bluuebunny/crossref_metadata_2025 huggingface dataset:
The geochemistry and significance of plugs intruding the Tertiary Mull-Morvern lava succession, western Scotland
Authors: Kerr Andrew C.
Published: January 2010

Synopsis

The Tertiary plugs of north Mull and Morvern, can be divided into three broad groups; (1) trachytes and mugearites; (2) diorites and tholeiitic dolerites with < 6 wt. % MgO and; (3) predominantly tholeiitic dolerites with > 6 wt. % MgO. Two trachytic trends are discernible, a low-iron and a high-iron trend. However, only the high-iron trend is found within the Tertiary Mull lava sequence. The origin of these two differentiation trends may be related to the composition of the primary magma, with more tholeiitic magmas fractionating to produce the lower-iron trachytes. The more MgO-rich plugs are invariably tholeiitic and are chemically unlike any of the preserved lavas within the Mull succession. The absence of this composition and of the low-iron trachyte compositions within the lava succession suggests that these magmas were possibly erupted near the top of the lava pile and have since been eroded away. The plugs may have acted as substantial feeders of the lava succession during its later stages of formation, while in the earlier stages the lavas were probably erupted from fissures. The absence of plugs associated with the Skye lavas, contrasts with the Mull and Antrim lava fields, and may be due to the more-intermittent nature of the Tertiary volcanic activity on Skye.
Estimates of the eroded overburden and the Permian–Quaternay subsidence history of the area west of Orkney
Authors: Evans D. J.
Published: January 2010

Synopsis

Due partly to the perceived lack of preservation of strata younger than Devonian in age, the area onshore mainland Scotland and that offshore occupied by the West Orkney Basin, has long been regarded as emergent or close to sea level since end-Devonian times. Boreholes drilled within the West Orkney Basin have revealed much of the assumed Devonian fill of the West Orkney Basin to be Permo-Triassic in age, questioning this long held view. The post-Triassic subsidence history of the basin remains unknown. Well 202/19-1 penetrated Triassic mudstones, from which sonic and density data may provide evidence of an eroded overburden and thereby information regarding the subsidence or burial history of the West Orkney Basin. The availability of just one borehole does not permit the establishment of a porosity-depth relationship (shale burial curve) for shales/mudstones within the basin. However, available data when plotted against published shale depth–density and depth–velocity curves, provide eroded overburden estimates of between 1.3 and 1.6 km for the basin. Additionally the deposition of 250 m of post-erosional Late Tertiary/Quaternary sediments indicates that the eroded overburden was 1.85 km prior to reburial, which it is suggested, represents a reasonable estimate of the total amount of eroded late and post-Triassic overburden. Absolute uplift of 1.75–2.25 km from end-Cretaceous to Late Tertiary times is then calculated for the basin in general. Implications arise for palaeogeographic reconstructions and the timing of Devonian age source rocks entering the oil window. In addition to hydrocarbon generation during Late Devonian–Carboniferous times, further phases would be likely during Permian–Cretaceous burial. The eroded overburden and absolute uplift values suggest the submergence beneath Cretaceous seas of areas long considered at or close to sea level since end-Devonian times. This includes large areas of the Scottish Highlands.
Basal Wenlock biofacies from the Girvan district, SW Scotland
Authors: Clarkson E. N. K. , Harper D. A. T. , Höey A. N.
Published: January 2010

Synopsis

Basal Wenlock shelly biofacies from the Knockgardner Formation (middle Straiton Group) of the Girvan district are dominated by brachiopods and trilobites assigned, respectively, to the
Howellella–Protochonetes
and the
Podowrinella
faunas. The
Podowrinella
fauna is consistently developed across the Midland Valley in Llandovery–Wenlock boundary rocks but the association is not known outside Scotland. In contrast the
Howellella–Protochonetes
fauna is more variably developed and restricted to the western part of the Midland Valley; but the components of this type of fauna occur in Wenlock and Ludlow rocks elsewhere. In Scotland both associations occur in nearshore, commonly storm-dominated sediments. The contrasting distributional patterns of the mobile and sessile benthos may reflect the differing life strategies of both the larval and adult stages in each group. Lithofacies within the upper Llandovery–lower Wenlock Straiton Group are revised within the regressive framework of the region.
Olenellus
and conodonts from the Durness Group, NW Scotland, and the correlation of the Durness succession
Authors: Huselbee Maxine Y. , Thomas Alan T.
Published: January 2010

Synopsis

Olenellus
is recorded from the basal Grudaidh Formation of the Durness Group for the first time, thus confirming the Lower Cambrian age of that part of the succession. Lower Ordovician conodonts have been collected from near the top of the Eilean Dubh Formation, showing that the Cambrian-Ordovician boundary must lie within that unit, at a level somewhat lower than formerly supposed. Previous correlations are reviewed in the light of these new data. There is no positive evidence for rocks of early Lower Cambrian (Placentian) age in NW Scotland. The occurrence of
Salterella
in the Pipe Rock Member (Eriboll Formation) and the An t-Sròn and basal Grudaidh formations, and of
Olenellus
in the second two, indicates that part of the sequence belongs to the
Olenellus
Biozone (Toyonian Stage, Branchian Series) of the late Lower Cambrian. The upper part of the Grudaidh and lower part of the Eilean Dubh formations are probably of Middle Cambrian age, while the upper part of the Eilean Dubh spans the Upper Cambrian to earliest Ordovican. If non-sequences are present within the Eilean Dubh Formation, they are of only short duration. Previously published evidence shows that the higher formations of the Durness Group range from Tremadoc to Llanvirn in age.
Sedimentology of Late Devensian glaciofluvial outwash in the Don Valley, Grampian Region
Authors: Aitken John F.
Published: January 2010

