bluuebunny/crossref_metadata_2025 huggingface dataset:
The relationship between isotopic ages, uplift and sedimentation during Ordovician times in western Ireland
Authors: Dewey J. F. , McKerrow W. S. , Moorbath S.
Published: January 2010

Synopsis

During Ordovician times, at least 36 000 feet of sediments accumulated in the South Mayo Trough, which lay to the north of a rising cordillera of Dalradian metamorphic rocks in Connemara, western Ireland. A complex faulted relationship existed between trough and cordillera. K-Ar isotopic ages, showing a spread within the range 475 to 420 m.y., are interpreted as representing the time during which the cordillera was progressively uplifted, eroded, and cooled.
The sequence of sedimentary structures in turbidites, with special reference to dunes
Authors: Allen J. R. L.
Published: January 2010

Synopsis

The relationship between bed form, grain-size of load, and flow power known from equilibrium-state, open-channel experiments, is revised for turbidity currents, whose power is time-dependent with respect to a point in their path. The revised relationship suggests that cross-bedding, indicative of dune beds, would occur in turbidite sandstones only if the parent turbidity currents had been furnished with sufficiently coarse-grained sediment. Otherwise, the turbidite sandstones are expected to show parallel laminations directly succeeded upward by cross-lamination. The available field evidence is consistent with these conclusions, and some previous difficulties regarding dune structures in turbidites appear now to be resolved.
Volcanism and the Ardross Fault, Fife
Authors: Francis E. H. , Hopgood A. M.
Published: January 2010

Synopsis

The relationship of volcanic necks and related rocks to folded and faulted Viséan strata between Elie and St. Monance suggests that the Ardross Fault was the final expression of a major north-easterly tectono-volcanic structure which was active intermittently throughout Upper Carboniferous, and possibly early Permian, times. A sequence of volcanic and tectonic episodes began with folding and faulting on NNE. and SE. lines, probably early in the Namurian. The main volcanism is probably late Namurian, but may have continued into the Westphalian and Stephanian. The Ardross Fault, a dextral strike-slip structure, though with a strong vertical component, is later than the volcanism and is off-set by later SE. faulting.
Preservation of folding in the Carn Chuinneag-Inchbae hornfels
Authors: Harker R. I.
Published: January 2010

Synopsis

Folds described from the aureole of the Carn Chuinneag–Inchbae igneous complex formed during the emplacement of the intrusion. Consequently these folds cannot constitute evidence of widespread pre-intrusion regional metamorphism.
A review of the structure and stratigraphy of the Moinian of Ardgour, Moidart and Sunart—Argyll and Inverness-shire
Authors: Brown R. L. , Dalziel I. W. D. , Johnson M. R. W.
Published: January 2010

Synopsis

The structural geometry is the result of four episodes of deformation (F
1
–F
4
), with most major folds belonging to the second or third episodes. Major F
1
folds are probably absent (on stratigraphical evidence) but slides of the F
1
episode are not ruled out. Complex F
2
geometries—with curvilinear axes, and antiforms which turn into synforms when traced along traces—are found where F
2
folds are ‘folded’ by F
3
folds, and also remote from F
3
fold hinges. Intense inhomogeneous flattening explains these features, and it is considered that this flattening may be part of the second, rather than the third deformation. In the prevailing high-temperature conditions, the amount of flattening seems to be a function of rock-type and it is possible to distinguish between the simpler structures in thick psammites and the more complicated, highly flattened, structures in pelitic/striped rocks. The major rock units probably represent a stratigraphic sequence, from bottom to top, 1. Morar Division, 2. Glenfinnan Division and 3. Loch Eil Division.
An Application of Markov Chain Analysis to the Ayrshire Coal Measures Succession
Authors: Doveton J. H.
Published: January 2010

Synopsis

The vertical ordering of rock types in a Coal Measures succession is analysed in terms of an ‘embedded Markov chain’ model. The presence of a statistically significant ‘memory’ within the sequence is proved and a Markov model of combined first and second order properties established. The form of the model is one of loosely repeating basic units (corresponding to cycles) whose internal structure is suggestive of origin in fluvial and floodplain environments and control by local vegetational and sedimentary factors. Prediction of the cycle member content distribution by various models indicates that the ‘cyclic’ behaviour of the succession is satisfactorily accounted for by the second order Markov model, although there is the possibility of an additional longer term control.
Notes on the geology of Trearne Quarry (Upper Viséan), Ayrshire and on the palaeoecology of its productid brachiopods
Authors: Shiells K. A. G. , Penn I. E.
Published: January 2010

Synopsis

The palaeoecology of some of the species of productid brachiopods which occur in the limestones and shales of Trearne quarry is discussed. The limestones, some of which are peri-reefal, carry a more diverse productid fauna than the shales but the density distribution is not related to rock type. Smaller species occur in the shales which tend locally to develop a high density, mono-specific,
Antiquatonia insculpta
(Muir-Wood) community.

Statistical analysis of orientation data shows that
A. insculpta
and
Pugilis scoticus
(J. Sowerby) lived with the visceral disc in a subvertical position and with randomly trending hinge-lines.
A. insculpta
lived with its hinge-line plunging at 20° to the horizontal while
P. scoticus
lived with its hinge-line in at least two positions: one plunging at 20° to the horizontal and the other horizontal. Such infraspecific versatility makes generalisations about the living positions of productids suspect.
The Loch Nant area, Argyllshire, and its significance in the structural history of the Loch Awe Syncline
Authors: Borradaile G. J. , Roberts John L. , Treagus J. E.
Published: January 2010

Synopsis

The examination of a small area of Dalradian rocks near the axial zone of the Loch Awe Syncline, on its north-western limb, shows that an inverted succession faces upwards to the south-east on a primary slaty cleavage.

