bluuebunny/crossref_metadata_2025 huggingface dataset:
A seismic event near the Hebrides Terrace Seamount
Authors: Jacob A. W. B. , Neilson G. , Ward V.
Published: January 2010

Synopsis

At 10
h
47
m
59
s
GMT on April 13, 1980 a seismic event occurred at about 56·5° North, 10·5° West near the Hebrides Terrace Seamount. The seamount is believed to be an early Cenozoic volcanic feature (Buckley and Bailey 1975) and lies in deep water in the eastern part of the Rockall Trough. The event may have been either an earthquake or a large underwater explosion. The seismic evidence, based on recordings from stations in Scotland and Ireland, is that it was an earthquake. It is the first earthquake to be recorded from the contiguous continental margin to the West of Britain and Ireland.
Glacial meltwater channels in the northern isles of Shetland
Authors: Flinn Derek
Published: January 2010

Synopsis

In Shetland sub-glacially formed meltwater channels are almost confined to two small areas in the north of the islands of Yell and Unst. These two areas are almost devoid of glacial striae and till, both of which are widely distributed throughout the rest of Shetland, indicating that the whole area was covered by ice during the last glacial maximum. The restriction of the meltwater channels to these small areas shows that they were formed before the downwasting stage and, therefore, probably at the ice front.
The distribution and stratigraphical significance of the marine bivalve
Saxicavella jeffreysi
Winckworth in the Quaternary deposits of Scotland
Authors: Graham D. K.
Published: January 2010

Synopsis

The marine bivalve
Saxicavella jeffreysi
Winckworth, which is believed to be widely distributed at the present time, but scarce, is shown to occur commonly in some Scottish Quaternary deposits. Its apparent confinement to Post-glacial strata, deposited in temperate conditions, suggests that it is a useful stratigraphical and environmental indicator.
Imbricate structure in the Ettrick area, Southern Uplands
Authors: Webb Barry
Published: January 2010

Synopsis

Details of the imbricate structure of the Silurian greywackes across part of the Central Belt of the Southern Uplands are described. The evidence implies that the major structures are the result of the progressive shearing of early folds which formed penecontemporaneously with the deposition of the sediments. Local zones of intense imbrication are related to the presence, in these localities, of more ductile lithologies interbedded with the greywackes. Thrusts pre-dating the early folds are nowhere recognisable.

This structural interpretation predicts that the imbricated greywackes extend to depths of some 3 km whereas the LISPB profile suggests that the basement is not present until a depth of about 15 km. If the grey-wackes form part of an accretionary wedge then the primary decollement between the wedge and the underlying basement cannot occur immediately below the greywackes, at the horizon of the Moffat Shales, but must occur within the underlying sequence of ocean floor basalts.
Sedimentation of a sub-aqueous esker-delta at Strabathie, Aberdeenshire
Authors: Thomas G. S. P.
Published: January 2010

Synopsis

A sequence of Late-Devensian sediments exposed at Strabathie, Aberdeenshire, was deposited by a sub-glacial meltwater stream discharging from a tunnel in the base of an overhanging ice margin that abutted directly into a pro-glacial lake basin. At the tunnel exit coarse esker-delta gravels, intercalated with diamict released by roof collapse, were deposited by rapidly decelerating flow. As the tunnel mouth retreated these deposits built up as a ridge of overlapping fans protruding into the lake basin. Outward from the ridge a series of pulsating density underflows, generated by variations in discharge and load, by tunnel mouth collapse and by slump, distributed sediment across the lake floor as a series of distally fining turbidites. Throughout the lake, melt of debris contained in icebergs calved from the ice margin contributed significantly to sedimentation and generated a distinctive assemblage of dropstone, dump and grounding structures.
The structure of the Shiant Isles sill complex, Outer Hebrides
Authors: Gibb F. G. F. , Henderson C. M. B.
Published: January 2010

Synopsis

Previous authors have differed in their views on the number of separate intrusions forming the classic alkaline basic sill complex of the Shiant Isles: the suggested number varies from one to five. From a discussion of the possible relationships between the various units, partly based on new field and petrographic evidence we conclude that there are at least three and probably four distinct sills present.
Rb–Sr dates on Precambrian rocks from marine exploration wells in and around the West Shetland Basin
Authors: Ritchie J. D. , Darbyshire D. P. F.
Published: January 2010

Synopsis

Rb-Sr whole rock dating of metamorphic basement has yielded an age of 2527 ± 73 Ma. This suggests that the crystalline basement of the NW continental shelf is at least partly of late Scourian age. Dated samples from two other wells recorded ages of c. 400 Ma and c. 700 Ma.
The Structure of the Balquhidder-Crianlarich region of the Scottish Dalradian and its relation to the Barrovian garnet isograd surface
Authors: Watkins Keith P.
Published: January 2010

Synopsis

The Balquhidder–Crianlarich region of the Scottish Dalradian has undergone a complex history of deformation and metamorphism. The earliest recognizable phase of folding produced a major NW closing recumbent synform which may be correlated with regional F
2
(nappe forming) folds in the west-central Highlands. This was refolded by upright ENE plunging folds. Minor structures associated with both folding episodes are developed and interference fold patterns occur. The area is bisected by a late sinistral oblique-slip fault system which juxtaposes terrains of significantly different tectonic levels.