Synopsis

Detailed sedimentological investigations in the Don Valley, Grampian Region, have allowed the subdivision of the outwash succession into four main lithofacies associations, namely proximal braided outwash, distal braided outwash, overbank deposits and distal alluvial fan deposits. In addition two types of diamicton have been identified; firstly, basal diamicton sheets which mantle bedrock and are interpreted as probable lodgement tills and, secondly, more localised diamictons capping and interbedded with the outwash deposits, which are interpreted as debris flows from ice (‘flow tills’). Many of these successions display deformation features and faulting as a probable consequence of deposition on top of and banked against stagnant ice. This provides evidence for the style of deglaciation of the Don Valley which was by stagnation and
in situ
melting rather than by active retreat.
The stratigraphy and depositional context of a temporary exposure in the Anstruther Formation (Strathclyde Group), Anstruther Wester, Fife
Authors: Kassi A. M. , Weir J. A. , Browne M. A. E. , McManus J.
Published: January 2010

Synopsis

A temporary exposure in the Anstruther Formation (Strathclyde Group: Viséan, Asbian) behind the now-demolished Anstruther Wester swimming pool uncovered 13 m of strata within a cyclical sedimentary succession. A total of 68 m of this succession were logged from an arbitrary 10 m below the base of the Johnny Dow’s Pulpit sandstone to 5.2 m above the Billow Ness Marine Band.

The measured section includes two complete and two incompletely measured cycles representing variations on a primitive ‘Yoredale’ pattern, in which the transgressive marine shale–carbonate shelf facies is largely suppressed in favour of upward-coarsening progradational prodelta and delta front, and aggradational delta plain facies.

Each cycle commenced in a non-marine to marginal marine coastal environment in which shales, thin dolostones (some oncolitic), and ‘musselband’ shales and dolostones were deposited (the mussels are non-marine bivalves). Shales were succeeded by progradational channelized delta front facies, and aggradational delta plain facies also including channel-fill sandstones, typically with pedogenic tops. Variations in cycle thickness relate partly to fluctuations in the supply of sand-grade sediment, and partly to contemporary subsidence, possibly related to tectonic processes.

Comparisons are made with the late Brigantian Lower Limestone Formation at St Monans, which together with the Anstruther Formation forms part of a transgressive megasequence initiated late in the Devonian with continental, alluvial, redbeds.
Ordovician radiolaria from bedded cherts of the Southern Uplands
Authors: Danelian T. , Clarkson E. N. K.
Published: January 2010

Synopsis

Dilute hydrofluoric acid leaching of radiolarian cherts has yielded the first identifiable radiolaria from the Northern Belt of the Southern Uplands. The radiolaria are abundant, as are sponge spicules, and occur with spindle-shape hollow biomorphs of unknown affinity. The red-brown chert sequence at Hawkwood Burn may be correlated with the upper Llanvirn (Llandeilian)–Caradoc
Haplentactinia juncta
–
Inanigutta unica
assemblage in
Nazarov’s (1988)
biozonation. The presence of
Protoceratoiciskum
sp. and the absence of typical Arenig morphotypes indicates that the greenish-grey cherts near Crawford can also be tentatively regarded as of Llanvirn-Caradoc age (
sensu

Fortey
et al.
1995

).
A geological perspective on the Stone of Destiny
Authors: Fortey N. J. , Phillips E. R. , McMillan A. A. , Browne M. A. E.
Published: January 2010

Synopsis

The petrography of a sample detached from the Stone of Destiny during the late nineteenth century by the Geological Survey of Great Britain, is described. The observations are compared with past geological descriptions of the Stone of Destiny and speculation regarding its origin, and are set against new petrographic descriptions of samples of Old Red Sandstone lithofacies from Geological Survey collections. The lithology of the Stone resembles that of Lower Devonian sandstones from the Perth area. In particular, the texture, mineral assemblage and colour are similar to those of sandstones from the Scone Formation in the vicinity of Quarry Mill, near Scone Palace itself. It is thus possible that this area contains the bed from which the Stone was hewn, although comparable rocks may exist within other exposures of the Old Red Sandstone lithofacies in Scotland.
A welded pyroclastic deposit within the Dinantian Clyde Plateau Volcanic Formation, near Eaglesham, in the East Renfrewshire Hills of the Midland Valley
Authors: MacPherson K. A. T. , Phillips E. R.
Published: January 2010

Synopsis

This paper describes the first recorded occurrence of a welded lapilli-tuff in the Dinantian, Clyde Plateau Volcanic Formation. The pyroclastic succession which is exposed near Eaglesham, in the East Renfrewshire Hills, comprises three principal units. The lowest, a coarse volcaniclastic breccia formed by mass movement, is overlain by two fining-upward sequences which grade from a basal pyroclastic breccia into lapilli-tuff. The fining-upward and bedded nature of these upper units, coupled with their lack of diagnostic features indicative of pyroclastic ash flows, has led to the conclusion that they are ashfall deposits. Each deposit probably represents an eruptive unit, with the basal breccia indicating a vent-clearing episode during the initial stages of eruption. The heterogeneously welded lapilli-tuffs from the lower of the two cooling units may, therefore, be interpreted as primary, welded ashfall tuff.
The occurrence of zirconian aegirine and calcic catapleiite (CaZrSi
3
O
9
.2H
2
O) within a nepheline syenite, British Tertiary Igneous Province
Authors: Preston Jeremy , Hole Malcolm , Bouch Jon , Still John
Published: January 2010

