bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dalradian slides and basin development: a radical interpretation of stratigraphy and structure in the SW and Central Highlands of Scotland
Authors: ANDERTON R. 
Published: December 2007

Movements on syndepositional listric faults are responsible for many of the lateral variations in Dalradian stratigraphy. Sedimentary facies and thickness variations show that the surface traces of these faults correspond, in many cases, to what have previously been interpreted as tectonic slides, although normal faults, thrusts and sedimentary contacts may also mark their position.
Three main episodes of faulting are described in the Islay to Lochaber area. Appin Group sedimentation was controlled by a fault now represented by the Loch Skerrols Thrust-Fort William Slide-Ossian steep belt. In the Islay-Jura area an anomalously thick Islay Subgroup succession accumulated in a half-graben bounded by a listric normal fault to the NW and terminated by transfer faults at each end. The deposition of a thick Easdale Subgroup section was controlled by movements on what is now the Benderloch-Ballachulish Slide. This listric fault terminates southwards in the Scarba Fault and probably extends north into the Ossian steep belt.
The thinness of the Appin and lower Argyll Group succession between the Ericht-Laidon and Bridge of Balgie Faults is an original feature. The stratigraphic gap represented by the Boundary Slide here is reinterpreted as a disconformity. However, further east the Boundary Slide may well be a listric fault, movement on which accommodated the thick succession around Schiehallion.
The development of the major structure was influenced by the geometry of the sedimentary basins. The Schiehallion-Tummel area is reinterpreted as lying on the lower limb of the Ben Lui fold. This resolves the problem of the emplacement of the Tay nappe which is likely to be a gravity structure derived from above the Ossian steep belt.
Ordovician intrusions of the Strumble Head-Mynydd Preseli region, Wales: lateral extensions of the Fishguard Volcanic Complex
Authors: BEVINS R. E. , LEES G. J. , ROACH R. A. 
Published: December 2007

A major doleritic and gabbroic sill complex, with minor microtonalitic components, cuts Ordovician strata to the east of Fishguard. Their age has long been equivocal. New geochemical data, combined with petrographic analyses, indicate that the intrusions represent an eastward extension of the Ordovician (Llanvirn) Fishguard Volcanic Complex lavas and high-level intrusions of the Strumble Head region. In addition similar doleritic intrusions crop out to the west of Strumble Head, as far as Traeth Llyfn.
The data presented here confirm earlier conclusions that the FVC has tholeiitic affinities and that compositional variations largely result from low-pressure fractional crystallization. The petrogenetic relationships of the microtonalites are, however, as yet equivocal. Incompatible element discriminant diagrams indicate that the parental basic magmas were derived by melting of a slightly depleted mantle source similar to N-type MORB, to which had been added a minor supra-subduction zone LIL element component. The data are consistent with emplacement of the magmas in a marginal basin environment.
The sedimentology and diagenesis of organic-rich sediments
Authors: MACQUAKER J. H. S. , CURTIS C. D. 
Published: December 2007

Despite comprising more than 60% of the sedimentary record, mudrocks have received disproportionately little study, both in terms of their sedimentology and diagenesis. This is perhaps surprising considering their economic importance as the source rock for most commercial hydrocarbons. To readdress this imbalance, a British Sedimentological Research Group/Petroleum Group meeting entitled ‘The Sedimentology and Diagenesis of Organic-Rich Sediments’ was held at Sheffield University on the 24–25 September 1987. The overall intentions of the meeting were: (a) that it should be interdisciplinary, (b) bring together research workers interested in diverse aspects of mudrock sedimentology and diagenesis (from both organic and inorganic backgrounds) and (c) to expand the generally sketchy mudrock data base.
With these aims in mind some 60 people gathered in Sheffield to hear two days of talks and examine a variety of posters dealing with topics that ranged from palaeoenviron-mental interpretation to inorganic geochemistry of mudrock sequences.

In a keynote address,
I. N. McCave
(Cambridge) presented a stimulating talk on mud deposition in modern environments. He particularly emphasized the important role of particulate organic matter as a clotting agent. He showed that the chemistry of this organic clotting agent influenced its ‘clotting ability’, and that, in turn, its chemistry was dependent on total oxygen concentrations in the water column. As a result he noted that the organic/inorganic ratio in mudrock sequences from different localities varied despite them having similar overall accumulation rates.

