bluuebunny/crossref_metadata_2025 huggingface dataset:
Modes of life of arthropods from the Burgess Shale, British Columbia
Authors: Briggs D. E. G. , Whittington H. B.
Published: November 2011

The modes of life of twenty three species of arthropods from the Shale are reviewed, with special reference to locomotion and feeding. Six groups are recognised, predatory and scavenging benthos, deposit-feeding benthos, scavenging and possibly predatory nektobenthos, deposit-feeding and scavenging nektobenthos, nektonic filter-feeders, and a miscellaneous sixth group that includes a questionable example of parasitism and a species that doubtfully grazed on algae. These animals had but limited powers of walking, digging, raking or swimming. Within these limitations a range of morphological adaptations and modes of feeding had been evolved, by Middle Cambrian time, a range comparable to that found in Recent marine forms. Arthropods in the Shale dominated, in numbers of individuals and possibly in biomass, a fauna dwelling above, on and in a muddy substrate at a depth of about 100 m.
Gross morphology and the mode of life of two species of lobster from the Lower Cretaceous of England:Meyeria ornata(Phillips) andMeyerella magna(M'Coy)
Authors: Simpson Martin I. , Middleton Richard
Published: November 2011

Macrurous decapod crustaceans are generally uncommon and are often incompletely preserved. However, at certain horizons in the Speeton Clay (Ryazanian–Albian) and Atherfield Clay (Lower Aptian) of Yorkshire and the Isle of Wight respectively, macrurans form the dominant element of the fauna. Two species in particular,Meyeria ornata(Phillips) andMeyerella magna(M'Coy), are not only very common in these formations, but are also very well preserved. Recent collections have yielded a large number of specimens of both species. This material is examined with the aid of SEM techniques, gross morphology is discussed, and the details of the exoskeletons are compared. In the case ofM. magna, examples are figured which show traces of a colour pattern and the effects of regeneration on the first pereiopods. A discussion is included of the possible function of the appendages inM. magnaandM. ornata, and of their other, unique features. Finally, the mode of life of both species is inferred from a consideration of their morphology, and of the evidence from their preservation, distribution and relationships with associated faunas.
Moulting in phacopid trilobites
Authors: Speyer Stephen E.
Published: November 2011

Phacopid trilobites, unlike most trilobites, lack functionally articulated libregenae. This distinction presumably dictated ecdysial strategies which were fundamentally different from those forms with sutured cephala.Phacops rana(Green) andGreenops boothi(Green) from the Middle Devonian Hamilton Group (New York) are preserved in circumstances which illustrate certain aspects of their moulting behaviour. Undisturbed exuviae display five different moult patterns; these suggest two basic modes of exuviation in phacopid trilobites (Body-upright and Body Inversion Moult Procedures).

Certain Hamilton beds yield clusters ofPhacopscomprising complete and/or moulted remains. Complete trilobites in body clusters display varied orientations which, when considered in conjunction with exuvial patterns in moult clusters, suggest ecdysial procedures that involved body inversion and erratic tergal contractions (Body Inversion Moult Procedures). Ensembles where in thoracopygidia are upright and outstretched indicate hyperextension of the thorax and disarticulation of the cephalo-thoracic suture (Body-upright Moult Procedures).Phacopsmoult ensembles are characterised by inverted and tightly recurved thoracopygidia, whereasGreenopsensembles comprise outstretched, usually upright thoracopygidia with cephala that are frequently upright. Classic ‘Salterian’ patterns are uncommon inPhacops ranaand have not been recognised inGreenops boothi.Variations in moult procedure are attributed to differences in functional morphology and substrate consistency.
Cyrtoctenus wittebergensissp. nov. (Chelicerata: Eurypterida), a large sweep-feeder from the Carboniferous of South Africa
Authors: Waterston C. D. , Oelofsen B. W. , Oosthuizen R. D. F.
Published: November 2011

Cyrtoctenus wittebergensissp. nov. is described from a unique holotype from the Witteberg Group of the Cape Supergroup. It is a giant hibbertopteroid eurypterid having combs and specialised movable spines of crytoctenid type (Størmer & Waterston 1968) on the more distal podomeres of the second to fourth prosomal appendages. The function of the combs and their associated movable spines is discussed and it is suggested that together they formed a unique adaptation of eurypterid structures to sweep filter-feeding, the combs forming the filters and the spines the cleaners. The digestive tract is remarkably preserved and shows a spiral valve, posterior to the stomach, which is interpreted as an adaptive feature in this large arthropod to increase the absorptive area of the gut.

The new evidence provided by the South African specimen has required the re-interpretation of the disarticulatedCyrtoctenusspecimens previously described from Europe.Disjecta membrarecently obtained from the Tournaisian of Foulden, Berwickshire, which may belong toCyrtoctenus, are described and show characters previously unknown in Scottish material but similar to certain features in the South African specimen.