Synopsis

Minor occurrences of nepheline syenite are present in a hypabyssal intrusion composed predominantly of alkali olivine dolerite, at Cnoc Rhaonastil, Islay. Their mineralogy is dominated by albite and kaersutite, but minor, strongly zoned sodic pyroxenes of the hedenbergite-aegirine solid solution series are present. These pyroxenes contain up to 5.30 wt% ZrO
2
. Two Zr-rich end-member substitutions are important: (1) NAZAL (NaZrAlSiO
6
) and (2) FM-NAZ (Na(Fe,Mg)
0.5
Zr
0.5
Si
2
O
6
), although the latter is probably dominant. There is no clear overall interdependence between zirconium content and pyroxene end-member compositions, implying crystallization was from localized Zr-rich domains in a residual felsic liquid. The earlier crystallization of pure calcic catapleiite (CaZrSi
3
O
9
.2H
2
O) may have caused localized depletions in the Zr content of the melt. As far as we are aware, this is the first reported occurrence of zirconian aegirine from Scotland, and only the second reported occurrence of stoichiometric Ca-catapleiite in the literature.
Laxfordian metamorphic conditions of the Palaeoproterozoic Loch Maree Group, Lewisian Complex, NW Scotland
Authors: Droop G. T. R. , Fernandes L. A. D. , Shaw S.
Published: January 2010

Synopsis

The supracrustal rocks of the Loch Maree Group (LMG), which form a Palaeoproterozoic cover to the Scourian basement of the Lewisian complex, underwent amphibolite-facies regional metamorphism during the Laxfordian orogeny. Micro-structural studies indicate that the peak of metamorphism in both the Loch Maree and Gairloch outcrops of the LMG was preceded by at least one major phase of ductile deformation, recorded by annealed lineations and foliations and by inclusion trails in minerals. At Loch Maree, this involved intense WNW–ESE stretching. The metamorphic peak occurred statically and was followed by (i) intense top-to-NW shearing, recorded by mylonitic fabrics particularly associated with the Loch Maree Thrust and (ii) several generations of open folding. These retrograde fabrics and folds reflect tectonically-induced uplift and exhumation during late Laxfordian times.

Thermobarometric studies were undertaken on low-variance rocks that had experienced relatively little retrogressive deformation. A garnetiferous calc-silicate rock, an ironstone and two dolomitic marbles from the Gairloch outcrop yielded Laxfordian peak-metamorphic conditions of 530 ± 20°C and 6.5 ± 1.5 kbar consistent with the epidote–amphibolite–facies assemblages. In general, the mylonites of Loch Maree outcrop proved unsuitable for thermo-barometric work, but a protomylonitic garnet–staurolite–mica schist yielded peak-metamorphic conditions of 630 ± 30°C and 6.5 ± 1.5 kbar. Temperatures during mylonitization were still high enough to stabilize garnet (i.e. > 470°C) which recrystallized as tiny neoblasts in the mylonites.

The peak-metamorphic pressures imply burial of the supracrustal LMG to
c.
24 ± 5 km, requiring substantial early Laxfordian tectonic thickening of the crust. Thus the main phase of basement–cover interleaving occurred before the development of the mylonitic fabric marked by the Loch Maree Thrust. Geothermal gradients at the metamorphic peak were moderate (
c.
20–30°C km
−1
), consistent with metamorphism in tectonically thickened crust. Existing tectonic models for the Laxfordian fail to account for the tectonic burial of the LMG to mid-crustal depths.
Interpretation of magnetic anomalies over the Isle of Arran
Authors: Tantrigoda D. A.
Published: January 2010

Synopsis

Aeromagnetic anomalies over the Isle of Arran and adjacent areas were converted into pseudogravimetric anomalies. A three-dimensional interpretation of the pseudogravimetric anomaly was performed using an iterative technique. This suggests that the subsurface of Arran below the northern granite contains a large normally magnetized body which resembles a truncated cone extending to a depth of 6.5 km with a magnetization of 0.93 A m
−1
.
Xenoliths of Southern Uplands ‘basement?’ in a lamprophyre dyke, Central Belt, Glenluce, SW Scotland
Authors: Floyd J. D. , Phillips E. R.
Published: January 2010

Synopsis

Lamprophyre dykes intruding Gala Group (Upper Llandovery) metagreywackes in the Central Belt of the Southern Uplands commonly contain a few xenoliths, usually of quartzite or vein quartz. However, on the coast south of Glenluce, one dyke contains a suite of incognate xenoliths of foliated and non-foliated meta-igneous rocks in addition to quartz, meta-greywacke and cognate xenoliths. These incognate xenoliths may represent samples either of the basement underlying the Southern Uplands or dioritic/tonalitic intrusions emplaced at depth into the sedimentary cover.
New observations on the Kildonnan Member, Lealt Shale Formation, Middle Jurassic, Isle of Eigg
Authors: Hudson J. D. , Wakefield M. I.
Published: January 2010

Synopsis

New exposures prove the position of the Algal Bed in relation to underlying strata at the type section of the Kildonnan Member. A measured section is given and its significance briefly assessed.
Middle Hettangian (Lower Jurassic) ammonites from Isle of Raasay, Inner Hebrides, and correlation of the Hettangian-lowermost Sinemurian Breakish Formation in the Skye area, NW Scotland
Authors: Morton Nicol
Published: January 2010