Continuing with aspects of mudrock deposition,
P. B. Wignall
(Birmingham) documented the importance of storm events in
The significance of garnet in the Permo-Carboniferous volcanic rocks of the Pyrenees
Authors: GILBERT J. S. , ROGERS N. W. 
Published: December 2007

Garnet occurs within rhyolitic to dacitic lavas, ignimbrites and volcaniclastic sediments of the Pyrenean calc-alkaline Permo-Carboniferous volcanic rocks. On the basis of texture and major and trace element composition, the garnet is interpreted as having a phenocrystal as opposed to a xenocrystal or restite origin.
The Pyrenean silicic volcanics are strongly peraluminous, consistent with derivation as a partial melt from a sedimentary source. They were erupted contemporaneously with the Hercynian thermal anomaly, which produced regional granulite facies metamorphism and anatectic granites. The ‘Late Hercynian granodiorites’ were also intruded at about this time. Geochemical data suggest that the petrogenesis of the volcanic rocks differed from that of the granodiorites.
REE garnet/matrix partition coefficients for garnets from a welded rhyolitic ignimbrite are similar to those reported for other phenocrystal garnets in rhyolites. REE abundances imply that the garnets crystallized from a HREE depleted melt and this is considered to reflect the effects of garnet in the restite. Experimental constraints suggest that the garnet crystallized at pressures >4–5kb, implying that the rhyolites originated from > 14–17km depth and were erupted rapidly from these depths in order for the garnet to survive. These figures place constraints on the thermal regime prevailing in the late stages of the Hercynian orogeny.
Short Paper: Palynological evidence from the Porthleven area, south Cornwall: implications for Devonian stratigraphy and Hercynian structural evolution
Authors: WILKINSON J. J. , KNIGHT R. R. W. 
Published: December 2007

Detailed structural and lithological mapping combined with a paly-nological study of Devonian sediments in the Porthleven area, have revealed that previous structural and stratigraphic interpretations are seriously in error. Palynomorphs recovered from sediments classically assigned to the Gramscatho Group and generally regarded as pre-Famennian indicate a late Famennian age. A reinterpretation of the section is proposed which emphasizes the importance of imbricate thrusting and local facies variations.
Interpretations of the Devonian geology of south Cornwall have been hindered by the lack of palaeontological control on the ages of the main lithostratigraphic units. This paper details new palynomorph assemblages which necessitate a reinterpretation of the structure and stratigraphy of the south Cornish nappe and thrust terrain (Rattey & Sanderson 1984; Barnes & Andrews 1986; Holder & Leveridge 1986).

Palynology.
A suite of 14 samples was collected from the parautochthonous Mylor Slate Formation and allochthonous Portscatho Formation (Holder & Leveridge 1986), on the west coast of the Lizard Peninsula (Fig. 1). Palynomorphs were recovered from three samples representative of the sequence exposed immediately southeast of Loe Bar [SW646237-SW647234]. Within this section, traditionally referred to the Gramscatho Group, sediments of both Mylor and Gramscatho affinity are intercalated. The finer grained (Mylor-type) lithologies were preferentially sampled and yielded comparatively diverse, rich and remarkably well-preserved (although opaque) palynomorph assemblages. Yields range from 22–146 specimens per gramme of sediment. The kerogens were oxidized using potassium chlorate and fuming nitric acid, and in transmitted light were found to be composed almost exclusively of miospores, with occasional acritarchs
Tectonic evolution of the Northumberland Basin; the effects of renewed extension upon an inverted extensional basin
Authors: COLLIER R. E. LL. 
Published: December 2007