The metamorphic zonation is inverted. The garnet isograd surface cuts the axial plane of the recumbent synform; thus, peak metamorphism post-dates nappe emplacement. No tectonic means of overturning the metamorphic zonation can be invoked; it follows that metamorphism occurred in a negative thermal gradient.
The basic lavas of the Eastern Red Hills district, Isle of Skye
Authors: Bell★ Brian R.
Published: January 2010

Synopsis

Major- and trace-element data from hydrothermally altered basic lavas from the Eastern Red Hills district of the Tertiary igneous centre of Skye indicate that members of two distinct assemblages are present—a transitional series, with characteristic light rare-earth-element (REE) enrichment ((Ce/Yb)
N
> 3.5), showing affinities to the voluminous plateau lavas of north Skye, and a distinctly tholeiitic assemblage typified by relatively flat REE patterns ((Ce/Yb)
N
< 3.5) and Ti/Zr 100–110. The REE data suggest that this tholeiitic group belongs to the previously defined Fairy Bridge magma type, which appears to have evolved in the upper crust by low-pressure crystal fractionation involving olivine and plagioclase. These tholeiites have REE patterns which are very similar to those of the subvolcanic granites of the district ((Ce/Yb)
N
≈ 3.0–3.5), suggesting a probable cogenetic relationship between the tholeiites and the granites.
A crinoid columnal morphospecies from the Upper Ordovician of Girvan and Kazakhstan
Authors: Donovan Stephen K.
Published: January 2010

Synopsis

Crinoid pluricolumnals similar to the distinctive pentameric morphospecies
Malovicrinus
(col.)
implicatus
Stukalina, 1970, occur in the Caradoc Craighead Limestone of Strathclyde (Ayrshire). The Scottish specimens differ slightly from the illustrations of Russian material in having less angular axial canals and by showing longitudinal offset of meres. Both Kazakhstan and Craighead lie near the Caradoc equator and the migration of this organism may indicate an ancient circumequatorial ocean current which carried larval crinoids. Alternatively the Craighead specimens are possibly the result of convergent evolution.
The biostratigraphy of an early Flandrian tufa at Inchrory, Glen Avon, Banffshire
Authors: Preece R. C. , Bennett K. D. , Robinson J. E.
Published: January 2010

Synopsis

A deposit of early Flandrian tufa nearly 6 m thick has formed near Inchrory in Glen Avon, Banffshire. It comprises six buried soils within alternating units of relatively hard tufa (with occasional leaf impressions) and layers with a more powdery lithology. Serial sampling and quantitative analyses of the Mollusca, Ostracoda and pollen indicate that the tufa was deposited by springs trickling across wet ground. These analyses have given important biogeographical information on the migration of certain taxa into Scotland during the Flandrian.

Tufa formation at Inchrory apparently began sometime after
c.
9700 B.P. when the valley was relatively unshaded except for occasional patches of
Betula
woodland. An expansion of shade-demanding Mollusca occurs at about 400 cm from the top and pollen analyses from these levels indicate the presence of
Corylus avellana
scrub. A radiocarbon date of 7360 ± 60 B.P. (Q-2355) was obtained from charcoal from a buried soil between 345–350 cm. Above this point there is little change in the composition of the land Mollusca although a pollen spectrum from 150 cm indicates that
Pinus sylvestris
has now become an important forest constituent in the valley. The occurrence of the land snail
Vertigo alpestris,
known living at only two Scottish sites, is noteworthy. The cessation of the tufa formation probably occurred sometime after
c.
6000 B.P.
A Jurassic age for an outcrop of ‘Durness Limestone’ on Skye
Authors: Oak K. A. , Donovan S. K.
Published: January 2010

Synopsis

Isocrinid crinoid columnals have been identified from a small outcrop south of Creag Strollamus, Skye. This outcrop has previously been recorded as Durness Limestone but the crinoid evidence proves its age to be post-Palaeozoic. Lithologically the rocks resemble the Jurassic (Lower Lias) Lower Broadford Beds, from which
Isocrinus
sp. has been recorded in the
bucklandi
Zone, although columnals are also known from the
semicostatum
Zone (Upper Broadford Beds).
Depth of deposition of Early Holocene raised sediments at Irvine deduced from algal borings in mollusc shells
Authors: Ben Akpan Etie , Farrow George E.
Published: January 2010

Synopsis

Micro-borings attributed to the chlorophytes
Phaeophila
and
Eugomontia
and the cyanophytes
Hyella
and
Plectonema
are recorded from shells in the early Holocene sediments of Irvine. The basal gravel beds generally show a higher density of algal borings and a greater percentage of algal-infested shells than the overlying sand unit. Borings of
Eugomontia
and the sponge
Cliona
and the calcareous algae
Melobesia
and
Lithothamnium
, are restricted to the basal gravel. Pockets of broken
Lithothamnium
observed in the sand unit are interpreted as reworked. By comparison with Recent micro-endolithic algal assemblages in the Firth of Clyde, it is concluded that the basal gravel formed in a low energy marine environment about 10 m deep: the overlying sands represent a true raised beach.
Conflicting interpretations of the Silurian agnathan,
Jamoytius
Authors: Ritchie A.
Published: January 2010

Synopsis

Jamoytius kerwoodi
White, a Middle Silurian agnathan from the Lesmahagow Inlier, central Scotland, has been the subject of considerable controversy since it was first described in 1946. In a recent review of earlier intepretations of
Jamoytius
and its affinities Forey and Gardiner (
Bull. Br. Mus. (Nat. Hist.) Geol.
35
, 1981) make statements which are not substantiated by existing material or by evidence from new specimens. A specimen of
Jamoytius
, used but not figured by the writer in earlier accounts, is now illustrated to clarify the nature and extent of the
Jamoytius
branchial apparatus. Recent Carboniferous fossil lamprey discoveries strengthen the evidence for a link between
Jamoytius
and the petromyzontids.
The petrology and structure of Dalradian metabasaltic dykes of Jura: implications for early Dalradian evolution
Authors: Graham Colin M. , Borradaile Graham J.
Published: January 2010

Synopsis

Massive tholeiitic metadolerite dykes cutting Dalradian metasediments of the Jura Quartzite formation of Jura and Islay are comparable in major and trace element composition to other Dalradian metabasic rocks of the SW Highlands. Trace element geochemistry indicates that these dykes are usually less evolved than most of the overlying metabasaltic sills and volcanics in mainland Argyllshire, consistent with their likely role as feeders to the sills and volcanics.