Synopsis

Liasicus Zone (middle Hettangian) ammonites, allocated to a new species,
Franziceras sorleyi,
are described from Hallaig, Isle of Raasay and indicate that the Breakish Formation (formerly lower Broadford Beds) there is older than previously thought. The new finds have been integrated with the limited available biostratigraphic information from the rare record s of Hettangian and basal Sinemurian ammonites, and with local lithostratigraphy based on marker beds, to develop a new interpretation of correlations within the Skye–Raasay–Applecross area. This concludes that there was a diachronous early Jurassic transgression and facies change from the continental red beds of the Stornoway Formation into the marginal marine carbonate-dominated sediments of the Breakish Formation.
The Glen Tilt diorite: crystallization, petrogenesis and relation to granitic rocks
Authors: Beddoe-Stephens B.
Published: January 2010

Synopsis

The Glen Tilt diorite forms a significant component of a late Caledonian, calc-alkaline, predominantly granitic intrusive complex on the north-west side of the Loch Tay Fault. It intrudes Grampian Group and lowermost Appin Group Dalradian metasedimentary rocks. The diorite is massive and contains common to abundant hornblende, variable amounts of biotite and clinopyroxene and late-stage intergranular quartz and K-feldspar. Opaque oxide and titanite ar e minor components. Associated granitic rocks comprise biotite granodiorite/granite and muscovite-bearing leucogranite. Dominantly north-easterly trending porphyritic microdiorite dykes are common in the area and cut elements of the granitic plutons.

Petrographical, mineralogical and chemical variation in the diorite is the result of crystal fractionation and accumulation processes. Comparison with experimental studies together with thermobarometric estimates suggests the body crystallized at 2–4 kbar and under hydrous conditions; early clinopyroxene exhibits a reaction relationship with later crystallizing hornblende. Pressure estimates are consistent with phase assemblages developed in contact metamorphosed pelitic rocks. Bulk rock and mineralogical chemical comparison suggest the porphyritic microdiorite minor intrusions are co-magmatic with the main diorite.

Field relations and petrographical observations indicate that biotite granodiorite/granite is emplaced early in the intrusive sequence and that localized melt remobilization and back-veining accompanied diorite emplacement. Leucogranite probably occurs later in the intrusive sequence although the complex as a whole was probably emplaced in a short time span. The chemical compositions of the main plutonic elements suggest they are not directly related by differentiation of a common magma but more likely represent contribution s from differing mantle and crustal sources. The complex as a whole probably represented the site of a magma chamber that fed coeval Siluro–Devonian volcanism, the ascent of magma probably being focused along the Loch Tay Fault and an intersecting NW trending structure.
An occurrence of silicic volcanic rocks in the early Palaeogene Antrim Lava Group of Northern Ireland
Authors: Mitchell W. I. , Cooper M. R. , Hards V. L. , Meighan I. G.
Published: January 2010

Synopsis

The Donald’s Hill Ignimbrite Formation is a one metre thick silicic welded ash-flow tuff with a 30 km long outcrop at the western margin of the Antrim Plateau in Northern Ireland. It occurs at the base of the early Palaeogene Antrim Lava Group and is the first record of voluminous silicic volcanism in the Northern Ireland sector of the British Tertiary Volcanic Province. Globally, this occurrence of silicic pyroclastic flow material at the
base
of a flood basalt sequence is unusual.
Ordovician limestone clasts in the Lower Old Red Sandstone, Pentland Hills, southern Midland Valley Terrane
Authors: Armstrong H. A. , Owen A. W. , Clarkson E. N. K.
Published: January 2010

Synopsis

In the southern part of the Scottish Midland Valley Lower Old Red Sandstone sedimentary and volcanic strata of the Lanark Group unconformably overlie inliers of largely marine Silurian rocks. The oldest of the four formations of the Lanark Group is the Greywacke Conglomerate Formation which contains clasts predominantly of greywacke, with subordinate volcanic rocks, cherts and limestones. The greywackes are known to have been derived from a cryptic source which lay to the south and east of the Midland Valley. Contrary to earlier, Silurian, age assessments of limestone clasts from the Greywacke Conglomerate Formation of the Pentland Hills, a conodont faunule described herein belongs in the uppermost Llanvirn to lower Caradoc
P. anserinus
Biozone. There are no Ordovician rocks exposed within the Pentland Hills inlier, and thus our new age data suggest that along with the other clasts, the limestones in the Greywacke Conglomerate are exotic to the Pentlands Sub-basin. The source area had a cover succession that included mid-Ordovician shallow marine carbonate and flysch.
The provenance of Devonian sandstones from Shetland: a Sm-Nd and trace element study
Authors: Knudsen T.-L.
Published: January 2010

Synopsis

A Sm-Nd isotope and trace element study has been performed on a selection of four whole rock samples of Devonian sediments, two impure/banded quartzite boulders and two unfoliated granite/granophyre boulders from a Devonian conglomerate. Included in the study are also three samples of Caledonian metasediments (from the Whiteness, Clift Hills and Yell Sound Divisions) and one Archaean tonalite gneiss (the Wilgi Geos Group) from Shetland. The Devonian sediments and the granite boulders have relatively low Nd model ages of 1.0 to 1.1 and 1.3 to 1.5 Ga, respectively, which suggests the presence of Caledonian juvenile material in both of these rock types. The Proterozoic metasediments have Nd model ages in the range 1.8 to 2.5 Ga, while the tonalitic gneiss has a high Nd model age of 2.9 Ga. The Caledonian metasediments form two compositionally contrasting groups where the Yell Sound and Clift Hills Divisions and the two impure quartzite boulders all have relatively low time-corrected
143
Nd/
144
Nd ratios and low Nb-and Sr-contents relative to the Whiteness Division. These two groups of Caledonian metasediments together with representative Caledonian ophiolite rocks define a compositional field of time-corrected
143
Nd/
144
Nd ratios and Nb and Sr contents, within which plot the compositions of the Devonian sediments and the granite/granophyre boulders. Cr is generally immobile at surface and low-grade metamorphic conditions, but is less suitable as a provenance indicator due to the wide variations in the Cr-content in Caledonian juvenile rocks.
Tetrapod trackways
(Matthewichnus
sp. and?
Pseudobradypus
sp.) from the Coal Measures (Carboniferous) of Central Scotland
Authors: Clark N. D. L. , Jewkes M.
Published: January 2010