The Northumberland sedimentary basin has a history of repeated extensional and contractional tectonic phases and a study of the deformation interference pattern and sedimentary record allows the identification of the tectonic state through time. Initial rifting is represented by a thick Dinantian sedimentary fill, but Carboniferous extension is thought to have ceased by the early Namurian.
In order to explain the development of certain facies patterns during the Westphalian thermal subsidence phase of the evolution of the Northumberland Basin, some syn-depositional extensional fault movements are required. At other times in the Westphalian, compaction-induced subsidence was the dominant control on facies distribution. A single phase of E–W to SE–NW Variscan compression commenced during or after late Westphalian times and ceased prior to the intrusion of the Whin sills and dykes. Subsequent Permo-Mesozoic extension, with a right-lateral shear component, re-activated pre-existing normal fault lines. These later structures may be interpreted as being listric in form, shallowing onto decollement surfaces within the Carboniferous basin fill and overlie the buried faulted margin at the southern side of the basin.
Tectonic fabric of Sierra Leone, West Africa: implications for Mesozoic continental breakup
Authors: VENKATAKRISHNAN RAMESH , CULVER STEPHEN J. 
Published: December 2007

A lineament map interpreted from Landsat images has been integrated with available geological and geophysical data from both offshore and onshore regions of Sierra Leone. The lineament patterns are related to intraplate and plate marginal reaction of pre-existing structures during Mesozoic rifting events that resulted in strong tectonic controls on magmatism.
Of four main lineament trends, the NNW-SSE to N–S, NNE–SSW, and ENE–WSW trends are directly relatable to Archaean fabric in the Leo Uplift. A NW-SE trend reflects coast-parallel late Mesozoic dykes that follow the Rokelide Pan–African fabric (reactivated Archaean NNW and N–S trending structures).
NW–SE trending faults defining offshore basins are segmented and offset by ENE–WSW trending continental extensions of Ocean fracture zones. Both the Guinea and Sierra Leone Fracture Zones have nucleated on ENE–WSW trending sinistral Archaean shear zones in the Leo Uplift.
The four lineament trends focused Mesozoic magmatic events through protracted reactivation, Spatial and geometric relationships between the magmatic provinces and tectonic fabric indicate that intraplate deformation occurs far inland during rifting events. The angular relationships between the Permo–Triassic NE trending Guinea Belt, the Jurassic–Triassic NW–SE trending coast-parallel dykes, and the ENE–WSW trending Ocean fracture zones centred on the eariy Jurassic Freetown basic igneous complex, suggest that the Sierra Leone–Liberia continental margin evolved as an obliquely-sheared, rift–rift–transform passive margin during Mesozoic continental breakup.
Thrust-related metamorphism in basement windows of the central Scandinavian Caledonides
Authors: LINDQVIST J. E. 
Published: December 2007

The late Caledonian metamorphic evolution of the basement beneath the Caledonian allochthons of the central Scandes has been determined by studying mafic schists and phyllonites of the crystalline basement, and the overlying Vendian and/or Cambrian sedimentary rocks. The studied rocks occur along the Caledonian front and in tectonic windows within the Scandinavian Caledonides.
A gradual westwards increase in metamorphic grade is recorded, which varies from upper diagenetic conditions in the autochthonous rocks along the eastern thrust front of the Caledonides to middle amphibolite facies in the western parts of the Nasafjäll and Tømerås windows. Locally, strain-related deviations from this pattern occur. Further west the grade of Caledonian metamorphism of the basement increases and reaches the eclogite and granulite facies.
The Scandian metamorphic conditions in the basement rocks studied prevailed in the mid- to late Silurian, at pressures of 8 ± 2 kbar and temperatures of 550 ± 50°C in the Tømmerås window, and 7 ± 2 kbar at 550 ± 50 °C in the Nasafjäll window. Uplift and cooling followed thereafter, continuing into the Devonian. The final retrograde metamorphism was characterized by temperatures of 450 ± 50°C at pressures of about 3 kbar in the Nasafjäll and Tømmerås windows.
The occurence of syn-schistosity amphibolite-facies assemblages implies heating of the basement rocks during nappe emplacement. Available time constraints suggest that this was a relatively rapid process. In late Silurian to early Devonian, the prograde phase was followed by uplift and erosion. The metamorphic evolution also demonstrates that early Devonian thrust movements were associated with a decrease in the thickness of the nappe pile.
Eustatic and tectonic controls upon Quaternary coastal sedimentation in the Corinth Basin, Greece
Authors: COLLIER R. E. LL. 
Published: December 2007