Metamorphic assemblages in the Jura dykes and in greenschist facies metabasic rocks elsewhere in the SW Highlands are identical, and the metamorphic fluid phase behaviour in both groups of rocks appears to have been similar.

Reconstruction of pre-tectonic dyke geometries suggests that the dykes were intruded perpendicular to bedding as a NW–SE group responding to NE–SW crustal tension (contemporaneously with extrusion of the volcanic rocks). This evidence, together with that of sedimentary-basin and syndepositional-fault geometries, may indicate changes in the direction of relative crustal tension from NE–SW to NW–SE and back to NE–SW during oblique or strike-slip (transtensional) rifting of a subsiding continental margin during Argyll Group times.

The dominance of sill intrusion relative to dyke intrusion in SW Highland metabasaltic rocks is analogous to the intrusive behaviour of basic magma in modern deep rifted sedimentary basins such as the present day Gulf of California. Expulsion of water from adjacent sediments and establishment of large-scale hydrothermal systems may explain the abundance of post-crystallisation spilitic alteration of SW Highland metabasaltic rocks.
Time and duration of Tertiary igneous activity of Rhum and adjacent areas
Authors: Mussett A. E.
Published: January 2010

Synopsis

Two new
40
Ar–
39
Ar plateau dates are given for the Rhum central complex (58.4 ± 0.8 (2σ) Ma) and lavas (60.1 ± 1.0 Ma).

These are considered in conjunction with available geological, radiometric and palaeomagnetic evidence to show that the formation of the central intrusive complex of Rhum, its subsequent unroofing, followed by the intrusion of lavas in Rhum, Canna and Skye, together with the development of most or all of the Cuillins centre of Skye probably occurred within the single reversed polarity interval 26r lasting about 2.8 Ma about 59 Ma ago. In all three areas igneous activity extended into the following interval of normal magnetisation, though only just in the cases of Rhum and Canna.
Deposition, Diagenesis and Structures of the Cheese Bay Shrimp Bed, Lower Carboniferous, East Lothian
Authors: Hesselbo Stephen P. , Trewin Nigel H.
Published: January 2010

Synopsis

The laminated dolomites and mudstones in the Lower Carboniferous succession containing the Cheese Bay Shrimp Bed are interpreted as the deposits of a thermally stratified freshwater lake or brackish lagoon in which clastic/organic laminites accumulated. Drainage systems in the area were probably disrupted by volcanic activity, and seismic activity strongly affected the semi-consolidated sediments to produce a variety of pull-apart, fold, fault and sediment injection structures. During diagenesis intense dolomitisation of the laminites and associated sediments took place.
Camptonite-Monchiquite dyke swarms of Northern Scotland; Age relationships and their implications
Authors: Baxter A. N. , Mitchell J. G.
Published: January 2010

Synopsis

New
40
K/
40
Ar data for the camptonite-monchiquite dyke suite of the Northern Highlands give a late Visean age for the east-west trending Loch Eil–Loch Arkaig (326 ± 8 Ma) and Loch Monar (323 ± 9 Ma) swarms. Three dykes from the Thurso area give ages of 249–268 Ma, confirming earlier work indicating a late Permian age for the NE–SW trending Orkney swarm.

In conjunction with published data which show a Stephanian-basal Permian age (291 ± 5 Ma) for the NW–SE Ardgour swarm, the three principal swarm trends of the camptonite-monchiquite suite therefore represent tectonomagmatic events of quite different ages. Different structural controls on orientation appear to have operated for each trend. Thus the Visean east–west dykes may have utilised a prexisting late Caledonian fracture system; the Permo-Carboniferous NW–SE swarm is contemporaneous and co-linear with a well described zone of taphrogenic subsidence and volcanism extending across western Britain while the late Permian NE–SW Orkney dykes follow a Caledonide trend typically associated with Permo-Triassic extensional tectonism and basin formation in that area.
Palaeomagnetism of the Carboniferous E–W dyke swarm in Argyllshire
Authors: Esang C. B. , Piper J. D. A.
Published: January 2010

Synopsis

The majority of 21 sampled dykes in this swarm have a coherent reversed magnetisation linked to the c. 320 Ma, Lower-Upper Carboniferous boundary, age of intrusion. Fifteen sites define a palaeopole at 354.6°E, 35.0°S (dp = 2.5, dm = 5.0), coinciding precisely with the apparent polar wander path for Europe at 320 Ma.
Layering in the Gars-bheinn ultrabasic sill, Isle of Skye: a new interpretation, and its implications
Authors: Bevan J. C. , Hutchison R.
Published: January 2010

Synopsis

The Gars-bheinn sill is intruded into plateau basalts on the southern margin of the Cuillin igneous complex. The sill is composed dominantly of peridotite, but near its top it contains feldspar-rich, pegmatitic layers. Field evidence and mineralogical data suggest that the feldspar-rich layers were emplaced by the injection of fluids into already consolidated peridotite, and that the peridotite and feldspar-rich layers are not cogenetic as was formerly supposed. This has necessitated revision of the intrusive sequence in the southern Cuillin.
Cumulate relations in the ‘Younger Basic’ masses of the Huntly–Portsoy area, Grampian Region
Authors: Munro M.
Published: January 2010