The taxonomic relationships within the Hibbertopteroidea are discussed in the light of the new combination of characters found inC. wittebergensis. Two families are recognised in the superfamily, the Hibbertopteridae, includingHibbertopterusandCampylocephalus, and the new family Cyrtoctenidae which is here erected to includeCyrtoctenus, Dunsopterusand possibly alsoHastimima.
Biomechanical approaches to eurypterid cuticles and chelicerate exoskeletons
Authors: Dalingwater John E.
Published: November 2011

Microstructural features of eurypterid cuticles are analysed from a biomechanical viewpoint: some fibrous elements are now considered to resemble the macrofibres of extant arthropod cuticles; possible preferred orientation zones inMycteropsare related to directional stresses; pore canals are not viewed as acting as crack-stoppers but laminae (sensuDennell 1978) may have served this function. Could some eurypterids have walked on land?—this problem is approached by using extantLimulusas a model. It leads on to the use of scaling exponents to determine the limits that possessing an exoskeleton places on the size of land arthropods: moulting may be the limiting factor. Possible critical factors limiting the size of aquatic arthropods are discussed briefly.
The use of models in the understanding of Cambrian arthropod morphology
Authors: Bruton David L. , Jensen Aage , Jacquet René
Published: November 2011

Large scale models in polyester and araldite have been made of Sidneyia, Leanchoilia and Emeraldella from the Middle Cambrian, Burgess Shale. Details are given of how the models have been produced and used in functional morphology studies, particularly with respect to walking in Sidneyia.
Some controversial aspects of the morphology and anatomy of Ostenocaris cypriformis (Crustacea, Thylacocephala)
Authors: Pinna Giovanni , Arduini Paolo , Pesarini Carlo , Teruzzi Giorgio
Published: November 2011

The present work deals with the structure of the cephalic part, traces of the digestive system and gills of Ostenocaris cypriformis (Thylacocephala). The structure of the cephalic part has provoked the most substantial controversy since it has been interpreted as being formed by a pair of enormous compound eyes or as a sac structure that we have called the cephalic sac. Particular attention has been devoted to the minute structure of the cephalic sac. Structures that we have previously termed ‘microsclerites’ can be readily observed, but are by no means easy to interpret.

In many specimens, the basal part of the cephalic area contains abundant traces of alimentary residues. The area thus appears to be part of the digestive system. Our observations do not enable us to give a definitive picture of the anatomical organisation of these animals but do lead to substantial corrections of previously proposed interpretations.
Conchyliocarida, a class of fossil crustaceans: relationships to Malacostraca and postulated behaviour
Authors: Secretan Sylvie
Published: November 2011

Conchyliocarida, from the Jurassic of France, have a conch-like carapace enclosing the whole body. The number of their somites, identified by the visible appendages, excludes them from Malacostraca. Caridean-like characters, including the large lamellar gills, bring them nearer to Malacostraca, end exclude them from other Classes. Their large functional compound eyes and the morphology of their limbs suggest a benthic life and predatory behaviour.

Conchyliocarida are represented by several forms at La Voulte sur Rhône, which are compared and contrasted to related forms elsewhere.
Structural and U–Pb isotopic study of late Archaean migmatitic gneisses of the Presvecokarelides, Lylyvaara, eastern Finland
Authors: Luukkonen Erkki J.
Published: November 2011

The migmatitic gneiss complex of Lylyvaara in the eastern part of Finnish Presvecokarelides of the Baltic Shield shows evidence of a polyphase deformational and metamorphic history and of the emplacement of a number of mafic and felsic igneous intrusions at various stages during this history. Sequential structural development has been established on the bases of refolding and cross-cutting relationships. U–Pb zircon and sphene isotopic data combined with structural studies indicate that the first six deformational phases took place in late Archaean (=Presvecokarelian) times. The seventh deformational phase is constrained as being early Proterozoic (=Svecokarelian) from regional considerations.

The gneissic foliation in the dominant tonalitic to trondhjemitic palaeosome is parallel to lithological layering (So). Mostly it is composite S1–S2; only in F2 fold hinges can separate S1 and S2 be unequivocally distinguished. There, both of these fabrics, which were formed in amphibolite facies conditions of metamorphism during D1 and D2 have retained their identity despite extensive tectonic overprinting. Further tonalitic or granodioritic material was intruded during D3 or between D2 and D3. Effects of the third deformational phase (D3) ar6e expressed only locally as asymmetrical and polyclinal folds, which deform S1–S2 and F2. These folds now have a northeasterly axial trend and they show considerable variations in the style of their parasitic structures. F4 folds are common. They are dextral and asymmetrical, have NW—NNW-trending axes and show complex interference patterns with F2 and F3 folds. During D4, much aplogranitic neosome material was emplaced in NW—SE-trending movement zones, which correspond to the axial planes of F4 folds. Superimposition of F5 and F6 structures on previously formed patterns add to the structural complexity although they only result in minor modifications. Both are open and upright and locally have associated cleavages or healed fractures (S5, S6). D7 is expressed throughout the migmatitic complex as narrow NW—SE-trending shear zones which reactivate the S4 trend.

U–Pb zircon isotopic data indicate that the metamorphism associated with gneiss formation took place 2843 ± 18 Ma ago. U–Pb sphene ages of c. 2660 Ma and 2620 Ma indicate that metamorphic conditions prevailed for a very considerable time. An aplogranitic neosome related to F4 axial planes gave a 2657 ± 32 Ma U–Pb zircon age, while granodiorite and pegmatite dykes related to D6 yielded U–Pb zircon ages of c 2670 Ma and 2640 Ma, respectively.
Molasse basins of Europe: a tectonic assessment
Authors: Friend P. F.
Published: November 2011

Sedimentary basins are structures that formed either by subsidence of an area relative to its surroundings, or by uplift of the surroundings. The basin is defined by its sedimentary fill, and the vertical kinematics of the fill are reflected by stratal wedging, unconformities and, or, faulting. The following basin mechanisms are distinguished: locally (a) stretch, (b) thrust and piggy-back, (c) local uplift, and regionally (d) stretch-and-cool, (e) load-and-flex and (f) cratonic uplift.

