bluuebunny/crossref_metadata_2025 huggingface dataset:
Cross-stratification as a criterion of palaeocurrent direction in flysch deposits
Authors: Jipa Dan
Published: January 2010

Synopsis

Measurement of the line of intersection between foreset laminae and normal bedding gives the most reliable estimate of palaeocurrent direction in ripple cross-lamination. Accepting a possible error of ± 20°, it is necessary to make only one or two measurements per locality.
Intra-bed palaeocurrent variations in a Silurian flysch sequence, Kirkcudbrightshire, Southern Uplands of Scotland
Authors: Scott Kevin M.
Published: January 2010

Synopsis

Palaeocurrent indicators
within
individual sandstone beds in the Riccarton-Raeberry Castle flysch succession show the following upward differences between erosional, sole-marking currents and depositional currents:

Grain elongation-imbrication orientations in poorly laminated basal parts of beds show statistically significant and highly variable deflections from sole-markings.

Internal current lineations within laminated portions of beds indicate deflections averaging 25 degrees.

Small-scale cross-laminations within the upper part of many beds were formed by currents of which 36 per cent diverged more than 90 degrees from sole-markings.

Terminal currents, forming cross-laminated transverse ripples on bed tops, were commonly normal to initial currents but some had reversed directions.

Sense of deflection was not constant but two successions showed predominant counterclockwise current rotation. Magnitude of deflections in each section correlates crudely with sole-marking trend dispersion. An example of total lateral filling of sole-markings was observed.

Two of five beds in which vertical changes in grain orientation were studied showed increasing upward deflection corresponding with upward decrease in grain size.

During each sand influx, changing resolution of forces due to fluid energy, associated with decreasing competency in the case of deposition of a graded bed, and the downslope force of gravity probably caused the current variation.
The sequence of internal structures in turbidites
Authors: Walton E. K.
Published: January 2010

Synopsis

An attempt is made to show how both conditions of transportation and conditions of deposition have to be considered in the interpretation of sequences of internal structures in beds of greywacke and flysch sandstone. Interpretation of graded and laminated divisions involves not only velocity distance (or time) curves but also rates of deceleration.
The value of point-count modal analysis of greywackes
Authors: Welsh William
Published: January 2010

Synopsis

The results of some simple statistical tests on modal analyses of several groups of thin-sections of greywackes are presented. The tests suggest that modal analyses are of some value in providing additional information of use for comparison purposes by a single worker using his own data but that direct comparisons between workers are severely limited by operator variance factors.
The age of the Durine Member of the Durness Limestone Formation at Durness
Authors: Higgins A. C.
Published: January 2010

Synopsis

Conodont faunas from the Durine Member of the Durness Limestone Formation have yielded sixteen species. These faunas bear a close resemblance to previously described ones from North America and Scandinavia and suggest an age for the upper part of the Durine Member near the Arenig-Llanvirn boundary. This is somewhat at variance with Poulsens’ suggestion that the whole of the Durine Member is of Llanvirn age.
Metamorphism of minor intrusions associated with the Newer Granites of the Western Highlands of Scotland
Authors: Dearnley R.
Published: January 2010

Synopsis

A late Caledonian phase of regional metamorphism is outlined in the Western Highlands. Minor intrusions associated with the Newer Granites are found to exhibit varying degrees of regional metamorphism in which the zonal ‘isograds’ trend about north-east-south-west, approximately parallel to and increasing in grade towards the Great Glen. There is a major break in the zoning along the line of the Great Glen Fault.
Structural history of the Silurian rocks of the coast west of Gatehouse, Kirkcudbrightshire
Authors: Weir J. A.
Published: January 2010

Synopsis

The rocks exposed in the coastal sections between Gatehouse and Creetown, Kirkcudbrightshire, are considered to belong to the Hawick Rocks (Upper Valentian), and have been affected by five main episodes of deformation, three of which are of Caledonian age. The first phase produced E.N.E.-W.S.W. similar folds and associated tensional strike faults, forming the structural basis of the area and determining the outcrop distribution. During the second phase these folds were modified, and a new set of concentric folds, comparable in strike but with axial surfaces dipping at around 45° S.S.E., was generated, along with a conjugate set of wrench faults. Folds of the third phase have E.-W. axes and steep eastward plunges. The three phases are equated respectively with
F
1
F
2
and
F
3
of the Whithorn area (
Rust 1965a
). The fourth phase gave rise to folds with near-horizontal axial planes, and frequently developed as minor thrusts, and the final deformation gave rise to dextral kink-bands trending N.-S. The two last are correlated with
F
4
and
F
5
of Whithorn, to which Hercynian and Alpine dates are provisionally allocated. A swarm of dykes was emplaced between the first and second phases, and further dykes were intruded after the second phase.
The Caledonian history of the north-eastern Irish Sea region and its relation to surrounding areas
Authors: Simpson Alexander
Published: January 2010

Synopsis

In the light of recent work in the Isle of Man and the Lake District, the Caledonian histories of these two areas are outlined and correlated. The tectonic history of this north-eastern quarter of the Irish Sea region consists of two evorogenic episodes of severe Caledonian deformation. The earlier tectogenesis took place during the Lower Ordovician after the infilling of a rapidly subsiding geosynclinal trough. The importance of this orogenic phase within the British Caledonides is considered by comparison with surrounding areas. The structures produced during the subsequent end-Silurian evorogenesis are examined and compared with those formed at this time elsewhere in the British Isles.
The origin of the basic and ultrabasic rocks of the Loch Ailsh alkaline intrusion, Assynt
Authors: Parsons Ian
Published: January 2010