The late Quaternary sedimentology and palaeogeography of the Corinth Isthmus in central Greece is re-interpreted. A series of beach-to-shoreface sub-sequences are seen, each characteristically having an overall fining-up character. These occur within a coastal facies belt which has prograded to the west.
Computer modelling illustrates the interaction of tectonic displacements and eustatic sea-level variation as controls of facies patterns. Late Pleistocene-Holocene facies geometries are predicted on the basis of published sea-level data over that time interval. On coastlines undergoing tectonic uplift, such as the Isthmus of Corinth, depositional patterns may be characterized by transgressive wedges. These sub-sequences merge basinwards below sea-level minima. Each transgression relates to a major eustatic sea-level peak. Such first order models are modified by variations in the rate of tectonic deformation, the second control on relative sea-level position.

Modelled facies patterns are tested on the basis of new
230
Th/
234
U dates obtained from sclerac-tinian corals of the Corinth canal area. Dated sub-sequence sediments correspond in age to late Pleistocene eustatic highs and observed facies patterns correlate with the major late Pleistocene-Holocene eustatic transgressions of
c
. 100 ka periodicity. Episodes of intrabasinal normal faulting are isolated from a structural history otherwise dominated by uplift across the Isthmus. Quantification of post-depositional vertical tectonic displacements is achieved, constraining the eustatic base-level at the time of deposition of a dated horizon by reference to the global late Quaternary sea-level curve. The original depositional level is then subtracted from the present outcrop level. Using available
230
Th/
234
U dates to establish syn-depositional base-levels, minimum uplift rates of the order of 0.3 m ka
−1
are calculated across the area, averaged through the late Pleistocene and Holocene.
The influence of a sudden climatic change on marine deposition in the Kimmeridgian of northwest Europe
Authors: WIGNALL PAUL B. , RUFFELL ALASTAIR H. 
Published: December 2007

A sudden change from humid style to semi-arid style deposition markedly affected the accumulation of the Upper Kimmeridge Clay in southern England. Many of the changes appear to be related to a change in sedimentation rate at this time. Thus softground faunas are replaced by firmground faunas; diagenetic dolostones formed in the methanogenic zone are replaced by sulphate reduction zone carbonate nodules; and depositional gradients, recorded by lateral biofacies changes, becomes steeper. The evidence available is in accord with a decline in offshore sedimentation rates during this interval. Other changes, such as a decline in kaolinite abundance, were more directly controlled by the ‘drying-out’ of the hinterland. Similar changes, elsewhere in the marine geological record, could be used as climatic indicators.
The climatic change is part of a wider, northern hemisphere dry event which affect a broad area in the late Jurassic. The Kimmeridge Clay of southern England was one of the last depositional environments to be influenced by the climatic change at this latitude.
The stratigraphy of a sheet of supracrustal rocks within high-grade orthogneisses and its bearing on Late Archaean structure in southern West Greenland
Authors: CHADWICK BRIAN 
Published: December 2007

An extensive sheet of presumed middle Archaean supracrustal rocks within high-grade orthogneisses in inner Godthåbsfjord includes a section 3 km thick with exceptional preservation of pillow structures in low K tholeiitic amphibolites unambiguously indicating way up. The amphibolites are associated with pillow-structured and pyroclastic, komatiitic ultramafic schists, dunitic-harzburgitic sills, a stratiform gabbro, pyritous metacherts and quartzo-feldspathic gneisses and schists with field and chemical characteristics suggesting they formed as acid-intermediate tuffaceous sediments.
The sheet is tectonically overlain by older orthogneisses (Amîtsoq) with tracts and enclaves of the early Archaean Isua/Akilia supracrustal association. It is underlain by younger orthogneisses and granites with tracts of older, variably reworked Amîtsoq gneisses. Rocks of the higher level were emplaced on a tectonic slide which marks the upper boundary of the supracrustal sheet. The original lower boundary with Amîtsoq gneisses in the lower level may also have been a slide which has been obscured by emplacement of younger orthogneisses. Composite dome-in-dome structures with intervening synclinal cusps were superimposed on the sub-horizontal layer cake structure of the supracrustal sheet and the higher and lower levels of orthogneisses. Syntectonic granitic and amphibolite dykes (Kangilíngua dykes) were emplaced in parts of the synforms, whilst granite emplacement and feldspar blastesis took place in the cores of some domes. The dome and cusp system appears to be part of a regional series of late Archaean, steeply inclined to upright structures trending northeast in the Godthåbsfjord region. In inner Godthåbsfjord the system evolved in response to buoyancy forces generated by injection of basaltic magmas and partial melting of orthogneisses at depth within a regime of regional compression associated perhaps with transcurrent intraplate motions.
Extinction and migration in Silurian trilobites and conodonts of northwestern Canada
Authors: CHATTERTON BRIAN D. E. , EDGECOMBE GREGORY D. , TUFFNELL PAMELA A. 
Published: December 2007

