bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conference Report
: Metamorphic studies: research in progress
Authors: Brown Michael 
Published: December 2007

Report of the inaugural meeting of the Metamorphic Studies Group held at Burlington House, 5 March 1981. The meeting was organized by Dr M. Brown.

A Metamorphic Studies Group, jointly sponsored by the Geological Society of London and the Mineralogical Society of Great Britain, was formally established at an inaugural meeting on ‘Metamorphic studies: research in progress’ held at Burlington House on 5 March 1981. The meeting was attended by over 150 participants, ranging from professors to research students, who were rewarded with a programme of 18 papers of high quality which covered a wide range within the field of metamorphism.
A programme of topics arranged broadly in order of increasing temperature and pressure conditions was opened by Arny Sveinbjörnsdottir, one of two research students who contributed papers to the meeting. Her paper, o n water-rock interaction in Krafla (fluid derived from meteoric water) and Reykjanes (fluid derived from seawater), Iceland, both of which are high temperature hydrothermal systems, used log activity diagrams to relate alteration mineralogy to fluid composition and concluded that the present mineralogy in both systems appears to be in equilibrium with the fluid composition.
In the next 4 papers, all concerned with low-grade (or low-grade to medium-grade) metamorphism, the important role of the fluid phase in metamorphism was emphasized. Aguirre, Levi & Offler, in their contribution, demonstrated that fluid chemistry and temperature were the main variables which controlled the development of sequences of mineral assemblages characteristic of the zeolite facies, prehnitepumpellyite facies, prehnite-pumpellyite/greenschist facies transition and
The geological history of Maio, Cape Verde Islands
Authors: Stillman C. J. , Furnes H. , LeBas M. J. , Robertson A. H. F. , Zielonka J. 
Published: December 2007

The oldest igneous rocks on Maio are pillow lavas of Mid-Ocean Ridge pillow basalts character which have been tilted and uplifted about 4 km from the ocean floor to outcrop as a partial ring, dipping steeply away from a central plutonic complex made up of pyroxenites, essexites, syenites and carbonatites. The ocean floor volcanic rocks are overlain conformably by a stratigraphically continuous pelagic carbonate succession which demonstrates a shallowing depositional environment from the Upper Jurassic to Upper Cretaceous times, when tuffaceous beds indicate renewed volcanism. The tuffs are associated with rudites demonstrating the emergence of the island and amongst the clasts are plutonics indicating Upper Cretaceous magmatism and the unroofing of the volcano to a substantial depth. Deformation under compressive stress resulted in the folding and local repetition by thrusting of this sedimentary cover, which, together with the plutonic core, had been intensively injected by major sills.
The Mesozoic succession has been planed off and overlain with marked unconformity by a largely Neogene sequence of volcanic and terrestrial sedimentary rocks. There is a hiatus throughout the Palaeogene, and constructional activity appears to recommence with ankaramitic hyaloclastite and lava deltas and subaerial ankaramitic flows. These are overlain by fluvial sediments and tuffs.
Stratigraphically above these is an extensive plateau of silica-undersaturated lavas, olivine-melilitites and nephelinites, which rest on a planed and locally lateritized surface. At topographically higher levels in the eastern part of the island there are thick ankaramitic lavas and pyroclasts which evidently flowed eastward through valleys cut down into the Mesozoic strata, and appear to be of Pliocene age.
The subsequent history of the island appears to be non-volcanic.
Chemical variation in Hercynian basalts relative to plate tectonics
Authors: Floyd P. A. 
Published: December 2007