Synopsis

The field relationships and textural and mineralogical features of basic syenites, ultrabasic rocks and dolomites associated with leucocratic syenites in the Loch Ailsh intrusion demonstrate that both basic syenites and ultrabasic rocks are the products of reaction between dolomite and syenite.
The structural history of the Lewisian rocks north-west of Loch Tollie, Ross-shire, Scotland
Authors: Bhattacharjee C. C.
Published: January 2010

Synopsis

In the Lewisian rocks north-west of Loch Tollie corresponding deformation during three successive phases of the Laxfordian orogeny is shown in meta-sediments, hornblende-schists, amphibolites and acid gneisses. Isoclinal folds, some drag folds and open folds and associated axial planar schistosity/foliation and mineral and intersection lineations were developed during the
main phase
of deformation. Asymmetrical folds, of which the Tollie anticline is the most prominent, refold the isoclinal folds and the associated main phase structures. Antiforms predominate, the synforms being largely represented by shear-belts. This
mid phase
deformation produced the dominant N.W.-S.E. trend of the lithological layers and the main phase foliation and the pattern of alternating belts of south-easterly and north-westerly plunging main phase lineation. After the emplacement of acidic veins and sheets,
late phase
deformation resulted in the development of steeply-plunging brittle folds and shear-belts with pseudo-tachylite.
Pyrope from Elie, Fife
Authors: Colvine R. J. L.
Published: January 2010

Synopsis

The garnets from a vent at Elie, Fife, have been collected and analysed. This analysis is compared with recent analyses of pyrope from, a number of other environments. On the basis of this comparison and the occurrence of the pyrope as xenocrysts in the vent agglomerate of Elie Ness Neck, a primary precipitate origin from a magma in depth is postulated.
British and Swedish Ordovician species of
Cybeloides
(Trilobita)
Authors: Ingham J. K.
Published: January 2010

Synopsis

The Ordovician encrinurid trilobites
Cybeloides girvanensis
(Reed) and
C. loveni
(Linnarsson), formerly assigned to the genus
Paracybeloides,
are redescribed. Specimens of
Cybeloides
from several British localities are identified with the former species. A teratological pygidium of
C. loveni
is noted. It is suggested that the development of spines in these species was, at least partly, an adaptation for attaining a concealed position.
Lanarkopterus dolichoschelus
(Størmer) gen. nov., a mixopterid eurypterid from the Upper Silurian of the Lesmahagow and Hagshaw Hills inliers, Scotland
Authors: Ritchie Alexander
Published: January 2010

Synopsis

New material of
Mixopterus dolichoschelus,
a large eurypterid from the Upper Silurian inliers in Lanarkshire and Ayrshire, Scotland has made possible the first full description of the form, with dorsal and ventral reconstructions. In many features (shape of prosoma, nature of the large ‘walking’ legs (III))
M. dolichoschelus
differs significantly from the Norwegian
Mixopterus kiaeri
Størmer and it is proposed that the Scottish species be placed in a new genus for which the name
Lanarkopterus
is proposed. A comparison of the enlarged, spinose legs (III) in
Megalograptus, Lanarkopterus
and
Mixopterus
suggests a new interpretation of joint numeration in the last two genera.
A chemical study of five amphibolite bodies from the Lewisian of Gairloch, Ross-shire
Authors: Power G. M. , Park R. G.
Published: January 2010

Synopsis

Ten samples from each of five separate amphibolite bodies have been analysed by emission spectrography for Cr, V, Ni, Co, Sc, Zr, Cu, Sr, Ba, TiO
2
, MnO, MgO, CaO and total iron as Fe
2
O
3
. FeO was determined by titration. The application of simple statistical tests to the results reveals significant differences in the chemical composition of the samples from different bodies. The chemical information is found to be a useful complement to the geological interpretation of the rocks and illustrates the potential value of studies of this type.
Late glacial marine algae from Greenock and Renfrew
Authors: Brett D. W. , Norton T. A.
Published: January 2010

Synopsis

Fossil algae attributable to
Desmarestia aculeata, Sphacelaria pennata, Sphacelaria plumigera
and
Laminaria
sp. from the late glacial beds of Greenock and Renfrew are described and illustrated. A fossil echinoderm identified as
Strongylocentrotus dröbachiensis
and found with the algae is also illustrated. The four species of algae are clearly inhabitants of cold seas although they occur through a wide latitudinal range. This is in accord with the view that the beds were laid down under Arctic conditions.
Palaeozoic and Tertiary transcurrent movements on the Great Glen fault
Authors: Holgate Norman
Published: January 2010

Synopsis

Two periods of major transcurrent movement on the Great Glen fault are here recognised: (1) a sinistral shift (essentially that of Kennedy 1946) of about 83 miles, which occurred in late Lower or early Middle Old Red times; and (2) a dextral shift of 18 miles which was initiated at the close of the strictly regional phase of the Hebridean Tertiary vulcanicity. The north-westerly dyke-swarms of the latter are dislocated by the dextral movement at the Great Glen and Firth of Lorne faults, while the extension of the Great Glen fault across SE. Mull is deformed and locally transgressed by intrusives emplaced about the Mull Early Caldera. The crustal stress system causing dextral shift on the Great Glen fault terminated the period of intrusion of north-westerly dykes; a few later dykes in Mull show an east-north-easterly trend in conformity with the new direction of regional stress maximum. The maximum age of the dextral movement is therefore indicated by the minimum age value for the dykes of the north-westerly swarm; at about 52 m.y., this corresponds to early Eocene times. The same dextral movement has dislocated an ancient river system which formerly flowed eastwards across the Scottish Highlands.
Investigation and treatment of leakage through Carboniferous rocks at Clubbiedean Dam, Midlothian
Authors: Sivasubramaniam A. , Carter Anne V. F.
Published: January 2010