Basin patterns are reviewed for the three main Phanerozoic episodes for which molasse-like features of sedimentation or tectonics are claimed. Sediment accumulation rates are used as an index of the vigour of basinal activity.

Within the area of the Caledonian orogen, Devonian basinal activity was locally very rigorous, some of it being late orogenic and some post-orogenic, and mostly apparently of ‘stretch-type’. The orogenic area stood high, relative to sea level, throughout Devonian times, but outside the orogenic area, the basins were less vigorous and marine.

Within the area of the Hercynian orogen, and outside it, Permian basins were generally not so active, apparently reflecting a different style of orogenesis. However, the whole area was standing high, relative to sea level. The Triassic basins, though post-orogenic, were rather more vigorous, although a marine transgression records the general lowering of the continental surface. Major evaporites accumulated in these settings.

In Cenozoic times, the narrow orogenic belts formed the most active basins, and these were of load-and-flex type, reflecting the importance of thrust-sheet movement, itself perhaps a result of the presence of Triassic evaporites. Other non-orogenic basins reflect both ‘stretch’ and ‘stretch-and-cool’ mechanisms. Only the Spanish basins appear to have been standing high, relative to sea level, perhaps in response to cratonic uplift.
Textural properties of regoliths on vegetated steep slopes in upland regions, Scotland
Authors: Innes J. L.
Published: November 2011

The textural properties of many sediments provide a good indication of their provenance, but surprisingly little information is available on the transitional stages between the breakdown of a rock and the incorporation of the material into a fluvial sediment. These transitional stages are important as certain fractions (particularly the finer ones) may be selectively removed. Regoliths developed on steep slopes represent an early stage in the debris cascade and they are here examined in detail to assess the role of parent lithology on the textural properties of the regolith. There are substantial variations between lithologies, although the majority of regoliths are dominated by coarser fractions and are poorly sorted. Most particle size distributions show some degree of fit to both log-normal probability distributions and Rosin distributions. Differences from these can be ascribed to the processes operating on steep slopes, particularly the influx of sand- and silt-sized material by colluvial processes and the removal of clay-sized material by leaching. The regoliths form a distinct facies type which may be recognisable in the geological record.
Upward coarsening sedimentation units and facies lineages, Old Red Sandstone, Scotland
Authors: Bluck B. J.
Published: November 2011

Proximal braided stream deposits of the Old Red Sandstone of central Scotland are characterised by a variety of upward coarsening units formed during downstream migration gravel bars. Transitional variations in thickness, grain size and structure of these units, and their associated sediments are used to establish facies and paths of facies change (lineages). Three facies lineages are recognised which are interpreted as recording the downstream changes the structure of sediments of three different types of braided river systems. Lineages differ from each other in proportion of sandstone, channel depth and the structure of upward coarsening units: lineage 1 represents alluvium formed in a river system which produced texturally mature gravels and which increased in depth downstream; lineage 2 comprises sediments deposited in shallow channels which become shallower downstream; lineage 3 represents a downstream change from conglomerate to sandstone and from an unchannelled to achannelled regime.

Stream depth and ratio of sand to gravel exert fundamental controls on the structure of alluvium. Thick (thickness >50 m) sections showing vertical changes in clast size often comprise single facies lineage. Thick upward coarsening sequences are found with lineages 2 or 3 and upward fining with lineage 1 or 3.
Observations on Eristophyton Zalessky, Lyginorachis waltonii Calder, and Cladoxylon edromense sp. nov. from the Lower Carboniferous Cementstone Group of Scotland
Authors: Long Albert G.
Published: November 2011

Fifteen specimens of Eristophyton stems from the Lower Carboniferous Cementstone Group of Berwickshire and East Lothian have been examined. Three possess medullary rays comparable to E. waltonii Lacey, the others have rays like E. beinertianum (Göpp.) Zalessky. In one specimen assigned to E. waltonii a leaf-trace subdivides outside the secondary xylem to form an arc of six separate bundles. Another stem of E. waltonii has attached closely spaced petiole bases one of which is clearly identifiable as Lyginorachis with six vascular bundles arranged in an arc. Stems of Eristophyton from five localities occur associated with petioles or rachises possessing a U-shaped vascular bundle with abaxial ridges like L. waltonii Calder. As these may occur mixed with rachises agreeing with L. brownii Calder the latter is regarded as synonymous. Detached petioles found associated with E. beinertianum may possess four or six basal bundles. The evidence suggests that the U-shaped petiolar bundle passes down into four then six basal bundles and such petioles are associated with both E. waltonii and E. beinertianum. Calder (1935, pl. 1, fig. 2) showed dichotomy in the petiole bundle.

