bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Ophiolite Mélange of Masirah, Oman
Authors: Moseley F. , Abbotts I. L. 
Published: December 2007

The Masirah Ophiolite consists of serpentinites, gabbroic intrusions, an extensive sheeted dyke complex, pillow lavas, and sediments. It is truncated to the W by a NNE-trending, 5 km wide vertical mélange zone: a megabreccia with blocks up to 2 km long of all the above lithologies. The mélange trend is perpendicular to that of the sheeted dyke complex, a common relationship between a transform fault and spreading centre. Many of the features of the mélange can be explained by serpentinite diapirism along a major ocean crust fracture. However, the distribution of other reported ophiolites along the SE coast of Arabia and the intrusion of the Masirah Ophiolite by granite, whose geochemistry indicates melting of continental crust, both suggest upthrust of ocean crust onto the Arabian continent.
The Masirah Mélange and the dyke trends within the ophiolite are parallel, respectively, to the Owen Fracture (and other transforms) and to magnetic anomalies in the Indian Ocean. It is suggested that both mélange and ophiolite are related to a late Cretaceous stage in the evolution of the Indian Ocean, and may not correlate with the Semail Ophiolite of the Oman Mountains, as has been previously supposed.
The Loch Doon granite: an example of granite petrogenesis in the British Caledonides
Authors: Brown G. C. , Cassidy J. , Tindle A. G. , Hughes D. J. 
Published: December 2007

The Loch Doon igneous complex lies to the N of the Solway–Shannon Iapetus Ocean suture line through the British Isles, but in a region lacking the Proterozoic continental basement which is known to exist further N. It comprises a genetically related magma suite ranging from hypersthene diorite margins through quartz monzonite to granite at the centre. Petrochemical data, studies of xenolith and autolith densities and field radiometric mapping indicate that the suite lacks sharp internal boundaries but is gradational and based on a monzodiorite parental magma which evolved through a two-stage crystal fractionation process. The early crystallization of dioritic margins was dominated by pyroxene-plagioclase precipitation and these minerals were joined later by biotite as acidic residual liquids developed. Biotite formation and fractionation at the expense of pyroxenes is related to contamination of the magma by water from the roof zone. Partial assimilation of roof material, particularly in the form of xenoliths, and mixing between cumulates and residual liquids are also recognized but are of relatively minor importance.
These petrochemical, geophysical and isotopic studies of the Southern Uplands granites indicate the generation of parental magmas by the partial fusion of metabasaltic lower crust or crustal underplate as a late event in the evolution of the Iapetus Ocean.
Tertiary volcanism in northern E Greenland: Gauss Halvø and Hold with Hope
Authors: Upton B. G. J. , Emeleus C. H. , Hald N. 
Published: December 2007

Subaerial plateau basalts, initially
c
. 1 km thick, overlie Cretaceous or older formations and are locally separated from pre-Tertiary rocks by (
a
) a quartzitic conglomerate and (
b
) a (younger) sequence of tuffaceous sediments and hyaloclastites. The plateau lavas are divisible into a Lower (typically microphyric, quartz tholeiitic) Series and an Upper (typically porphyritic, olivine tholeiitic) Series. N–S and NE–SW trending antithetic faults give rise to ocean-facing fault-line scarps and landward-facing dip slopes. Dolerite sills, abundant beneath the lava pile, occasionally cut the Lower Series lavas. While dykes trend in various directions, a very prominent NE–SW swarm (mainly quartz tholeiitic) traverses Hold with Hope, deflecting to more nearly N–S across Gauss Halvø.

A large volcanic centre (Myggbukta Complex) lies across the main dyke swarm in the vicinity of the deflection and may be genetically related to the swarm. The complex involves propylitized basaltic, rhyolitic and intermediate lavas and pyroclastic rocks, together with volcanogenic sediments, cut by a profusion of basic to acid intrusive sheets. Formation of this complex at a late stage in the volcanic history of the region was attended by subsidence and crustal down-sagging. The main dyke swarm, whose trend roughly parallels that of the spreading axes N and S of the Jan Mayen Fracture Zone, may reflect subordinate rifting to the W of the principal rift zones along which spreading was taking place.
30 km E of Myggbukta, the Kap Broer Ruys granophyre/felsite is a partially unroofed intrusion around which a broad metamorphic aureole has been superimposed on the Mesozoic and Tertiary sediments and lavas. The southern coastal region of Hold with Hope, connecting the Myggbukta and Kap Broer Ruys centres, may indicate a zone of crustal weakness which determined the initiation of the Jan Mayen Fracture Zone.
Concretionary phosphorite from SW Africa
Authors: Bremner J. M. 
Published: December 2007