No evidence has been found to support the pre-cleavage folding recognised from the same area by Harris and Berridge (1969), nor their re-interpretation of the stratigraphy.

It is concluded that the succession established by Bailey (1913) still holds and that the Loch Awe Syncline is a primary structure, coeval with the nappe forming movements of the Scottish Highlands.
A xenolithic dyke at M’Inroy’s Point, Gourock, Renfrewshire
Authors: Herriot A.
Published: January 2010

Synopsis

A Tertiary tholeiitic dyke intruded into sedimentary rocks of Lower Carboniferous age is locally rich in xenoliths of siliceous and argillaceous rocks possibly of Upper Old Red Sandstone age. The xenoliths and the country rocks have suffered thermal metamorphism with the production of glass, tridymite, cordierite, pyroxenes and biotite in the former and tridymite, cordierite, biotite and lime-garnet in the latter. From considerations of the stability fields of tridymite, melt-products and the solidus of dolerite, it is estimated that the PT conditions under which the presently exposed levels of the dyke crystallised were approximately 500 bars and 1,000° C, possibly representing a cover in Tertiary times some 6,200 ft (1,900 m) thick.
Geophysical investigations on the continental shelf and slope north of Scotland
Authors: Watts A. B.
Published: January 2010

Synopsis

A gravity, magnetic and seismic reflection survey of the continental shelf and slope around the Orkneys, Hebrides and Shetlands was completed by Durham University on RRV John Murray in 1968. The Bouguer gravity anomaly map shows a large gravity ‘high’ reaching 94 mgal which is continuous for 155 miles (250 km) and tends approximately NNE. across the shelf. This is interpreted as being due to a seaward extension of Lewisian basement rocks exposed on the Scottish mainland. Large amplitude gravity ‘lows’ also occur on the shelf and slope. A gravity ‘low’ 56 miles (90 km) west of the Shetlands has been interpreted as being due to a deep sedimentary basin infilled by Mesozoic–Tertiary sediments and bounded on its SE. margin by a large normal fault. Recent sediments form the continental slope which gently truncates the older Caledonian structures observed on the shelf.
Relation of Cleavage and Metamorphism in the Macduff Slates
Authors: Fettes D. J.
Published: January 2010

Synopsis

Field and textural evidence from a coastal traverse immediately west of Macduff indicates that the main phase of regional metamorphism separates in time the movements which produced the slaty cleavage and folds at Macduff from those which produced the strain-slip cleavage and monoclines on the steep western limb of the Boyndie Syncline. The slaty cleavage of the Macduff Slates is, therefore, thought to be equivalent to the early movements in the rest of the Dalradian; an important conclusion in the light of the recent discovery of Lower Ordovician fossils in the Macduff Slates.
Some geochemical distinctions between Moinian and Lewisian rocks, and their use in establishing the identity of supposed inliers in the Moinian
Authors: Winchester J. A.
Published: January 2010

Synopsis

Whole-rock analysis of Moinian rocks, and comparisons of their compositions with those of Foreland Lewisian rocks, shows that persistent chemical differences occur. Sedimentation processes explain adequately the lower FeO/ TiO
2
and K/Rb ratios, and the high concentration of zirconium characteristic of the Moinian.

Whole-rock analysis of rocks from supposed Lewisian ‘inliers’ shows that they are compositionally similar to the gneisses of the Lewisian Foreland. It is suggested that post-Moinian metamorphism was not accompanied by wholesale chemical changes, and that original compositional differences between Lewisian and Moinian rocks are preserved. Knowledge of these compositional differences may therefore serve to identify or confirm the presence of Lewisian inliers in places where their field appearance is not readily distinguishable from the Moinian.
The Lewisian chronology of the southern region of the Scottish mainland
Authors: Moorbath S. , Park R. G.
Published: January 2010

Synopsis

K-Ar measurements on gneisses and basic intrusive bodies from the Torridon, Gairloch and Gruinard Bay areas demonstrate (i) the existence of a few relict Badcallian (≡ Early Scourian of Sutton and Watson 1969) dates of
c.
2600 m.y. in the Gruinard Bay area, (ii) the emplacement of Scourie dykes at Torridon, as well as of the Aundrary basite sheet near Gairloch, at least 2200 m.y. ago, and in the case of the dykes probably during the waning stages of the Inverian metamorphism, (iii) the occurrence of the first Laxfordian metamorphism at
c.
1700 m.y. ago, of the second Laxfordian metamorphism at
c.
1500 m.y. ago, and of the third (retrogressive) Laxfordian metamorphism in the Gairloch area at
c.
1400 m.y. ago, (iv) post-Laxfordian cataclasis and reheating at Torridon
c.
1150 m.y. ago.

The significance of these results is discussed in detail and compared and contrasted with published age data.

A statistical re-examination of the lead isotope results of Moorbath
et al.
(1969), from the areas covered in this paper only, confirms that the parent rocks of the typical basement gneisses were already in existence
c.
2900 m.y. ago and were probably subjected to their highest-grade metamorphism at that time.
North-south geofractures in Scotland and Ireland
Authors: Russell M. J.
Published: January 2010

Synopsis

The suggestion is advanced that north-south trending faults and Carboniferous synclinal troughs, as well as a crustal inhomogeneity in central Scotland, were formed in response to a stress field in which the direction of relative tension was oriented east and west relative to the present pole. These structures are considered to be higher homologues of three major extension failures (geofractures) at the base of the Upper Crust which are separated by distances of 45 and 55 km. In Ireland (like Scotland, situated close to the continental margin) north-south geofractures have previously been postulated to explain the distribution of major ore deposits (Russell 1968, 1969).