The geochemistry of Hercynian basalts is reviewed with special reference to SW England. Hercynian basalts have the following chemical features: (1) relative enrichment in incompatible elements, (2) fractionated rare earth element (REE) patterns ranging from mild to strongly light-REE enriched, and (3) generally low large-ion-lithophile (LIL)/high field strength (HFS) element ratios. High and variable alkali contents and K/Rb ratios are indicative of low-grade alteration. Basalts are predominantly tholeiites, although alkali basalts may be developed on some trough margins. Basalts from different sedimentary troughs within the main Hercynian tectonic zones are characterized by specific incompatible element abundances and ratios. These variations are interpreted in terms of variable fractional crystallization, partial melting and mantle heterogeneity.
Hercynian volcanism was typically bimodal with basic and acid products characterizing the Rheno-Hercynian and Saxo-Thuringian zones. Activity in the Moldanubian zone was more variable with a high proportion of calc-alkali andesites. Two systematic chemical changes throughout the Devonian and Carboniferous have been recognized, with both light/heavy REE and LIL/HFS element ratios increasing with time. These features may relate to the introduction of LIL-enriched fluids derived by dehydration of subducted lithosphere that caused progressive metasomatism of the overlying mantle wedge.
Chemical discrimination of tectonic setting demonstrates that most of the basalts typify the continental intra-plate environment, although early Devonian basalts produced in the initial stages of continent rifting have some of the chemical features of incompatible element enriched oceanic basalts. An ensialic back-arc basin model underlain by a shallow northward-dipping subduction zone provides a possible explanation for the spatial and temporal variation in the Hercynian volcanic rocks.
Magma and sediment—II Problems of interpreting palaeovolcanics buried in the stratigraphic column
Authors: Francis E. H. 
Published: December 2007

President's anniversary address 1982
The preservation of volcanoes—never more than partial—involves a complex interaction of processes and these operate over periods of time which are often undervalued. From a review of the relative rates of these processes it seems that short-lived structures such as Surtseyan ash-rings may be preserved, albeit in modified form, around their whole circumference. For larger composite volcanoes, however, growth and remoulding by activity is balanced by penecontemporaneous and later erosion in such a way that the central and most of the proximal zones are likely to be removed before they can be buried either by transported volcaniclastic or regional epiclastic sediments. Even the preservation of distal zones may be asymmetrical. A one-sided hinge-line subsidence-sedimentation model is therefore suggested to explain the elongate lens-shaped aspects of the many extrusive piles known to lie approximately concordantly within stratigraphic sequences formed in both continental and littoral environments.
Temperate, meteoric diagenesis of Pliocene skeletal carbonates from eastern England
Authors: Balson P. S. 
Published: December 2007

The Crags of eastern England include marine skeletal carbonates which were deposited and lithified under temperate conditions. The Coralline Crag (Pliocene), in particular, exhibits a variety of carbonate cement types which indicate exposure to meteoric groundwaters during a regressive episode.
The Coralline Crag has been divided into an upper division of dominantly well sorted skeletal calcarenites and calcirudites and a lower, poorly sorted silty calcarenite division. ‘Dogtooth’ sparcement and rudimentary syntaxial cement overgrowths on echinoderm fragments are characteristic of the sediments of the upper division, which has undergone extensive aragonite dissolution. This division is consequently relatively evenly cemented. In the underlying sediments aragonite dissolution has not occurred and the sediments have remained largely uncemented, with cement restricted to irregular patches where growth of intra- and inter-particle equant spar has effectively eliminated porosity. In contrast with the upper leached sediments, syntaxial echinoderm overgrowths show a greater development but only where interference from surrounding sediment and sparry cement was absent. The elongate shape of the Coralline Crag outcrop may be the result of preferential cementation of the upper, coarser, well sorted calcarenites originally deposited as an elongate sediment body, possibly as an offshore sandbank.
The Waitakere Limestone, a temperate algal carbonate in the lower Tertiary of New Zealand
Authors: MacGregor A. R. 
Published: December 2007