Phosphorite concretions, fish debris, quartz, rock fragments and minor amounts of molluscs occur along the eastern edge of a diatomaceous mud belt off the coast of SW Africa (Namibia). The concretions consist of light- and dark-coloured coprolites and dreikanters, predominantly of pebble and granule size; and irregular, tabular, and oval to spherical particles that predominante in the granule to very coarse sand fractions. Only the dark-coloured concretions were analysed geochemically, and these consist of francolite with minor amounts of Si, Al, Fe and K. The most abundant trace elements present are Sr, Zn, Ba and Th.
The interstitial fluids of the diatomaceous mud are supersaturated in phosphate along the landward flank of the mud belt, and this causes slow precipitation of apatite on diatom frustules. Concurrently, the fluids enhance the elimination or replacement of allogenic impurities from the concretions through diagenesis. Adsorption of phosphate by slow-settling mica–illite is a possible mechanism by which the phosphate concentration of the interstitial fluids is raised.
Devonian lake margin environments and processes, SE Shetland, Scotland
Authors: Allen P. A. 
Published: December 2007

The Devonian lake or lakes of SE Shetland were characterized by 4 environments: (1)a marginal environment dominated by the high energies of the surf zone and just lakeward of the breaker zone; (2) an additional marginal environment consisting of small, shallow, oxidizing lakes on a low-gradient coastal flood plain over which waters from the main body of the lake fluctuated; (3) an intermediate environment characterized by continuous to intermittent wave agitation, in water depths of probably <5 m; and (4) an offshore environment characterized by a lack of evidence for current or wave action, at depths of >5–10m.
The marginal environment was influenced by both wave and current processes. A friction dominated outflow produced sedimentary structures that indicate a south-easterly flow and depositional slope. Outflow competed with shoaling waves which advanced from E to W onto the lake shoreline. Where outflow was weakest, wave processes dominated. Longshore drift was an additional component in the movement of the nearshore waters. The Devonian lake or lakes of SE Shetland possessed rather shallow shoaling margins.
Low-temperature mineralization
Authors: Ineson P. R. 
Published: December 2007

Report of the Mineral Deposits Studies Group Sixth Annual General Meeting held at St. Peter’s College, University of Aston in Birmingham,
17–19
September
1980.

The Conference, ably organized by Dr R. A. Ixer with the co-operation of the University and the Department of Geological Sciences, to whom the Mineral Deposits Studies Group extend their thanks, was subdivided into 3 sections. The first day was devoted to a number of papers which covered varied aspects. Isotopic studies on the mineralization of the Ophir Valley, Colorado (Jackson), and the Ba-Zn deposit at Aberfeldy (Willan) were presented together with 2 papers on U mineralization in Namibia (Marlow and Clemmy). Ineson and Walters indicated the problems of correlating horizons and interpreting the attendant alteration associated with the igneous rocks in the South Pennine Orefield, while Alabaster & Pearce described the geological setting of the sulphide deposits in the Oman ophiolite complex. For this type of meeting, an unusual but interesting contribution by Broadbent et al. reviewed European Pb-Zn production and indicated recent research into new recovery processes for Pb, Zn and Cu as well as improving hydrometallurgical techniques.
Well over 100 people attended the second day, and were no doubt attracted by a number of papers related to Permo-Triassic mineralization. A review of the Permo-Triassic rocks and related mineralization was given by Clarke who, in proposing new genetic models, caused some disquiet amongst the audience. On a more localized scale, isotopic evidence indicating possible inter-relationships was presented by Harwood & Coleman, while Turner &
The composite floor of the Cretaceous back-arc basin of South Georgia
Authors: Storey B. C. , Mair B. F. 
Published: December 2007

