bluuebunny/crossref_metadata_2025 huggingface dataset:
A reassessment of the age and form of the Broadford Gabbro, Isle of Skye: new field evidence from Creag Strollamus
Authors: Johnston D. R.
Published: January 2010

Synopsis

The Broadford Gabbro has been reinterpreted as younger than the Outer Granites of the Eastern Red Hills Centre. Extrusive pyroclastic rocks, on the northern side of Creag Strollamus, are bound below by a weathered surface of one of the Outer Granites and above by a planar contact with the Broadford Gabbro. Other evidence includes chilled margins, back veining and relationships with members of the regional dyke swarm.

It is believed that the Broadford Gabbro has the form of a conformable sheet that has utilised a pre-existing thrust plane. An apparent ‘dyke’ of gabbro extending across the NE shoulder of Creag Strollamus is interpreted as a tabular projection from the sheet. A possible feeder dyke has a NW–SE orientation. parallel to the trend of the regional dyke swarm and to the axis of the Corran Lodge Granite.
Glacial striae and former ice movement: the evidence from Assynt, Sutherland
Authors: Lawson T. J.
Published: January 2010

Synopsis

The mapping of an extensive pattern of glacial striae on quartzite bedrock has enabled the reconstruction of basal flow patterns beneath the Late Devensian ice sheet. There is evidence for an earlier phase of ice movement in certain limited localities, believed to relate to ice build-up. Ice flow beneath a thick ice sheet that covered all but the highest parts of the terrain was followed by a phase in which basal flow was strongly influenced by topography. The ice sheet appears to have been warm-based throughout much of its existence.
Maximum altitude of Devensian glaciation on the Isle of Skye
Authors: Dahl Svein-Olaf , Ballantyne Colin K. , McCarroll Danny , Nesje Atle
Published: January 2010

Synopsis

A high-level periglacial trimline occurs on the mountains of Skye at altitudes of 750–870 m in the Cuillins,
c.
850 m on Blà Bheinn,
c.
760 m on Glamaig, 440–610 m on Trotternish and at
c.
480 m on Macleod’s Tables in Duirinish. Widespread survival of gibbsite in soils above the trimline indicates significantly more advanced weathering than in soils at lower altitudes, implying that the trimline marks the upper level of Devensian glacial erosion and thus defines the maximum altitude of the ice dome that developed on Skye during the Devensian glacial maximum. Three-dimensional reconstruction of the form of the ice surface suggests that glaciers descended steeply from west-facing corries in the Cuillins, whilst east-facing corries nourished an ice mass that escaped north via Glen Sligachan and SE over cols and around the southern end of the Cuillin ridge. Across central and northern Skye the ice surface descended more gently at gradients of 7.5–9.0 m km
−1
, declining to an altitude of
c.
450 m across Duirinish, Waternish and the northern tip of Trotternish. Implied basal shear stresses are consistent with those of an ice mass moving across a rigid bed, and the dimensions of the former ice dome indicate confluence of Skye ice and Outer Hebridean ice in the Minches.
The trilobites and brachiopods of the Wrae Limestone, an Ordovician limestone conglomerate in the Southern Uplands
Authors: Owen Alan W. , Harper David A. T. , Clarkson Euan N. K.
Published: January 2010

Synopsis

The Wrae Limestone is a conglomerate within late Caradoc or Ashgill (late Ordovician) siltstones near the southern edge of the Northern Belt of the Southern Uplands. Its interpretation exemplifies problems common to many orogens: separation of fossiliferous lithoclast ages from timing of final emplacement, separation of biofacies from temporal faunal correlation and the use of biofacies in determining provenance. The trilobites are closest to those of the lower Caradoc rocks at Girvan, north of the supposed Southern Uplands-Midland Valley terrane boundary. The edge of the Midland Valley platform may thus have been the source of the carbonate clasts. Some of the trilobites range through the spectrum of biofacies present in the Lower Caradoc of Girvan. However, species of
Phorocephala
and
Dubhglasina
suggest an origin at the margin of the Nileus association. The brachiopod assemblage is not directly comparable with any faunas in the Girvan–Appalachian belt. It is dominated by coarse ribbed orthoids. smooth triplesiids and several plectamboni-toids, having more in common with later Ordovician brachiopod biofacies associated with carbonate mudmounds, but overall the Wrae brachiopod assemblage is not particularly typical of any one benthic assemblage zone or precise substrate type.
The Shetland Ophiolite Complex: field evidence for the intrusive emplacement of the ‘cumulate’ layers
Authors: Flinn Derek
Published: January 2010

Synopsis

Unlike many other ophiolites, the lower-crustal sequence in the Shetland ophiolite has not been been formed in situ as a series of cumulate layers in the base of a magma chamber overlying the harzburgitic mantle. Field evidence shows that the layers were intruded sequentially above the mantle. Dunite rose as a fluid through mantle conduits, relics of which are preserved as invasive pods and sheets within the harzburgite. It formed an intrusive layer several kilometres thick between the mantle and an overlying banded wehrlite–clinopyroxenite layer, relics of which are preserved in places in the roof of the dunite intrusion as partially assimilated xenoliths and screens. A similarly uniform and thick intrusive layer of gabbro was emplaced immediately above the dunite layer and contains xenoliths and screens of the wehrlite–clinopyroxenite layer in both its base and its roof. A mixed gabbro–microgabbro layer lies immediately above the gabbro and has been cut repeatedly by parallel basic sheets giving the layer a quasi-sheeted-dyke appearance. However, the sheets are more nearly parallel than normal to the gabbro and dunite layers and have been intruded from outside the exposed layered sequence. The succession listed is lying on its side forming a nappe, in which both the layers and the sheets are vertical. It is not clear whether the succession had been rotated into this position before or after the sheets were emplaced. It is suggested that the dunite in the mantle was formed in the manner proposed by