Sparse stratigraphical evidence points to a late Tournaisian or Viséan age for the initiation of the postulated geofractures. They are considered to constitute the earliest evidence for the stress field that eventually caused lithosphere separation at Rockall Trough. This separation is inferred to have taken place at the end of Carboniferous times.
Middle Old Red Sandstone alluvial fan and talus deposits at Foyers, Inverness-shire
Authors: Stephenson D.
Published: January 2010

Synopsis

The Middle Old Red Sandstone at Foyers rests with marked unconformity on an irregular surface of schists, gneisses and rocks of the Caledonian Foyers granitic complex. Basal breccias, conglomerates and grits are widespread, giving way to more persistent grits and sandstones high in the sequence. Deep infilled channels occur, cutting earlier rocks, and
in situ
scree deposits are common. Field evidence suggests that the sediments may have formed as alluvial fan deposits in an arid intermontane basin, bordered by highlands to the south-east. The highlands probably terminated at a north-east-south-west trending fault scarp, possibly a manifestation of early movements along the Great Glen fault.
Sodic and ultra-sodic rocks of metasomatic origin from part of the Moine Nappe
Authors: Tanner P. W. G. , Tobisch O. T.
Published: January 2010

Synopsis

The field relationships, petrology and chemistry of suites of sodic augite-, sodic amphibole- and albite-bearing rocks from Loch Hourn and Glen Cannich, Inverness-shire are described. The sodic rocks occur in metasediments of Moinian (Late Precambrian) age and post-date the regional metamorphism and deformation. Feldspathized breccia and dyke-rocks occur in the Loch Hourn area, but most of the sodic rocks appear to have resulted from the introduction of albite-rich, water-saturated fluids along fractures in the country rocks. The metasomatism affecting the country rocks closely resembles fenitization but is chemically unusual in that it involves introduction of Na and Al and loss of K, Ca, Mg and Fe.
The petrochemistry of the epidiorites of the Tayvallich Peninsula, North Knapdale, Argyllshire.
Authors: Wilson J. R. , Leake B. E.
Published: January 2010

Synopsis

The geology of the Dalradian rocks near Tayvallich is described with a detailed geological map. 78 new chemical analyses of metamorphic rocks, each for 30 elements, are given including intrusive epidiorites, basic pillow lavas, agglomerates, grits, slates, limestones and calcareous slates. Basic volcanic glasses have been locally showered into the sediments. The epidiorites are albite-chlorite-calcite-quartz-sphene (epidote) rocks with actinolite being confined to rocks with mg in excess of 0.44. Metasomatic movement occurred between the margins and centres of the pillow lavas and is also believed to have affected the volcanic glasses. The sedimentary rocks can be distinguished from the epidiorites by a number of chemical characteristics including the high P, Ti and Nb of the epidiorites and their differing trends of variation such as Cr against Niggli mg. The Loch Awe epidiorites are characterised by high Zr and P and are less tholeiitic than epidiorites higher in the Dalradian sequence. They may be shallow intrusions and extrusions of a magma that had undergone substantial intratelluric differentiation.
Structures in the south-eastern portion of the Strontian granitic complex, Argyllshire
Authors: Munro M.
Published: January 2010

Synopsis

Structures in a portion of the Strontian complex adjoining Loch Linnhe are fully described for the first time. Using this new data it is possible to derive the probable shape, structure and lithology of the portion of this complex which has been displaced by the Great Glen Fault with more certainty than was previously possible. These predicted characteristics differ in certain important respects from the structures and relations visible in the Foyers complex and it is concluded that there is less justification for assuming that the Foyers and Strontian complexes represent fragments of a single body which has been disrupted by movements on the Great Glen fault than has been believed in the past.
A sub-bottom profiling survey of the St. Magnus Bay deep, Shetland
Authors: McKay A. G.
Published: January 2010

Synopsis

This survey of St. Magnus Bay, Shetland revealed an infilled elongate basin beneath the deep inner part of the bay. Speculations as to the origin of the bay by meteorite impact remain unconfirmed.
Amphibolitization of Scourian granulites
Authors: Beach A.
Published: January 2010

Synopsis

Scourian granulite-facies gneisses from north-west Scotland occur as relict masses surrounded by amphibolitized granulites. During amphibolitization the gneisses suffered both deformation and metamorphism. Ortho- and clinopyroxenes were replaced by hornblende and hornblende-quartz intergrowths forming corona textures. Seven hornblende and plagioclase analyses are presented. Microprobe scans across the hornblende coronas show that compositional gradients in Si, Al, Fe, Mg and Na existed which were later obliterated by recrystallization. It is suggested that overall loss of Ca and Mg and gain of Na occurred by diffusion through the intergranular fluid during amphibolitization. The water causing amphibolitization is considered to have entered the granulite system along tectonically determined zones.
Basic minor intrusions north of Loch Laxford, Sutherland and their significance in Lewisian chronology
Authors: Dash B. , Chowdhary P. K. , Bowes D. R.
Published: January 2010