Part of an ophiolite sequence and pre-Jurassic continental basement rocks are remnants of the composite floor of the Cretaceous back-arc basin system on South Georgia. The partially preserved ophiolite consists of pillow lavas and breccias, inter-bedded tuffs, basic and silicic dykes and occasional sills. It is intruded by a composite gabbro-plagiogranite pluton and smaller gabbroic plutons. The basement gneisses are intruded by layered gabbros, diorites, granitic rocks and numerous basic dykes. A migmatitic aureole surrounds the plutonic rocks, which are fragmented and net-veined by remobilized crustal rocks.
The mafic rocks of the ophiolite sequence and basement complex are geochemically similar and both formed by differentiation of a mantle-derived, sub-alkali tholeiitic magma in a former back-arc basin tectonic setting. The plagiogranite and silicic dykes and lavas of the ophiolite and some of the silicic rocks within the basement formed by differentiation of the basic magma. The remainder of the granitic rocks within the basement are geochemically distinct, comprising remobilized basement rocks and a calc-alkaline pluton of a remnant magmatic arc.
The back-arc basin formed by emplacement of the tholeiitic magma within pre-existing basement rocks. Up to 80% extension of the continental crust occurred prior to rifting and development of the back-arc basin.
Invertebrate and vertebrate pathways of anaerobic metabolism: evolutionary considerations
Authors: Livingstone D. R. 
Published: December 2007

A review of anaerobic metabolism (end-products, energy-substrates and enzymes) of the invertebrate and vertebrate phyla reveals three main pathway-types. The lactate and opine pathways yield, respectively, high and medium rates of energy production and are used for maintaining or increasing metabolic activity. The glucose-succinate pathway is a high (relatively) efficiency pathway used for anoxia survival.
The distribution of the pathways amongst the phyla is consistent with their phylogeny. A relationship between the Mollusca and Sipuncula is possibly indicated. A hypothetical scheme of the evolution of the pathways indicates early presences for amino acid based pathways, the opine pathways and a fourth pathway-type, the aspartate-succinate pathway.
A consideration of chemical, fossil and functional approaches to the reconstruction of the beginning of life suggests an early role for the opine pathways in providing energy for the burrowing of infaunal worms of the Precambrian era. Biological rather than chemical factors are concluded to have been the main pressures for the evolution of anaerobic metabolism.
The upper mantle and deep crust beneath the British Isles: evidence from inclusions in volcanic rocks
Authors: Upton B. J. G. , Aspen P. , Chapman N. A. 
Published: December 2007

Coarse-grained inclusions in Upper Palaeozoic alkali basalts, occurring in over 60 localities in the British Isles, include samples of the underlying mantle and lower crust. The ultramafic assemblages imply an extremely heterogeneous upper mantle involving a tectonized spinel lherzolite and harzburgite matrix transected by younger bodies of wehrlite, websterite, clinopyroxenite, orthopyroxenite, garnet-pyroxenite and assorted kaersutite- and biotite-rich ultramafites. Associated megacrysts include anorthoclase, sanidine, clinopyroxene, kaersutite, Ti-biotite, garnet, Ti-magnetite, Mg-ilmenite, apatite, zircon and corundum. These originated in part from disaggregation of pegmatoidal bodies of alkaline felsic rocks, pyroxenites, lherzites and glimmerites. Plagioclase-pyroxene rocks (basic granulites) are probably samples of the lower crust, with quartzo-feldspathic gneisses possibly derived from shallower levels in a chemically-zoned crust. Other inclusions described include apatite-magnetite rocks, biotite- and hornblende-albite rocks and unfoliated tonalites, diorites, trondhjemites and granites.
A high-grade (granulite-facies) feldspathic basement is inferred to underlie all the major N British structural provinces, including the Midland Valley and Southern Uplands. Anorthosite xenoliths imply that anorthositic rocks compose some part of the 'basement' in S and central Scotland.
Late Proterozoic lavas of the Central Arabian Shield—evolution of an ancient volcanic arc system
Authors: Roobol M. J. , Ramsay C. R. , Jackson N. J. , Darbyshire D. P. F. 
Published: December 2007