Synopsis

Clubbiedean Reservoir is impounded by an earth dam founded on calcareous shales and sandstones through which leakage paths have developed as a result of solution of the calcareous matrix of the sandstones. There is a history of attempts to plug the leaks in the reservoir floor. Recently the foundations of the dam were investigated by a series of cored boreholes and a grout curtain was subsequently established below the embankment. This curtain has reduced the leakage to negligible proportions.

The foundation investigations are described and the local geology discussed. The construction and effectiveness of the grout curtain are considered in detail.
The last glaciation and deglaciation of central Lanarkshire
Authors: McLellan A. G.
Published: January 2010

Synopsis

Directions of ice movement have been deduced from glacial evidence (breached cols, striae, till fabrics and drumlins) and from fluvioglacial evidence (eskers and meltwater channels). The last glaciation of central Lanarkshire was effected by ice from both the Highlands and the Southern Uplands. It is shown that the Perth Readvance may have extended less far east than formerly supposed, and the Carstairs esker system is considered to be related to the wastage of an earlier ice cover. Doubts are raised about the value of till fabrics in the interpretation of ice movements.
Distribution of elements in igneous rocks of the normal calc-alkaline sequence
Authors: Gribble C. D.
Published: January 2010

Synopsis

Compilations of published data on the abundance of elements in normal plutonic igneous rocks are given in 14 graphs, each of which depicts the data for a particular group of elements.
Structure of the Lewisian rocks between Strath Dionard and Rhiconich, Sutherland, Scotland
Authors: Dash B.
Published: January 2010

Synopsis

The Lewisian rocks of the Strath Dionard–Rhiconich district consist essentially of acid gneiss, amphibolite and calc-silicate rock (Rhiconich group) with pegmatitic, granitic and basic minor intrusions (post-Rhiconich group rocks). The earliest structural element in the Rhiconich group is a lithological layering, possibly an original sedimentary feature, now largely obscured due to the subsequent deformation and metamorphism. Penetrative foliation associated with small intrafolial folds and mineral lineation related to the deformation of the
Gualin phase
are affected by generally asymmetrical folds including the large Strath Dionard antiform and the associated structures related to the
Dionard phase
of deformation. The later open folds, pseudotachylitic crush-rock and joints are related to the
Leacach phase
of deformation. The three phases of deformation were variously accompanied by recrystallisation and migmatitic activity and developed in a series of rocks comparable with those of the southern belt of Lewisian at a crustal level above that of the pyroxene-granulites of the central belt.
The Insch layered intrusion
Authors: Clarke P. D. , Wadsworth W. J.
Published: January 2010

Synopsis

The Insch layered intrusion comprises an olivine-rich Lower Zone, followed by an olivine-free (labradorite–2 pyroxene cumulates) Middle Zone, and an olivine-bearing Upper Zone in which alkali feldspar becomes an important constituent. The overall cryptic layering is extreme (Fo
80→5
, An
80→40
, En
82→25
, and Ca
40
Mg
50
Fe
10
to Ca
40
Mg
5
Fe
55
) but the lower part of the intrusion is hardly exposed and the continuity of the sequence (especially in the range An
80–60
and En
82–52
) can only be inferred. The total thickness of the intrusion may be as much as 18 000 ft but only the top 3000 ft are known in any detail. The Middle Zone cumulates appear to be intricately associated with later gabbros which may be close in composition to the parent magma of the intrusion.
Isotopic ages of dykes and pegmatitic gneiss from the southern islands of the Outer Hebrides
Authors: Lambert R. St J. , Evans C. R. , Dearnley R.
Published: January 2010

Synopsis

Potassium-argon ages of 1720, 1565, and 1500 m.y. from dykes from South Uist and Benbecula confirm the existence of Laxfordian activity in the southern part of the Outer Hebrides. The pegmatitic gneiss of Ardivachar, South Uist, yields a whole-rock rubidium-strontium isochron age of 2560±80 m.y., closely correlating with the post-Scourie Group pegmatites of the mainland.
The Loch Ryan Fault
Authors: Kelling G. , Welsh W.
Published: January 2010

Synopsis

Geological evidence is presented for the presence of a major fault near the east coast of Loch Ryan, a fracture whose existence was previously suggested from geophysical studies of the region by Mansfield and Kennett (1963) and Bott (1964). The location and nature of this fault have been determined from the repetition of a distinctive stratigraphical horizon on both sides of the loch, despite the regional fold plunge, and from a shift in the line of expression of the Southern Uplands Fault. This inferred fracture, the Loch Ryan Fault, is estimated to have a west-wards downthrow of approximately 5000 ft (1525 m).
Eolian sediments in the basal New Red Sandstone of Arran
Authors: Piper D. J. W.
Published: January 2010