Appearances and disappearances (lineage turnover) of trilobite and conodont evolutionary species’ clades in Silurian shelf marginal sections of the Mackenzie Mountains are concentrated at particular stratigraphical levels. A depth/energy curve generated for this region shows three major and several minor transgressive-regressive cycles in the Llandovery and Wenlock Series. A comparison of this curve with conodont and trilobite distributional data supports the thesis that there are cause/effect relationships between changes in sea level and migration, evolution and extinction events of these marine organisms. The rate, amount and direction of change in depth were important factors in the migration and extinction of clades. The depth/energy curve for the region fits the pattern expected for a passive downdropping shelf responding to global, eustatic sea-level changes. Emigrations and extinctions are associated with rapid transgressive episodes and concentrated at three levels: lower Llandovery, lower Wenlock, and middle or lower part of the upper Wenlock. The early Wenlock event was the most impressive. A further concentration of extinctions and/or migrations, not considered here, occurred later in the Ludlow, associated with a regional regression. Phyletic evolution is most convincingly demonstrated in fossil collections from intervals of gradual regression.
A model is proposed that predicts that a similar pattern of extinctions occurred around the Silurian world, in regions of similar palaeotectonic regime, and that global extinction patterns of clades, between episodes of mass extinction, were not random. Episodes of high extinction (turnover pulses) were caused by perturbations of the environment, foremost of which were rapid changes in the depth of the seas on the continental shelves. Because taxonomic loss during these extinction/emigration episodes was generally at low (below generic) levels, resolution of Silurian turnover patterns requires data collected at the evolutionary species level.
The Tavua Caldera, Fiji: a complex shoshonitic caldera formed by concurrent faulting and downsagging
Authors: SETTERFIELD T. N. , EATON P. C. , ROSE W. J. , SPARKS R. S. J. 
Published: December 2007

The shoshonitic Tavua Volcano in Viti Levu, Fiji, developed from a submarine to a subaerial environment, and comprises lava flows, dominantly of absarokite composition, with debris flows and conglomerates on its flanks. The Tavua Caldera formed in the centre of the volcano. Within the caldera, avalanche deposits are overlain by the Turtle Pool Formation, which consists of lacustrine sediments, shoshonite lavas and hydrovolcanic/pyroclastic lapilli tuffs. Subsequently the Inner Caldera formed in the centre of the Tavua Caldera. This was infilled by the Morrisons Pool Formation, which comprises lavas and pyroclastic rocks of banakite composition, with minor intercalated sediment. Thus the magmas became progressively more evolved.
In addition to normal movement along regional and concentric faults, subsidence (which exceeds 3 km) was accomplished via substantial downsagging. Evidence for this is the consistent centripetal dip of caldera fill material, which locally exceeds 50° in parts of the Turtle Pool Formation. Centripetal dips are also recognized in pre-caldera rocks immediately outside the Tavua Caldera.
Subsidence was episodic, caused by periodic, non-explosive withdrawal of underlying magma to erupt on the flanks and in part within the caldera. Downsagging and fault movement were responsible for approximately equal amounts of subsidence, and their interaction produced a caldera with the shape of a stepped funnel.