The Waitakere Limestone is a shallow-water temperate algal carbonate ranging from upper Eocene (Runangan) to lower Oligocene (Whaingaroan) in age. The principal components of the rock are coralline algae 37–72%, benthonic foraminifera 1–9.2%, bryozoa 1–10% and echinoids 1–4%, set in a spar matrix 13–32%. Glauconite l–9% is ubiquitous.
Surface temperatures may have been as high as 20°C, but possibly as low as 12°C; water depth was 1–12 m, with adjacent sea grass probable. However, no evidence was obtained for the widely recognized temperature drop at the end of the Eocene. known elsewhere in New Zealand. The limestone fits well into the cooler-water foramol type, and within this the bryozoan assemblage.
Structural dating of a Precambrian pegmatite in Moine rocks of northern Scotland and its bearing on the status of the 'Morarian Orogeny'
Authors: Powell D. , Brook M. , Baird A. W. 
Published: December 2007

A cross-cutting pegmatite emplaced into low grade, non-migmatitic, Proterozoic, Moine metasediments on the western sea-board of Inverness-shire, Scotland, gives Rb-Sr muscovite ages of 746–776 Ma which are interpreted as minimum estimates for the age of formation of the pegmatite. Intrusion followed at least one phase of folding and schistosity production in the country rocks and an early phase of syn-kinematic garnet growth, correlated with the regional D
2
tectono-metamorphic event. The pegmatite was folded and suffered considerable grain size reduction under metamorphic conditions during the regional D
3
deformation episode.

The dilational character and low grade context of the pegmatite show that it was not a product of melting in place during metamorphism of the adjacent Moine Schists. Its lack of initial, syn-kinematic crystallization textures and fabrics, together with the absence of evidence that might relate its emplacement to any regional phase of compressive ductile deformation, would be compatible with a considerable time lapse between its intrusion and the earlier deformation and metamorphism of the host rocks. We have, however, no direct evidence for the extent of this interval.
The relationship of the pegmatite to the earlier deformation and metamorphism of the host rocks provides clear evidence for substantial Precambrian orogenic activity but the age of this activity, whether 'Morarian' and, or, 'Grenvillian', remains a matter of interpretation.
Geochemical characteristics and comparison of the basic rocks of the Lizard Complex and the basaltic lavas within the Hercynian troughs of SW England
Authors: Floyd P. A. 
Published: December 2007

The S Cornish basaltic rocks constitute a separate chemical province relative to the rest of the SW England Hercynian volcanic suites. In particular they are characterized by (a) lower incompatible element abundances, (b) generally lower large-ion-lithophile/high field strength element ratios, and (c) being mildly enriched in the light REE. Within this province some of the basalts have chemical features akin to incompatible element enriched MORB.
Tectonically the S Cornish province can be divided into (a) the S Cornish mélange zone (N Lizard-Roseland area), and (b) the Mylor sedimentary trough (Penwith-Camborne area), both of which contain localized basaltic lavas. These basalts are compared with the Lizard ophiolite and associated hornblende schists which have compositions ranging from depleted to enriched MORB. The exotic volcanic megaclasts within the mélange zone are not chemically related to the ophiolite and as such do not represent the dismembered volcanic portion of the Lizard ophiolite.
If the Lizard ophiolite and the hornblende schists represent different segments of a Palaeozoic oceanic area lying to the S, the ocean-floor type Hercynian basalts of S Cornwall are interpreted as an abortive attempt to produce oceanic crust in a rifted continental margin during the early Devonian.
Tectonic studies: annual meeting 1982
Authors: Williams Graham 
Published: December 2007

Report of a meeting of the Tectonic Studies Group held at University College, Cardiff, 15–17 December 1982. The meeting was organized by Dr G. D. Williams.