Synopsis

A Carboniferous sandstone slab containing two trackways from the Coal Measures of Scotland was donated to the Hunterian Museum in 1926. These trackways have never previously been described and consist of smaller
Matthewichnus
and larger ?
Pseudobradypus
tracks. This occurrence is one of only two known from the Carboniferous of Scotland in museum collections the other being in the collections of the Paisley Museum.
‘Where ignorance is bliss ‘tis a folly to be wise’ (Thomas Gray 1716–1761) – controversy in the basement blocks of Scotland
Authors: Bluck B. J.
Published: January 2010

The Millennium Issue

The year 2000 is the Millennium year and it is appropriate that the Scottish Journal of Geology should mark it in some way. The Editorial Board feel that at this time, at the beginning of what is arguably its 4th century, it is important to bring out the unique and varied character of Scottish geology. After some discussion it was decided to invite short essays from scientists for whom the geology of Scotland has had a special importance and who have themselves had a particular influence on Scottish Geology.

We asked for personal approaches to what is significant about the geology of Scotland. In what way has it inspired? Is it because of the intrinsic importance of the discoveries made here or more simply the influence of the environment? We hoped that some contributions would take a more geopolitical view. How much influence has Scotland had on the development of the science of geology as a whole and is there anything left here to discover?

We have been delighted with the contributions we have received. A recurrent theme has been the influence of place and it is clear that many of our contributors are as aware of the scenery and their feelings about this important legacy as they are about the (in some ways) more mundane geological issues. Many have included a historical viewpoint, and have reminded us how great a part was played in the last century by observers in Scotland in putting the science of geology together from its diverse beginnings.

These contributions appear in both issues of this volume of the Journal and are identified by photographs of the authors and brief notes on their careers.
The architecture of the Shetland Ophiolite
Authors: Flinn Derek
Published: January 2010

Synopsis

The Bouguer anomaly gravity map of the islands of Unst and Fetlar in northeast Shetland shows a high amplitude positive gravity anomaly overlying the metagabbro outcrop (average density 3.0 Mg/m
3
) of the Shetland ophiolite in Unst. The aeromagnetic map of the same area shows a high amplitude positive magnetic anomaly overlying the serpentinised ultramafic layers (average density of 2.62 Mg/m
3
) of the ophiolite lying west of the metagabbro. Geologically-predicted gravity-adjusted profiles across the ophiolite confirm the geological interpretation of the ophiolite as a nappe of ultramafic and basic vertical layers overlying the schist-gneiss basement. The base of the nappe reaches a maximum depth of about 3 km (assuming an average density for the basement of 2.75 Mg/m
3
). The magnetic properties of the serpentinites are too variable to be used in modelling. However, the aeromagnetic profiles along the gravity traverses are closely matched by calculated magnetic profiles based on selected notional susceptibilities.
Platinum-group element mineralization within ultramafic rocks at Corrycharmaig, Perthshire: implications for the origin of the complex
Authors: Power M. R. , Pirrie D.
Published: January 2010

Synopsis

Alloys and complexes of the platinum-group elements (PGE) Pt, Pd, Ru, Rh, Ir and Os occur as discrete platinum-group minerals (PGM) throughout the chromite-dominant lithologies of the Corrycharmaig ultramafic body. PGM are either enclosed by chromite or occur in association with secondary Ni sulphide (heazlewoodite). The PGM enclosed by chromite are large (up to 40 μm), euhedral and interpreted to be primary magmatic in origin. Those that occur in association with heazlewoodite are small (<2 μm) and appear to have partitioned into the sulphide phase during alteration and metamorphism and subsequently exsolved. The dominance of Ru, Ir and Os (Ir PGE or IPGE) suggests that either the Corrycharmaig protolith was enriched in these elements relative to Rh, Pd and Pt (Pt PGE or PPGE) or that primary PPGE have been removed from the system. Previous interpretations for the genesis of the Corrycharmaig body have included ophiolite complexes or, more recently, komatiitic intrusions. The nature of the chromite mineralization and chemistry along with the presence of large laurite (IPGE-rich) grains enclosed by chromite are more indicative of an ophiolitic origin.
A Middle Devonian chasmataspid arthropod from Achanarras Quarry, Caithness, Scotland
Authors: Anderson Lyall I. , Dunlop Jason A. , Trewin Nigel H.
Published: January 2010

Synopsis

A new fossil of the rare and little known arthropod group Chasmataspida (Chelicerata), is described as
Achanarraspis reedi
gen. et sp. nov. from the Middle Devonian (late Eifelian) of Achanarras Quarry, Caithness, Scotland. This is the first known occurrence of arthropod remains from this locality. Chasmataspids appear to be closely related to eurypterids and fossils of these groups have been confused with each other in the past.
Achanarraspis
resembles Lower Devonian chasmataspids from Germany, the Midland Valley of Scotland and the Severnya Zemlya Archipeligo, Siberia, but is distinguished from these taxa in possessing a carapace which is distinctly longer than the preabdomen, sharp lateral epimera on all postabdominal tergites, and a distinctive telson morphology. The Middle Devonian age makes
Achanarraspis
the youngest chasmataspid yet known and significantly extends the known stratigraphical range of the group. Other occurrences of arthropods from the Caithness Flags are reviewed and include conchostracan crustaceans, incomplete eurypterids and a now lost xiphosuran specimen collected in the late 1800s.
Rogercooperia,
a new genus of Ordovician glossograptid graptolite from southern Scotland and New South Wales, Australia
Authors: Sherwin L. , Rickards B.
Published: January 2010