Kelemen
et al.
in 1995

, that is that MORB produced by adiabatic melting in the mantle was undersaturated in orthopyroxene and reached the top of the mantle by intergranular flow through the mantle during which the porosity along the flow path was increased by dissolution of the pyroxenes, thus concentrating the flow into dunite conduits. Under these circumstances the flow of liquid MORB through the solid dunite conduits, because of increased porosity and decreased grain adhesion, could possibly lead to fluidization of the dunite in the conduits. The fluidized dunite would be forced upwards out of the mantle to form the overlying intrusive dunite layer.
Na-biotite in Dalradian pelitic schists, Angus
Authors: Dempster T. J. , Jackson R. A.
Published: January 2010

Synopsis

Na-biotites have been found within pelitic schists in lower amphibolite facies Dalradian metasediments. These micas are optically very similar to normal K-biotites which they partially replace, although the Na-biotites do contain a more prominent 001 cleavage. The formation of the Na-biotites is linked to the local infiltration of a Na-rich fluid during retrogression and was dependent on late deformation opening fluid pathways within existing biotite porphyroblasts. Micas of such unusual compositions (up to 3 wt% Na
2
O) have not previously been reported from pelitic rocks.
Structural analysis of the Dalradian rocks of the Loch Leven area, Inverness-shire
Authors: Ikeda Takeshi
Published: January 2010

Synopsis

Two phases of deformation are responsible for the main structure in an area north of Loch Leven, west of Kinlochleven. The first phase of deformation is associated with the formation of schistosity that is sub-parallel to bedding and relates to large scale overturned folds in the stratigraphy, including the Mamore Syncline. The second phase of deformation corresponds to the development of crenulation cleavage that trends NE-SW to east-west throughout the area. The NE-SW trending bedding and the first schistosity in the north are rotated into north-south in the middle and NNW-SSE in the south of the area by this phase of deformation. The Loch Leven Antiform is, thus, attributed to this stage of deformation. The locally developed third phase deformation may relate to the gentle bending of the second phase fold axes.
A Caledonian age for the Kiloran Bay appinite intrusion on Colonsay, Inner Hebrides
Authors: Muir R. J. , Ireland T. R. , Bentley M. R. , Fitches W. R. , Maltman A. J.
Published: January 2010

Synopsis

A sample of hornbendite from the Kiloran Bay intrusion on the island of Colonsay in the Inner Hebrides, previously of uncertain age, has yielded a U-Pb zircon SHRIMP age of 439.0 ± 8.8 Ma (2σ). This age is the same, within error, as the Caledonian Appinite Suite on the Scottish mainland. The distinctive geochemical characteristics of the Appinite Suite, high Mg, K, Cr, Ni, Sr, Ba and the light REE, are faithfully reproduced in the Kiloran Bay intrusion. There are no published Sr and Nd isotopic data for the Appinite Suite, but the Rb-Sr and Sm-Nd isotope systematics of the Kiloran Bay rocks are comparable with the late Caledonian Granites. Proterozoic (1.7 Ga) Nd model ages and inherited zircons indicate the involvement of old crusta material during magma genesis. Correlation of the Kiloran Bay intrusion with the Appinite Suite supports a Colonsay Group–Dalradian Supergroup correlation. However, difficutlies remain in correlating the structural history of the two successions and a stratigraphic link cannot be proven.
Ductile fault rocks and metamorphic zonation in the Dalradian of the Highland Border SW of Stonehaven, Kincardineshire
Authors: Phillips E. R. , Auton C. A.
Published: January 2010

Synopsis

High strain zones, characterized by shear fabrics and mylonites, have been identified within lower amphibolite-grade, coarse granular metasandstones of the Glen Lethnot Grit Formation of the Southern Highland Group (Dalradian) along the Highland Border, south-west of Stonehaven. The rocks comprise part of a polydeformed, regionally metamorphosed, Neoproterozoic sequence, bounded to the north by the post-orogenic Mount Battock Granite (Late Caledonian) and to the south-east by the Highland Boundary Fault Zone. Early regional D1 and D2 structures have been rotated by a major monoform, the Highland Border Downbend (D4), to produce a steeply dipping, downward facing succession. The mylonitic metasand-stones contain a variety of kinematic indicators, including asymmetrical pressure shadows, S-C fabrics, shear bands and an extensional crenulation cleavage, which yield a sense of shear of top-towards-the SE (present structural position). Regional syn- to post-D2 metamorphism resulted in the development of prograde pelitic mineral assemblages which overgrow earlier Dl structures. Mylonitic fabrics within the high strain zones, developed during D2, both deform and are also overgrown by syn- to post-kinematic biotite porphyroblasts. The high strain zones may represent part of a major ductile structure active during the Dalradian D2–D3 tectonothermal event, which contributed to the development of strong metamorphic gradients and narrowing of mineral assemblage zones within the Highland Border.
The Bothkennar Gravel Formation (‘buried gravel layer’) of the Forth Estuary
Authors: Peacock J. D.
Published: January 2010

