bluuebunny/crossref_metadata_2025 huggingface dataset:
Sm-Nd isotopic study of garnets and their metamorphic host rocks
Authors: van Breemen O. , Hawkesworth C. J.
Published: November 2011

In this feasibility study, Sm/Nd and 143Nd/144Nd ratios have been determined on garnets and coexisting mineral and whole-rock phases from a selection of amphibolite facies rocks, granulite facies rocks and an eclogite. In two micaceous schists and an eclogite the distribution coefficient of the Sm/Nd ratio in garnet relative to other phases is in the range 2-3, i.e. comparable to values for phenocrysts in igneous rocks. In two granulite facies rocks the garnets have Sm/Nd distribution coefficients relative to other phases in the range 13-20 and have yielded precise ages.

Garnet from a granulite facies shear zone from the Limpopo belt in southern Africa, of Archaean age, has yielded concordant duplicate ages of 1974±14 Ma and 1988±14 Ma. These results have been interpreted as relating to the last tectonic event in the region, long after the main gneiss-forming event. Garnet from a granulite facies xenolith from a Carboniferous vent in the Midland Valley of Scotland has yielded an age of 356±10 Ma; this is related to the onset of basic magmatism in the region.
Structural and metamorphic development of migmatites in the Svecokarelides, near Tampere, Finland
Authors: Campbell D. S.
Published: November 2011

Five generations of structures (F1–F5), excluding faults, can be recognised in granitoid and trondhjemitoid migmatites with quartzofeldspathic neosome development associated with F1–F4 structures. Areal variation in metamorphic grade is shown by the zonal development of muscovite-sillimanite, potassium feldspar-sillimanite and potassium feldspar-cordierite assemblages in the palaeosomes. The climactic metamorphism, associated with MS2–MP2 mineral growth, occurred at between 675°C, 4 kb and 825°C, 6·5 kb. These pressure-temperature conditions are consistent with at least some neosome development having resulted from partial melting. The occurrence of a relatively shallow metamorphic geotherm and the resultant products are assessed in relation to metamorphic conditions known from elsewhere in the Svecokarelides.
A numerical taxonomic study of species of Trinucleidae (Trilobita) from the British Isles
Authors: Temple J. T.
Published: November 2011

British and Irish species of the trilobite family Trinucleidae are investigated by numerical taxonomie methods. Forty-five attributes are defined, relating mainlyto the dorsal surface of the cephalon, and several of them representing new concepts. Of the 106 described species from the British Isles, 31 are fully codable on the basis of topo types. An analysis is based on these species, together with 28 partly topotypically codable species and samples of 9 other species (undescribed, non-topotypic or non-British). The relations of the species are depicted in an ordination derived by principal components analysis of the interattribute correlation matrix and with superimposed minimal spanning tree. On the basis of the ordination most of the analysed species can be grouped into two subfamilies, Trinucleinae and Cryptolithinae (including Marrolithinae);thersitesis excluded from Reedolithinae. Trinucleinae and Cryptolithinae are strongly differentiated on they1axis of the ordination. The two subfamilies show parallel evolution during the Ordovician in general cranidial attributes (e.g. increasing length, declination of fringe). In Trinucleinae the fringe also shows evolutionary changes (e.g. increases in numbers and regularity of arcs); in Cryptolithinae the fringe evolves very little. Ordination of the attributes is by non-linear mapping based on a distance matrix derived from the interattribute correlation matrix by the transformation (tanh-1|r|)-1. Lectotypes of 12 species are here selected:albidusReed,ceryxLamont,gibbsiiSalter,girvanensisLamont,hibernicusReed,inconstansWhittard,persulcatusReed,praeteritaReed,rhodesiWhittard,sortitaReed,subradiatusReed andthersitesSalter.
Structure and metamorphism of rocks beneath the Semail ophiolite of Oman and their significance in ophiolite obduction
Authors: Searle M. P. , Malpas J.
Published: November 2011

Metamorphic rocks showing an inverted metamorphic zonation from upper amphibolite fades immediately beneath the peridotite to greenschist fades at lower levels, crop out discontinuously along the base of the Semail ophiolite thrust sheet in the Oman Mountains of eastern Arabia. These metamorphic rocks show polyphase deformation, mylonitic fabrics, and have been disrupted, folded and imbricated, and in places form tectonic inclusions in a serpentinite melange. In the more intact sequences, garnet-clinopyroxene amphibolites, with rare hornblende-bearing marbles and banded quartzites, occur at the higher levels, whilst a wide range of metasedimentary and metabasaltic rocks occur in the greenschist fades. Low glaucophane content of amphiboles and low jadeite content of clinopyroxenes suggest relatively low pressures of crystallisation. The distribution coefficient KD for co-existing garnet and clinopyroxene suggests a temperature range of 670 to 750°C. Residual heat from the recently formed ophiolite probably provided the dominant heat source for metamorphism, although frictional heating could have supplemented this. The metamorphic rocks were produced during Cenomanian-Turonian (late Cretaceous) times.