A petrological assessment of 11 volcano-sedimentary belts in the Central Arabian Shield (CAS) using 118 new analyses is presented. The same samples have been used in a Rb-Sr dating programme also reported in this volume. The oldest volcano-sedimentary belts (‘sequence’ C; >900 Ma) are chemically immature bimodal suites of low-K tholeiites and sodic dacite/rhyolite depleted in lithophile elements. These lavas have chemical characteristics similar to immature island arcs such as the Tonga–Kermadee and Lesser Antilles arcs. Younger lavas of ‘sequence’ B (900–700 Ma) are slightly more mature in composition, being predominantly calc-alkaline and low-K arc tholeiite series with higher lithophile element contents. They are comparable with Pacific island are averages. The youngest voluminous lavas (‘sequence’ A; 700–570 Ma) are generally calc-alkaline or high-K, calc-alkaline series lavas with moderately high lithophile element abundances. They are comparable to volcanic arcs such as Central America and Indonesia, which are transitional between island arcs and continental margin volcanic arcs.
The cratonization process in the CAS thus involved the superimposition of three volcano-sedimentary sequences, formed in progressively maturing volcanic arcs. Early-formed, immature island arcs were succeeded by chemically more mature island arc deposits and then by deposits formed in volcanic arc(s) transitional between island arcs and continental margins. The evolution ceased at this stage and probably did not advance to the equivalent of an Andean continental margin.
Calcrete and other soils in Quaternary limestones: structures, processes and applications
Authors: Braithwaite C. J. R. 
Published: December 2007

Quaternary limestones commonly include descriptions of calcrete, caliche and soils which embrace both surficial deposits in which dissolution and cementing phenomena interact on a calcareous substrate, and soils or other sediments where carbonates are precipitated as cements. Three genetic groups are recognized, in which (1) a soil profile is developed by surface alteration of existing marine sediments; (2) deposits accumulate superficially on a lithified surface; and (3) soil-like materials have been added to unconsolidated marine sediments by surface processes including infiltration.
Sediments range from unaltered marine grainstones through poorly sorted wackestones to mudstones. Diagnostic structures include pisoliths and other glaebules. laminae, grain aggregates, birdseyes and other vugs, and rootlets as well as fractures and brecciation not found in other environments. The most common precipitated carbonates are micrites, but needle fibres, whiskers and prismatic crystals occur. Crystal morphology is controlled in part by the level of supersaturation. rapid evaporation leading to micrite precipitation and whiskers, but also by the pressure of organic contaminants. Distribution of cements and structures is irregular, relating to percolating groundwater streams. Cements may be isopachous but meniscus structures, cement bridges and microstalactites occur. These vadose textures may not be developed where evaporation rates are high. Irregular areas of replacive (neomorphic) spar and displacive calcite growths occur in some examples but criteria for recognition are not firmly established.
Dated recent examples lie between 400 and 18,300 years B.P. but deposits on Aldabra and in Kenya are intercalated with marine sediments which extend to 200,000+ years B.P. The recognition of these terrestrial intervals within otherwise marine sequences enables sea level changes to be identified and correlated with other climatic data to separate local patterns of uplift or subsidence.
Preliminary comparison of diagenetic stratiform copper mineralization from Redstone, NW Territories, Canada,and Kamoto, Shaban copperbelt, Zaire
Authors: Chartrand F. M. , Brown A. C. 
Published: December 2007

Recent studies of stratiform copper mineralization in the Redstone copperbelt of the NW Territories, Canada, indicate analogies with sediments of modern intertidal and supratidal environments. Textural analyses show that mineralization occurred in microbial-laminated carbonate units during diagenesis following initial enrichment of the carbonates in iron sulphides and evaporitic sulphates.
Similar features have been described for the dolomitic beds hosting the well-known Kamoto ores of the Shaban copperbelt. The present work gives a brief comparison of the Redstone and Shaban host-rocks and their mineralization. Similarities include the interpreted shallow marine/red-bed sequence and the presence of stromatolitic and microbial-laminated structures in the carbonates. However, the Shaban host-rocks are more magnesian than those at Redstone, and silicification in Shaba surpasses the more normal diagenetic silification seen at Redstone. The copper, copper-iron and iron sulphides of Redstone and Shaba exhibit similar peneconcordant arrays across their respective basal carbonate horizons, but cobalt is important only in the Shaban mineralization. A more detailed comparison of host-rocks and mineralization in these two copperbelts is currently in progress.
Long-lived fault zones and their influence on the tectonic development of the southwestern Barents Sea
Authors: Gabrielsen R. H. 
Published: December 2007