Synopsis

Basic minor intrusions show cross-cutting relations to the regionally-developed Lewisian quartzo-feldspathic gneisses and amphibolites north of Loch Laxford. Their emplacement during the Laxfordian episode is indicated by the isotopic date of
c.
1900 m.y. for the gneisses which they cut and the later emplacement of pegmatite and the development of crush-rock. Correspondence of chemical composition and mineralogy with other Lewisian basic igneous masses showing longer tectonic and metamorphic histories, together with difficulty of establishing whether concordance is the result of igneous or tectonic activity, makes such rock masses unsuitable for use as stratigraphic time-markers.
Ice wastage in Glenmore, upper Spey valley, Inverness-shire
Authors: Young J. A. T.
Published: January 2010

Synopsis

A complex system of fluvioglacial landforms, which is part of more widespread evidence of ice sheet wastage in Upper Speyside, is described and discussed. The pattern of features that has been developed is shown to be dependent on a range of local environmental factors as well as on the changing physical condition of the ice. Three distinctive phases of ice wastage, each related to different meltwater outlets, are identified.
Some Scottish Carboniferous davidsoniacean brachiopods
Authors: McIntosh M. J.
Published: January 2010

Synopsis

Material for the species discussed is drawn from the Lower and Upper Limestone Group and lowest Passage Group (P
2
and E
2
zones.) Apart from
Schellwienella rotundata
Thomas, which is found in sandy sediments, members of the superfamily are found in muddy or bioclastic limestones with little arenaceous material. Six species are figured, namely
Orthothetina leei
(Thomas),
O. neilsoni
(Thomas),
Schellwienella radialis
(Phillips),
S. rotundata, S. scotica
(Reed), and
Brochocarina wexfordensis
(Smyth). Six more are both figured and described or redescribed (
Orthothetina thomasi
(Sarycheva and Sokol'skaya),
Schellwienella crenistria
(Phillips),
Brochocarina trearnensis sp. nov., Apsocalymma shiellsi gen. et sp. nov.,
and
Serratocrista cylindricosta
and
S. dalriensis spp nov.
) and a new subfamily, the Schellwienellinae, is proposed.
Chemical changes during retrogressive metamorphism of Lewisian granulite facies rocks from Coll and Tiree
Authors: Drury S. A.
Published: January 2010

Synopsis

The chemical compositions of granulite and amphibolite facies representatives of four metamorphic rock types with different bulk compositions and origins, from a Precambrian metamorphic complex in North-west Scotland, are assessed in the light of its tectonic and metamorphic history. Several striking chemical differences exist, which are thought to have been imparted by retrogressive metamorphism of an early granulite facies complex in which all four rock types were present. The main changes incurred in the conversion of granulite facies rocks to amphibolite facies, and common to all four rock types, involved influx of K, Rb, Th and some other elements and loss of Ba, Sr, P and rare earth elements in the whole complex. Some redistribution of elements occurred. Continued retrogression of gneissic rocks to greenschist facies involved further geochemical changes.
Tectonic and metamorphic history of the Upper Findhorn, Inverness-shire, Scotland
Authors: Piasecki M. A. J.
Published: January 2010

Synopsis

Moinian and Dalradian metasediments which surround the Findhorn Newer Granite Complex form a northwesterly extension of the Ballapell succession.

The metasediments were first folded by regional-scale isoclinal F
1
folds following the Caledonian trend. These were then refolded by open, near-upright F
2
crossfolds, and later by tight, also near-upright F
3
folds trending N to NE which now often dominate the megascopic rock fabric.

High grade metamorphism with widespread migmatization accompanied F
1
folding. Localized migmatization and recrystallization followed F
1
and F
2
folding, becoming more widespread after F
3
folding. A later metamorphism foliated and recrystallized a suite of early minor intrusions belonging to the Findhorn Newer Granite Complex.

The Upper Findhorn rocks are situated centrally within the orthotectonic Caledonides. Their tectonic history is correlated with that of the Iltay and Ballapel Dalradians, but their thermal history is comparable with that of the Moines west of the Great Glen Fault.
The Blackstones Tertiary igneous complex
Authors: McQuillin R. , Bacon M. , Binns P. E.
Published: January 2010

Synopsis

Seismic, gravity, magnetic and sampling evidence show that the Blackstones Bank in the Sea of the Hebrides is the outcrop of a Tertiary ultrabasic intrusion whose form may be approximated as a vertical cylinder of diameter 16 km and depth to base 22–30 km. The intrusive body is partly overlain by Mesozoic and younger sediments. Little disturbance is seen in the country rock of either the roof or walls of the pluton.
The evolution and transport of the Tay Nappe
Authors: Harris A. L. , Bradbury H. J. , McGonigal M. H.
Published: January 2010

Synopsis

A traverse through steeply inclined rocks north-west from Birnam is the equivalent of a vertical section at one point through the Tay Nappe. This traverse demonstrates increasing complexity and intensity of deformation at successively lower structural levels in the nappe. It suggests that the second episode of deformation (D2) at a low level was largely responsible for the emplacement of the nappe by simple shear, and that displacements of the order of 6 km during this episode can be demonstrated in the limited thickness of rocks exposed in the district. The earliest deformation (D1) induced two cleavages in the Southern Highland (Upper) Dalradian sandstones—one analogous to slaty cleavage and the other a tectonic striping produced by pressure solution. One set of folds, now downward-facing following D4 downbending, is associated with these cleavages. D2 deformation strongly modified the limbs and ‘facing’ characteristics of the D1 folds.
Thermal causes of the Dalradian metamorphism in the central Highlands of Scotland
Authors: Richardson S. W. , Powell R.
Published: January 2010