The sub-ophiolite metamorphic rocks, together with basal serpentinite, Triassic alkaline and tholeiitic basalts (Haybi volcanic group), mountain-sized ‘exotic’ limestones and an upper Cretaceous sedimentary melange, comprise a distinct thrust slice termed the Haybi complex, which always overlies marine sediments of the allochthonous Hawasina complex and underlies the Semail ophiolite. The rocks of the Haybi complex are bounded by major thrust planes, the Semail thrust above and the Haybi thrust beneath, which truncate all schistosities, fold axes, imbricate thrusts and associated features. A model for ophiolite obducton is presented based on a palinspastic reconstruction of the allochthonous rocks on the Oman continental margin.
Structural evolution of Svecokarelian migmatites, southern Finland: a study of Proterozoic crustal development
Authors: Hopgood A. M.
Published: November 2011

Svecokarelian migmatites in the Jussarö area of the southern Finnish archipelago comprise tonalitic gneiss, amphibolite, metagabbro, microgranite, the metamorphosed derivatives of sediments, including carbonates and graded argillites, together with later-emplaced potassic granite, and basic and acidic pegmatites. The rock assemblage shows evidence of repeated deformation; a succession of 15 sets of folds (and fold-related structures) is identified and documented. There are two sets of early intraf oliai isoclinal folds (Faa and Fab), isoclinal folds (Fbr), recumbent folds (Fx), upright open folds (Fy), tight upright folds (Fbb), two sets of asymmetrical folds (Fc and Fd), ‘scar’ folds (Fb1, Fcb Fd1), slip folds Fb, conjugate shear folds (Fe), angular folds (Fn), open warps (Fw) and tight ductile shears (Fds). From isotopie evidence reported elsewhere, the evolution of this crustal segment of the Svecokarelides is known to have spread over a period of approximately 200 m.y. from c. 1900 m.y. to c. 1700 m.y.
Tectonic position of the Dalradian rocks of Connemara and its bearing on the evolution of the Midland Valley of Scotland
Authors: Leake Bernard E. , Tanner P. W. Geoff , Macintyre R. M. , Elias E.
Published: November 2011

The Dalradian terrane of Connemara was thrust southsoutheastwards about 460 Ma ago (Rb–Sr and K–Ar ages). It rides on a major thrust of post-D age over mylonitised acidic volcanic rocks of putative lower Ordovician age and contains a number of thrusts of similar age. Several major S- to SE-directed thrusts also limit the southeastern margin of the Dalradian rocks in Mayo and Tyrone. It is suggested by analogy with Ireland that during mid-Ordovician times the Highland Boundary fault in Scotland could have been a thrust zone which carried the Scottish Dalradian rocks over a lower Ordovician basement now represented only as fragments in the Highland Border Complex.
Early Palaeozoic metamorphic history of the Midland Valley, Southern Uplands–Longford-Down massif and the Lake District, British Isles
Authors: Oliver G. J. H. , Smellie J. L. , Thomas L. J. , Casey D. M. , Kemp A. E. S. , Evans L. J. , Baldwin J. R. , Hepworth B.C.
Published: November 2011

A model for the early Palaeozoic metamorphic history of the Midland Valley and adjacent areas to the S in Scotland, England and Ireland is based on the results of new field mapping, thin section petrography, electron probe microanalysis, X-ray diffractometry, conodont and palynomorph colouration and graptolite reflectance measurement.

The oldest metamorphic rocks of the Midland Valley of Scotland, excluding xenoliths in post-Silurian lavas, are possibly the blueschist occurrences in the melange unit of the Ballantrae complex. These may be tectonised remnants of (?)pre-Arenig ocean-floor subducted during closure of the Iapetus Ocean. In the early Ordovician, the melange terrane was dynamothermally metamorphosed during obduction of newly-formed ocean crust. The obduction process piled up a thick sequence of various ocean-floor types such that burial metamorphism in parts reached pumpellyite-actinolite facies; elsewhere prehnite-pumpellyite and zeolite facies was attained.

Whilst the Midland Valley acted as an inter- or fore-arc basin during the Late Ordovician and Silurian and experienced burial metamorphism, an accretionary prism was formed to the S. Accretion, tectonic burial and metamorphism of ocean-floor and trench sediment was continuous in the Southern Uplands and the Longford-Down massif of Ireland through Late Ordovician to Late Silurian times. Rocks at the present-day surface vary from zeolite facies to prehnitepumpellyite facies. Silurian trench-slope basin sediments can be recognised in part by their lower grade of burial metamorphism. Greenschist facies rocks of the prism probably lie close to the surface.

The Lake District island-arc terrane of Northern England has an early Ordovician history of burial metamorphism up to prehnite-pumpellyite facies. The Late Ordovician and Silurian metamorphic history is one of sedimentary burial complicated by tectonism and intrusion of granite plutons to a relatively high level. The Iapetus suture is marked by a weak contrast in metamorphic grade.
Pre-Carboniferous history of the Midland Valley of Scotland
Authors: Bluck B. J.
Published: November 2011

The pre-Carboniferous Midland Valley of Scotland comprises three tectonic elements: an arc, a proximal fore-arc basin and a marginal basin. These tectonic elements have been juxtaposed by strike-slip and thrust faulting, both of which have effected a 300% reduction in the width of the orogenic belt.