Synopsis

The ‘Younger Basic’ masses of the Huntly–Portsoy area have been found to contain a number of separate cumulate bodies ranging up to 3–4 km in dimensions. Olivine, plagioclase and augite are the dominant cumulus phases throughout, and although the composition of these phases varies from one body to another, consistencies in the compositional variation suggest that the individual cumulate units are probably fragments of a large stratiform intrusion that has been subjected to post-magmatic disruption. Although some disturbance may have occurred when a later pulse of magma was emplaced to form the granular noritic and gabbroic rocks associated with the cumulates, it is concluded that the fragmentation of the latter was mainly associated with a regional episode of post-‘Younger Basic’ shearing and mylonitization.
Disruption of the ‘Younger Basic’ masses in the Huntly–Portsoy area, Grampian Region
Authors: Munro M. , Gallagher J. W.
Published: January 2010

Synopsis

Continued investigations in the Huntly–Portsoy area have been assisted by the availibility of data from shallow drillholes, trenches and commercial geophysical surveys, and have shown that the ‘Younger Basic’ masses in this area have complex structures and relationships. Earlier maps of these masses have been modified and previously unrecognized bodies of deformed ‘Younger Basic’ rocks have been identified near Portsoy. It has been established that sheared and mylonitized ‘Younger Basic’ rocks occur widely and that the contact relations and internal structure of the igneous masses have been greatly disrupted by post-magmatic deformation. It is concluded that the ‘Younger Basic’ rocks in the Huntly–Portsoy area lie within an important mylonite zone which trends N–S and dips steeply, and is comparable to the mylonite zones which have affected the Belhelvie and Insch ‘Younger Basic’ masses.
The problem of anomalous local limestone-pelite successions within the Moine outcrop; I: metamorphic limestones of the Great Glen area, from Ardgour to Nigg
Authors: Rock N. M. S. , Jeffreys L. A. , Macdonald R.
Published: January 2010

Synopsis

Small outcrops of folded calcareous metasediments, surrounded by otherwise lime-poor Moine rocks, occur along both sides of the Great Glen: (from SW to NE) in Ardgour, beside Loch Lochy, in Gleann Liath and Glen Urquhart, and near Inverness, Rosemarkie and Nigg. Further examples lie in Glen Dessarry to the NW. Outcrops cover from a few m
2
to several km
2
, and vary from pure limestones, with much rarer dolostones, to Ca-Mg-Fe-silicate ‘skarns’. The few previously described examples have been contradictorily assigned to the Lewisian, Moine, Dalradian, and even Durness Limestone. The mineralogical range in each outcrop is generally similar, indicating amphibolite-facies metamorphism. Several limestones are intimately associated with graphitic, kyanite or sillimanite-rich pelites (also atypical of the local Moine), and with the margins of synformal (D
2
or D
3
), foliated intrusions. Chemically, the calcareous rocks are strikingly homogeneous, as revealed by cluster analysis, and by very high correlation coefficients between ‘immobile’ trace elements (Ti, P, Y, Zr, Nb, Ce, Th), between Cr, Co and Ni, and between K and Rb, Ba or Pb. Mg also correlates inversely with Sr, as the dolomite/calcite ratio varies. This homogeneity suggests that most of the calcareous rocks belong to a single, now dismembered lithostratigraphical formation. Over 100 analyses of Lewisian ‘limestones’, and over 400 covering most of the Dalradian limestone formations, show quite different and far less homogeneous geochemistries. In particular, the Great Glen limestones cannot be equated with the geographically nearest Dalradian limestones, in the Appin–Ballachulish–Lismore area, as revealed by discriminant and correlation analysis. Field and regional considerations argue that the limestones are unlikely to be either Cambro-Ordovician, or an integral part of the Moine succession. As a working hypothesis, they should be assigned to a separate, provisional lithostratigraphical assemblage, whose relationship to the Lewisian, Moinian and Dalradian remains to be established.
Clast composition and provenance of psammites in the Colonsay Group and Bowmore Sandstone, SW Argyllshire
Authors: Saha Dilip
Published: January 2010

Synopsis

The detrital clasts within the Colonsay Group and Bowmore Sandstone include blue quartz with inclusions of rutile needles, feldspars, fragments of quartz granulite, deformed acid gneiss, pegmatites and vein quartz. In addition to these, the Bowmore Sandstone contains pebbles of chert, ferruginous sandstone and quartzite derived from sedimentary and metasedimentary rocks. The suite of clasts indicates a Lewisian-type provenance which included regions of Scourian granulites, and in the case of Bowmore Sandstone, one or more group of supracrustal rocks. The difference in the provenance of the two groups probably reflects a temporal and/or geographic separation at the time of deposition. The common and widespread occurrence of blue quartz within the Colonsay Group, Bowmore Sandstone and other late Precambrian to lower Palaeozoic horizons in Scotland and Ireland suggests a wide distribution of Scourian granulites within the Lewisian which formed areas of positive relief during the late Precambrian.
Walls Formation, Western Shetland: distal alluvial plain deposits within a tectonically active Devonian basin
Authors: Melvin J.
Published: January 2010