Synopsis

Analysis of carbonate and pelitic mineral assemblages at the base of the Dalradian Series near Spean Bridge, Inverness-shire, leads to the conclusion that the temperature at the peak of regional metamorphism reached 535°C at a depth of 18.5 Km. In the light of the general parallelism of the garnet isograd (taken as nearly isothermal) and the base of the Dalradian, the thermal event is modelled in one dimension using an average heat production for the Dalradian of 4.0 × 10
−1 3
cal/cm
3
s and a temperature-dependent thermal conductivity with room-temperature average value of 7.8 × 10
−3
cal/cm s K. It is argued that the thermal inertia of the upper crustal rocks during metamorphism is offset by their concurrent erosion and that a steady state model is a reasonable approximation to the complex transient thermal history over the 20–40 m.y. period during which deformation, heating and erosion were taking place. The heat flow through the base of the Dalradian at the metamorphic climax was about 1.3–1.6 × 10
−6
cal/cm
2
s; this is attributed to heat production within an underlying 10–20 Km thick Moinian basement together with a normal, or slightly higher than normal, conductive flux from the mantle beneath. If a Lewisian-like lower continental crust underlies the Moinian it would have reached temperatures high enough to permit partial fusion and could be the source of calc-alkaline largely post-metamorphic-climax igneous rocks found in the area.
Trace element indicators of the genesis of the Rhum layered intrusion, Inner Hebrides
Authors: Henderson P. , Gijbels R.
Published: January 2010

Synopsis

Almost constant concentration of nickel in cumulus olivine crystals taken from the bases and tops of many of the macrorhythmic units of Rhum indicates that a large volume of magma, if predominantly liquid, was needed to produce each unit. Some units represent less than 2 per cent by mass of a liquid parent magma.

Rare earth element concentrations in cumulus plagioclases indicate that the parent magma was enriched in the light relative to the heavy rare earths. The estimated rare earth abundance pattern of the parent magma suggests that the melt was produced from a small amount of partial melting of upper mantle material.
The Age of the Hoy Lavas, Orkney
Authors: Halliday A. N. , McAlpine A. , Mitchell J. G.
Published: January 2010

Synopsis

The Hoy Lavas are alkaline olivine basalts, occurring at the base of presumed Upper Old Red Sandstone, and resting unconformably on Middle Old Red Sandstone strata. Mean conventional K-Ar ages of the lavas are discordant and range from 300 to 333 Ma. A cross-cutting monchiquite dyke yields a conventional K-Ar age of 235 Ma.
40
Ar–
39
Ar stepwise degassing analyses of two samples indicate an age of approximately 370 Ma for the lavas. A revision of the age of the Givetian/Frasnian boundary is suggested.
The Archaean Evolution of the Lewisian Complex of Gruinard Bay
Authors: Davies F. Bryan
Published: January 2010

Synopsis

South-east of Gruinard Bay, the Lewisian gneiss complex is cut by metadolerites derived from Scourie dykes which occupy two directional sets and record low Laxfordian finite strains. The gneisses record effects of pre-dyke deformation of an early complex of plutonic granodioritic and tonalitic gneisses which in places retain magmatic features and show intrusive relationships with remnants of supracrustal rocks and layered ultramafic-leucogabbro sheets occurring as agmatite complexes within the gneisses. The regional structure outlined by these agmatites is dominated by large-scale mushroom-type interference patterns produced from the refolding of major tight to isoclinal folds with NW dipping axial surfaces by close to tight major folds with NE dipping axial surfaces. Minor shear belts occur on the limbs of the larger late folds. The pre-dyke history of the Gruinard Bay complex is similar to that of the type-Laxfordian complex, north of Scourie.
The Cuillin layered igneous complex—evidence for multiple intrusion and former presence of a picritic liquid
Authors: Hutchison R. , Bevan J. C.
Published: January 2010

Synopsis

Much of the western Cuillin is formed by part of a funnel-shaped intrusion comprising layered ultrabasic rocks which range upwards from dunite to peridotite to allivalite (feldspar-olivine cumulate). The funnel-shaped intrusion has a marginal border group on which allivalites are banked. Recent mapping indicates that a peridotite mass previously regarded as a sill, is part of this layered sequence, and that inner, ultrabasic cumulates to the E are merely a downthrown portion of the same funnel-shaped mass. The eastern rocks were cut by a later pyroxene-rich magma from which feldspar-olivine-pyroxene cumulates were formed. In the lower dunite-peridotite-allivalite series (Unit 1), cumulus olivine and feldspar range from Fo
90–86
and An
91–85
, respectively. In the upper unit (Unit 2) of feldspar-olivine-pyroxene cumulates cryptic variation is more complex; feldspar cores are An
84–83
, and olivines range from Fo
77–67
.

The high level of the Cuillin complex suggests that there was insufficient room for a layered basic intrusion some 10,000 metres thick. Evidence is presented for successive pulses of ultrabasic magma, indicating that the complex as a whole comprises intrusions of tholeiitic affinity ranging broadly with time from ultrabasic to gabbroic, rather than a tectonically disrupted single, layered basic intrusion.
The structural history of the Cheviot and adjacent regions
Authors: Robson D. A.
Published: January 2010