Synopsis

The Bothkennar Gravel Formation ‘buried gravel layer’, which is widespread below the Flandrian carse clays (Claret Formation) of the Forth estuary, is interpreted as having been formed chiefly by ice-rafting of sediment from the shore during the Loch Lomond Stadial (11–10 ka BP), and it is proposed that ice-rafting was an important agent of sediment transport and deposition around the Scottish coast at that time. The implications of this hypothesis for the history of sea-level change in the Forth estuary are briefly discussed, and it is suggested that conclusive evidence is lacking for sea levels below OD in the Grangemouth area during the Loch Lomond Stadial.
Sedimentological and micromorphological examination of a Late Devensian multiple diamicton sequence near Moneydie, Perthshire, east-central Scotland
Authors: Menzies J. , van der Meer J. J. M.
Published: January 2010

Synopsis

Re-investigation of a site at Shochie Burn near Moneydie in east-central Scotland suggests that earlier interpretations need to be modified. At this site, in the past, two tills were recognized as indicative of two separate ice advances. Previously, this site was known as a stratotype for the Perth Readvance in eastern Scotland. The evidence for a regional readvance is no longer accepted but the two-till problem remains unexplained. Present investigations suggest that the two tills are part of a large package of sediments deposited as stacked layers of a subglacial deforming bed that have been tectonized by a very short and local ice readvance perhaps of the type that occurs as a winter readvance. Sedimentological and micromorphological evidence points to the tills as not being separate but of the same depositional phase undergoing subglacial deformation and/or local marginal tectonization following subglacial transport in a deforming bed environment resulting in the incorporation of proximal outwash sediments. The till at Shochie Burn exhibits evidence, both at the macro- and microscale, of intense deformation under high porewater pressures that are attributable to the strong plasmic microstructures, fold structures, shear zones, Riedel shears, and of possible submarginal freezing conditions resulting in localized brecciation and foliation structure development. This is the first site in this area to indicate the presence of subglacial deforming bed conditions followed by marginal glaciotectonism, therefore continued research is necessary to establish this modified view of subglacial conditions in this part of Scotland.
A Lower Ordovician (Arenig) radiolarian fauna from the Ballantrae Complex, Scotland
Authors: Aitchison Jonathan C.
Published: January 2010

Synopsis

Recent examinations of Lower Ordovician (Arenig) cherts from the Ballantrae Complex, Scotland have resulted in the discovery of a moderately well-preserved radiolarian assemblage. Elements of the fauna are distinctive indicating that even early radiolarian forms have excellent biostratigraphic potential. The abundance of radiolarians in chert and the ease with which they can be extracted suggest that they are a potentially valuable tool for use in investigations into the timing of the development of Early Palaeozoic orogenic systems. A new family of Radiolaria the Proventocitiidae fam. nov., previously informally described from Spitsbergen (Fortey and Holdsworth 1971), is formalized herein. One new species,
Proventocitum holdsworthi,
sp.nov., is described;
Proventocitum
sp.A is described under open nomenclature.
Biostratigraphy of the Currarie Formation on the northwestern edge of the Southern Uplands: implications for the cessation of basic volcanism
Authors: Armstrong H. A. , Rushton A. W. A. , Owen A. W. , Floyd J. D.
Published: January 2010

Synopsis

The Currarie Formation forms part of the deep water succession near the northern margin of the Southern Uplands. It comprises red and green mudstones (distal turbidites), chert and interbedded lava and lava breccia and overlies basalt lavas. The age of the Currarie Formation is critical in providing a minimum age for the end of basic volcanism in the northernmost part of the Southern Uplands and a maximum age for the onset of northerly derived turbidite flysch. It also allows biostratigraphical correlations to be made across the Southern Upland Fault. Graptolites indicative of the lower
Nemagraptus gracilis
Biozone and the first record of the conodont species
Protopanderodus varicostatus
from the formation indicate an earliest Caradoc (early Aurelucian) age for the Currarie Formation. This dates the cessation of basic volcanism in the northernmost part of the Southern Uplands as earliest Caradoc. However, the waning of volcanism may have been diachronous, continuing into the upper TV.
gracilis
Biozone in the area between the Southern Upland–Glen App and Carcow faults in a succession thought to have been developed further to the south than the Currarie Formation. The onset of coarse turbidite deposition followed within the same graptolite zone marking the onset of a major phase in uplift of the Midland Valley terrane and subsidence in the Southern Uplands basin.
The genus
Paracarbonicola
and associated forms in the Carboniferous rocks of Scotland
Authors: Brand P. J.
Published: January 2010

Synopsis

Species of the bivalve genus
Paracarbonicola
Eagar occur at scattered intervals in the Carboniferous rocks of Scotland. Although individual numbers are high at most horizons, occurrences are rare in the stratigraphical column. The type species,
P. elegans
(Kirkby), together with another species,
P. antiqua
(Hind), are confined to rocks of Dinantian age in Fife and the Lothians. The species
Carbonicola antiana
Pastiels and
C. ultimus
Rehor are tentatively assigned to the genus and specimens referred to these species have been found in rocks of Namurian age (E1–E2). The species
Carbonicola pervetusta
Bennison, referred to
Paracarbonicola
by
Eagar (1977)
is considered to belong to a new genus.
Late Caledonian calc-alkaline dykes from the east coast of Aberdeenshire
Authors: Thomas C. W.
Published: January 2010

Synopsis

A suite of previously undescribed microdioritic and lamprophyric dykes crop out on the east coast of Scotland, some 10–12 km south of Aberdeen, where they intrude polydeformed and metamorphosed Southern Highland Group (Dalradian) psammites. The dykes have calc-alkaline basaltic to andesitic compositions. Several contain notably high levels MgO, Cr and Ni and they are also enriched in incompatible elements. They display a range of macroscopic features indicating emplacement at high, possibly subvolcanic, levels and there is evidence for multiple intrusion. Hydrothermal alteration generated greenschist-facies epidote–actinolite and subsequent chlorite–calcite assemblages.
Late Ordovician (Ashgill) ostracodes from the Drummuck Group, Craighead Inlier, Girvan district, SW Scotland
Authors: FLOYD JAMES D. , WILLIAMS MARK , RUSHTON ADRIAN W. A.
Published: January 2010