Rocks which span Arenig to Late Devonian or Early Carboniferous times and which are found S of the Highland Boundary fault have no clasts of certain Dalradian provenance despite substantial uplift of the Dalradian block at this time. This, combined with other evidence, suggests the Midland Valley to have been remote from this rapidly uplifting terrane. The Dalradian block, eroded down by c. 410 Ma was thrust southeastwards in Late Devonian–Early Carboniferous times. However, this thrust movement was minor, yielding little sediment, but it caused Dalradian rocks to cover the northern margin of the Midland Valley where (1) the source for part of the Old Red Sandstone rocks existed and (2) the faults along which the Midland Valley block was transported to dock against the Dalradian block are thought to be present. The existing Highland Boundary fault is therefore seen as a late Old Red Sandstone reverse fault which covered more significant older structures.
Distribution of anatomically-preserved floras in the Lower Carboniferous in Western Europe
Authors: Scott Andrew C. , Galtier Jean , Clayton Geoffrey
Published: November 2011

Twelve localities of Lower Carboniferous strata in Scotland (Loch Humphrey Burn, Glenarbuck, Pettycur, Oxroad Bay and the Berwickshire localities of Cove, Burnmouth, Gavinton, Edrom, Foulden) and in France (Esnost, Roannais, Montagne Noire) have been investigated with particular regard to their anatomically preserved floras. New data on the composition and preservation of the assemblages, their geological setting and stratigraphical age, using palynology in particular, are presented. Present data suggest that four successive groups of floras obtained from these localities can be recognised: from the Montagne Noire (mid to late Tournaisian), from the Berwickshire localities and Oxroad Bay (late Tournaisian to early Viséan), from Loch Humphrey Burn and possibly Glenarbuck (mid Viséan) and from Roannais, Esnost, and Pettycur (late Viséan). The similarities and differences between the floras are discussed with particular emphasis on stratigraphical as opposed to ecological controls. Comparisons are made with the New Albany Shale floras of the U.S.A., the Saalfeld and Glätzish-Falkenberg floras from the German Democratic Republic. The data suggest that the ferns and pteridosperms show the most striking changes through the Lower Carboniferous strata.
Charnockite and related neosome development in the Eastern Ghats, Orissa, India: petrographic evidence
Authors: Park Adrian F. , Dash B.
Published: November 2011

Charnockite and homophanous leptynite are two quartz–feldspar neosomes in the late Archaean granulite-migmatite Eastern Ghats terrane of Orissa, India. Three phases of deformation and metamorphism are recognised to have preceded a late phase, or phases in which deformation was not intense. An early granulite facies event (D1–M1) produced basic granulites and khondalite (sillimanite-garnet aluminous paragneiss). A second event (D2–M2) involved some retrogression but temperatures and pressures remained high (possibly c. 750°C—>5 kb). D3–M3 was associated with the development of open folds (F3) with axial planar shear zones in pinched antiforms; temperatures and pressures were also falling (c. 650°C— 4kb), but the shear zones acted as a control on the development of firstly homophanous leptynite, and secondly charnockite. In both cases, neosomes of quartz and potassium feldspar have myrmekitic textures and intergranular occurrence. The palaeosome became strained and garnet–biotite and garnet–biotite–clinopyroxene ± orthopyroxene mineral assemblages were formed in association with the development, respectively, of homophanous leptynite and charnockite. The persistence of straining in the palaeosome and the presence of poikilitic textures indicate that this typical assemblage does not represent one in thermodynamic equilibrium. This has important consequences for geothermobarometry.

The structural control on neosome development reflects a regional characteristic where shear zones are the site of peralkaline plutons, fenitisation, carbonatites and epigenetic graphite development. The peculiar features of charnockite are seen as just one of several aspects related to the fluxing of hot CO2-dominated fluids from either the deep crust or mantle during the late Archaean development of the Indian craton.
New finds of Drepanophycus spinaeformis Göppert from the Lower Devonian of Scotland
Authors: Rayner R. J.
Published: November 2011

Drepanophycus spinaeformis Göppert is a long ranging Devonian plant. Although reported from numerous localities, it is far from well understood. Observations on specimens from the Emsian Strathmore Group of Scotland have revealed variation in forms of branching including root-like axes on branches interpreted as rhizomes. The anatomy of the xylem is described from uncompressed pyrite permineralisations. Cuticle characteristics are also described and discussed. The systematic position of the plant is debated since, although the morphology of the leaves, leaf traces, roots and xylem indicate an affinity with the lycopods, there is some doubt as to whether sporangial position permits inclusion in this group.
Metabentonite geochemistry: magmatic cycles and graptolite extinctions at Dob's Linn, southern Scotland
Authors: Batchelor R. A. , Weir J. A.
Published: November 2011

The Moffat Shale Group is a condensed, variable and partly pelagic sequence of mudrocks of Llandeilo—Llandovery age. The sequence has a five-fold lithological subdivision based mainly on the occurrence of grey mudstones within a succession otherwise dominated by fully euxinic black graptolitic mudrocks. Associated with the black mudrocks, especially in the Llandovery, are metabentonite beds which achieve a climax, both in thickness and in number, within the top quarter of the mudrock sequence. A geochemical and mineralogical study has confirmed a volcanic origin for the metabentonites. Major element data highlight a carbonate-dominated environment above the gregarius—convolutus Zones boundary. Phosphorus levels reach a peak at the same boundary, as well as at the Caradoc—Ashgill boundary where phosphorite horizons are known from Wales and Norway. Immobile trace elements have highlighted regular changes in source magma composition. Prolonged periods of crystal fractionation in magmas of intermediate composition gave rise, on eruption, to large volumes of silicic ash which had a deleterious effect on graptolite species and led to local extinctions. Regular fluctuations in ash composition from silicic to intermediate are ascribed to alternating fractionation and magma mixing cycles.
Some supracrustal (S-type) granites of the Lachlan Fold Belt
Authors: White A. J. R. , Chappell B. W.
Published: November 2011