Synopsis

The Walls Formation of western Shetland is a severely deformed, structurally isolated sequence of sandstones and siltstones of probable middle Devonian age. The sequence is probably extremely thick, and can be subdivided into a number of distinct sedimentary lithofacies. These include: trough and planar cross-stratified sandstones; very low angle to horizontally stratified sandstones; small scale trough cross-laminated sandstones; ripple cross-laminated silty sandstones; alternating siltstones and sandstones; and siltstones. The lithofacies occur in three distinct lithofacies associations, which represent deposition within high sinuosity (meandering) streams, sheltered floodplains and low sinuosity (braided) streams respectively. The braided stream sequences are the most common, and include sheet flood deposits which may indicate that the streams were ephemeral in nature. The sandstones are generally finegrained, and arkosic to subarkosic in composition; in places they contain high proportions of a varied suite of heavy minerals. Syndepositional seismicity is reflected by overturned and convolute lamination which is abundant throughout the succession. The Walls Formation represents first-cycle erosion of the emerging Caledonian mountains, and deposition upon a distal alluvial braidplain within a rapidly subsiding basin. Basin development may have been controlled by strike-slip tectonics, related to movement on the transcurrent Melby and Walls Boundary Faults.
The Tay nappe and associated folding in the Ben Ledi–Loch Lomond area
Authors: Mendum J. R. , Fettes D. J.
Published: January 2010

Synopsis

Recent mapping in the Ben Ledi—Loch Lomond area has shown the southern closure of the Tay nappe to consist of three major folds, the Aberfoyle anticline, Ben Ledi antiform and Benvane synform. The D
1
age of these folds is clearly demonstrated by cleavage-bedding relationships and younging reversals. The previously unrecognised Benvane synform, the structurally lowest major fold, is responsible for the regional inversion of the flat belt. It is defined both on structural and stratigraphical grounds. The D
2
event is dominantly a product of a deformation event in which simple shear increases in intensity downwards. The limit of significant D
2
deformation cuts the major D
1
fold hinges. D
4
is responsible for the Highland Border downbend, the major monoformal structure which divides the area into a flat belt and a steep belt. The steep belt lies adjacent to the Highland Boundary fault and provides a section through the structurally high levels of the Tay nappe.
The implications of clay mineralogy to palaeoclimate and provenance during the Jurassic in NE Scotland
Authors: Hurst Andrew
Published: January 2010

Synopsis

Clay mineral logs for the Jurassic succession at Brora are presented as vertical profiles in lithostratigraphic units. The shale clay mineralogy is dominated by ordered illite/smectite and kaolinite. A sub-tropical, possibly seasonal, climate is inferred. High kaolinite content is attributed to reworking of probable Carboniferous kaolinitic regoliths, uplifted and eroded due to initiation of the formation of the Viking Graben. Kaolinite abundance is not due to tropical weathering in the Jurassic. A Jurassic weathering environment more humid than in the Triassic is proposed, eroding a variety of sedimentary rocks and a high-grade quartzose metamorphic terrain.
New Scottish Carboniferous fenestrate Bryozoa
Authors: Bancroft Adrian J.
Published: January 2010

Synopsis

Carboniferous strata in the Midland Valley of Scotland contain an abundant and diverse bryozoan fauna; two new species of fenestrate Bryozoa are described here:
Polypora binodus
sp. nov. and
Penniretepora wilsoneri
sp. nov.
Molybdenum mineralization on Unst, Shetland Isles
Authors: Neary Christopher R. , Prichard Hazel M.
Published: January 2010

Synopsis

Molybdenite-bearing chlorite veins associated with siderite nodules have been discovered in Queyhouse talc quarry which is situated in the serpentinised basal part of the Shetland ophiolite on the island of Unst. The mineralization may be associated with acidic intrusive activity following the subduction and emplacement of the ophiolite complex.
Palaeomagnetism of volcanics and sediments of the Eday Group, Southern Orkney
Authors: Robinson M. A.
Published: January 2010

Synopsis

This study presents the progressive demagnetisation results for 173 specimens from the Eday Group (upper Middle Old Red Sandstone), Orkney; including 85 from a contemporaneous lava and its baked contact, and 88 from Eday Group sediments. There is general agreement between stable NRM directions in the lava and its baked contact in the Eday Flags, which together give a mean direction after tectonic dip correction of D̄ = 191°, Ī = 41°, corresponding to a palaeomagnetic pole at 8°N, 167°E. This may provide an approximate estimate of the upper Middle Devonian palaeomagnetic pole relative to Orkney.

All the palaeomagnetically stable sites elsewhere in the Eday Group sediments show a high blocking-temperature (T
B
) component which give an
in situ
mean direction of D̄ = 191°, Ī = −20°, corresponding to a palaeomagnetic pole position of 41°N, 163°E. This component is believed to be of secondary origin, and probably relates to a late Palaeozoic remagnetisation, as is apparently the case elsewhere in the Devonian of Europe and the USSR. However, there is insufficient between-site variation in tectonic dip to ascertain incontrovertibly the relative ages of remanence acquisition and deformation, which is generally considered to predate deposition of the Upper ORS.

A single site in the Eday Marls shows two poorly-defined ancient components, a low-T
B
one in approximate agreement with the result from the lavas and a high-T
B
component in a similar orientation to that found elsewhere in the Eday Group sediments. These are thought to correspond to an early (? detrital) remanence and late Palaeozoic remagnetisation respectively.
Geological interpretation of palaeomagnetic results from Devonian rocks of Hoy, Orkney
Authors: Storetvedt K. M. , Meland A. H.
Published: January 2010

Synopsis

The palaeomagnetic record of Devonian Volcanics of Hoy (∼370 Ma), occurring at the base of the Hoy Sandstone (Upper Devonian), exhibits coherent groups of remanence directions. An original shallow magnetization axis, repeatedly reported from studies of Old Red Sandstone rocks of Caithness, is confirmed, but the data suggest also that the tectonic unconformity between the Middle Devonian strata (upon which the volcanics rest) and the Hoy Sandstone originated at around the time of the volcanic activity. A secondary magnetization of inferred Permian age has been uncovered from the underlying Middle Devonian sediments (Lower Eday Sandstone). This overprinted component of magnetization, which is a pronounced feature in various Caithness rocks, is reported here for the first time for Orkney rocks. The Permian overprinting event is held responsible for the demonstrable loss of argon in the Devonian volcanics, rendering also the K/Ar ages for other igneous rocks in the region highly suspect.
A brief history of Scottish palaeontology 1834–1984
Authors: Clarkson E. N. K.
Published: January 2010

Synopsis

The place of Scotland in the history of palaeontology has been of great importance because of the richness and variety of fossils and since many unusual biofacies and types of preservation are represented. Much of the early work in Scotland was undertaken by amateurs, and the informed amateurs still have an important role to play in palaeontology. A brief account is given of the history of the more important discoveries such as, for instance, the graptolites of the Southern Uplands, the fishes of the Old Red Sandstone, the Rhynie Chert and the Elgin reptiles, of some of the personalities involved, and of modern developments from this work.