Synopsis

In the basal New Red Sandstone of Arran (Brodick Beds), interbedded eolian and water deposited sediments are found. Sedimentological features known from comparable modern environments, but not hitherto described from any other ancient sediments, include granule ripples, gravel deflation pavements, pebbles rolled into eolian sands, and fulgurites. Much of the eolian sand was deposited in dunes indicating a wind direction predominantly to the south-west. It has not been possible to determine the detailed morphology of the dunes.
Metasediments in the Rhiconich group of the Lewisian between Loch Laxford and Durness, Sutherland
Authors: Chowdhary P. K. , Dash B. , Findlay D.
Published: January 2010

Synopsis

Metasedimentary quartzite and calc-silicate rock are of widespread distribution in the Rhiconich group of the Lewisian between Loch Laxford and Durness. Field relations, mineralogy and chemical composition are used as criteria for recognition, the mineral assemblages being indicative of amphibolite facies metamorphism. The calc-silicate rock has a mineralogical and chemical composition consistent with metamorphosed marl.
Sedimentation in the meandering River Endrick
Authors: Bluck B. J.
Published: January 2010

Synopsis

The River Endrick carries gravel and finer sediment in a pool and riffle channel. Point bars and riffles, which alternate along most of the channel, are foci of active particle-size segregation within the general downstream size decline: they are therefore centres of facies change. This differentiation results in sediment of a particular size being systematically and repeatedly placed in similar parts of the channel: on point bars, for example, proportionately more gravel is found at the apex and more sand in the cross-over reaches of the meander. Cross-stratal dip direction in these sediments is roughly parallel to the local flow and is therefore different in sand and gravels. It also follows that sand has a higher standard deviation of cross-bed dip orientation than gravel. The bed forms of the river often have only a superficial thickness of related sediment: they were built by a lower stage of flow than most of the sediment enclosed by the form, and in this sense forms give an erroneous measure of structure.

The meanders move phase downstream so that at point bars crescents of differentiated sediment accrete on the inside, as older crescents are eroded from the outside or cut bank of the channel. In this way the river builds up a facies mosaic whose interface zig-zags downstream, and the cut bank exposes a section with a lateral size decline opposite to that of the facing point bar. Sedimentary successions show more variability within than between bars and the use of this fact, together with the variation in dip of cross-strata and other criteria, facilitates the independent reconstruction of the scale and sinuosity of the river.
Palaeontological evidence bearing on the age of Dalradian deformation and metamorphism in Ireland and Scotland
Authors: Skevington D.
Published: January 2010

Synopsis

The occurrences of fossils, mainly graptolites, in sediments deposited prior and subsequent to metamorphism of rocks of the Dalradian Series are reviewed and discussed. The available evidence suggests that this event had terminated by early Arenig time, at the latest, in western Ireland and south-west Scotland, but occurred, or persisted, later in northern Scotland.
The Eastern Gneisses of South Uist
Authors: Coward M. P.
Published: January 2010

Synopsis

The Eastern Gneisses of South Uist which overlie the Outer Isles Thrust consist of three units; the Corodale Gneiss mass which is interpreted as an igneous body; the Mashed Gneiss; a group of quartzo-feldspathic gneisses and an intervening zone of phyllonites, the Usinish Mylonites. The phyllonites appear to have been formed by intense deformation at the margin of the igneous body.

Three phases of deformation have affected the Corodale Gneiss and are tentatively correlated with Laxfordian deformation phases affecting the rocks below the thrust. The igneous body is cut by dykes and is considered to be a member of a widespread group of basic to intermediate intrusions which post-date the Scourian gneiss-forming events, but pre-date the emplacement of Scourie dykes.

There is evidence for an eastward increase in metamorphic grade during an early Laxfordian episode, prior to the main deformation, and an eastward decrease in metamorphic grade during the three main Laxfordian deformation-phases.
The last glaciers in the Lochnagar area, Aberdeenshire.
Authors: Sissons J. B. , Grant A. J. H.
Published: January 2010

Synopsis

Moraines in Glen Callater, Glen Muick and the four corries of Lochnagar are used to delimit a glacial readvance. The freshness of the forms and their relation to large solifluction lobes imply that the readvance is the Loch Lomond or Zone III Readvance. The very different type of interpretation recently given by Sugden for the adjacent Cairngorm area is discussed and rejected.
The Loch Lomond Readvance moraines of Mull and Menteith
Authors: Gray J. M. , Brooks C. L.
Published: January 2010

Synopsis

A radiocarbon date of 11 330±170
b.p
. for shells from the Kinlochspelve Moraine on the Isle of Mull indicates that a readvance of ice took place there during Zone III. The ice apparently scooped up marine deposits laid down during the preceding Zone II (Alleröd) climatic amelioration.

Analysis of pollen from clays in both the Kinlochspelve and Menteith moraines substantiates this opinion and together with radiocarbon dates and geomorphological evidence enables correlation of both moraines with the Loch Lomond Readvance. On Mull the mapping of moraines and thick drift deposits indicates that an ice cap and several separate glaciers existed on the island at this time.
A radiometric age for pegmatite cutting the Belhelvie mafic intrusion, Aberdeenshire
Authors: van Breemen O. , Boyd R.
Published: January 2010

Synopsis

A Rb-Sr isochron for four muscovites, one K-feldspar and one whole rock from pegmatites cutting sheared gabbro in the Belhelvie mafic complex yields an age of 477±5 m.y. and initial Sr
87
/Sr
86
of 0.7185±0.0016. This age provides a minimum limit for all Late Caledonian deformation in the area. Evidence presented suggests that the Belhelvie pegmatites are part of a regional suite.
Zinnwaldite granite from Glen Gairn, Aberdeenshire
Authors: Hall A. , Walsh J. N.
Published: January 2010