Synopsis

Relief of NW to SE stress at the end of Silurian times led to intensive volcanic, followed by major and minor intrusive activity in the Cheviot region during the Lower Old Red Sandstone period. During the Upper Old Red Sandstone period, uplift and erosion took place, such that by the beginning of Carboniferous times, the roof of the granite stock was already exposed. In the Carboniferous period subsidence occurred, leading to the great accumulation of sediment in the Northumberland trough, with at least some deposition across the Cheviot region. Hercynian movements were represented by W–E compression throughout the NE of England and southern Scotland. In the sediments adjacent to the Cheviot igneous region, these movements were heralded by folding; they continued as shear-faulting both in the Cheviot igneous block and in the adjacent sediments and they were followed by the intrusion of the whin dykes and the Great Whin Sill. Tertiary movements began with the intrusion of the Acklington dyke, followed by N–S compression with shear faulting. A late phase of movement, responsible for much of the present-day topography, was manifested by normal faulting and tilting. Throughout the history of the region, fault movements were re-activated along Lower Palaeozoic trends.
The Metamorphism of the Dalradian rocks of Scotland.
Authors: Atherton Michael P.
Published: January 2010

Synopsis

The metamorphism of the Dalradian rocks of Scotland is reviewed and commented on, attention being paid to the nature and spatial distribution of the zones and their significance in PT modelling. Reactions defining Barrovian and Buchan isograds are listed and figured and the importance of textural and chemical disequilibrium discussed. The effect of rock composition on the isograds is examined and a T-X diagram constructed to indicate the probable metamorphic mineral sequence for the average pelitic Dalradian composition. The history of ideas on the genesis of the migmatites is outlined and it is concluded that they may well be polygenetic, and those in the NE may even be of Pre-Caledonian age. The role of oxidation and reduction reactions is briefly mentioned and the late cooling reactions are described, from which it can be seen that the climatic assemblages have often been markedly modified.

The pressures and temperatures of the metamorphism, determined from phase considerations are plotted on a PT diagram and compared to the isotope results. Finally, evidence is used to suggest that although the fundamental cause of metamorphism might be a normal heatflow across the mantle/crust boundary and within the tectonic pile, the evidence at the present level indicates some of the metamorphism is due to high level magma and perhaps heat focussing along major structures.
Structural age of the Vagastie Bridge granite, Sutherland
Authors: Fergusson I. W.
Published: January 2010

Synopsis

The Vagastie Bridge granite is observed to cut folds associated with the main metamorphism of the surrounding psammites of the Moine assemblage, confirming recent radiometric evidence that the granite belongs to the suite of Caledonian Newer Granites in the Northern Highlands, and is not equivalent to the Carn Chuinneag granite.
Palaeomagnetism and palaeogeography of the Southern Uplands block in Ordovician times
Authors: Piper J. D. A.
Published: January 2010

Synopsis

The major Ordovician igneous outcrops within the Southern Uplands were studied to evaluate the position of this region with respect to adjacent crustal plates during the later history of the Iapetus Ocean. Post-Arenig, pre-Caradocian gabbros and serpentinites of the Ballantrae Complex yield palaeomagnetic poles of 26°E, 10°S (dψ = 10.9, dχ = 18.8°) and 27°E, 12°S (dψ = 5.5, dχ = 9.7°) respectively after a.f. and thermal cleaning. Although 95 per cent confidence circles overlap with other British Ordovician data, magnetic inclinations are systematically shallower than contemporaneous results from England and Wales and correlate closely with other data from N of the Southern Uplands Fault line. A similar result is found from palaeomagnetic study of the (Lower Caradocian) Bail Hill Volcanics. The palaeomagnetic results support faunal and tectonic evidence that the major crustal separation in Ordovician times existed between the Southern Uplands and the northern Lake District. The visible ophiolite slices along the approximate line of the present Midland Valley represent pre-Llanvirnian obduction in a northerly direction of an earlier ocean basin.
Folding and thrusting in the upper Glen Oykel area, Assynt
Authors: Milne K. P.
Published: January 2010

Synopsis

The earliest tectonic event affecting Lewisian, Torridonian and Cambrian rocks in upper Glen Oykel involved a tight overturned syncline and anticline, the common limb of which developed into a previously unrecognized thrust, named here the Glen Oykel Thrust. The Loch Ailsh Syenites were probably intruded after this thrust. The disruption of the Torridonian rocks by the earlier thrust caused the Assynt Thrust to deviate sharply to remain within these sediments. In quartzites below the Assynt Thrust deformation is concentrated at the centre of an eastward bulge in the thrust surface.
A Geophysical Survey of South Kintyre
Authors: Wilson C. D. V.
Published: January 2010

Synopsis

Seismic, gravity and magnetic data indicate a basin of Old Red Sandstone, probably fault bounded and about 1 km deep, between the south coast of Kintyre and Sanda Isle, where the Dalradian basement has been uplifted.

A gravity high near Southend is interpreted as due to concealed faulting in the southern limb of the Campbeltown syncline, together with a hidden basic intrusion. Adjacent to this high there is a chain of minor intrusives with weak magnetic anomalies. The deeper faulting in the Dalradian, the shallower faults in the Old Red Sandstone, the hidden basic mass and the outcropping intrusions may all be tectonically related. The structures may be part of the Highland Boundary Fault zone.
Basic minor intrusions in the Lewisian gneisses of southern Lewis, Outer Hebrides
Authors: Taft M. B.
Published: January 2010

Synopsis

A structural study of basic minor intrusions of southern Lewis gives evidence for three distinct phases of intrusion, separated by phases of folding. Dates of structurally comparable intrusions on South Rona and the Scottish mainland suggest that at least one of the igneous phases on Lewis may have been intruded during the Laxfordian orogenic episode. The recognition of three different phases of basic activity, and the similar mineralogies of these, and intrusions elsewhere in the Lewisian, implies that detailed structural studies are necessary in order to express their significance in overall Lewisian history.
Origin of complex sulphide nodules related to diagenesis of lacustrine sediments of Middle Devonian age from the Shetland Islands
Authors: Hall A. J. , Donovan R. N.
Published: January 2010