The southwestern Barents Sea shows a complicated network of fault complexes and systems with various geometrical and genetic characteristics: trend, relation to basement, reactivation, fault plane geometry, and regional significance. Using these parameters, a classification of the fault complexes has been made, and a correlation to onshore faults has been attempted.
The area is subdivided into several fault blocks separated by deep-seated zones of weakness (first and second class fault systems). These are reactivated in connection with later (Mesozoic) movements in the area, and have acted as foci of strain so leaving the central area of the blocks relatively strain free. A third class of fault systems is of local significance, and reflects deformation limited to the interior of the fault blocks.
The Pleistocene succession of the Severn Estuary: a revised model based upon amino acid racemization studies
Authors: Andrews J. T. , Gilbertson D. D. , Hawkins A. B. 
Published: December 2007

This paper reports the results and stratigraphic implications of amino acid racemization studies of fresh- and/or inter-tidal molluscs from: (i) the important Pleistocene sequences of Kenn Church, New Blind Yeo Drain, Yew Tree Farm and Kenn Pier (Avon County); (ii) the previously undescribed Pleistocene beach deposits beneath the Llanwern steel mill, South Wales; and (iii) re-prepared and re-analysed shells from the Th/U-series dated beach deposits in Belle Houge Cave, Jersey, Channel Islands.
These studies indicate the complexity of sea level change in the area. In amino acid Group II (Oxygen isotope stage 5e; 120,000–130,000 years BP) sea level reached 4–5 m OD and possibly 12 m OD. This episode is correlated with similar Group II beach deposits on the Gower coast, and freshwater deposits in SW and SE Britain. The data suggest these Group II deposits are different in age from the Ipswichian interglacial, inter-tidal deposits at Selsey.

A Group IV age is attributed to freshwater deposits at Yew Tree Farm and Kenn
Pier
which collected just above a contemporary sea level or included re-worked earlier inter-tidal rocky shore faunas. These are provisionally correlated with the Group IV deposits in the Thames Estuary at Purfleet (
c.
400,000–600,000 years BP). Since these deposits are thought at post-date glacial deposits previously identified at Kenn and Court Hill, Avon, this glacial episode is now regarded as being much older than the Wolstonian glacial stage with which it had been correlated previously.
The Pontesford Lineament, Welsh Borderland
Authors: Woodcock N. H. 
Published: December 2007

The NE-trending Pontesford Lineament centres on the Pontesford-Linley and adjacent faults in the Shelve/Longmynd inlier. To the NE it is usually drawn along the SE edge of the Cheshire Basin and to the SW along a variety of lines parallel to or converging with the Church Stretton Fault. New mapping and reassessment of published data suggest that SW of the Pontesford-Linley Fault the lineament is logically drawn along the Clun Forest Disturbance, a post-Pridoli (late Silurian) fold/fault belt, then across the NW side of the Llandrindod inlier to flank the Tywi Lineament.
The lineament was intermittently active at least from mid-Ordovician through to Triassic time, with both strike-slip and dip-slip displacements that involved the upper part of the Precambrian basement. Late Ordovician and early Silurian strike-slip was particularly important. The lineament controlled the sites of several Silurian sedimentary basins. Ordovician contrasts across the lineament can be explained either by contemporary fault control or by subsequent large displacements juxtaposing unlike terranes.
The long history of reactivation and basement control on the Pontesford Lineament is typical of lineaments throughout Wales and the Borderland. It suggests that both Caledonian and Variscan structural trends N of the Variscan Front may be inherited from older, pre-Silurian or even Precambrian, basement structures.
Comparative geobarometry of pelitic hornfelses associated with the Newer Gabbros: a preliminary study
Authors: Droop G. T. R. , Charnley N. R. 
Published: December 2007

Physical conditions of contact metamorphism have been estimated for pelitic hornfelses collected from the inner aureoles of the Morven–Cabrach, Knock, Huntly and Belhelvie ‘Newer Gabbro’ intrusions using a few well-calibrated mineral equilibria.
Inner aureole temperature estimates range from 700°C to 850°C. Calculated pressures all fall between 4 kbar and 5 kbar, implying the existence of between 15 km and 18.5 km of overburden at each locality at the time of intrusion of the Newer Gabbros.

The results indicate that the four Newer Gabbros mentioned above were all emplaced at a similar crustal level, and that there has been no net regional tilting of the NE Dalradian since then. The results are not incompatible with some large-scale, late-stage (D
3
) gentle folding as implied by the regional isograd pattern.