Synopsis

Zinnwaldite granite occurs in Glen Gairn, Aberdeenshire. Chemical analyses of both the granite and the zinnwaldite are given, and it is suggested that there may be an affinity between this granite and the mineralisation observed in neighbouring areas.
The Late Precambrian/Lower Cambrian Bonahaven Dolomite of Islay and its stromatolites
Authors: Spencer Anthony M. , Spencer Margaret O.
Published: January 2010

Synopsis

The Bonahaven Dolomite (?295 m thick) lies in the Dalradian sequence between the Port Askaig Tillite (beneath) and the Jura Quartzite (above) and is best developed on Islay (Inner Hebrides). The sequence in the formation at five coastal outcrops is figured and four members erected. Member 3 (?150 m thick) contains stromatolite structures at ten horizons. These are described in terms of their bed geometry (laterally continuous, discontinuous), lamination (0.5–2 mm thick) and growth structures (stratiform, laterally linked hemispheroids, columnar, irregular). Ptygmatic sandstone crack–structures are ubiquitous in thinly interbedded sandstone/siltstone beds; they are thought to be subaqueous contraction cracks. The apparent palaeoclimatological contradiction posed by a dolomite overlying a tillite is discussed, and it is suggested that late Precambrian dolomites may not have needed a warm climate to form.
The tectonic evolution of a Lewisian complex on Coll, Inner Hebrides
Authors: Drury S. A.
Published: January 2010

Synopsis

The heterogeneous Lewisian rocks of Coll show the effects of at least six phases of deformation. The absence of common, penetrative linear fabrics, and of representatives of the Scourie swarm of basic dykes, so useful in relative dating in most areas of Lewisian, limits rigorous analysis and regional correlation of tectonic events. To some extent the limitations have been overcome by examination of the effects of each phase on earlier structures, and of the geometry of the fold forms produced.

Although some evidence points to earlier structures, the oldest decipherable event took place during granulite-facies metamorphism. Basic dykes were emplaced under the same conditions and were suitably modified. Since the intrusive episode the complex has been subjected to several tectonic episodes, each characterised by distinctive structural features. In each case, compositionally contrasted lithologies were affected in different ways. The rheological state of the whole complex is suggested to have varied during its evolution.
Torridonian volcanic sediments
Authors: Lawson D. E.
Published: January 2010

Synopsis

Detailed evidence of volcanic activity within the Torridonian is provided for the first time. A distinctive sedimentary unit within the Stoer Group contains abundant angular volcanic fragments including pumice, shards and devitrified glass (interpreted as palagonite) which comprise from 40 to 80% of the sediment. The unit, which averages about 12 m in thickness, forms a significant marker horizon which can be traced some 50 km from Stoer southwest along the coast to Poolewe. Accretionary lapilli are the best indication of contemporaneity of volcanic activity with deposition of the unit. Their best development is at Coigach where they occur throughout 10 m of the upper portion of the unit which attains its maximum thickness here. This abundance, in combination with thickness, suggests that the eruptive source-vent was within several kilometres of Coigach.

Indications of geometry and areal extent are in the main limited to a section along the strike. Throughout most of the outcrop conformable stratigraphic relations exist with the underlying and overlying sediments. The sharp, clear-cut basal contact is an erosional surface, broadly planar with minor relief. At Stoer, however, the unit abuts and laterally intrudes a high (>3 m) bank of sandstones and mudstones, warping and contorting them and carrying away blocks as large as 2.5 m.

Irregular, branching, pipe-like segregations of pink authigenic feldspar (which originated during emplacement of the unit and in some cases are slightly post depositional but not unrelated in time) are of late vapour phase origin; some may represent fossil fumaroles.

This volcanic sediment horizon was deposited as an ash flow resulting from a highly explosive eruption of phreatic nature. Deposition occurred primarily in the shallow water, near-shore environment where conditions were favourable for local transition to hot lahars.
Sedimentology and palaeogeography of the Upper Old Red Sandstone in the Scottish Border Basin
Authors: Leeder Michael
Published: January 2010

Synopsis

The Upper Old Red Sandstone of the southern Scottish Borders is a wholly fluviatile succession. The basal unconformity with the Silurian shows evidence of exhumed, ?pre-Upper O.R.S. topography.

Facies association 1 comprises fining-up cycles of sandstone and siltstone deposited by high sinuosity stream systems. Facies association 2 comprises fining-up cycles deposited by low sinuosity streams which may have been braided or non-braided. Facies association 3 comprises conglomerates, pebbly sandstones and sandstones deposited by low sinuosity, braided stream channels. Facies association 4 comprises thick sequences of thinly bedded sandstones, siltstones and conglomerates laid down in persistent flood basins.