S-type granites have properties that are a result of their derivation from sedimentary source rocks. Slightly more than half of the granites exposed in the Lachlan Fold Belt of southeastern Australia are of this type. These S-type rocks occur in all environments ranging from an association with migmatites and high grade regional metamorphic rocks, through an occurrence as large batholiths, to those occurring as related volcanic rocks. The association with high grade metamorphic rocks is uncommon. Most of the S-type granites were derived from deeper parts of the crust and emplaced at higher levels; hence their study provides insights into the nature of that deeper crust. Only source rocks that contain enough of the granite-forming elements (Si, Al, Na and K) to provide substantial quantities of melt can produce magmas and there is therefore a fertile window in the composition of these sedimentary rocks corresponding to feldspathic greywacke, from which granite magmas may be formed.

In this paper, three contrasting S-type granite suites of the Lachlan Fold Belt are discussed. Firstly, the Cooma Granodiorite occurs within a regional metamorphic complex and is associated with migmatites. It has isotopic and chemical features matching those of the widespread Ordovician sediments that occur in the fold belt. Secondly, the S-type granites of the Bullenbalong Suite are found as voluminous contact-aureole and subvolcanic granites, with volcanic equivalents. These granites are all cordierite-bearing and have low Na2O, CaO and Sr, high Ni, strongly negative εNd and high 87Sr/86Sr, all indicative of S-type character. However, the values of these parameters are not as extreme as for the Cooma Granodiorite. Evidence is discussed to show that these granites were derived from a less mature, unexposed, deeper and older sedimentary source. Other hypotheses such as basalt mixing are discussed and can be ruled out. The Strathbogie Suite granites are more felsic but all are cordierite-bearing and have chemical and other features indicative of an immature sedimentary source. They are closely associated with cordierite-bearing volcanic rocks. The more felsic nature of the suite results in part from crystal fractionation. It is suggested that the magma may have entered this “crystal fractionation” stage of evolution because it was a slightly higher temperature magma produced from an even less mature sediment than the Bullenbalong Suite. The production of these S-type magmas is discussed in terms of vapour-absent melting of metagreywackes involving both muscovite and biotite. The production of a magma in this way is consistent with the low H2O contents and geological setting of S-type granites and volcanic rocks in the Lachlan Fold Belt.
Petrogenesis of a two-mica ignimbrite suite: the Macusani Volcanics, SE Peru
Authors: Pichavant Michel , Montel Jean-Marc
Published: November 2011

The Miocene-Pliocene Macusani ash-flow tuffs and glasses from SE Peru are a rare example of two-mica felsic peraluminous volcanic rocks. They outcrop in three separate tectonic basins of the Cordillera Oriental in the Central Andes. In the Macusani field, the rocks are characterised by andalusite and muscovite phenocrysts. Compositions are both very felsic and peraluminous, similar to two-mica granites. Field relations, age differences and isotopic heterogeneities suggest that several distinct magma batches were involved. Two separate magmatic stages are recognised: (1) partial melting and evolution at or near the source region, and (2) shallow-level crystallisation and eruption. Magma genesis involved partial melting of metapelitic materials, with internally controlled. High heat flux, rapid heating, elevated temperatures and F-rich compositions were essential for the production of these mobile, H2O-undersaturated magmas. Chemical variations between the erupted products can be attributed to different degrees either of partial melting in somewhat variable source materials and (or) of fractional crystallisation at shallow levels. We discuss some important differences between the magmatic evolution of the Macusani Volcanics and of Hercynian and Himalayan two-mica granites.
Thermal modelling of stepwise anatexis in a thrust-thickened sialic crust
Authors: Zen E-an
Published: November 2011

One-dimensional modelling of the thermal history of a sialic crust thickened by multiple overstack thrusting of upper crustal material shows that anatexis is likely. Both the uplift rate and the length of the incubation period between end of tectonism and start of uplift are important controls on the amount and temperature of the melt. Heat of fusion does not significantly affect the long-term thermal structure of the crust if the melt is not extracted because only a small fraction of conductive heat is converted to latent heat, though short-term thermal effects of latent heat can be locally important.