In addition different rachises are known possessing a more massive U-shaped bundle but lacking sclerotic nests and sparganum outer cortex. These are assigned to Cladoxylon edromense sp. nov. Cortical nests occur in both E. waltonii and L. waltonii and may be compared with the sclerotic plates in the compressions of Diplotmema dissectum Brongn. and D. patentissimum Ett.. The evidence supports the view that Eristophyton is a pteridosperm with bifurcate fronds known as L. waltonii Calder when petrified and comparable to Diplotmema when compressed.
Geochemistry and original nature of Precambrian khondalites in the Eastern Ghats, Orissa, India
Authors: Dash B. , Sahu K. N. , Bowes D. R.
Published: November 2011

The quartz-sillimanite-garnet rocks of the Precambrian khondalite assemblage of Orissa consist dominantly of SiO2 + Al2O3 + Fe2O3 + FeO (average c. 95%) with Fe2O3 > FeO. An average analysis (H2O and CO2 free) also shows MgO, CaO and Na2O having 1·0, 0·5 and 0·4%, respectively. Compared with average crustal abundances, enrichment is shown in SiO2, Al2O3 and Fetot and depletion shown in MgO, CaO, Na2O and P2O5 with that for CaO being more than an order of magnitude and that for Na2O being a factor of >7. On an SiO2–Al2O3–Fetot plot a clearly defined field, elongate nearly parallel to the SiO2–Al2O3 sideline, is similar to that for deeply weathered soil profiles in Brazil. This correspondence also extends to enrichment, stability or depletion, compared to crustal averages, for Ce, Co, Cu, Ga, La, Ni, Nb, Th, U, Y, Zn and Zr, but not for Ba, Cr and Rb. In addition comparison of the proportions and ratios of alkalis and alkaline earths in average khondalite and in a weathering profile over a granodiorite, considered to be typical of the weathering of continents, shows remarkable similarities.

The major and trace element data are consistent with the khondalites being granulite facies—upper amphibolite facies metamorphic equivalents of a deeply weathered soil profile. Associated quartzites and calc-silicate granulites are interpreted as having been silcretes and calcretes, respectively. This interpretation implies (1) the previous existence of a large stable cratonic mass on which the soil profile formed, (2) climatic conditions suitable for the development of such a profile, (3) topography, drainage systems and groundwater movement in Precambrian times similar to those of present day peneplane regions, (4) the presence of free oxygen in the atmosphere, (5) rapid covering (e.g. by products of volcanism) to preclude mass wasting, (6) a Precambrian stratigraphy in the crystalline rocks of the Eastern Ghats region similar to that of South India, and (7) orogenesis that involved tectonic repetition of lithological units and a mechanism for taking products of surface weathering down to granulite facies P–T conditions and subsequently elevating them.
Carboniferous dikes of West Connacht, Ireland
Authors: Mitchell J. G. , Mohr P.
Published: November 2011

Vigorous Carboniferous extensional tectonism and associated igneous activity is a feature of Ireland and the neighbouring areas of Newfoundland and Britain. In West Connacht, Ireland, dolerite dikes of late Carboniferous age are newly recognised and distinguished from Tertiary dolerites. In the N, the 320 Ma-old Logmor dike trends N–S across the Ordovician South Mayo Trough, and has an evolved, mildly alkaline basalt geochemistry. In the S, in Connemara, a diffuse and arcuate swarm of ENE–NE trending, 305 Ma-old dolerite dikes, the Teach Doite swarm, cuts the Galway Granite batholith and its envelope of Dalradian gneisses. These more tholeiitic dolerites reveal the mineralogical and geochemical effects of varying degrees of pervasive hydrothermal alteration, imposed on an original magmatic composition similar to that of mid-ocean ridge basalts. Variscan overprinting on k–Ar ages from West Connacht dolerites clusters at 300, 245 and 205 Ma. Overprinting is also a feature of much of the Galway Granite. Carboniferous diking in West Connacht may have responded to nascent opening of the proximate North Atlantic, its pattern related to domal uplift adjacent to the rifted zone.
Evidence for late Ordovician amalgamation of volcanogenic terranes in the Iapetus suture zone, eastern Ireland
Authors: Murphy Finbarr C.
Published: November 2011

A major transcurrent fault in the zone of the Iapetus suture in eastern Ireland separates Ordovician (pre-Ashgill) terranes. The stratigraphy of each terrane belongs to a dismembered volcanic arc system: the northern terrane is characterised by acid plinian eruptions and derivative sediments which are displaced relative to the andesitic southern terrane volcanism. Each was a separate palaeoenvironment with its own lithostratigraphical character and faunal elements which were juxtaposed across the fault. However, the late Ashgill to Silurian sediments in both terranes form part of a regional overstep sequence which links across the suture zone, such that the palaeogeographical contrasts were eliminated by the Silurian. The inference is that the detached terranes were gradually amalgamated by late Ordovician transtensional movements. This occurred when regional scale subduction-related volcanism had ended. Final assembly by early Devonian sinistral transpressive movements juxtaposed a northern terrane, akin to the Lake District/SE Ireland calcalkaline volcanic province, with a southern terrane in the tholeiitic province of eastern Ireland. As distinct from a singular fault trace, the Iapetus suture is regarded as a 100 km wide zone of anastomosing late Caledonian transcurrent faults whose precursors were active during late Ordovician (i.e. Taconic) terrane amalgamation.
A terminal debris-flow lobe in the northern Pennines, United Kingdom
Authors: Carling P. A.
Published: November 2011