Palaeocurrents show persistent stream flow from south west to north east and grain and pebble compositions are consistent with igneous and sedimentary sourcelands in Galloway. A gross upward trend to coarser, braided channel facies may have resulted from isostatic uplift in the hinterlands. The southern Border streams formed part of an interior drainage basin (Border Basin) with its centre to the north west of the present day Cheviot hills.
Crustacean faecal pellets,
Favreina
, from the Middle Jurassic of Eigg, Inner Hebrides
Authors: Scoffin Terence P.
Published: January 2010

Synopsis

Crustacean faecal pellets,
Favreina
sp. have been found, preserved uncompacted within articulated bivalves, in a thin limestone band of the Estheria Shales of the Bathonian, Great Estuarine Series of Eigg, Inner Hebrides. Though the pellets are well preserved they were not detected without the aid of staining.
Granophyre pebbles in Tertiary conglomerate on the Isle of Canna, Inverness-shire
Authors: Emeleus C. H.
Published: January 2010

Synopsis

Porphyritic granophyre pebbles in Tertiary conglomerate on Sanday, Isle of Canna, are identical with granophyre exposed in western Rhum. It is suggested that a west-flowing river, postulated by Geikie to account for features of the Canna conglomerates, received detritus from a tributary draining north-west Rhum. Porphyritic felsite associated with conglomerate on Compass Hill (Canna) may have been derived from eastern Rhum. The Tertiary lavas of Rhum, Canna and Sanday appear to be of distinctly later date than lavas on Eigg and Muck.
The igneous rocks of the Boganclogh area, N.E. Scotland
Authors: Busrewil M. T. , Pankhurst R. J. , Wadsworth W. J.
Published: January 2010

Synopsis

The Boganclogh intrusion, which appears to be a westerly extension of the Insch mass, is chemically and petrologically subdivided into three principal units which occupy roughly east-west belts.

Ultrabasic Group. This consists of serpentinites and peridotites and is probably related to the Lower Zone cumulates of the Insch mass.

Ferrodiorite Group. This is believed to be equivalent to the Insch Upper Zone. The high value of the Sr
87
/Sr
86
isotopic ratio in the ferrodiorites at the time of crystallization (0.711) is ascribed to isotopic exchange with Sr in the country rocks, as has been proposed for the Insch Upper Zone.

Quartz–Biotite Norite Group. These rocks form a central belt and are distinct from any of the Insch material. However, a chemical and isotopic comparison with similar rocks from the Haddo House, Arnage and Morven-Cabrach intrusions indicates a common mode of origin, probably involving introduction of water from country rocks into the regional basic magma.
A gravity survey of the Cairnsmore of Fleet granite and its environs
Authors: Parslow G. R. , Randall B. A. O.
Published: January 2010

Synopsis

A regional gravity survey of part of Galloway has defined two major negative anomalies, one centred over the Cairnsmore of Fleet granite and the other over Wigtown Bay. The former indicates that the granite probably continues to a depth of 11 km, has outward dipping contacts, and a sub-surface cupola-like protruberance to the south-west of the exposed portion of the massif. The gravity low in Wigtown Bay is thought to be indicative of an unexposed sedimentary basin which has a depth between 220 and 720 m. This basin extends in a north-westerly direction at least as far as the Cree estuary.
The dolerites of Ardnamurchan
Authors: Gribble C. D.
Published: January 2010

Synopsis

Detailed petrochemical work on dolerites from, each of the three centres of Tertiary igneous activity in Ardnamurchan suggests that the (calculated) composition of the initial magmatic liquid giving rise to the Centre 1 dolerites is SiO
2
52.5%, TiO
2
1%, A1
2
O
3
13.5%, total iron 9.5%, MgO 8.5%, CaO 12%, Na
2
O 2% and K
2
O 1%, on a water-free basis. The early dolerites of Ardnamurchan (Centre 1) are relatively richer in SiO
2
, Cu and Ba, and poorer in A1
2
O
3
and Na
2
O than the late dolerites of Centres 2 and 3.
The Loch Loyal syenites
Authors: Robertson R. C. R. , Parsons Ian
Published: January 2010

Synopsis

The Ben Loyal syenite has steep outward dipping contacts on its N. and W. sides and a gentle outward dip towards the SE., with extensive thermal alteration and veining of overlying country rock. Magnetic anomalies suggest that the Cnoc nan Cullean intrusion is not connected to the Ben Loyal syenite at the surface. The Ben Loyal intrusion is subdivided into a laminated marginal syenite and a structureless core syenite. The lamination, ascribed to flow of a crystal mush, is usually concordant with the enclosing Moine and with xenoliths of the latter. Chemically the body is homogeneous but the core syenites are hypersolvus, one-feldspar rocks; the laminated syenites subsolvus, two-feldspar assemblages. This is ascribed to alkali feldspar unmixing facilitated by outward diffusion of water and by disturbance of the advancing crystal mush. The satellite sheets of Ben Stumanadh may have more normative
or
than Ben Loyal and alone show
C
. Cnoc nan Cullean is a distinct intrusion with more
or
and less
Q
. Only Ben Loyal shows
ac
. The three intrusions are chemically and petrographically distinct.
Islay shelly till with
Palliolum groenlandicum
Authors: Peacock J. D.
Published: January 2010

Synopsis

Shell fragments from till exposed on the west side of Loch Gruinart, Islay, consist mainly of the thin-shelled arctic bivalve
Palliolum groenlandicum
(Sowerby 1842), an otherwise rare species in Quaternary deposits in western Scotland. A local derivation is suggested.
Raised beach gravels and ice wedge casts at Old Kilpatrick, near Glasgow
Authors: Rose J.
Published: January 2010

Synopsis

Landforms, sediments, and sedimentary structures at Old Kilpatrick reveal a beach ridge disturbed by involutions and ice wedge casts. The relationship of the beach ridge to other shorelines and radiocarbon dated marine shells shows that east of Old Kilpatrick the Clyde Basin was submerged by an arm of the sea up to a level of about 34 m, while west of Old Kilpatrick ice remained across the mouth of the Clyde. The relationships between the date of ice wastage, shoreline development, and late-glacial climatic change suggest that the ice wedge casts were formed during Younger
Dryas
time, and demonstrate that during this period, 10 800–10 300 years ago, mean annual temperature in western central Scotland fell at least as low as −6° C.
The offshore extension of the Loch Gruinart Fault, Islay
Authors: Dobson M. R. , Evans D. , Whittington R.
Published: January 2010