Model results show that commonly <15% of mantle heat flux is converted to latent heat; even during peak melting in the most productive models, less than half of incremental mantle flux is converted. The results have obvious implications on the acceptability of proposed heat sources for crustal anatexis. Fusion could retard crustal temperature rise by nearly 100°C, but the system would recover except for situations of very rapid uplift. Understanding of the thermal evolution of a burial-uplift system requires knowledge not only of the timing of anatexis but of the pooling and movement of the magma, as well as the duration and nature of the incubation period; we are poorly equipped to measure these events. The model predicts that the characteristic time for anatexis in a thickened sialic crust is several tens of millions of years, comparable to the time lapse between orogenies; in making geological interpretations of magmatism, this time lag must be considered.
The fossiliferous Silurian rocks of the Dunquin inlier, Dingle Peninsula, County Kerry, Ireland
Authors: Holland C. H.
Published: November 2011

The history of investigation of the Silurian rocks of the Dunquin inlier, Dingle Peninsula, County Kerry, Ireland is briefly reviewed. The Dunquin Group of upper Wenlock (Homerian) to middle Ludlow (Ludfordian) sedimentary and volcanic rocks is divided into five formations: the Ferriters Cove, Clogher Head, Mill Cove, Drom Point and Croaghmarhin Formations, the last of which reaches the Ludlow and passes transitionally into the succeeding continental Dingle Group, probably largely Přídolí in age. The Dunquin group is of varied shallow marine sediments with a continental episode probably represented in the Mill Cove Formation. The biostratigraphy of the other four formations is considered in relation to a full faunal list. Details of representative sections and exposures are provided. There is brief comment on the palaeogeographical setting of the inlier.
A study of the Dinantian marine macrofossils of central Scotland
Authors: Wilson R. B.
Published: November 2011

The stratigraphy, classification and correlation of the marine strata in the Dinantian (Lower Carboniferous) succession of central Scotland are discussed. Correlations of eight principal marine bands in the upper part of the sequence are proposed and four Hosie limestones are recognised in Fife. The marine macrofossils are listed and their vertical and lateral distribution discussed. Biofacies maps of the main marine faunas are presented, which indicate an eastern origin for the marine transgressions and suggest the existence of a river entering the region to the N of Glasgow. Observations are made on the range of host-sediments in which the most commonly occurring genera are found and palaeoecological interpretations are made concerning the main components of the faunas. Some evidence is given to suggest that some elements of the faunas migrated into the region from the E. The palaeogeography is discussed and a correlation is outlined between epifaunal forms at some horizons and areas of less subsidence in the general regional pattern of differential subsidence.
The Dalradian rocks of the Lecht, NE Scotland: stratigraphy, faulting, geochemistry and mineralisation
Authors: Nicholson K. , Anderton R.
Published: November 2011

Air photo interpretation and geochemistry have been used to supplement sparse field data in compiling a reconnaissance geological map of the area around the Lecht. Upper Appin and lower Argyll Group rocks are exposed, the best marker horizons being correlatives of the Appin and Jura Quartzites. Scatter plots, Q mode factor analysis and Pearson correlation coefficients of geochemical data were successfully used in the correlation of the pelite and limestone outcrops. The presence of major recumbent folds is inferred. The area is cut by numerous minor faults which are thought to be related to a major transcurrent fault, the probable north-eastern continuation of the Loch Tay fault, which was active in Lower Old Red Sandstone times.

The Lecht manganiferous ironstone is a seepage-bog ore type deposit derived by weathering of the local Dalradian sequence. Despite intensive leaching, this sequence still shows anomalously high levels of several elements, particularly Mn, Ba and Zn. In addition, stratiform sphalerite and manganiferous garnet are present in Blair Atholl Subgroup limestone and pelite horizons, respectively. Mineralogical and geochemical evidence suggests the presence of Zn–Pb–(Ag)–(?Au) exhalative mineralisation within the upper Appin Group Dalradian of the region, of which the Lecht represents the distal manganiferous expression.
A review of Ordovician agnostid genera (Trilobita)
Authors: Nielsen Arne Thorshøj
Published: November 2011

The definition and scope of Ordovician genera of agnostid trilobites are discussed, and the generic affiliation of Ordovician species and well-illustrated material referred to in open nomenclature is assessed. Some 198 Ordovician species plus 25 species of uncertain latest Cambrian/earliest Ordovician age are enumerated, representing 24 genera and subgenera, of whichGeragnostus (Novoagnostus)n.subg. andLotagnostus (Semagnostus)n.subg. are new.Geragnostellais ranked as a subgenus ofGeragnostus. The species ofArthrorhachisare tentatively divided among atardusspecies group and anelspethispecies group. Species ofDividuagnostusare divided among asensu strictogroup and an early species group.PseudorhaptagnostusLermontova, 1951 is restored as senior synonym ofNeoagnostusKobayashi, 1955. It is concluded that Ordovician agnostids were largely adapted to temperate and colder water habitats.
Ascent mechanism of felsic magmas: news and views
Authors: Weinberg Roberto Ferrez
Published: November 2011

Transactions of the Royal Society of Edinburgh: Earth Sciences 87, 95–103, 1996
Nature and significance of beerbachites in the Ballantrae ophiolite, SW Scotland
Authors: Jelínek E. , Souček J. , Bluck B. J. , Bowes D. R. , Treloar P. J.
Published: November 2011

Metamorphosed abyssal ocean-floor tholeiitiic rocks, little affected by crustal contamination and probably formed at a spreading ridge, occur as a dyke complex in banded gabbros with oceanic affinities and as small tectonic lenses in serpentinised peridotite. Igneous textures and mineral assemblages have been partly or completely replaced in both dykes and gabbros. Metamorphic development of clinopyroxene and very Ti-rich hornblende at 900-1000°C was followed by a low temperature actinolite-chlorite assemblage and then by pectolite-bearing veins. Geochemical variations resulting from magmatic and metasomatic processes have been distinguished and plots of major and trace elements used to establish tectonic environment. The very high temperature metamorphic mineral growth associated with beerbachite formation indicates that the dyke rocks were in a high heat-flow environment for a considerable time, presumably in the vicinity of a spreading ridge. Obduction of a very hot slab of oceanic lithosphere accounts for the superimposed mineral assemblages.