On 17 July 1983 heavy rainfall resulted in a flash-flood in the headwaters of the West Grain, a small stream tributary to the River Wear in the northern Pennines. Associated with the flood was a series of three boulder-lobes. The morphology of these lobes and the associated sediment facies are described and used to estimate the hydro-dynamic mode of transport and deposition. Estimates of the shear-strength and viscosity are consistent with the initial conclusion (based on the sedimentology) that the deposits represent low-viscosity debris-flows. The boulder snouts moved as inertial grain-flows with an associated pebbly-core exhibiting a degree of matrix strength imparted by intergranular friction. A degree of reworking of the upper surface of the core by fluidal flow during core motion and immediately upon deposition was also identified. The full sedimentary sequence therefore represents debris-flow core deposits subject to low dispersive pressure evolving into fluidal debris-torrent deposits.
The shape of the Upper Carboniferous non-marine bivalve Anthraconaia in relation to the organic carbon content of the host sediment
Authors: Eagar R. M. C.
Published: November 2011

Anthraconaia lived on clay grade sediments. In highly variable life assemblages of the A.prolifera group of the E German Wettin Shales (Stephanian C) organic carbon percentage of the host sediment correlates with wu/m and A/L ratios of the shell (where wu is the maximum width ventral to the line of maximum growth, m, L the maximum length measured parallel to the line of the hinge, and A the length anterior to the umbo). Decrease in the organic carbon of the sediment is associated with decrease in umbonal development, elongation of the shell along the m axis, and straightening and reflection of the ventral margin; the latter becomes subparallel to the dorsum or to the m axis with a concomitant decrease in size. These results confirm and amplify earlier work on Anthraconaia in the Appalachian coalfields. The same morphological trends in relation to organic carbon characterise the Anthraconaia modiolaris group of Britain, both within a single succession in upper Westphalian A sediments in Yorkshire, and also in three shell bands of Lower Westphalian B age in S Wales, Yorkshire and central Scotland. In the last named, above the Musselband Coal, statistical formulae (of Leitch 1940) for the species A.salteri are shown to define neither the type assemblage nor its stratigraphical position. The shell-shape/organic carbon relationship has been broadly confirmed on other horizons of lower Westphalian B age in the Scottish and Pennine coalfields. Far from embarrassing the stratigrapher, the relationship, which reflects ultimately trophic level of deltaic palaeoenvironments, contributes to our understanding of non-marine bivalve faunas, especially of the apparent regional distribution of ‘species’ of Anthraconaia.
Snowmelt modelling in the Cairngorms, NE Scotland
Authors: Ferguson R. I. , Morris E. M.
Published: November 2011

Snowmelt modelling is of potential value in flood forecasting, reservoir management, and understanding stream acidification. It involves meteorological extrapolation, snowmelt calculation, meltwater routing, and snowpack depletion. A simple conceptual model using air temperature can reproduce the general pattern of daily streamflow in basins of >100 km2 but is prone to parameter instability. At a point scale and with the benefit of automatic weather station data the energy balance approach is superior to temperature index methods, but the roughness length parameter is again unstable in time and space. Even in a small (0·4 km2) basin this approach has to be coupled with an adequate flow routing model. Current research is comparing alternative models and data inputs in an intermediate-sized basin.
Experimental and computational aspects of overbank floodplain flow
Authors: Ervine D. A. , Ellis J.
Published: November 2011

The propagation of a flood wave through a river system is influenced by a complex process of energy dissipation. This is especially the case when overbank flows are a feature of the flood movement, producing more defined lateral movement of flow and high rates of fluid shear at the main channel/floodplain interface. The present paper concentrates on the physical and numerical modelling of river flows during overbank flow. A general description of the flow behaviour is outlined, including an investigation into the nature of the shear interaction between channel and floodplain. The paper advances a method for determining energy losses for the case of meandering channels with overbank flow and a method of sub-dividing the floodway for stage-discharge prediction. A state-of-the-art study of numerical modelling of flood propagation is outlined, including selected case histories on how the overbank flow situation has been handled to date, as well as comment on the current means of representing energy dissipation relying on calibration of the numerical model against observed field data.
Sediment yields in lowland Scotland derived from reservoir surveys
Authors: Duck Robert W. , McManus John
Published: November 2011

The sediments on the floors of nine reservoirs in the Midland Valley of Scotland have been examined to establish rates of sedimentation and catchment sediment yields. Information from Cullaloe, Drumain, Harperleas and Lambieletham Reservoirs (Fife), is compared with data from Glenfarg and Glenquey Reservoirs (Tayside) and earlier studies on Hopes, N Esk (Lothian) and Kelly (Strathclyde) Reservoirs. The earth-fill dams were constructed between 1850 and 1935 below catchments ranging from 1·53 to 23·5 km2 in area. They are situated on sedimentary, volcanic or intrusive igneous rocks mainly of Devonian or Carboniferous age. In most areas bedrock is obscured by mantles of drift. Six of the catchments are dominated by moorland terrain with local afforestation. Mixed arable farming and woodland characterise the remainder. The higher basins receive on average over 1400 mm of precipitation per annum, while in the lower basins some 800 mm falls.

