequent deformation within the axial planes of the folds. The various patterns of distribution shown by the fold axes in the Southwest Highlands are related to regional variations in (1) the initial attitude of the mean fold axis relative to the stretching-direction and (2) the amount of deformation within the axial planes of the folds. Measurement of strain indicators such as breccia fragments confirms that the strain ratios determined from the distribution of fold axes provide a reasonable estimate of the strain. Previous ideas concerning the development of these oblique folds are discussed in the light of the present work.
An interpretation of the structural evolution of the Laxford Front, north-west Scotland
Authors: Beach A. , Coward M. P. , Graham R. H.
Published: January 2010

Synopsis

The Laxford Front is a zone of complex rotational deformation which separates intensely deformed Laxfordian migmatites from heterogeneously deformed pyroxene granulites. The dominant sense of movement shown by shear zones is sinistral and north side upwards, implying that the migmatites were moving upwards from beneath the Scourian granulites.

The main rock types are, from south to north: a zone of relatively undeformed pyroxene granulite; a zone of regularly folded amphibolite facies gneisses with metagabbro-anorthosites and metasediments; a planar zone of granite sheets, and a zone of migmatites.

The post granulite facies structural history of the Laxford Front can be adequately described in terms of three phases (
F
1
to
F
3
) of deformation. The first and second phases are separated by a phase of dyke intrusion, the ‘Scourie dykes’. The Scourian zone of granulites acted as a competent body throughout each phase of deformation, though the southern limit of ductile deformation occupied a more northerly position for each successive phase. A model for the
F
2
strain trajectories is proposed.

There is no evidence to indicate that the migmatites were folded into a basement of pyroxene granulites as suggested by Bowes (1962) and Holland (1966). The Laxfordian migmatites were on the same tectonic level as, or possibly lower than, the Scourian granulites prior to the
F
1
deformation.
The Upper Old Red Sandstone of Fife and Kinross: a fluviatile sequence with evidence of marine incursion
Authors: Chisholm J. I. , Dean J. M.
Published: January 2010

Synopsis

Arenaceous redbeds in the eastern part of the Stirlingshire-Fife Upper Old Red Sandstone basin are described, and a new system of nomenclature is proposed for the lithostratigraphical units recognized. Sedimentological features, including palaeocurrent data, indicate that deposition was controlled by an eastward-dipping palaeoslope, and that most of the sequence was laid down in fluviatile environments. Evidence is put forward to show that a wedge of sandstone up to about 110 m thick near the top of the sequence represents the deposits of a marine transgression that advanced westwards into the basin, beginning not long after the deposition of a distinctive faunal horizon of Famennian or Tournaisian age. The transgression did not penetrate into the Stirlingshire part of the basin, and the regression, which was accompanied by uplift of the source areas, allowed fluviatile conditions to spread back eastwards into the Fife and Kinross area once more. There may locally be a disconformable relationship between the Upper Old Red Sandstone and the overlying Calciferous Sandstone Measures, but there is no detectable angular unconformity between the two sets of strata.
The supposed Perth Readvance in the Perth district
Authors: Paterson I. B.
Published: January 2010

Synopsis

In the course of a detailed investigation of the glacial deposits in the Perth district, only at Moneydie, where at a single locality two till layers are separated by stratified sediments, and in the Almond valley, where kettled outwash gravel rests on laminated marine silts and clays, was evidence found which appears to support the concept of the Perth Readvance, proposed by Simpson (1933) and dated between about 13 500 B.P. and 13 000 B.P. by Sissons (1967
a
). Readvance of ice at Moneydie is, however, believed to be a local event confined to the valley of the Shochie Burn and an explanation for the sedimentary relationships in the Almond valley is suggested which is compatible with the retreat of a major ice-sheet from the Angus coast. The sequence of sea-level changes inferred from the deposits in the lower Almond valley does not support the concept of an important readvance, nor does the general sequence recognized in Central Scotland by Sissons and others (1966). The Main Perth Shoreline, associated by Sissons and Smith (1965) with the supposed Perth Readvance, is believed to reflect abundant sedimentation at a time when rapid eustatic sea-level rise accompanying an abrupt climatic amelioration kept pace with the isostatic response by the land.
The Madadh Rocks: A Tertiary olivine dolerite sill in the Outer Hebrides
Authors: Mackinnon A.
Published: January 2010

Synopsis

The remnants of a Tertiary sill on the east side of North Uist are described and compared with rocks of similar composition from northern Skye and the Shiant Isles.
Isotopic studies on the palaeoecology and diagenesis of the Great Estuarine Series (Jurassic) of Scotland
Authors: Tan F. C. , Hudson J. D.
Published: January 2010

Synopsis

Over 700 carbon and oxygen isotopic analyses of fossils and carbonate rocks refine previous interpretations of the Great Estuarine Series. Many of the fossils are unaltered mineralogically and isotopically.
Praemytilus
and
Liostrea
inhabited water of variable isotopic composition and salinity; growth temperatures around 22°C are suggested for
Praemytilus
. Some
Unio
inhabited freshwater; other
Unio
, and
Neomiodon
, have normal marine
δ
C
13
and
δ
O
18
, which is contrary to palaeontological expectation.

Fossil-matrix isotopic contrasts show the dominant influence of diagenesis on whole-rock isotopic composition. Early diagenetic carbonates have variable, usually low,
δ
C
13
(to −29), showing algal and bacterial influence. Sparry calcite cements have low
δ
O
18
but positive
δ
C
13
. Isotopic data confirm the solution-reprecipitation mechanism for the replacement of aragonitic shells by calcite.