Though the scope of palaeontology has broadened to include palaeoenvironmental and ecological analyses, important new discoveries are still being made in Scotland, as witness in recent years the first known conodont animals and the earliest known complete amphibian. It is expected that significant discoveries will continue to be made and that studies will become increasingly co-operative and interdisciplinary.
Isotopic and chemical constraints on the building of the deep Scottish lithosphere
Authors: Halliday A. N. , Stephens W. E. , Hunter R. H. , Menzies M. A. , Dickin A. P. , Hamilton P. J.
Published: January 2010

Synopsis

The Scottish late Caledonian granites define a chemical province characterised by high Na, Ba and Sr abundances, particularly towards the north and west where they also have higher Zn, REEs and La/Y and lower Rb and Th. A comparison with data for inclusions found in younger volcanics and hypabyssal intrusions and thought to have been excavated from the mantle and lower crust indicates that the source of at least some of the chemical variation in the granitic magmas lies in the lithospheric mantle. The asthenosphere or postulated subducted slab material from the Iapetus ocean floor cannot have directly contributed significant amounts of these elements to most of the granitoids. Further, isotopic data clearly indicate that lower crust-derived materials are essential components of the more evolved granites, implying that considerable melting took place near the Moho.

The age of the lower crust parallels the changes in chemistry in the lithospheric mantle which suggests that the Moho is not a major tectonic discontinuity. The Mid-Grampian line probably represents the rifted continental edge during Dalradian deposition. There is no isotopic evidence for primary crust of Grenville age under Scotland; rather the lower crust appears to be a complicated mixture including some components which are very young (probably Lower Palaeozoic) under the Midland Valley. The only location where clearly enriched mantle has been identified is under the Lewisian of the Outer Hebrides. The lower crust in this region is also Lewisian, apparently metasomatised. We tentatively suggest that the chemical enrichments and depletions in the lithosphere north of the Mid Grampian line are most simply explained by a volatile flushing mechanism.
Petrology and origin of iron-rich silicate–magnetite–quartz rocks from Flowerdale near Gairloch, Wester Ross
Authors: Williams Patrick J.
Published: January 2010

Synopsis

A body of banded iron formation occurs within amphibolite facies rocks of the supracrustal Lewisian Loch Maree Group in Flowerdale near Gairloch. The body exhibits a transition from oxide facies (banded quartz–magnetite rocks) to silicate facies (relatively massive garnet–grunerite rocks) which is probably related to variation of the original depositional environment. Intermediate lithologies consist of complex stratified mixtures of quartz, magnetite, grunerite, garnet (almandine), hornblende (ferro-pargasite), biotite (annite 85%), chlorite (ripidolite) and calcite. The rocks retain small-scale primary compositional heterogeneities and sedimentary structures. The silicate-bearing assemblages are derived from chamositic protoliths which were probably deposited in shallow water.
An early Arenig age for the Pinbain sequence of the Ballantrae Complex
Authors: Rushton A. W. A. , Stone P. , Smellie J. L. , Tunnicliff S. P.
Published: January 2010

Synopsis

The Pinbain volcano-sedimentary sector of the structurally involved ophiolitic Ballantrae Complex (early Ordovician) has yielded Bendigonian (early Arenig), graptolites including
Tetragraptus
cf.
decipiens
T. S. Hall and
Acrograptus
cf.
filiformis
(Tullberg). These graptolites contradict previous assumptions that the Pinbain sequence was one of the younger sectors of the Ballantrae Complex which has elsewhere yielded graptolites indicative of an age-range from lowest Arenig (Lancefieldian 3) to upper Arenig (Castlemainian-Yapeenian).

Adjacent to the southern margin of the Pinbain sequence, but structurally separate from it, the well-known mélange section has provided only fragmentary fossils undiagnostic of age. The only evidence for the age of the mélange is, therefore, the presumed correlation of contained clasts with radiometrically-dated early Ordovician lithologies exposed elsewhere in the Ballantrae Complex.
Groundwater resources in the Orkney Islands
Authors: Robins N. S. , Ball D. F.
Published: January 2010

Synopsis

The sandstones and siltstones of Devonian (Old Red Sandstone) age in the Orkney Islands have low permeability derived mainly from cracks and joints. Although the groundwater potential is only moderate, demand is correspondingly low. The groundwater is chemically potable except in one borehole where pumping has exceeded the safe yield of the aquifer.
The Triassic–Jurassic junction at Golspie, inner Moray Firth Basin
Authors: Batten D. J. , Trewin N. H. , Tudhope A. W.
Published: January 2010