Synopsis

A seismic survey has been carried out in the eastern Malin Sea between Colonsay, Islay and the Donegal coast of Eire, and has revealed the presence of major dislocations both to the north and south of Islay. These faults are considered to be the submarine extensions of the Loch Gruinart Fault. It is proposed that the Loch Gruinart Fault is connected to the Leannan Fault in the south-west and to the Great Glen Fault in the north-east. To the south-west of Islay, the fault forms the north-west boundary of a sedimentary basin in which about 1 km of sedimentary rocks (probably Permo-Triassic) is preserved; post-Palaeozoic fault movements appear to be dip-slip.
Lower Border Group (Tournaisian) stromatolites from the Northumberland basin
Authors: Leeder Michael
Published: January 2010

Synopsis

Lower Border Group stromatolites contain detrital, micritic and calcareous algal filament laminae. Growth forms include domes, blisters, polygons, pillars, clubs, cusps, crinkles, bioherms and oncolites. Environments of growth are interpreted from comparisons with Recent stromatolites and from the evidence of associated carbonate lithofacies. Stromatolites in the Liddel Formation are often of intertidal origin and their outcrops mark the former northern shorelines of the Northumberland gulf sea. Seaward accretion of algal flats over shallow subtidal carbonate lithofacies gave rise to shoreline regressional sequences, now seen in vertical sections. Stromatolites in the Main Algal Formation are of shallow subtidal origin and accreted in central parts of the gulf sea.
K–Ar results from Western Ireland and their bearing on the timing and siting of Thulean magmatism
Authors: Macintyre R. M. , McMenamin T. , Preston J.
Published: January 2010

Synopsis

Potassium-argon ages measured for several small igneous bodies which outcrop in western Ireland range from 55 m.y. to 61 m.y. and confirm a Tertiary age for these intrusions. These results together with geochronological information available for localities elsewhere in the British Tertiary Province are critically assessed. It is apparent that major igneous activity was confined to the interval 60 m.y.–50 m.y. The distribution in time probably comprises a major phase of extrusive and plutonic activity with dyke injection
c.
59 m.y., with a later phase, predominantly of dyke intrusion,
c.
52 m.y. The distribution in space appears to have been controlled by a series of NW.–SE. and N.–S. trending lineaments. The former may result from plate separation but both trends and the line of parting may have been determined by pre-existing lines of crustal weakness. These were preferentially exploited by bursts of igneous activity
c.
? 80 m.y., 59 m.y. and 52 m.y. which correlate with the incidence and modification of sea-floor spreading during the early evolution of the North Atlantic. There is no evidence for systematic magmatic migration with time, thus denying an origin for the Province by drift in the vicinity of a localised mantle “plume” or “hot-spot”.
Recent discoveries of Carboniferous fishes in Edinburgh
Authors: Wood S. P.
Published: January 2010

Synopsis

A recent collection of fossil fishes from concretions in the Lower Oil Shale Group (Lower Carboniferous) of the Wardie Shore north of Edinburgh has enabled the fish-bearing strata, originally described as 70 ft of black shale, to be subdivided on characteristics of the concretions. Other horizons above and below these strata also yielded specimens. The numbers of various genera collected from these beds have been expressed as a table, which may form the basis for future studies on palaeoecology. The abundance of well preserved elasmobranchs is the most important result of this work, and may make necessary a reconsideration of the environment.
Petrochemistry of the Early Carboniferous (Dinantian) Lavas of Scotland
Authors: Macdonald R.
Published: January 2010

Synopsis

This review is focussed on the early Carboniferous (Dinantian) stage of the complex Carboniferous-Permian volcanic cycle in central and southern Scotland (The “Midland Valley petrographic province”). Stress is particularly laid on aspects of the petrochemistry and petrogenesis not previously recognized or sufficiently discussed in the literature. The scarcity of analytical data for rocks from critical parts of the province means that much of the discussion must be of a preliminary nature; areas where further research is required are indicated.

The Dinantian lavas, dominated by a range of mildly undersaturated and hypersthene-normative (transitional) alkaline basalts, have associated nepheline or hypersthene-normative hawaiites, mugearites, benmoreites, quartz-trachytes and rhyolites. Several geographically distinct magmatic lineages are recognized, varying in such parameters as degree of silica undersaturation, Fe/Mg ratios and Na
2
O/K
2
O ratios at comparable values of differentiation index. TiO
2
and P
2
O
5
contents also vary from suite to suite.

The proportions of each lava type are variable in different areas, but three volcanic associations are rather arbitrarily distinguished; one showing a spectrum of rocks from ankaramitic basalt to trachytes and rhyolites: a second dominated by plagioclase-phyric basalts and hawaiites: and thirdly, an association consisting largely of olivine-clinopyroxene-phyric basalts, with more differentiated rocks scarce or absent. Though data are very scarce for post-Dinantian lavas, it is suggested that there has been a progressive change in basic magma chemistry with time during the Carboniferous, later alkaline magmas being increasingly silica-undersaturated. This change was accompanied by a change in the nature of the volcanism, which became more explosive, tuffs and agglomerates representing an increasing proportion of the eruptive products.