Synopsis

The Lady Burn and South Threave formations of the Drummuck Group (Ashgill Series,
anceps
Biozone) of the Craighead Inlier, southwest Scotland yield low diversity marine ostracode faunas characterised by the binodicope
Kinnekullea comma
(
Jones 1879
), palaeocopes including
Euprimites limus
sp. nov. and a tetradellid (
Vittella
? sp.), and podocopes.
Kinnekullea comma
is re-described. It may have widespread correlative value as it occurs in the Portrane Limestone of Ireland and is similar to, and possibly conspecific with,
Kinnekullea
species from the Ashgill of the Baltic States. The occurrence of typical Baltic ostracodes in the Drummuck Group supports the suggestion that by the late Ordovician the palaeocontinents of Laurentia and Baltica were in close geographical proximity.
New evidence on the origin and Jurassic age of palaeokarst and limestone breccias, Loch Slapin, Isle of Skye
Authors: Farris M. A. , Oates M. J. , Torrens H. S.
Published: January 2010

Synopsis

A limestone breccia which is interpreted as a palaeokarst fill of early Jurassic age, is described from Southern Skye, lying above the Durness Limestone Group and below the Broadford Formation, as previously defined. Such breccias have been described from parts of the Camas Malag Formation and where they are overlain directly by Jurassic limestones, these are now assigned to the Broadford Formation.

For the first time, direct biostratigraphical evidence is presented for the age of these limestone breccias here, where they overlie and partly fill a palaeokarst surface on the Durness Limestone. Faunal evidence also demonstrates that their deposition occurred under fully marine conditions. The Triassic age previously assigned to the Camas Malag Formation is rejected and, at its type locality, this Formation is assigned an early Jurassic age.
Maximum altitude of Late Devensian glaciation on the Isle of Mull and Isle of Jura
Authors: Ballantyne Colin K.
Published: January 2010

Synopsis

Evidence provided by striae, ice-moulded rock, erratics and perched boulders indicates that the last (Late Devensian) ice-sheet reached an altitude exceeding 760 m on Mull and 660 m on Jura. The highest summits on both islands support periglacial blockfields, suggesting that they remained as nunataks above the ice surface. This interpretation is supported by analyses of clay-fraction mineralogy, which shows that gibbsite (a pre-Late Devensian weathering product) is widespread in blockfield samples but rare in samples below the inferred limit of glaciation, implying removal by Late Devensian glacial erosion. Maximum ice-sheet altitudes of 760–840 m and 660–700 m are inferred for the Ben More massif on Mull and Paps of Jura respectively. Reconstruction of ice-sheet configuration in the Inner Hebrides area suggests that the 900 m ice-surface contour followed the west coast of the mainland, but the altitude evidence is insufficient to constrain the westwards extent of the ice sheet. Inferred ice-surface altitudes and directions of ice movement are incompatible with most theoretical models, and even the ‘best fit’ model of ice dimensions in this area underestimates maximum ice thickness by ≥ 60 m.
Sedimentology and depositional history of the Claret Formation (‘carse clay’) at Bothkennar, near Grangemouth
Authors: Barras Beverley F. , Paul Michael A.
Published: January 2010

Synopsis

The estuarine sediments of Flandrian age which comprise the Claret Formation in the Bothkennar area can be divided into bedded, mottled and laminated facies on the basis of primary sedimentary structures, frequency of silty laminae and the nature and extent of bioturbation. The mottled facies can be further subdivided by the style of bioturbation. The facies are very similar in overall particle size distribution and mineralogy. Biogenic traces occur in all the facies and have been tentatively matched to organisms present in the modern infauna Equation ()of the Firth of Forth. The succession of facies has been controlled by the fall of relative sea-level since the Flandrian maximum and records an emergent sequence from sub-tidal (probable water depth around 20 m) to inter-tidal. In the Bothkennar area four local subdivisions can be recognized in the Claret Formation, which reflect changes in sedimentary environment consequent on the reduction in water depth.
A regional geochemical assessment of some terrane relationships in the British Caledonides
Authors: Stone P. , Plant J. A. , Mendum J. R. , Green P. M.
Published: January 2010

Synopsis

Regional geochemical data have been systematically collected across the British Caledonides and interpreted, using single and multielement image analysis, to provide geochemical constraints on terrane relationships. In the Hebridean Terrane, the Lewisian rocks show the characteristics of a large ion lithophile element (LILE) depleted lower crustal complex and seem unlikely to have been the source for the bulk of the overlying Torridonian clastic rocks. The psammite-dominated Moine Supergroup and the Dalradian rocks of the Grampian Group have closely similar evolved chemistries consistent with derivation from a higher crustal level than that of the currently exposed Lewisian complex. Across the Scottish Highland terranes the principal geochemical discontinuities coincide with the Moine Thrust Zone, the boundary between the Grampian Group and the Appin and Argyll Group Dalradian rocks, and the Highland Boundary Fault. The geochemical evidence provides little support for the Great Glen Fault as a significant terrane boundary. South of the Southern Upland Fault, which also coincides with a major geochemical discontinuity, a range of elements indicates division of the Southern Uplands terrane into northern and southern zones. These are transitional between the Orlock Bridge and Moffat Valley faults and reflect a change in sedimentary provenance during the early Silurian. Basic and ultrabasic elements, especially Cr, show exceptionally high levels over early Llandovery strata possibly indicating derivation from Iapetus Ocean crust obducted further NE as the Scandian Orogen was initiated. The geochemical characteristics of the southern part of the Southern Uplands Terrane continue into the Windermere Supergroup of the English Lake District, emphasising the continuity of mid- to late-Silurian deposition across the Laurentia–Avalonia (Iapetus) suture zone.
Invited Review: Contribution of the Scottish Offshore to the advancement of geology
Authors: Glennie K. W.
Published: January 2010