Synopsis

Rogercooperia phylloides
(Elles & Wood 1908) gen. nov. and
R. paucispinosus
(Sherwin & Rickards) form the basis of a new genus evolutionarily related to the last of the glossograptids in the
wilsoni
Biozone (early Caradoc) of Scotland, UK and the
calcaratus
Biozone (highest Gisbornian) of New South Wales, Australia. The similar genus
Nanograptus
Hadding (1915), from the early Caradoc of Scandinavia, is reviewed, and is considered a late evolutionary derivative of
Cryptograptus
Lapworth (1880).
Rogercooperia
and
Nanograptus
are convergent genera. Although of different evolutionary lineages both show loss of proximal spinosity, loss of rhabdosomal spinosity, and lessening of thecal spinosity, resulting in an overall similar appearance. The loss of spinosity is typical of many lineages of biserial graptolites in the late Caradoc and Ashgill. The early development of the colonies, in both genera, includes a low metasicular origin of thl
1
, again a late evolutionary feature.
Silurian cephalopods from the Pentland Hills
Authors: Holland Charles Hepworth
Published: January 2010

Synopsis

The nautiloid cephalopod fauna of the Silurian rocks of the Pentland Hills, Scotland is described. Though fragmentary, the available material permits assignment to 14 genera, for 10 of which specific names are given. Nearly all of the material is from the Wether Law Linn Formation and mostly from its lower part. Implications as to stratigraphical age are discussed. The fauna of the Wether Law Linn Formation has something of a Wenlock flavour.
A side-scan sonar image of a glacially-overdeepened sea loch, upper Loch Etive, Argyll
Authors: Howe John A. , Overnell Julian , Inall Mark E. , Wilby Andrew D.
Published: January 2010

Synopsis

Loch Etive in Argyll on the west coast of Scotland, is a 30 km long, up to 145 m deep sea loch of glacial origin. A unique side-scan sonar image with new accompanying bathymetric data of the upper basin of the loch has been obtained, covering an area of 19.5 km
2
. These data illustrate the morphology of the loch floor and the depositional processes that have been active in the loch since the end of the last (Younger Dryas stadial) glaciation, approximately 10 ka
bp
. The new bathymetry reveals the complex physiography of the loch with the deepest (> 100 m) regions confined to the SW with slope angles of 5–15°. Towards the head of the loch water depths are shallower, with < 50 m common and the loch floor is also smoother with slope angles of 2–5°. Using the side-scan image, areas of high and low acoustic backscatter have been identified. The high backscatter areas correspond to regions of exposed outcrops of
in situ
granite, with localized glacial erratics on the loch floor, and the low backscatter areas to deeper-water basins containing fine-grained sediments. Other features observed are submarine cliffs, downslope creep of water-laden sediments on the steeper loch slopes, and outwash submarine fans from rivers.
The significance of a Hastingsite granite in the Carn Chuinneag–Inchbae Complex
Authors: Harker R. Ian , Leahy Timothy
Published: January 2010

Synopsis

The discovery of a late stage hastingsite gneissic granite in the Inchbae mass (possibly coeval with the riebeckite gneissic granite in the Carn Chuinneag mass) indicates that different physico-chemical conditions prevailed during the last granitic stages of the two masses. This, along with other evidence at the North and SE contacts, is in accord with a previous view that the Inchbae mass is at a different stratigraphic level (lower) relative to the Carn Chuinneag mass.
The influence of rock mass strength on the form and evolution of deglaciated valley slopes in the English Lake District
Authors: Brook M. S. , Tippett J. M.
Published: January 2010

Synopsis

Selby established the fact that on many rock slopes a condition of ‘strength–equilibrium’ exists in which slope gradients are in adjustment with the mass strength of the underlying rock. An established assessment technique, the rock mass strength (RMS) classification, can be used to quantify rock slope condition and, in combination with slope gradient, determine the status of rock slopes with respect to a statistically-defined ‘strength–equilibrium envelope’. This technique has been applied to 59 glacial valley slopes in the English Lake District, an area with characteristic ‘U-shaped’ glacial valleys, deglaciated around 11 ka
bp
. Overall, two-thirds of the slopes examined plot within the limits of the strength-equilibrium envelope, whilst the remainder are ‘understeepened’ or ‘oversteepened’ with respect to their RMS. ‘U-shaped’ valleys possess slopes that are yet to respond measurably to post-glacial erosion or readjust significantly. Evidently, slopes in similar deglaciated environments with tectonic, climatic and relief characteristics comparable with those of the Lake District need more than 11 ka (and probably much more) to evolve into strength-equilibrium. The implication is that even if slopes plot within the strength-equilibrium envelope they are in a pseudo-equilibrium condition, indicating that the Selby strength-equilibrium theorem is inapplicable to landscapes deglaciated
c.
11 ka
bp
.
Macrofauna and palaeoenvironment of marine strata of Windermere Interstadial age of the east coast of Scotland
Authors: Peacock J. D.
Published: January 2010