Spatially associated pillow lavas have been affected by crustal contamination and are not comagmatic with the dykes. There are petrochemical characters indicating that some of the lavas are ocean-floor basalts. For other lavas, features suggesting emplacement in a continental or an island-arc environment could also be consistent with development in a marginal basin. However, there is so much variation in composition of pillows from margin to centre, from small to large and from metasomatic activity, that their compositional fields cannot be used for discrimination of basaltic type with the same confidence as for the dykes. Accordingly, it is suggested that the petrochemistry of sheeted dyke complexes, rather than of pillow lavas, be used for this purpose in the study of ophiolites.
An alternative astronomical calibration of the lower Pleistocene timescale based on ODP Site 677
Authors: Shackleton N. J. , Berger A. , Peltier W. R.
Published: November 2011

Ocean Drilling Program (ODP) Site 677 provided excellent material for high resolution stable isotope analysis of both benthonic and planktonic foraminifera through the entire Pleistocene and upper Pliocene. The oxygen isotope record is readily correlated with the SPECMAP stack (Imbrie et al. 1984) and with the record from DSDP 607 (Ruddiman et al. 1986) but a significantly better match with orbital models is obtained by departing from the timescale proposed by these authors below Stage 16 (620 000 years). It is the stronger contribution from the precession signal in the record from ODP Site 677 that provides the basis for the revised timescale. Our proposed modification to the timescale would imply that the currently adopted radiometric dates for the Matuyama–Brunhes boundary, the Jaramillo and Olduvai Subchrons and the Gauss–Matuyama boundary underestimate their true astronomical ages by between 5 and 7%.
Late Cenozoic plateau uplift and climate change
Authors: Ruddiman William F. , Kutzbach John E.
Published: November 2011

Sensitivity experiments with general circulation models show that uplift of plateau and mountain regions in Southern Asia and the American west during the late Cenozoic was an important factor in the evolution of Northern Hemisphere climate. The climatic trends simulated in the uplift experiments agree in direction with most trends observed in the geological record, including the tendencies toward greater regional differentiation of climate, and particularly the fragmentation into wetter and drier climatic patterns at middle latitudes. These climatic trends result from (1) increased orographic diversion of the mid-latitude westerlies, and (2) increased summer heating and winter cooling over the plateaus, which enhances seasonally reversing (monsoonal) changes in wind directions.

Most previous hypotheses addressing the physical impact of orography on climate have focused on mountain ranges and have stressed relatively local responses such as upslope precipitation maxima, cooling of mountain crests due to lapse-rate effects on rising terrain, and lee-side rainshadow effects. In contrast, our results emphasise the importance of large-scale plateau orography. By redirecting the basic directions of wind flow both at surface and upper-tropospheric levels, these rising plateaux cause far-reaching climatic changes that extend across the continents as well as over the oceans.
A first-order global model of late Cenozoic climatic change
Authors: Saltzman Barry , Maasch Kirk A.
Published: November 2011

The theory of the Quaternary climate will be incomplete unless it is embedded in a more general theory for the fuller Cenozoic that can accommodate the onset of the ice-age fluctuations. Here we construct a simple mathematical model for the late Cenozoic climatic changes based on the hypothesis that forced and free variations of the concentration of atmospheric greenhouse gases (notably CO2) coupled with changes in the global ocean state and ice mass, under the additional influence or earth-orbital forcing, are primary determinants of the climatic state over this long period. Our goal is to illustrate how a single model governing both very long-term variations and higher frequency oscillatory variations in the Pleistocene can be formulated with relatively few adjustable parameters. Although the details of this model are speculative, and other factors neglected here are undoubtedly of importance, it is hoped that the formalism described can provide a basis for developing a comprehensive theory and systematically extending and improving it. According to our model the major near-100 ka period ice-age oscillations of the Pleistocene were caused by the downdraw of atmospheric CO2 (possibly a result of weathering of rapidly uplifted topography) to low enough levels for the ‘slow climatic system’, including glacial ice and the deep ocean state, to become unstable.
Radiocarbon ages and the full-glacial to Holocene transition in seas adjacent to Scotland and southern Scandinavia: a review
Authors: Peacock J. D. , Harkness D. D.
Published: November 2011

Water of southerly origin replaced polar water very rapidly on the coast of NW Europe and an interstadial marine circulation with a weak North Atlantic Drift was fully established off both west Scotland and southern Scandinavia by roughly 12 800BP. A ‘warm’ interval detected in marine strata on the western Scottish coast at the beginning of the Windermere (Bølling plus Allerød) Interstadial lasted from this date to perhaps 12 400 BP and another towards its close from about 11 250 to shortly after 11 000 BP. During the Younger Dryas Stadial polar water returned by about 10 850 BP and was present until about 10 200–10 100 BP. The changes in water circulation at the beginning and end of the Windermere Interstadial and at the end of the Younger Dryas seem to have taken place within the limits of radiocarbon dating, perhaps within a few decades. Warming at the beginning of the Holocene Interglacial may have taken place in two phases, during the first of which, from about 10 100 BP to possibly 9600 BP, marine temperatures seem to have been lower than at present, more especially on the east coast of Scotland and in southern Sweden. Full marine interglacial circulation may not have been established until 9500 BP. Water depth in the Faeroe–Shetland Channel may have been a major factor in controlling sea and air temperature from Scotland northwards during the Windermere Interstadial and Holocene Interglacial and, by implication, during earlier interglacials and interstadials.
The Glas Eilean lavas: evidence of a Lower Permian volcano-tectonic basin between Islay and Jura, Inner Hebrides
Authors: Upton B. G. J. , Fitton J. G. , Macintyre R. M.
Published: November 2011