Synopsis

Since the late 1960s, the search for hydrocarbons in the seas around Scotland has led to an enormous increase in geological knowledge. In addition to new data related directly to the origins and entrapment of hydrocarbons, the geology of Scotland can now be linked to that of Scandinavia and other parts of adjacent Western Europe via rock sequences in the Central and Northern North Sea which, especially for the Mesozoic and Tertiary, are mostly not represented on the Scottish land surface. Part of the ‘missing’ history of Scotland during that time span can now be deduced from the surrounding offshore geology. Apart from the valuable stratigraphical input, important new information has been gained on aspects of sedimentology (e.g. the distribution of Late Permian evaporites and Early Tertiary turbidites) and structural geology. The previously unknown Central-Viking Graben, trending roughly N-S, began to form in the mid-Permian along the ‘median line’ between Britain and the continent, and was subsequently infilled with Permian sediments, now locally at depths in excess of 10 km. High quality, closely constrained seismic data have shown up previously unknown patterns of extensional and transtensional faults in three dimensions.
Mid-Caradoc (Ordovician) ostracodes from the Craighead Limestone Formation, Girvan district, SW Scotland
Authors: Williams Mark , Floyd James D.
Published: January 2010

Synopsis

Ostracodes occur in shallow marine limestones and deeper marine graptolite-bearing mudstones of the Ordovician (Caradoc Series) Craighead Limestone Formation, SW Scotland. The fauna of the limestones, a well preserved, palaeocope-rich association, comprises
Oepikella (O. tunnicliffi
sp. nov.),
Platybolbina, Levisulculus, Distobolbina
and
Leperditella
species, and rare podocopes including
Monoceratella teres
Teichert 1937a. These taxa were previously unknown from the British Ordovician. The faunas of the mudstones are mostly indeterminate moulds.
Monoceratella teres
has a widespread occurrence in Ordovician carbonate-rich sequences of the eastern United States, but is stratigraphically long-ranging (North American late Whiterockian – early Mohawkian series). The North American affinity of the fauna from the limestone is also indicated by
Platybolbina
cf.
punctata
(Kraft 1962),
Levisulculus
cf.
michiganensis
Kesling 1960a and
Leperditella
sp., although at generic level, most of the ostracode taxa also occur in Scandinavia. This supports the suggestion that, by Caradoc times, the Iapetus Ocean no longer represented a barrier to migration between shallow marine-shelf ostracodes of the Laurentia and Baltica palaeocontinents.
Eurypterids from the Early Devonian of the Midland Valley of Scotland
Authors: Braddy Simon J.
Published: January 2010

Synopsis

A new specimen of
Parahughmilleria sp.
is described from the Early Devonian Dundee Formation (Arbuthnott Group, Lochkovian) from the Tillywhandland Quarry (Forfar) in the Midland Valley of Scotland. The diversity of eurypterids from the Midland Valley assemblage is reinterpreted to comprise six species (although systematic revisions await the discovery of more material and formal revisions of each genus):
Pterygotus anglicus
Agassiz, 1844 (including
Pterygotus minor
Woodward, 1864, here interpreted as a juvenile),
Tarsopterella scotica
Woodward, 1872 (including
Erieopterus brewsteri
Woodward, 1864, here interpreted as a juvenile),
Stylonurus powriensis
Page, 1856 (including
Stylonurus? ensiformis
Woodward, 1864, here interpreted as a partial piece (telson) of a large individual),
Pagea sturrocki
Waterston, 1962,
Nanahughmilleria pygmaea
Salter, 1859 and
Parahughmilleria sp.
Functional evidence and their general occurence favours a benthonic mode of life for the stylonurids, which inhabited fluvial systems surrounding ‘Lake Forfar’, whereas the pterygoids and hughmillerids inhabited the lacustrine facies.
Regional variation in gold mineralization in the vicinity of the Glengaber Burn, Scottish Borders
Authors: Chapman R. J. , Leake R. C. , Floyd J. D.
Published: January 2010

Synopsis

The alluvial gold at Glengaber Burn in the valley of the Megget Water is of interest because of its coarse size and historical working. A total of 350 alluvial gold grains from 17 sites in Glengaber Burn and the vicinity have been studied using the technique of microchemical characterization, and two major types of gold have been identified, each with well defined geographical distribution. Type 1a gold contains only pyrite inclusions, and has an Ag content of between 8% and 11%. Type 1b has a similar Ag content, but the inclusion assemblage contains galena together with pyrite. Type 2a gold typically contains between 3% and 7% Ag, and a suite of inclusions comprising chalcopyrite, sphalerite, tetrahedrite, arsenopyrite and gersdorffite. Type 2a gold occurs in a SW–NW trending zone which contains the catchments of the Glengaber and Craigierigg Burns. Type 2b gold is confined to the catchment of the Cramalt Burn and contains an inclusion suite similar to Type 2a, but is more silver-rich. The abundance of alluvial gold of all types falls dramatically to the south of Megget Water, although the occurrence to the north of the Glengaber Burn and Craigierigg Burns has not been established. The distribution of Type 1a gold is mutually exclusive with Type 2a and flanks the zone of Type 2a and 2b to both east and west suggesting zonation in a single mineralizing event. Type 1b gold occurs to the west of Type 1a and is probably unrelated to the other gold types. The mineralization acting as the source for the alluvial gold could be controlled by deep structures roughly perpendicular to the regional strike, revealed by prominent gravity lineaments, and their intersections with other structural features.
A thyreophoran dinosaur from the Early Bajocian (Middle Jurassic) of the Isle of Skye, Scotland
Authors: Clark N. D. L.
Published: January 2010