Synopsis

The Dunrobin Bay Formation is redefined to include as its basal member the Dunrobin Pier Conglomerate which was previously assumed to be unfossiliferous and tentatively dated as Rhaetian (Late Triassic). Temporary exposures of organic-rich horizons within the deposit have yielded assemblages of palynomorphs dominated by pollen grains of the Circumpolles group.
Kraeuselisporites reissingeri
(Harris),
Converrucosisporites luebbenensis
Schulz, and
Pilospora
sp. cf.
P. parva
(Cookson and Dettmann) are among the more common associated forms. Although taxonomically impoverished, the overall composition of the palynoflora suggests a ?latest Rhaetian to Hettangian (Early Jurassic) age and accumulation in a freshwater environment. The conglomerate is interpreted as the deposits of braided alluvial streams on an alluvial fan derived from vegetated areas to the southwest. It is unconformable upon Triassic calcretes and silcretes which were formed in a hot, fairly arid climate. The hiatus between the two units represents a period of local erosion before deposition of the conglomerate during a period of increased rainfall.
The comparative geochemistry of some Highland pelites (Anomalous local limestone–pelite successions within the Moine outcrop; II)
Authors: Rock N. M. S. , Macdonald R. , Szucs T. , Bower J.
Published: January 2010

Synopsis

Within the Moine outcrop, three types of ‘anomalous’ pelitic rocks form local, probably allochthonous successions (nearly all with limestones): (1) sillimanite-gneisses (± garnet, kyanite) in Ardgour, Glen Dessarry and Glen Loy, each intimately involved with major intrusions; (2) kyanite-schists (± garnet, staurolite) in Glen Lui, Glen Urquhart and Strathspey, each associated with major faults or slides; (3) fault-bounded biotite–muscovite pelitic gneisses in Gleann Liath. Different authors have assigned these successions variously to the Lewisian, Moinian, Dalradian, Cambro-Ordovician, or to an unknown lithotectonic unit (e.g. ‘Grantown series’). The sillimanite-gneisses are
restites
, carrying local cordierite, corundum, hypersthene, spinel etc. Compared with typical Highland pelites, they have more variable but higher contents of elements carried in refractory minerals (e.g. Al, Y, Zr, Nb, Ce, Th), and correspondingly lower contents of elements carried in fusible minerals (e.g. Si, Ca, Na, Rb). Their present chemistry cannot therefore reveal their stratigraphical affinities. The anomalous kyanite-schists and pelitic gneisses, however, appear to approximate sediment compositions, and are compared chemo-stratigraphically with mineralogically equivalent Lewisian, Moinian and Dalradian rocks, using discriminant analysis on 161 analyses from > 50 localities. Lewisian, Moinian and Dalradian kyanite-pelites are distinguishable not only from each other (e.g. Lewisian examples carry lowest Al, K, Ti, P, Rb, Y, Nb, Ce, Pb, and highest Fe, Mg, Ca and Cr), but also from the Glen Urquhart and Gleann Liath anomalous pelites. The latter are therefore tentatively assigned to a separate lithotectonic unit, the ‘Albynian’, so far only identified near the Great Glen fault. The Strathspey and Glen Lui kyanite-schists are chemically closest to Dalradian kyanite-schists, supporting the existing view that the ‘Grampian Moines’ may include Dalradian strata.
A review of Scottish marine shell radiocarbon dates, their standardization and interpretation
Authors: Sutherland Donald G.
Published: January 2010

Synopsis

A list of published marine shell radiocarbon dates is produced by applying a standard set of operations to the pretreatment and subsequent assessment of such dates. Marine shell dates, in general, when compared to other such dates in the same stratigraphic sequence, give results that are consistent with their stratigraphic relationships. Marine shells also give results that are comparable with dates obtained from terrestrial materials. The radiocarbon dates on ice-transported or over-ridden marine shells show a threefold division: ‘infinite’ dates that may relate to an Early Devensian ice sheet build-up; dates from the Middle/Late Devensian that indicate Late Devensian ice expansion in the Outer Hebrides; and dates from the Lateglacial related to the Loch Lomond Readvance. The many marine shell dates from the head of the Firth of Clyde and the Clyde estuary imply that the area around the mouths of the sea lochs was deglaciated by
c.
13,000 yr BP and that there was an ice-free period in the inner sea lochs from at least
c.
12,400 yr BP till at least
c.
10,800 yr BP prior to the maximum of the Loch Lomond Readvance.
Pelites of the Glen Urquhart serpentinite–metamorphic complex, west of Loch Ness (Anomalous local limestone–pelite successions within the Moine outcrop: III)
Authors: Rock N. M. S. , Macdonald R. , Drewery S. E. , Pankhurst R. J. , Brook M.
Published: January 2010

Synopsis

The c. 6 km
2
complex comprises graphitic/pyritic, mainly kyanite-rich pelites, interbanded with metalimestones and invaded by foliated serpentinites. It is enveloped by typically Moinian psammites, semipelites and pelites. Previously regarded as a Lewisian inlier, or as integral to the Moine succession, or as a transitional Moinian–Dalradian or Dalradian–Durness Limestone facies, its allochthonous status is in fact suggested by (1) its singular lithology; (2) its unique association with a large serpentinite; (3) associated sharp and local gravity and magnetic anomalies; (4) a blastomylonitic slide zone separating the complex from its Moine envelope; (5) local and regional petrological differences between pelites of the complex and Moine succession. A previous model, in which muscovite-rich Moine pelites developed by K-metasomatism (‘granitisation’) of kyanite-schists within the complex, via (a) shimmerisation (conversion of kyanite to shimmer aggregate); and (b) coarsening of shimmer aggregate to muscovite, is ruled out by new whole-rock and microprobe data. These suggest shimmerisation was a near-isochemical, small-scale redistribution of alkalis and water [approximately
kyanite
+
biotite
+
quartz
+
water
=
muscovite
(
shimmer aggregate
) +
chlorite
], and show large compositional differences between shimmer aggregates and coarse muscovites. Rb–Sr isotopic data imply Late Caledonian (c. 459 Ma) metamorphism in the complex, but also imply a significant earlier history for the kyanite-schists. Overall, data not merely invalidate a Glen Urquhart ‘Lewisian inlier’, but also as yet preclude correlation of the complex with the Moine or Dalradian. It is attributed in the interim to a separate lithotectonic unit, the ‘Albynian’, which may lie between (or be diachronous with) some part of the Moinian or Dalradian successions.
The megacryst and inclusion assemblage from the Black Rock vent, Ayrshire
Authors: Alexander R. W. S. , Dawson J. B. , Patterson E. M. , Hervig R. L.
Published: January 2010