Synopsis

A laminated, carbonaceous-calcareous-siltstone facies (the Devonian Upper Melby Fish Bed, Shetland) of non-glacial varve origin deposited in a tropical, stratified lake, shows a complicated diagenesis. Sulphide nodules in this sequence, containing pyrite, chalcopyrite, covellite, bornite, sphalerite, galena and tennantite, show an equally complex development. The first period of growth produced a concentric zonation of pyrite and pyrite with sphalerite and galena. Following fracture of the nodule, Cu, Fe-sulphides replaced pyrite. Pb, Zn and As were remobilised and/or introduced at this time. It is probable that lacustrine regression and transgression greatly affected the chemical properties of groundwaters and led in part to the complicated nodule and host rock diagenesis. The nodules were later cut by small veins of tectonic origin.
The Camas Malag Formation: an interbedded rhythmite/conglomerate sequence of probable Triassic age, Loch Slapin, Isle of Skye
Authors: Nicholson R.
Published: January 2010

Synopsis

The Camas Malag Formation, comprising interbedded rhythmites and orthoconglomerates, and lying unconformably on a very irregular surface of carbonate rocks of the Lower Palaeozoic Durness Group, is interpreted as a lacustrine deposit of Triassic age.

Boudins in adjacent Durness carbonates of rhythmite lithologies identical to those of the Formation are regarded as deformed fragments of tabular extensions of the latter deposited in cavities parallel to the bedding of the Durness rocks of the lake floor. They provide a minimum age for a deformation phase, earlier than the contact metamorphism produced by the Beinn an Dubhaich granite, in which dolerite sheets intrusive into Durness rocks also were deformed.
Intertidal sediments in the Auchenhew Beds (Triassic) of Arran
Authors: Pollard J. E. , Steel R. J.
Published: January 2010

Synopsis

Study of a 45 m succession of the Auchenhew Beds (Triassic) of western Arran, with a record of halite pseudomorphs, symmetrical ripple marks, flaser, wavy and lenticular bedding, bimodal palaeocurrents and particular vertical arrangements of lithologies and structures, has provided evidence of intertidal conditions, probably within the context of a relatively arid, low energy, muddy shoreline. The new observations lend support to earlier suggestions of a marine connection and influence at this time and necessitate some reconsideration of the environmental significance of trace fossils previously described from this area.
Proterozoic folds on the Northwest Caledonian Foreland
Authors: Soper N. J. , Barber A. J.
Published: January 2010

Synopsis

Recent isotopic studies have shown that parts of the Moine sedimentary sequence underwent orogenic metamorphism before 1000 Ma and this raises doubts as to the significance of the
c.
730 Ma ‘Morarian’ ages yielded by pegmatites from the Moine tract. From evidence readily available from Geological Survey publications we show that the Torridonian rocks of the NW Caledonian foreland were folded and eroded in Precambrian time. This folding was coeval with emplacement of the Morarian pegmatites, supporting the view that the Morarian was a tectonothermal event of regional importance, and permitting (but not establishing) the stratigraphic equivalence of the Upper Torridonian with the Moine rocks in western Sutherland.
The influence of bedrock on heavy mineral content of streams within a glaciated area of Perthshire
Authors: Abdalla A. Y. , Whyte F.
Published: January 2010

Synopsis

A systematic collection and comparison of heavy minerals from stream sediments, glacial deposits and bedrock in the Glen Artney–Glen Lednock area shows that, despite glaciation and the influx of foreign material, the present heavy mineral distributions in streams clearly reflect the local geology.
Pb isotopic composition of feldspars from Scottish Caledonian Granites, and the nature of the underlying crust
Authors: Blaxland Alan B. , Aftalion Margaret , van Breemen Otto
Published: January 2010

Synopsis

Common Pb isotopic ratios for 11 feldspar separates from Caledonian granite intrusions (400 Ma old) show a linear alignment on a
207
Pb/
204
Pb vs
206
Pb/
204
Pb diagram, the best-fit regression line suggesting a lower intercept age of 2700 Ma, using conventional growth-curve models. This accords well with previously published Pb ages for the Lewisian basement in north-west Scotland (
Chapman and Moorbath, 1977
), and strongly suggests a Lewisian Pb component in the Caledonian granites. Furthermore, the feldspars from the Southern Uplands granites are significantly more radiogenic than those from the Highlands and Midland Valley; this relationship is consistent with the presence of an older crustal layer beneath the more northerly regions which does not extend southwards into the Southern Uplands.
A magnetic survey of the aureole around the Cheviot granite
Authors: Robson D. A. , Green A. G.
Published: January 2010

Synopsis

A total field intensity map of the Cheviot granite stock and its aureole has been constructed from a ground-level proton magnetometer survey. Measurements on rock specimens, together with computer modelling, show that: (1) The andesitic lava of the aureole and the marginal variety of granite have high susceptibilities, but the unmetamorphosed andesite and rhyolite, and the granophyric and Standrop varieties of granite have lower susceptibilities; (2) The junction between the metamorphosed andesites and the underlying marginal granite forms a dome-like surface; (3) Some vertical movement on the Breamish fault and horizontal movement along the Harthope fault has occurred; (4) There are many xenoliths of metamorphosed andesite within the granite; (5) A shallow basin of granophyric and Standrop varieties is thought to lie within the central region of the granite stock; (6) The small negative anomaly over the Breamish fault may indicate that the marginal granite is only thin in that area; (7) The Biddlestone laccolith persists northward beneath the lava from Biddlestone quarry to the Breamish fault.
A goniatite from the Mill Hill Marine Band, Lower Limestone Group, of East Fife
Authors: Wilson Rennie M.
Published: January 2010