Subaerial lavas and intercalated sediments crop out on the islet of Glas Eilean and the Black Rock skerries in the Sound of Islay between Islay and Jura. The visible succession is c. 120 m thick and is traceable c. 2 km along strike (NNW–SSE). The lavas are alkali olivine-basalts containing olivine ± plagioclase and augite phenocrysts. Decreasing Mg, Cr and Ni upwards, coupled with decreasing average flow thickness and increasing amounts of inter-flow sediment, suggest progressively waning volcanic activity marked by decreasing ascent rates and greater degrees of differentiation. K-Ar dating on one sample gave an early Permian age of 285 ± 5 Ma. It is inferred that the lavas erupted from an isolated basalt volcano situated on a NNW–SSE trending fracture, associated with a narrow developing half-graben within the Dalradian metasediments. The tectonism and magmatism is inferred to be related to the ‘Clyde Belt’ of fault-bounded basins extending from Cheshire to the Little Minch.
Ocean temperatures and isotopic compositions through time
Authors: Hudson J. D. , Anderson T. F.
Published: November 2011

Fossil assemblages can give quantitative estimates of palaeotemperatures, by comparison with modern biota, only in the recent geological past. Oxygen isotopic palaeotemperatures on calcareous or phosphatic fossils are potentially available for the whole Phanerozoic. Their reliability is limited by physiological effects (generally believed minor), preservation (for which criteria are available), and by uncertainty in the isotopic composition of ancient seawater. The latter is greatly affected by glaciation. In the Cenozoic, the relative contribution of ice-volume change and temperature change in producing isotopic variations can largely be resolved by analysing planktonic and benthic foraminifera in deep-sea cores. For earlier times only continental shelf deposits are available. In the Mesozoic, reasonable assumptions about ocean isotopic composition lead to palaeotemperature estimates that suggest generally higher temperatures than at present, particularly for mid- to high latitudes. This agrees with estimates based on biotic distributions. Late Palaeozoic glaciation is reflected in variable isotopic compositions in high palaeolatitude areas. In the earlier Palaeozoic, well-preserved fossils indicate either oceans enriched in16O compared to today's or generally higher temperatures; controversy continues about the relative importance of the two effects.
Physiological adaptations to extreme pressures: the implications for palaeoecology
Authors: Macdonald A. G.
Published: November 2011

Present-day organisms have colonised two distinct high pressure environments: the deep sea and oil well and other crustal fluids. In the former, pressures attain 100 MPa and temperatures are generally less than 4°C. In the latter, the temperatures are high, up to 150°C, and occur in combination with pressures of up to 50 MPa. The high temperature is close to the limit of thermal stability of the macromolecules essential for life. The adaptation of present-day marine organisms to high pressure is known to involve modifications to their cell membrane lipids and subtle changes in both structural proteins and enzymes. There is no reason to suppose that they are close to the maximum pressure to which they could adapt and higher pressures could have been colonised in the geological past. The existence of “marker” compounds, characteristic of high pressure organisms, is discussed, and the possibility that isotope ratios are distorted by metabolic processes at high pressure is raised.
The persistence of Burgess Shale-type faunas: implications for the evolution of deeper-water faunas
Authors: Morris S. Conway
Published: November 2011

Discoveries, most of them recently, in more than thirty Lower and Middle Cambrian horizons with soft-bodied fossils have shown that forty-one of the genera occur also in the celebrated Burgess Shale (Middle Cambrian). Significantly, they tend to have lengthy stratigraphic durations which together encompass an interval from the early Lower Cambrian (Tommotian) to near the end of the Middle Cambrian. At least some genera have also wide geographical ranges, with occurrences around much of the Laurentian (N America) craton, and also in N and S China, Australia, Siberia, Spain and Poland. Although a few genera, e.g.Isoxys, may have been pelagic, for the most part these distributions are explained in terms of a deeper-water biota with an evolutionarily conservative aspect. Both the origins and further recruitment to this biota may have been from shallower water, with more limitedin situdiversification. It is speculated that this distinctive Cambrian biota was gradually driven to extinction with the arrival of Ordovician competitors, although some relics may have survived until at least the Devonian. This history has implications for our understanding of deeper-water faunas throughout the Phanerozoic, and supports the notion that archaic forms may take refuge in this environment.
Physiological characteristics of land plants in relation to environment through time
Authors: Spicer Robert A.
Published: November 2011