A stratigraphical review shows strongly variable isotopic composition of fossils from the Mytilus Shales, mainly marine values for the middle part of the Series, mainly freshwater for the Ostracod Limestones and Mottled Clays and a transgression in the Staffin Bay Beds.
The sedimentology and diagenesis of the Silurian rocks on the coast west of Gatehouse, Kirkcudbrightshire
Authors: Weir J. A.
Published: January 2010

Synopsis

Petrographical comparison and palaeocurrent analysis support correlation of the Lower Palaeozoic sediments cropping out along the coast between Gatehouse and Creetown, Kirkcudbrightshire, with the Carghidown Beds (Hawick Rocks,? Telychian) of the adjacent Whithorn area. The succession consists of a thick development of medium-grained turbidites, which display regional metamorphism in the lowest-grade greenschist facies, related to the first (f
1
– f

1
a

) episode of deformation. Superimposed on this is a carbonate metasomatism which may be related to the emplacement of the Cairnsmore of Fleet pluton, and a later episode of iron replacement which is associated with major strike-faults, and is probably connected with the Permo-Carboniferous weathering cycle. Eroding currents flowed mainly from the ENE. and depositional currents from the NNW., indicating derivation of the sediments from the tectonic landmass of Cockburnland. The petrography of these sediments suggests that in Telychian times Cockburnland may have consisted largely of Dalradian metasediments intruded by soda-granites, in association with a Cambro-Ordovician ophiolite complex with restricted outcrop. The sequence forms the basal part of a pile of flysch which ultimately filled in the Southern Uplands Trough.
Lower Carboniferous vulcanicity in the northern part of the Clyde plateau
Authors: Whyte F. , MacDonald J. G.
Published: January 2010

Synopsis

Studies of lavas and vents of Lower Carboniferous age in the Campsie and Kilpatrick Hills of the western Midland Valley of Scotland show that the earlier flows tend to be microporphyritic and were erupted largely from vents lying along a pronounced NE.–SW. trend. Later flows include a much larger proportion of feldspar-phyric basalts many of which may have been erupted from fissures now seen as dykes. A varied sequence of lavas in the Campsie Fells indicates the formation of differentiated magma possibly in association with the major central volcano Meikle Bin.
Ultrabasic inclusions from the Coalyard Hill Vent, Fife
Authors: Chapman N. A.
Published: January 2010

Synopsis

The petrography and field relations of a hitherto undescribed occurrence of Iherzolitic and amphibole-biotite pyroxenite inclusions in basanite and monchiquite sheets associated with one of the Fife tuff-pipes are briefly discussed.
The Beinn Bhreac Fold, southern Ross-shire
Authors: Fleuty M. J.
Published: January 2010

Synopsis

A major fold in the Moine nappe of northern Scotland, previously considered to be an anticlinal antiform, is shown to be a synform of uncertain facing direction. The structural history of the area and possible correlations with events in nearby areas are discussed.
Downward-facing structures in the Dalradian Leny Grits of Bute
Authors: Simpson A. , Wedden D.
Published: January 2010

Synopsis

An account is given of a continuous section in the Dalradian Lower Leny Grits, extending for 1 km north of the Highland Boundary Fault at Ardscalpsie Point on the west coast of Bute. This section is of particular interest because the rocks are of low metamorphic grade (chlorite zone) and display only a first deformation (D
1
) metamorphic fabric and associated D
1
structures. Further north in the island other later episodes of Caledonian deformation and metamorphism are successively imprinted on the primary fabric thereby complicating and obscuring the nature and geometry of the D
1
structures. Sedimentary way-up evidence shows that the Leny Grits young southeastwards while the primary (D
1
) structures are downward-facing.
The evolution of the Glencoe Cauldron
Authors: Roberts J. L.
Published: January 2010

Synopsis

Previous views concerning the volcanic history and structural development of the Glencoe Cauldron (Roberts 1966a) are considered in the light of recent work by Taubeneck (1967) and Hardie (1968). The assumption that the andesite lavas were derived from outside the cauldron, has important implications concerning its evolution. An analysis of those Group 2 and Group 3 rocks associated with the first cycle of caldera formation shows that this caldera was lop-sided. Volcanic activity was concentrated along the northeastern margin, and the caldera formed by the flap-like subsidence of the caldera floor. Following the work of Hardie (1968), it is proposed that the steep contact between the volcanic and metamorphic rock in the northeast of the cauldron represents the wall to this caldera (cf. Clough
et al.
1909). The eruptive products formed during this cycle of caldera formation, and the fault-intrusions which were emplaced during later cycles of caldera formation, indicate that the underlying magma chamber was layered. The volcanic activity resulting in caldera formation at the surface is related to the processes occurring within this chamber.
The origin of the Northumberland basin
Authors: Leeder M. R.
Published: January 2010

Synopsis

The Northumberland basin was initiated after eruption of alkali basalts onto the alluvial plains of the Upper Old Red Sandstone Scottish Border basin. The Birrenswark and Kelso Lavas are postulated as of upper mantle origin, produced by partial melting. Partial melting gave rise to slight upwarp and to areas of non-deposition with calcrete formation. Tensional stress in the upper crust arose locally from this upwarp and also from the regional effects of upper-mantle flow, as postulated by Bott (1964). Downfaulting along the Stublick/Ninety Fathom hinge line and basalt eruption along the pivot line of an incipient half graben led to basin initiation, Tournaisian marine transgression and southerly drainage from the Southern Uplands horst. Further volcanism, tending towards explosive central-vent activity with time, occurred along the northern basin margin in the Visean.