Synopsis

Sudeticeras
aff.
delépinei
Moore is recorded as the first identifiable goniatite obtained from the Mill Hill Marine Band in the Lower Limestone Group in East Fife. Its occurrence strengthens the assigning of the Lower Limestone Group to the P
2
goniatite zone and the Brigantian Stage.
The geology and origin of narrow closed channels in the Sound of Jura
Authors: Evans D. , Ruckley N. A.
Published: January 2010

Synopsis

Geological and geophysical investigations in the southern part of the Sound of Jura reveal numerous deep and narrow closed channels in a sequence of thick post-glacial muds. It is proposed that the channels were formed subsequent to the deposition of the sediments by the erosive action of the strong tides observed in the Sound. Several problems related to this mode of origin are considered, but more data are required to provide greater insight into the post-glacial history of the Sound.
The stratigraphical setting of the Cairnsmore of Fleet Pluton, Galloway
Authors: Cook D. R. , Weir J. A.
Published: January 2010

Synopsis

The granitic pluton of Cairnsmore of Fleet was intruded into the Moffat Shales (Caradoc-Fronian) and an overlying flysch facies. The flysch is divisible into two formations: the Craignell Formation, in the NW of the area, and the Knockeans Formation, to the SE. Within the Craignell Formation, an evolution of greywacke facies from basic through lithic to silicic is recognized, the base being diachronous from Idwian in the SE upwards to early Fronian in the NW. The Knockeans Formation, deduced to be the youngest unit, completes the evolutionary sequence of the greywackes from basic to a silicic facies, and is correlated with the Hawick Group (Telychian or later). The anomalous NW encroachment of flysch over pelagic facies may relate to a sedimentary source within a ridge located along the Iapetus oceanic suture.
The geology of an undersea tunnel at Irvine Bay, Ayrshire
Authors: Anderson J. G. C. , Gayer R. A.
Published: January 2010

Synposis

A 2 km long sea outfall tunnel and associated site investigation reveal a sequence of gently dipping strata of Productive Coal Measures (West-phalian) intruded by a Tertiary porphyritic basalt dyke, by a Permian volcanic neck and by Permian dykes of alkaline affinities. The stratigraphy and structure represent a westward extension of the north Ayrshire basin.
K-Ar age measurements on dykes of the Fishnish Bay area, Isle of Mull
Authors: Holgate N. , Macintyre R. M.
Published: January 2010

Synopsis

Potassium-argon measurements have been carried out on eight samples of E-W tholeiitic dykes exposed around Fishnish Bay. Chipped whole-rock samples give an age of 57.9 Ma

1

which is substantiated by age/mesostasis relations in powdered samples. A N-S dyke cut by the E-W tholeiites yields an age of 61 Ma. These measurements place constraints on the age of the NW-SE to N-S Hebridean Tertiary dyke-swarm, the Mull central intrusive complex, the dextral shift postulated for the Great Glen fault (Holgate 1969) and on the magnetic polarity time-scale for the lower Tertiary interval.
Assemblages of the ostracod
Cytheropteron montrosiense
Brady, Crosskey and Robertson from offshore Devensian deposits in the Minch, west of Scotland
Authors: Gregory Diane
Published: January 2010

Synopsis

Fossil microfaunal assemblages containing common
Cytheropteron montrosiense
Brady, Crosskey and Robertson have been recovered for the first time off the west coast of Scotland. It is suggested that low or variable salinities may be a major factor in controlling its distribution.
The Devonian sedimentation and tectonism of a rapidly subsiding, semi-arid fluvial basin in the Midland Valley of Scotland
Authors: Wilson Alan C.
Published: January 2010

Synopsis

Early Devonian fluvial sedimentation took place in a large, late-orogenic basin bounded by actively-subsiding high-angled faults. Deposition of gravels and sands took place on mountain-fringing bajadas from sheetfloods and braided streams; sands, silts and clays were deposited in adjacent flood-plains. Basin-margin faults, notably the Highland Boundary Fault, controlled subsidence of an elongate depositional basin and when movement on these was sufficiently rapid, coalescing bajadas were constructed. When the rate of source area uplift/depositional basin subsidence decreased, the uplands were reduced and floodplains initially encroached on to the inactive bajadas before extending over the former source areas.

The Devonian sedimentary rocks of the Midland Valley which accumulated under semi-arid conditions, indicate that varying rates of source uplift/depositional basin subsidence were the dominant controls influencing the nature of the depositional processes. Moreover the various vertical sequences of genetically-different deposits found in the study area also occur in other similar alluvial basin deposits and a model is formulated to demonstrate that these successions reflect a limited number of distinct evolutionary tectono-sedimentary sequences.
Lateglacial marine erosion and a jökulhlaup deposit in the Beauly Firth
Authors: Sissons J. B.
Published: January 2010

Synopsis

Closely-spaced boreholes and auger holes for a small area of carseland at the head of the Beauly Firth show a thin but widespread gravel layer between the lateglacial marine deposits and the Flandrian deposits. The gravel layer and adjacent fossil cliff are attributed to marine erosion during the Loch Lomond Stadial. Further down the Beauly Firth, at Inverness, a gravel deposit in a similar stratigraphic position covers at least 7 km
2
and has a maximum recorded thickness of 39 m. It is suggested that this large gravel deposit was laid down by the initial jökulhlaup from the Spean-Roy ice-dammed lake.