Measurements of thickness variations of the deposits have enabled the construction of isopachyte maps from which the volumes of entrapped materials have been derived. The computed catchment sediment yields vary from 2·l t km−2 yr−1 (Lambieletham) to 52·0 t km−2 yr−1 (Glenfarg). Sediments incorporate both mineral and organic matter, of which combustible material commonly forms 15–20% by weight. Siliceous tests of diatoms are also an important component of the deposits. The sediment yields computed are about an order of magnitude greater than those reported from rivers draining similar sizes of catchment within the Forth basin. There is a direct relationship between mean annual inflow to the reservoirs and sediment yield.
Forestry effects on suspended sediment and bedload yields in the Balquhidder catchments, Central Scotland
Authors: Ferguson R. I. , Stott T. A.
Published: November 2011

Outputs of suspended sediment and bedload from the 7·7 km2 moorland Monachyle basin and the 6·8 km2, 40%-forested Kirkton basin near Balquhidder, and inputs from tributary streams and mainstream bank erosion, are compared. Sediment yield is about three times higher in the forested basin and varies more sensitively with streamflow, suggesting greater availability of erodible sediment. The output is predominantly of suspended sediment and is derived mainly from tributary streams. Initial observations following partial moorland ploughing and forest clearfelling in 1986 indicate that erosion of timber loading areas and logging roads is the main sediment source.
Modelling the effect of acid deposition in upland Scotland
Authors: Whitehead P. G. , Neal C.
Published: November 2011

As part of the joint British-Scandinavian Surface Waters Acidification Programme, the Institute of Hydrology is establishing catchment studies in Scotland. Data from these catchment studies are being used to develop a range of models for investigating short-term and long-term changes in catchment acidity. Information on the modelling techniques available at the Institute of Hydrology is presented together with applications of the models to catchments in Scotland.
Trilobites from the Upper Ordovician Tangtou Formation, Jiangsu Province, China
Authors: Tripp Ronald P. , Zhou Zhiyi , Pan Zhenqin
Published: November 2011

Forty-one species assigned to thirty-seven named genera of trilobites are described from the Tangtou Formation at Tangshan and Lunshan, in Jiangsu Province, SE China.Nankinolithus nankinensisLu, the Zone fossil of the upper part of the Formation, is abundant. Many Tangtou Formation species occur also in the Huangnehkan, Linhsiang and Chiencaokou formations, and all are considered to be of early Ashgill age. The trilobites are closely related to those of theStaurocephalus clavifronsZone (Rawtheyan) of Poland, demonstrating the long duration and wide extent of deeper water faunas. There are also close links with the Ashgill faunas of Central Asia.

One new species,Amphitryon cheni, is established. The following morphological features are described: a small remopleuridine hypostome is unlike any other in construction;Nileus transversusretains genal spines to full grown size in some specimens, but loses them in others; the hypostome lacks the posteromedian cusp of other species. The hypostome ofParaphillipsinellais strongly styginid in conformation, and unlike that ofPhillipsinella. Telephina convexais the only species known with three spines on the librigena. The arrangement of pits inNankinolithus nankinensis, the type species, is described, including illustrations of the irregularities which occur in every fringe. A small bulb at the tip of the hypostome ofOvalocephalus(=Hammatocnemis) bears two backwardly pointing spinules, one above the other, on the vertical posterior margin. Three types of protaspides, and numerous meraspid parts are described.
Polyphase fold analysis of gneisses and migmatites
Authors: Hopgood A. M.
Published: November 2011

In spite of the structural complexity of polyphase deformed gneisses and migmatites and the absence of distinctive marker horizons, these rocks are amenable to structural investigation and interpretation with resolution of their tectonic history possible, particularly in regions of reasonable exposure. Although methods such as those employing interpretation of stereo-plots can seldom be used, direct observation of refold relationships on the outcrop using all available structural, igneous and metamorphic features will ultimately lead to the resolution of the deformational history. This is achieved by determining the relationships of fold sets observed at the various localities examined throughout the field of investigation and then combining these by correlation according to basic stratigraphical principles. The effects of weak deformation normally not discernible in complicated successions may be detected by the simple form of folded planar and linear structures in igneous masses emplaced in complex structures at intermediate stages in the deformational history.

Synthesis of the total succession and determination of the overall sequence of deformation in particularly complex terranes is made easier if at least one distinctive set of structures can be recognised throughout the area. These key structures have the effect of subdividing the long succession into two in which refold relationships are generally more easily determined. An example of the method is given using photographs from the migmatite terrane in southern Finland.
Hornblende-garnet metapyroxenite beneath serpentinite in the Ballantrae complex of SW Scotland and its bearing on the depth provenance of obducted oceanic lithosphere
Authors: Treloar P. J. , Bluck B. J. , Bowes D. R. , Dudek Arnošt
Published: November 2011

Minimum T and P conditions for the crystallisation of banded amphibole (tschermakitic pargasite)-bearing garnet metapyroxenites that occur beneath and within a tectonically emplaced unit of serpentinite are 900±70°C and 10–11 (possibly 14–15) kb. This indicates both a depth provenance of at least 35–45 km for the obducted oceanic lithosphre which forms part of the ophiolite assemblage of the Ballantrae complex and also a palaeoheat-flow of at least 20°C/km. The metapyroxenites are interpreted as representing the products of subsolidus recrystallisation of a mantle accumulate pyroxenite. Together with associated amphibolites and epidote-rich mylonites formed at higher levels, they constitute a thin, transported and telescoped aureole made up of tectonic pieces of successively-formed metamorphic rocks that welded on to the base of an upward-moving and progressively-cooling peridotite slab.