The spatially fixed sporophyte body of vascular land plants has to be adapted to both atmospheric and substrate environments. Potentially almost all stages in the life cycle of a land plant are fossilisable and the physiological adaptations to these environments are reflected in the morphology, anatomy, and chemistry of the plant. Although solutions to the plant's physiological problems have been refined through evolution, the basic responses to fundamental environmental parameters such as temperature, water availability, nutrient supply, gas exchange and light, evolved early in land plant history. These taxon-independent solutions can be used qualitatively, and sometimes quantitatively, to track changes in atmospheric and edaphic conditions throughout much of the Phanerozoic. Increase in body size and height in Middle and Late Devonian times was coupled with intense demand for light, nutrients and water supply and with elaborations of vascular systems, photosynthetic surfaces, organ abscission and ‘root’ organisation. During the Carboniferous extreme adaptations to substrate waterlogging evolved. Mycorrhizal associations and “phi” layers in Triassic roots represent early aspects of modern root physiology. From the mid-Cretaceous, angiosperms exhibit leaf architectural characteristics which in modern plants relate qualitatively to moisture and light, and quantitatively to temperature, while vessel size and distribution in trunk wood is related to water stress and susceptibility to freezing. The relative proportion of plants utilising C3, CAM, and C4photosynthetic pathways varies with environment. Isotopic analysis of plant fossils may demonstrate changing relative frequencies of photosynthetic pathways through time in relation to atmospheric composition and temperature.
The League of Nations and the Construction of the Periphery Introduction
Authors: JOHNS FLEUR , SKOUTERIS THOMAS , WERNER WOUTER
Published: November 2011

Since 2006, the Leiden Journal of International Law (LJIL) has been dedicating a series of special issues of its Articles section to the theme ‘International Law and the Periphery’. This issue marks the fourth in this series.
Empire des Nègres Blancs: The Hybridity of International Personality and the Abyssinia Crisis of 1935–36
Authors: PARFITT ROSE
Published: November 2011

The ‘Abyssinia Crisis’ of 1935–36 – in which one League of Nations member (imperial Ethiopia) was annexed by another (Fascist Italy) – presents one of the clearest twentieth-century illustrations of international law's ‘progress narrative’. International lawyers are encouraged to draw a salutary lesson from the crisis: namely that Ethiopia's sovereignty – and, indeed, the peace of the entire world – might have survived the 1930s if only international law had been properly enforced. Yet, the assumption upon which this lesson depends – to the effect that Ethiopia'sonlydiscursive contribution to the crisis was passively to regurgitate the relevant clauses of the Covenant – is profoundly ideological. For this assumption effects a double suppression: erasing Ethiopia's strategic construction of a hybrid, partially Abyssinian international law from the discipline's memory; and concealing from scholarly view the possibility that Ethiopia's annexation might have resulted from actions that werein accordance with, rather than in violation of, interwar international legal norms regarding sovereignty and the use of force.
Testifying about ‘Uncivilized Events’: Problematic Representations of Africa in the Trial against Charles Taylor
Authors: ANDERS GERHARD
Published: November 2011

The article presents an anthropological analysis of witness testimony about ritual murder, cannibalism, and secret societies in the trial against Charles Taylor in The Hague. In the first part, a comprehensive in-depth analysis of the testimony of one prosecution witness serves as a case study to illustrate the difficulties of assessing the veracity of witness statements on alleged atrocities linked to African religious and spiritual beliefs. The second part contextualizes the testimony heard in the trial against Charles Taylor by drawing on historical sources and the academic literature on West Africa. The analysis reveals striking parallels between the prosecution narrative and colonial representations of Africa as a mysterious and savage place.
Israeli Civilians versus Palestinian Combatants? Reading the Goldstone Report in Light of the Israeli Conception of the Principle of Distinction
Authors: KOT JEAN-PHILIPPE
Published: November 2011

Goldstone's recent retraction can leave the reader of the report that bears his name somewhat perplexed. Indeed, if the deliberate intent to target civilians could be discussed in some specific attacks listed, such a report nevertheless describes a pattern of behaviour that cannot be swept aside without disregarding the order of priorities set by the Israeli legal system itself. Through analysis of the new Israeli military code of ethics as well as the Israeli Supreme Court case law, this paper examines how civilians in Gaza were deliberately put at risk by a specific interpretation breaking down the flat rule of civilian immunity into a more complex construction opposing the Israeli soldiers’ right to life to the rights of an ‘enemy population’.
The Normative Erosion of International Refugee Protection through UN Security Council Practice
Authors: AHLBORN CHRISTIANE
Published: November 2011

Since the early 1990s, the UN Security Council has used its enforcement measures under Chapter VII of the UN Charter to address different aspects of international refugee protection from the root causes of forced displacement to the search for durable solutions to the refugee problem. At the same time, however, the Security Council has been criticized for impelling trends towards state security concerns that have emerged in the refugee-protection regime over the past two decades. By establishing safe areas in Iraq, Bosnia, and Rwanda, or linking refugee status to terrorism, the Security Council has been accused of violating established refugee-protection standards. This paper seeks to use the prism of international refugee protection to draw a more nuanced picture of the normative effects of SC actions on the development of international law generally. Shifting the analytical focus from the much-discussed responsibility of the Security Council for wrongful acts, it is submitted that the practice of the Security Council has had a considerable influence on the development and even making of norms in the field of international refugee protection, thereby eroding established refugee-protection standards. This normative erosion through the inherently political actions of the Security Council will be assessed with regard to the principal measures by which the Security Council has addressed international refugee protection, namely peace operations and economic sanctions.