Synopsis

The Black Rock in Ayrshire is a Carboniferous, basanitic vent containing an inclusion assemblage of single phase megacrysts and altered ultramafic xenoliths. The composition and occurrence of these inclusions separates them into two distinct groups. The megacrysts of clinopyroxene, amphibole, mica and feldspar belong to the Al-augite group; the ultramafic xenoliths are identified as amphibole lherzolites of the Cr-diopside group. The chemical compositions of the mineral phases from each group are very similar to other Scottish and world-wide examples of inclusions in undersaturated alkaline volcanics.
Mineralogy and geochemistry of manganese and iron veins, Arndilly, Banffshire
Authors: Nicholson Keith
Published: January 2010

Synopsis

Two veins, one composed of manganese oxides the other of iron oxides, occur 20 km south-east of Elgin in Grampian Region. They are hosted by the Dalradian (Lochaber Subgroup, Appin Group) Ben Aigan Quartzite which is intensely brecciated in some areas.

The manganese vein is considered to be composed primarily of coronadite and wad, with minor hollandite and pyrolusite; the presence of romanechite in minor quantities has also been tentatively suggested. Goethite is the principal mineral of the iron vein, together with lesser hematite. Analysis of the vein material by ICP-atomic emission spectrometry revealed enrichments in Ag, Ba, Cu, Mo, Pb, Sb, V and Zn in all manganese specimens. Elevated levels of this diagnostic elemental assemblage in manganese oxides is known, from other studies, to be indicative of a hydrothermal influence.

Although not of sufficient extent to be of economic significance in terms of manganese ore, the Arndilly deposit is considered, on the basis of geochemical and mineralogical evidence, to represent an oxide capping on stockwork-type mineralisation related to the Ben Rinnes granite. The whole of this area is regarded as prospective terrain.
A shelly biofacies from the graptolitic mudstones of the Lower Balclatchie Group (lower Caradoc) near Laggan, Girvan district
Authors: Harper D. A. T. , Owen A. W.
Published: January 2010

Synopsis

A hitherto undocumented benthonic shelly fauna from within the graptolitic mudstones of Laggan Burn is largely confined to the brachiopod
Onniella williamsi
sp. nov. and the trilobite
Diacanthaspis
(
D.
)
trippi
sp. nov. The fauna is of early Caradoc age and is considered to represent a rare occurrence of an indigenous deep water shelly biofacies within the outer shelf or slope environment of the middle Ordovician of the Girvan district.
Fluorite–barite–calcite–dolomite–iron–manganese mineralisation at Craigmuschat quarry, Gourock; a historical review
Authors: Nicholson Keith , Durant Graham P.
Published: January 2010

Synopsis

Two types of mineralisation are hosted by the Craigmuschat trachyte sill. The first occurs as geodes variably composed of fluorite, quartz, chalcedony, hematite, goethite, wad, romanechite, calcite, dolomite, baryte, gypsum, tourmaline, ankerite and prehnite. The second type, composed dominantly of hematite with lesser baryte, quartz, calcite and manganese oxides, is represented by coatings along joint planes and discrete veinlets. The proposed infilling of this quarry SSSI, with subsequent loss of much of the exposed mineralisation, initiated this review. Material from the quarry available in museums for examination is listed as an appendix.
The mode of emplacement of the Cairngorm Granite
Authors: Harrison T. N.
Published: January 2010

Synopsis

The Cairngorm Granite is a composite, stock-like body composed mostly of porphyritic and non-porphyritic biotite-granites, with numerous later minor granitic bodies that exhibit a variety of cross-cutting relationships. It is almost entirely structureless internally, its external contacts are vertical, discordant and unchilled, and country rock xenoliths are rare. It reached its present level of exposure by the stoping of very large blocks of country rocks, and no evidence is seen of diapiric emplacement. During its ascent the magma body behaved as a Bingham fluid, and the unusual rheological properties of this fluid are considered to have determined both the size and the number of xenoliths seen in the granite.
Late Flandrian solifluction on the Fannich mountains, Ross-shire
Authors: Ballantyne Colin K.
Published: January 2010

Synopsis

Five radiocarbon dates obtained for samples from a soil horizon buried by the downslope advance of a 0.4 m thick solifluction lobe on a 14° slope at 840 m in the Fannich Mountains yielded ages that range from 890 ± 120 B.P. to 530 ± 90 B.P. These radiocarbon ages are statistically indistinguishable from that of 660 ± 70 B.P. obtained for a sample from the same soil horizon 0.6 m downslope of the lobe front. As contamination of the samples to produce such similarity in ages is highly improbable, this evidence indicates very rapid, very recent advance of the solifluction lobe over a distance of at least 3 m at a rate hitherto unsuspected for recent solifluction in upland Britain and as great (if not greater) than any reported for similar features in other periglacial environments. The rapidity of lobe movement appears to reflect greatly accelerated recent activity, probably triggered either by climatic deterioration during the ‘Little Ice Age’ or by vegetation degradation caused by overgrazing.