Estimates of temperature of recrystallisation of the metapyroxenites were obtained using the garnet-pyroxene and garnet-amphibole exchange reactions as geothermometers. Estimates of pressure were obtained from assessments of the stability fields of the amphiboles, clinopyroxenes and garnets present and of the mineral assemblages in relation to published studies on the eclogite-granulite-amphibolite facies system.
Stratigraphy in an accretionary prism: the Ordovician rocks in North Down, Ireland
Authors: Craig Lorraine E.
Published: November 2011

Sediments, mainly sandstones, conglomerates and shales, accumulated in small turbidite fans along the northern arc–trench margin of the Iapetus Ocean from middle Ordovician to Silurian time. These fans, together with the underlying pelagic facies and part of the oceanic crust, were sliced and accreted northward resulting in the Lower Palaeozoic accretionary prism which forms the Scottish Southern Uplands and the Longford-Down inlier in Ireland. North Down is the continuation of the Northern belt of the Southern Uplands of Scotland into Ireland, bounded to the S by the Orlock Bridge fault. Lithological and petrographical comparison with the rest of the Northern belt indicates closer affinities with the Southern Uplands of Scotland than with the western end of the Longford-Down inlier. Major ENE—WSW-trending Caledonian strike faults define five blocks, in which new formations of Caradoc and ? Ashgill age are defined. Pillowed spilitic rock, interpreted as a fragment of the ocean-floor, is only recognised in the Ballygrot block. Pelagic and hemipelagic black shales and cherts are overlain by arenaceous sediments in all blocks.
Age constraints on basement of the Midland Valley of Scotland
Authors: Aftalion M. , van Breemen O. , Bowes D. R.
Published: November 2011

The existence of a basement of granulite beneath the Midland Valley is supported by investigations of inclusions in volcanic rocks and the geophysical studies of the LISPB experiment. To establish age constraints for this basement, a compilation is presented of available Rb–Sr whole-rock, common lead, U–Pb zircon and Sm–Nd radiometrie data for crystalline rocks in Scotland from the earliest recognised crust (c. 2900 Ma) to 380 Ma (“end” of Caledonian orogeny) including xenoliths in volcanic vents and boulders in conglomerates.

For rocks within the Midland Valley, isotopic data provide four lines of evidence. (1) An upper intercept U–Pb age of c. 1700 Ma for detrital zircons from a lower Palaeozoic greywacke from Dalmellington corresponds to a late stage of the Laxfordian orogenic episode (early Proterozoic) with possibly some overprinting during the Grenvillian episode (mid Proterozoic). (2) The common lead composition of the Distinkhorn granite suggests the participation of early Proterozoic basement during granite emplacement. (3) For xenoliths from the Carboniferous Partan Craig vent, one gives a Sm–Nd CHUR model age of 1180 ± 55 Ma, a second yielded a Sm–Nd garnet—potassium feldspar age of 356 ± 6 Ma and an upper intercept U–Pb age from zircons from the third is c. 2200 (± 240) Ma; for xenoliths from other vents, an Rb–Sr whole-rock isochron of 1101 ± 63 Ma and an Sm–Nd model age of c. 1100 Ma arerecorded. (4) A linear array corresponding to an apparent age of 770 ± 180 Ma on a Pb–Pb isochron diagram for Tertiary igneous rocks of Arran points to an underlying basement of late Precambrian orthogneiss.

The existence of basement made of products of the Grenvillian episode, or predominantly so, similar to the basement N of the Highland Boundary fault, is not inconsistent with the available evidence. However, zircons and other rock components appear to have an ultimate Lewisian provenance. At least in parts, there is also a strong late Proterozoic imprint. Further studies are required for an unequivocal solution.
U–Pb isotopic ages from a granulite-facies xenolith from Partan Craig in the Midland Valley of Scotland
Authors: Halliday A. N. , Aftalion M. , Upton Brian G. J. , Aspen Peder , Jocelyn J.
Published: November 2011

U–Pb isotopie data for zircons from a granulite-facies xenolith from a volcanic vent at Partan Craig in the southeastern part of the Midland Valley of Scotland display evidence of an early Proterozoic (>2·0 Ga) component. The xenolith is probably relict metasediment and the data therefore indicate old detritus in the sedimentary precursor. The exact ages of sedimentation and metamorphism are uncertain but these must be compatible with Sm–Nd data on similar xenolithic fragments from the same locality which constrain the ages to c. 1–0 Ga or younger.
Interpretation of Pb isotope compositions of galenas from the Midland Valley of Scotland and adjacent regions
Authors: Parnell John , Swainbank Ian
Published: November 2011