Synopsis

The proximal parts of the right ulna and radius of a thyreophoran dinosaur from Bearreraig Bay, Isle of Skye, represent the first occurrence of this type of dinosaur from the Middle Jurassic rocks of Scotland. The incompleteness of the bones and the lack of more diagnostic features does not allow a precise identification although the ulna has more features in common with that of a eurypodan (stegosaurs and ankylosaurs) than a basal thyreophoran. The earliest identifiable stegosaur from Europe that has similar proximal expansion of the ulna is the middle Callovian (Middle Jurassic)
Lexovisaurus
of England and France. The ulna of the ankylosaur
Mymoorapelta
from the Upper Jurassic of Western Colorado, also shows close morphological similarity to the Scottish bone. Other ankylosaur fragments have been recorded from as early as the late Bajocian (Middle Jurassic) of England. The stratigraphic horizon from which the new bones come from is the Bearreraig Sandstone Formation (Early Bajocian, Middle Jurassic).
Calcareous concretions yield the first U/Th date for the Late Devensian raised marine strata of eastern Scotland
Authors: Rowan J. S. , Duck R. W. , Black S.
Published: January 2010

Synopsis

This paper presents the first application of U-series disequilibria dating to the Late Devensian raised marine strata of Scotland. The Errol Clay Formation (ECF) is an extensive deposit of laminated glaciomarine silty-clays found offshore from and within the Firths of eastern Scotland. The stratigraphic significance of these deposits lies in their diachronous deposition following the retreat of the Late Devensian ice sheet, and local glaciotectonization following the readvance of the Younger Dryas. In spite of their importance to an understanding of the deglaciation of Scotland, the paucity and poor preservation of biogenic material have hitherto hampered radiocarbon dating of these sediments. A working clay pit at Gallowflat [NO 211 209], in the inner Firth of Tay, provided access to a 5.3 m section of the ECF. A characteristic feature of the lower ECF is that the basal sub-units are rich in calcareous concretions, believed to have formed rapidly at the sediment water interface during glaciomarine sedimentation. Eight individual concretions were hand-picked from the 1.4 m concretion rich sub-unit, 0.5 m above the Devensian till, yielding a U-Th age of 14.2 ±0.9 ka (2σ) using the total-dissolution isochron method. This date accords with the few
14
C dates presently available and offers a new approach to establishing the dynamics of the ECF deglaciation record.
Permo–Triassic rocks in boreholes in the Annan-Canonbie area, Dumfries and Galloway, southern Scotland
Authors: Holliday D.W. , Warrington G. , Brookfield M. E. , McMillan A. A. , Holloway S.
Published: January 2010

Synopsis

Recent boreholes provide new data on the sequence, age, lithology and geophysical log stratigraphy of Late Permian and Early Triassic strata on the northern edge of the Carlisle Basin. Late Permian evaporites (gypsum-anhydrite) and microfloras are recorded and described for the first time in onshore Scotland. The lower, argillaceous and evaporite-bearing strata are assigned to the Eden Shales Formation and are divided into three informal lithostratigraphical units, in ascending order ES1, ES2 and ES3. The Eden Shales grade upwards into the St Bees Sandstone Formation. The strata closely resemble those in neigh-bouring Cumbria, and help to refine some details of regional palaeogeography and correlation. Regional log correlation suggests that a significant evaporite-bearing Late Permian section is missing, probably cut out by faulting, in the Silloth-1A Borehole, the main deep borehole penetrating the Carlisle Basin.
Holocene coastal dune development on the South Erradale peninsula, Wester Ross, Scotland
Authors: Wilson Peter
Published: January 2010

Synopsis

Radiocarbon dates from peats within and below coastal dune sands at Opinan and Redpoint, Wester Ross, Scotland, provide age constraints on phases of peat accumulation, dune development, and podzolic soil formation. Although the two dune systems are only 4 km apart they do not share identical histories of landsurface stability and aeolian sand deposition. Most dune building occurred as relative sea level (RSL) was falling but because the dunes are perched on glacifluvial terraces several metres above RSL maximum, the creation of accommodation space consequent upon RSL fall was not a prerequisite for dune development. Some dune phases also correspond in timing with documented climate shifts to cooler, wetter and/or stormier conditions - in the Little Ice Age 400 cal. years
bp
, around 2500 cal. years
bp
, and at about 8100 cal. years
bp
. Preliminary estimates of the rate of podzolic soil development are similar to those reported for aeolian sandy parent materials elsewhere.
Conodont biostratigraphy of the Crawford Group, Southern Uplands, Scotland
Authors: Armstrong Howard A. , Floyd James D. , Tingqing Lu , Barron Hugh F.
Published: January 2010