Synopsis

Cold water of near normal marine salinity penetrated into eastern Scottish firths for a few hundred years early in the Windermere Interstadial, but thereafter conditions in the Firth of Tay and the innermost Firth of Forth became more brackish, probably because of falling sea-levels and estuarine infilling. The impoverished macrofaunal assemblages dominated by
Nuculana pernula
and
Yoldiella lenticula
resemble those of present-day high-boreal to arctic soft bottom communities associated with high rates of deposition, but several temperate molluscs known from contemporary deposits in the Clyde area are apparently absent. Deposition of mud was locally >20 mm per year in the firths of Forth and Tay, and >7 mm per year in the Cromarty Firth. These figures are comparable to those obtaining both in offshore estuarine basins during the decline of sea-level from the highest Flandrian raised beach in the Firth of Forth and in proximal glaciomarine environments elsewhere.
A Windermere Interstadial marine sequence: environmental and relative sea level interpretations for the western Forth valley, Scotland
Authors: Holloway L. K. , Peacock J. D. , Smith D. E. , Wood A. M.
Published: January 2010

Synopsis

Multidisciplinary investigations of a radiocarbon dated isostatically raised, shallow marine sequence have enabled environmental parameters, including estimates of relative sea level and water temperatures, to be reconstructed for the Windermere Interstadial (WI) in the western Forth valley. Detailed faunal (ostracod and macrofauna) and sedimentological (particle size and micromorphology) examination of the 2.28 m sequence at Moss-side of Boquhapple suggests the existence of a shallow fjord-style margin environment at the site. Comparisons between recent faunal analogues and the fossil record suggest that WI relative sea levels can be limited to between +15 and +30 m OD. Additional regional stratigraphical and geomorphological investigations augment this interpretation. New AMS
14
C dates suggest that marine accumulation at the site was established by
c.
12.8 ka
bp
, and continued to probably after
c.
11.5 ka
bp
. Palaeotemperature reconstructions from the macrofauna and ostracod records show some divergence, but suggest temperatures were lower than present. The upper 0.50 m of the sequence shows significant reworking, and micromorphological analysis of one sample from this marine deposit discloses a limited number of features consistent with subaerial (possibly periglacial) processes. The final lowering in relative sea level, possibly to below +7 m OD, is believed to have occurred during the Loch Lomond (Younger Dryas) Stadial.
Constraints on the age of the Bardahessiagh Formation, Pomeroy, County Tyrone
Authors: Candela Yves
Published: January 2010

Synopsis

A lack of exposure in the Well Field at Pomeroy, County Tyrone, Northern Ireland, allowed previous researchers to work only from loose blocks in attempting to deduce an age for the Bardahessiagh Formation, occurring in the Palaeozoic inlier of Pomeroy. Brachiopods, collected
in situ
from a trench dug in the Well Field, during the summer of 1992, are being used to refine the age of the Bardahessiagh Formation. Three different assemblages are described. The assemblage collected from the top member of the Bardahessiagh Formation shows strong similarities with that of the Kirkcolm Formation, Kilbucho, Scotland, indicating a Woolstonian age. Faunas from the middle member and the top part of the lower member of the Bardahessiagh Formation comprise species of which oldest record has been found from rocks of Longvillian age in Laurentia.
Biostratigraphy and palaeoenvironments of the Ballagan Formation (lower Carboniferous) in Ayrshire
Authors: Stephenson Mike , Williams Mark , Monaghan Alison , Arkley Sarah , Smith Richard
Published: January 2010

Synopsis

A local palynostratigraphical subdivision for the Ballagan Formation in Ayrshire is established, based on the Heads of Ayr coastal section. The lower part of the formation is characterized by a low-diversity CM Biozone
Colatisporites-dominated
assemblage, while the upper part is characterized by high-diversity assemblages containing
Acanthotriletes
cf.
macrogaleatus
and
Radiizonates mirabilis,
and assemblages dominated by
Leiosphaeridia
algal palynomorphs. Sedimentological analysis of the lower part of the formation suggests deposition in an arid coastal floodplain environment. Up sequence, there is a gradual reduction in sandstones, suggesting reduced fluvial influence. The Ballagan Formation yields ostracodes indicative of marginal marine and brackish environments, which supports the sedimentological interpretation. The lower part of the formation contains species that are typical of the Tournaisian
Beyrichiopsis glyptopleuroides-Eriella
Biozone, providing a stratigraphical tie with the CM Biozone assemblage. The upper part of the formation yields ostracodes that elsewhere have been reported from the Viséan, but
Lycospora pusilla,
the index taxon for the Viséan Pu palynomorph Biozone, was not recovered. Two age interpretations can be offered for this part of the section: either late Tournaisian or early Viséan. A late Tournaisian–early Viséan age for the Ballagan Formation would imply that
L. pusilla
is so rare in the lower parts of its range that dense sampling failed to recover it. By contrast, a Tournaisian age for the entire Ballagan Formation at the coast implies recalibration of some ostracode ranges. Above the Ballagan Formation, mid-Viséan palynomorph assemblages from the Lawmuir Formation allow the Heads of Ayr volcanic vent to be dated in the range late Tournaisian-mid-Viséan, implying correlation with the Clyde Plateau Volcanic Formation.
Glaci-tectonic deformation of proglacial lake sediments in the Cairngorm Mountains
Authors: Golledge Nick
Published: January 2010

Synopsis

Polyphase deformation of glaciolacustrine sediments in the Cairngorm Mountains suggests ice-margin oscillations within a plateau ice-field outlet lobe following the Late Devensian Glacial Maximum,
c.
18 ka
14
C
BP
. Lithostratigraphical analysis of exposures of glacial lake sediments in Gleann Einich reveals that an initial phase of proglacial thrusting was followed by a phase of subglacial deformation resulting from glacier-overriding from the south. Subsequent ice retreat led to the deposition of more extensive lake and delta sediments. This new model of active retreat supports recent theories of a Late Devensian deglaciation punctuated by ice-margin readvances.
Igneous rocks of the Georgeton burn, Cleish Hills
Authors: Hamill Brendan J.
Published: January 2010