The lead isotope compositions of 61 galenas from central and southern Scotland vary markedly between different regions. Most galenas from the southern Grampian Highlands yield isotope ratios (206Pb/204Pb 17·77 ± 0·25, 207Pb/204Pb 15·47 ± 0·05, 208Pb/204Pb 37·63 ± 0·26) less radiogenic than those from Midland Valley galenas (18·22 ± 0·12, 15·55 ± 0·05, 38·13 ± 0·14) whilst galena lead from the Southern Uplands (18·28 ± 0·12, 15·56 ± 0·03, 38·21 ± 0·18) is more radiogenic than that from the southern Midland Valley (18·12 ± 0·06, 15·52 ± 0·02, 38·06 ±0·10). The change in isotopie composition across the Highland Boundary fault reflects the presence or absence of Dalradian rocks which included a magmatic component of lead. Galenas from the Dalradian sequence in Islay, where igneous rocks are lacking, have a composition (18·14±0·04, 15·51±0·01, 37·90±0·02) more like Midland Valley galenas. In the Southern Uplands, galenas yield lead isotope ratios similar to those of feldspars from Caledonian granite (18·30 ± 0·14, 15·57 ± 0·04, 37·96 ± 0·15) analysed by Blaxland et al. (1979). The similar ratios reflect the incorporation of Lower Palaeozoic sedimentary rocks into the granite magma, rather than a granitic source for the mineralisation. The granites were then thermal-structural foci for later mineralising fluids which leached metals from the surrounding rocks. Within the Midland Valley, galenas hosted in Lower Devonian-Lower Carboniferous lavas are notably more radiogenic (18·31 ±0·12, 15·58 ± 0·06, 38·20 ± 0·16) than sediment-hosted galenas (18·14 ± 0·07, 15·52 ± 0·02, 38·08 ± 0·10). The Devonian lavas at least may have inherited lead from subducted (? Lower Palaeozoic) rock incorporated in the primary magma.
Aspects of the post-depositional evolution of Dalradian and Highland Border Complex rocks in the Southern Highlands of Scotland
Authors: Harte B. , Booth J. E. , Dempster T. J. , Fettes D. J. , Mendum J. R. , Watts D.
Published: November 2011

Palaeomagnetic data define a polar wander path for the Dalradian tectonic block of the Scottish Highlands but resolve no relative motion between the Dalradian and Midland Valley blocks from early Ordo vician onwards. The history of structural episodes (D1to D4) is traced for the Dalradian rocks of the Southern Highlands, and peak metamorphic temperatures are closely associated with D3in the 520–490 Ma (early Ordovician) time period, whilst retrograde events are mostly associated with D4. Throughout the structural history, the influence of a lineament or lineaments parallel to the Highland Border is seen and is particularly demonstrated by the formation of the major Highland Border downbend (D4) structure. This monoform is interpreted as lying structurally above a major step in the basement and is associated with uplift of the Dalradian flat belt in the period 460–440 Ma (late Ordovician).

The mechanism of emplacement of the slivers of Highland Border Complex (HBC) rocks adjacent to the Dalradian Supergroup along the Highland Boundary fault zone is considered given that structural and palaeontological evidence indicates the emplacement to be post- D3in the Dalradian rocks. The steep attitude of rocks along the Highland Boundary fault zone is probably due to vertical movements but either thrust or strike-slip movements are also indicated. Thrust emplacement prior to downbend formation (D4in the Dalradian rocks) would also precede uplift and have to take place at considerable depth (10–20 km). Thrust emplacement subsequent to downbend formation is difficult to reconcile with the existing structural relations, whilst strike-slip motion offers a straightforward mechanism of placement.
Geophysical model for the Midland Valley of Scotland
Authors: Davidson K. A. S. , Sola M. , Powell D. W. , Hall J.
Published: November 2011

A summary of previous gravity and magnetic field interpretations is presented along with a review of the LOWNET and LISPB models. Recently acquired seismological data are compared with the LISPB upper crustal model. The LISPB Layer 1 is found to represent an average of lower velocity (VP = 3·0–3·7 km s−1) Carboniferous and Upper Old Red Sandstone sediments, and higher velocity (VP = 4·0–5·5 km s−1) Lower Old Red Sandstone and Lower Palaeozoic sediments.

On the basis of high P-wave velocities along strike (VP = 60·6–1 km s−1), the LISPB Layer 2 S of Glasgow and Edinburgh is re-interpreted as a quartzofeldspathic crystalline layer of igneous or metamorphic origin, which is also seen to cross the surface of the Southern Uplands fault at around 2·5 km depth.

This interpretation implies that within the southern part of the Midland Valley, the Lower Palaeozoic sediments are nowhere thicker than about 3 km, as postulated under the Silurian inliers, and generally much less.
Sm—Nd ages from the Ballantrae complex, SW Scotland
Authors: Hamilton P. J. , Bluck B. J. , Halliday A. N.
Published: November 2011

The Ballantrae complex has yielded its oldest yet determined age of 576 ± 32 Ma from an Sm–Nd internal isochron for a block ‘eclogite’ interpreted as being a component of the mélange-olistostrome unit at Knockormal. This unit is possibly older than the main ophiolitic part of the complex and the ‘eclogite’ block provides evidence for the existence of oceanic crust older than c. 575 Ma on the southern margin of the Laurentian shield.

An Sm–Nd internal isochron from a high-grade metapyroxenite in the metamorphic aureole beneath an obducted slab of mantle peridotite at Laigh Knocklaugh yields an age of 505 ± 11 Ma. This is interpreted as close to the age of metamorphism and is older than the K–Ar age of 478 ± 8 Ma determined for the amphibolites of the aureole which underlie the metapyroxenite. The metapyroxenite had a provenance deeper in the oceanic crust than the amphibolite and the former has been structurally detached and justaposed against the latter in this telescoped metamorphic sequence.