Synopsis

Extensive new conodont collections from the Crawford Group, the oldest succession in the Southern Uplands of Scotland, support the previously documented biostratigraphical ages for the included formations. The Raven Gill Formation is lower Whitlandian, Arenig (comparable in age to the Dounans Limestone in the Highland Border Complex) and the Kirkton Formation is latest Llandeilian-Aurelucian, Llanvirn to Caradoc in age. It is concluded that there is a significant stratigraphical gap within the Crawford Group. The restricted and probably fault-bounded nature of the Raven Gill outcrops suggests that these may represent olistoliths within a mélange of Llandeilian-Aurelucian age. The chert-bearing succession of the Northern Belt of the Southern Uplands thus represents the juxtaposed sedimentary records of two entirely separate basins – the oldest pre-dates the Grampian assembly of the Laurentian margin, and the younger, the Northern Belt Basin
sensu stricto,
entirely post-dates this event.
Chirotherium barthii
Kaup 1835 from the Triassic of the Isle of Arran, Scotland
Authors: Clark N. D. L. , Aspen P. , Corrance H.
Published: January 2010

Synopsis

The mould of a track from SE Arran, and several
in situ
trackways and individual tracks, as well as a partial trackway on a loose block of Triassic sandstone, from western Arran, represent the first verifiable fossil tracks of
Chirotherium
from the Triassic of Scotland and support a Scythian (Lower Triassic) age for the base of the Auchenhew Beds. The grouping of the I-IV toes with toe V behind and lateral to the group is characteristic of
Chirotherium-like
tracks. A comparison with European and American Triassic trackways suggests that the tracks belong to the species
Chirotherium barthii
Kaup, 1835, first described from Hildburghausen, Germany.
The felt effects of the Carlisle earthquake of 26 December 1979
Authors: Musson R. M. W. , Henni P. H. O.
Published: January 2010

Synopsis

The earthquake of 26 December 1979, with an epicentre north of Carlisle, near Longtown, Cumbria, was one of the most significant British earthquakes of the second half of the 20th century. It had a magnitude of 4.7 ML (local magnitude) and was felt over an area of around 84 000 km
2
at intensity 3 EMS (European Macroseismic Scale), covering most of central Scotland, the Borders, Cumbria and the NE of England. It was the mainshock of a sequence of around 90 events recorded by the British Geological Survey (BGS), then the Institute of Geological Sciences (IGS), UK seismic monitoring network. BGS undertook a macroseismic (felt effect) survey for the mainshock, with around 4000 usable responses received, and also for the two largest aftershocks, which occurred on 1 January 1980 and 13 December 1980, both with magnitude 3.8 ML. The results of these surveys have not been published until now. The highest intensities were reached around the Carlisle and Longtown areas, where 6 EMS was assigned from reports describing chimney stack and roof damage, with debris falling into the street, cracks in walls and other similar effects. Macroseismic estimates of the parameters of the earthquake agree well with the instrumental parameters so far as epicentre and magnitude are concerned, but there is a significant discrepancy with respect to depth. Also, although the size of the felt area is consistent with what is expected from average UK intensity attenuation, there is a marked directionality to the energy release, resulting in the earthquake being much more perceptible to the north than to the south.
A case of profound astogenetic metamorphosis: the structure and affinities of
Awarograptus nodifer
(Törnquist, 1881)
Authors: Zalasiewicz Jan , Howe Mike P. A.
Published: January 2010

Synopsis

The late Telychian (Silurian: Llandovery) graptolite
Monograptus nodifer
Törnquist, 1881 has long been problematical, in part because Törnquist’s original material is missing and there has been doubt as to whether the specimens he subsequently described as
nodifer
in 1892 were of the same species. We conclude that the 1881 and 1892 descriptions refer to the same species, and propose a neotype from Törnquist’s original material. We demonstrate that
nodifer
shows markedly biform thecal character. The proximal thecae are essentially streptograptid. Growth of the ventral metathecal wall parallel to the protheca then heralds an abrupt change to the distal thecal style, which is characterized by tight, double recurvature, with a flange made of a further extension of the ventral metathecal wall; the new genus
Awarograptus
is created to encompass this remarkable morphology. Derivation was almost certainly from a streptograptid graptolite, by the distal introduction of a new thecal character. The biform thecal character might have had a reproductive, rather than hydrodynamic or feeding purpose.
The functional morphology and population structure of
Rastrites maximus
from the Southern Uplands
Authors: Rigby Susan
Published: January 2010

Synopsis

Rastrites maximus
is a species that shows relatively great intraspecific variation in the length, spacing and orientation of its thecae. The thecae are characterized by a long pair of spines made from the distal ends of a hood-like thecal hook. The metathecae are very thin and enclosed in a wide cowl, which is always preserved flattened. The rhabdosome rarely exceeds 12 thecae in length and was of a wide spiral form whose thecae showed torsion through about 11° per theca. It is never found complete beyond theca six because stresses transmitted to the stipe by these angled thecae caused the specimen to break once it was on the sea floor. This form, of a spiral graptolite with persistent ‘sails’ along each theca, would have been very stable and would have rotated through calm water in a sicula-down position with the thecal apertures widely separated for food gathering. The large rhabdosome and small zooid number and size suggest that this species was adapted for a predictable environment where populations were maintained close to their carrying capacity. Populations of
R. maximus
show a convex survivorship curve, which is typical of species living in stable environments where death is mediated by ageing.
An unlikely evolutionary lineage: the Rhuddanian (Silurian, Llandovery) graptolites
Huttagraptus? praematurus
and
Coronograptus cyphus
re-examined
Authors: Zalasiewicz Jan , Williams Mark , Akhurst Maxine
Published: January 2010