Some aspects of the petrogenesis of the Dinantian basic lavas are examined. A high-pressure (>10 kb) stage of fractionation variably involving clinopyroxene or olivine + clinopyroxene is required to explain the chemical variation in the basalts and hawaiites. More differentiated rocks may have evolved by crystal fractionation at lower pressures (within crustal magma reservoirs?) but insufficient data are available to test this hypothesis.
The Belhelvie mafic igneous intrusion, Aberdeenshire—a re-investigation.
Authors: Ashcroft W. A. , Boyd R.
Published: January 2010

Synopsis

A total field ground magnetic survey and a programme of shallow drilling have been used to augment conventional mapping techniques in the preparation of a new map of the poorly exposed Belhelvie igneous intrusion. The revised map differs considerably from previous maps and increases the landward area of the intrusion by 6 km
2
. Several new rock units have been found including a thin noritic band on the western margin, a septum of country rock which splits the northern half of the mass in two and, east of the septum, a sequence of peridotite, troctolite and gabbro. Near the coast the mass is cut by a fault running NE.–SW. with downthrow to the SE. on which side the mass is partly covered by Old Red Sandstone. The intrusion broadens as it nears the coast and continues out to sea, where the greater part of it is to be found.
Bajocian (Jurassic) stratigraphy in Skye, Western Scotland
Authors: Morton Nicol
Published: January 2010

Synopsis

Revised lithostratigraphical terminology for the subdivisions of the Bearreraig Sandstone Formation in Skye and Raasay is proposed. The sequence of Bajocian ammonite faunas in Trotternish, Skye is summarised. Lower Bajocian zones and subzones recognised are: Discites, Laeviuscula (with-subzones Ovalis (?) and Laeviuscula), Sauzei (with subzones Sauzei and Hebridica), and Humphriesianum (with subzones Cycloides, Humphriesianum and Blagdeni (?)). The Hebridica Subzone is proposed for strata with
D. pinguis
(Roemer),
D. hebridica
Morton and associated ammonites, which seem to fall between the Sauzei and Humphriesianum Zones as usually recognised.
The age of the Allt na Cuile Sandstones (Upper Jurassic, Sutherland).
Authors: Brookfield M. E.
Published: January 2010

Synopsis

New ammonite finds indicate that the Allt na Cuile Sandstones and overlying Loth River Shales range in age from at least basal Cymodoce Zone into the Mutabilis Zone (Kimmeridgian). These sediments differ markedly from the boulder bed facies of those zones to the north and south.
The basal spacing of potassic white micas and facies series variation across the Caledonides
Authors: Fettes D. J. , Graham C. M. , Sassi F. P. , Scolari A.
Published: January 2010

Synopsis

Analyses are presented of the b
0
-spacing value of almost 200 potassic white micas from the low temperature zone of the Scottish Caledonides. These measurements, which provide a relative geobarometer, indicate a gradual transition in the facies series of metamorphism into the area of ‘Buchan’ metamorphism. The use of this method to accurately define the shape of isobaric surfaces is suggested. The implications of the results are briefly discussed.
The Grampian Orogeny
Authors: Lambert R. St. J. , McKerrow W. S.
Published: January 2010

Synopsis

Review of existing plate tectonic theories of the Lower Palaeozoic development of the north and northwest British Isles leads to the conclusion that ridge-trench impingement theory can be used to integrate all known geological observations within one unified plate tectonic theory for the area. Consideration of the consequences of the progressive impingement of a ridge-transform system with a northwesterly-dipping subduction zone in Arenig time gives explanations for: (a) termination of Dalradian sedimentation in the Arenig; (b) initiation of Barrovian metamorphism at the same time; (c) development and history of the Girvan-Ballantrae complex; (d) initiation of the Highland Boundary Fault as a dextral transform fault in the Arenig; (e) its absence in western Scotland; (f) the postulated presence of a boundary fault southeast of Connemara and perhaps at Pomeroy; (g) the peak of metamorphism (Barrovian and Buchan types) in the Dalradian and associated basic intrusions in the Arenig in both Scotland and Connemara; (h) the development of the Moine Thrust (and related foreland folds and thrusts) also in the Arenig and (i) the origin of the South Mayo trough on oceanic crust. Related events explained by this model include the location of the Donegal batholith, the generally low-grade metamorphism of Donegal and southwest Scotland, the location of the Great Glen Fault and all known faunal province and Ordovician sedimentological data from the Midland Valley and Southern Uplands. It is proposed that this Lower Ordovician sequence of related events be termed the Grampian Orogeny, distinct from the later Caledonian Orogeny, which is tectonically and geographically separate.
The paragenesis of spinel- and garnet-amphibole lherzolite in the Rodel area, South Harris
Authors: Livingstone A.
Published: January 2010

Synopsis

The petrography and mineralogy of spinel- and garnet-amphibole lherzolites occurring in the granulite facies metasediments is described. Chemical analyses are presented for 7 lherzolites, 5 amphiboles, 5 orthopyroxenes, 3 clinopyroxenes, and a garnet. The spinel-amphibole lherzolites and chemically identical garnet-amphibole lherzolite conceivably represent spatially removed accumulates from the metagabbro-anorthosite complex. Garnet generation within the garnet-amphibole lherzolite and not the spinel-amphibole lherzolites is discussed, although both have probably been metamorphosed under identical conditions existing on the pressure-temperature boundary which separates the spinel and garnet lherzolite stability fields.