Synopsis

Basaltic rocks in the Cleish Hills of Kinross-shire, previously described as lavas of the Clyde Plateau volcanic series, are shown to be later intrusions. This re-interpretation raises doubts about published correlations of these rocks and the possible origin of igneous rocks and breccias in the Loch Leven area during the period 325–295 Ma.
Neodymium isotope characteristics of Ordovician sediment provenance on the Avalonian margin of the Iapetus Ocean
Authors: Stone P. , Evans J. A.
Published: January 2010

Synopsis

Whole-rock
ɛ
Nd data from early Ordovician, Skiddaw Group (English Lake District) sandstones support correlation of the northern (and oldest) part of the group’s outcrop (
ɛ
Nd range of −4.1 down to −8.5) with the Manx Group (Isle of Man) (
ɛ
Nd range of −4.7 down t o −7.2). Both groups were deposited on the Avalonian margin of the Iapetus Ocean, with constituent sediment derived from an earlier, possibly Precambrian, continental margin and volcanic arc situated further south in the Avalonian–Gondwanan hinterland. The Nd isotope data from the Skiddaw Group sandstones show a trend of increasing provenance maturity with time, possibly the effect of arc unroofing. The trend is diachronous, with relatively mature sediment being deposited in the south of the Lake District during the Arenig (
ɛ
Nd range for sandstones is −7 down to −9.3), whilst generally more juvenile sands fed into the north (
ɛ
Nd ranges up to −4.1). The mature sands subsequently extended northward and Llanvirn sandstones from the Skiddaw Group show the most consistently mature provenance characteristics (
ɛ
Nd range of −7.6 to −8.7). Manx Group data are relatively homogeneous with no clear temporal trends. Mudstone data from the Skiddaw Group divide into two populations separated by the Causey Pike Fault; there is no overlap in mudstone
ɛ
Nd across the fault. The more mature mudstones (
ɛ
Nd more negative than −8.1) lie to the south of the fault, an unexpected result in that the sequence there contains juvenile volcaniclastic interbeds. The
ɛ
Nd data rule out the adjacent parts of Avalonia as a possible sediment provenance. Instead, a more distant, Gondwanan provenance seems likely, with implications for basin geometry and the timing of rifting along the southern margin of the Iapetus Ocean.
Late Devensian marine deposits (Errol Clay Formation) at the Gallowflat Claypit, eastern Scotland: new evidence for the timing of ice recession in the Tay Estuary
Authors: Peacock J. D.
Published: January 2010

Synopsis

The Late Devensian arctic marine deposits (Errol Clay Formation) at the Gallowflat Claypit between Perth and Dundee are correlated with the type succession at nearby Inchcoonans, but include an expanded basal glaciomarine unit with rhythms interpreted as symmict varves. Laminated silt–clay couplets are thought to be tidal. Conditions were fully marine by 13.8 ka
bp
(based on new radiocarbon dates and a 400 a reservoir age). Following recession of the Tay–Forth glacier from its advanced Late Devensian position at the Wee Bankie Terminal Moraine, it is inferred that deglaciation of the middle Tay estuary some 100 km to the west took place between 14.5 and 14 ka
bp
. The possibility that there was a readvance of ice in the Tay and Forth estuaries during or close to the Heinrich iceberg discharge event H1 is briefly discussed.
A new, stratigraphically significant
Torquigraptus
species (Silurian graptolite) from the Southern Uplands Terrane
Authors: Williams Mark , Zalasiewicz Jan , Rushton Adrian W. A. , Loydell David K. , Barnes Robert P.
Published: January 2010

Synopsis

The helically coiled
Torquigraptus linterni
sp. nov. has a biostratigraphical range restricted to the
sedgwickii
and
halli
graptolite biozones of the upper Aeronian. In southern Scotland it occurs in the Moffat Shale Group (Birkhill Shale Formation) at the western end of the Ettrick Valley and at Dob’s Linn, and is also known from a mudstone interbed in turbidite sandstones to the north of the Megget Dam. Its associates include
Torquigraptus magnificus
(Přibyl & Münch), recorded for the first time in Scotland. Together, these two
Torquigraptus
species provide additional useful tools for correlation of lithostratigraphy in the central part of the Southern Uplands.
A Late Arenig (early Yapeenian) graptolite fauna and the coeval tectonic development of the Ballantrae Complex ophiolite, SW Scotland
Authors: Stone P. , Rushton A. W. A.
Published: January 2010

Synopsis

A Late Arenig graptolite fauna is known from one isolated occurrence within the Ballantrae Complex ophiolite; a borehole core taken near North Ballaird farm. Reassessment of that fauna shows it to be of early Yapeenian (Yal) (just possibly late Castlemainian; Ca4) age and confirms that it is significantly younger than all other dated components of the complex. Of particular importance are the records of
Arienigraptus gracilis
(Ruedemann),
Isograptus australis
Cooper and
Yutagraptus
?
v-deflexus
(Harris). The graptolitic sequence conformably underlies a microconglomerate bed in which the clasts are coated by algal encrustation. Some of those clasts are of serpentinite, which was therefore clearly available for erosion into shallow water during the early Yapeenian stage. It seems most likely that the serpentinite was structurally elevated during obduction of the ophiolite, a process driven by arc-continent collision. On a broad, regional scale this can be associated with the collisional event initiating the Grampian Orogeny, for the timing of which the early Yapeenian age of the North Ballaird graptolite fauna provides an additional control.