Synopsis

The Rhuddanian (Llandovery, Silurian) monograptid taxa
praematurus
Toghill and
cyphus
Lapworth are reassessed by review of existing and new collections. The eponymous species of the late Rhuddanian
cyphus
Biozone is now widely regarded as a typical
Coronograptus,
with essentially simple tubular thecae. Nevertheless, Lapworth, in drawing up his original description, was clearly referring mainly to biform graptolites of the
Monograptus revolutus
group, prominent on the type rock slabs. Nomenclatural stability is best served by referring to
cyphus
in its common usage, i.e. in the interpretation of Elles & Wood, largely based upon Lapworth’s material from Dob’s Linn, Scotland. The monograptid
praematurus,
a mid-Rhuddanian taxon, was originally described as a variety, and evolutionary precursor, of
Coronograptus cyphus.
However, it possesses more complex, geniculate, thecae, with well-developed thecal hoods, and probably represents one of the earliest
Huttagraptus
species.
Huttagraptus
?
praematurus
has a range restricted to the lower
atavus
Biozone and may be a subzonal marker for that interval. The roots of
Coronograptus
are obscure, but, in possessing essentially simple tubular thecae, it might be a separate offshoot from an
Atavograptus
stock.
The metamorphic basement geology of Mainland Orkney and Graemsay
Authors: Strachan R. A.
Published: January 2010

Synopsis

Small inliers of poorly known pre-Devonian metamorphic rocks are exposed in the west part of Mainland Orkney and on Graemsay. These rocks can be divided into three main groups. In order of decreasing age these are: (1) paragneisses (also including amphibolites); (2) foliated meta-granites, and (3) late, undeformed granitic and aplitic veins. There is evidence for three deformational episodes (D1–D3). D1 resulted in the gneissic foliation within the metasedimentary rocks and was associated with migmatization under mid- to upper amphibolite facies conditions. The meta-granites were probably intruded either prior to or during D2. This event resulted in the formation of a pervasive foliation within the meta-granites, as well as modification of SI fabrics within the host metasedimentary rocks. Metamorphic grade during D2 was probably within the amphibolite facies. D3 resulted in gentle, upright folding of earlier foliations. The paragneisses are correlated on lithological grounds with the high-grade Moine rocks of east Sutherland. Regional migmatization and D1 are assigned provisionally to the mid-Ordovician Grampian orogenic event recognized in east Sutherland. The meta-granites are assigned to the Silurian ‘Newer Granite’ suite and compared with the syn-tectonic plutons and sheets of central Sutherland. D2 and D3 are, therefore, tentatively assigned to the Scandian orogenic event.
Garnet pyroxenite xenoliths and pyropic megacrysts in Scottish alkali basalts
Authors: Upton B. G. J. , Aspen P. , Hinton R. W.
Published: January 2010

Synopsis

Pyropic garnet occurs within garnet pyroxenite xenoliths and as discrete crystals in Carboniferous–Permian alkali basaltic tuffs and hypabyssal intrusions. Eight localities are now known from the Midland Valley together with another in the NW Highlands. The xenoliths are inferred to have been derived from minor pyroxenitic intercalations in spinel lherzolite within the lithospheric mantle. Although pyrope crystals at Elie Ness are regarded as high-pressure phenocrysts cognate with the basanitic host, it is indeterminable whether discrete garnets at the other localities are phenocrysts or xenocrystal fragments derived from garnet pyroxenites. All, however, whether phenocrystic, xenocrystic or integral components of pyroxenitic xenoliths, are regarded as cognate in the sense of being products of high-pressure crystallization of late Palaeozoic basanite magmas. Kaersutite, phlogopite, hercynitic spinel, ilmenite and pseudomorphs after orthopyroxene occur as minor components in some of the garnet pyroxenite xenoliths.

Mineral compositional data (electron- and ion-microprobe) are presented, with comparisons to xenolith-megacryst suites elsewhere. The garnets have strong similarities with each other and with megacryst populations from alkali basalts outside the U.K. It is concluded that the pyroxenites originally crystallized from basaltic magmas as high-pressure cumulates from depths of >50 km and represent some of the deepest samples from the Scottish lithosphere.
Platinum-group minerals within the Ballantrae Complex, SW Scotland
Authors: Power M. R. , Pirrie D.
Published: January 2010

Synopsis

Platinum-group minerals (PGM) are present within the chromitites of the northern serpentinite belt (Pinbain Bridge area) of the ophiolitic Ballantrae Complex. A relatively uncommon but moderately diverse PGM assemblage is dominated by small (<10 μm) Ir-, Os-, or Ru-bearing phases including laurite (RuS
2
,) erlichmanite (OsS
2
), ?kashinite (Ir
2
S
3
) and Ir-Os-Ru alloys. Small euhedral laurite and erlichmanite grains are commonly enclosed within chrome-spinel grains, whilst anhedral Ir-, Os- and Ru-bearing sulphides and alloys are present within interstitial serpentinite. No PGM have been located in the more widely documented Poundland Burn chromitites of the southern serpentinite belt. The platinum-group mineral assemblage is typical of ophiolitic, chromitite-hosted platinum-group mineralization.
Dinosaur footprints from the Duntulm Formation (Bathonian, Jurassic) of the Isle of Skye
Authors: Clark N. D. L. , Booth P. , Booth C. , Ross D. A.
Published: January 2010

Synopsis

The first
in situ
dinosaur tracks from Scotland were discovered at the top of the Duntulm Formation (Bathonian, Jurassic) near to Staffin in northeastern Skye. Fifteen individual tridactyl footprints were recorded of which two pairs appear to have been part of the same trackway. The footprints are preserved as natural moulds on a mud-cracked sandstone surface. The individual track sizes range from about 30 cm to over 50 cm in length with narrow to broad digits suggestive of having been made by a medium to large bipedal dinosaur.