On the first day of the conference two field trips were held: the first to the Gower Peninsula led by R. Graham (Swansea) and the second to Pembroke led by G. Williams (Cardiff). In both cases, Variscan structures—thrusts, folds and shear zones—were studied. Also on 15 December, a workshop on techniques and uses of the orthographic net was presented by Declan DePaor (Galway).
The main contributions of the AGM were given on 16 and 17 December. During the first session, theoretical aspects of deformation were considered. J. S. Whalley (Portsmouth) and W. H. Owens (Birmingham) considered errors arising in calculating strain ellipsoids from two dimensional data using the program PASE5. D. DePaor (Galway) showed how the use of rank 3 tensors permits the description of complex structures in a simple way and he illustrated this using a zone of heterogeneous simple shear. Stress risers on a mesocopic scale are commonly observed, and A. Morris and J. Ague (Detroit) argued that features such as sedimentary pebbles, porphyroblasts, quartz veins and bed thickness variations may create a strain-sink effect that initiates and localizes deformation. C. J. Talbot (Dundee) discussed the effect of inverse and counter folding in incompetent layers and illustrated his talk with common examples from the Moines of the Fort William area and basic sheets in the Limpopo Belt. Transpression was
Metamorphic studies: research in progress
Authors: Brown Michael 
Published: December 2007

Report of a meeting of the Metamorphic Studies Group held at Burlington House, 7 March 1984. The meeting was organized by Dr M. Brown.

A Metamorphic Studies Group Meeting on ‘Metamorphic studies: research in progress’ and the third Annual General A Metamorphic Studies Group Meeting on ‘Metamorphic studies: research in progress’ and the third Annual General Meeting of the Group were held on March 1984 and more than 80 members participated. Nineteen papers were presented which covered a wide range of interests in metamorphic geology, including for the first time three papers on isotope geology. Six papers were given by research students. Overall, the large number of contributions to the meeting, the lively discussion of these contributions and the substantial attendance at the meeting suggest that the “current research” style of meeting is very worthwhile.
The morning session, chaired by B. Harte, was opened by R. P. Hall who presented an account the inter-relationships between metamorphism and magmatic and tectonic episodes in two contrasted areas within the Archaean craton of southern W Greenland. In Ivisgrtoq the rocks are at amphibolite facies and have never been to granulite facies. In contrast, in the eastern Sukkertoppen region the rocks are partly retrogressed from granulite facies. In such retrogressed granulites, the presence of ‘blebby’ hornblende and biotite after pyroxene is characteristic. Hall presented data on various reactions by which hypersthene has been replaced and concluded that enclosing acid gneisses in which no evidence granulite facies is preserved must have provided a metasomatic influx of elements such as potassium
Volcanic and geochemical stratigraphy of the Nussir Group of Arctic Norway—an early Proterozoic greenstone suite
Authors: Pharaoh T. 
Published: December 2007

The Nussir Group of West Finnmark is a suite of metabasaltic lavas and tuffs about 1.8 km thick, associated with continental and shallow marine sediments. This assemblage is typical of Karelian (Early Proterozoic) supracrustal sequences throughout northern Norway and northernmost Sweden.

Primary textures are well preserved and permit the establishment of a volcanic stratigraphy for the Nussir Group. The Krokvatn Formation is dominated by mafic aquagene tuffs while the overlying Svartfjell Formation is composed mainly of submarine pillow basalt. Petrographic evidence for the petrogenesis of the metabasalts is poor because of greenschist facies metamorphism during the Svecokarelian Orogeny
c
. 1840 Ma.

The earliest lavas have the most primitive compositions, but subsequent flows exhibit strong enrichment in Fe, Ti and incompatible elements as a consequence of extensive crystal fractionation. The tholeiitic nature of the suite is confirmed by the trace element data. The later lavas are more uniform and less evolved: and are considered to represent steady-state compositions produced by a periodically replenished/tapped open-system magma chamber.
The field relationships, lithological and geochemical evidence suggest that the Nussir Group lavas were erupted in a submarine rift basin within continental crust. They form part of an extensive tholeiitic magmatic province which occupied much of northern Norway, Sweden and Finland in the early Proterozoic. The tectonic environment of this province is poorly constrained by the geochemical data. Continental plateau basalt provinces such as the Columbia River and Karoo provide the closest Phanerozoic geochemical analogues.
Tectonic studies group: 14th annual meeting
Authors: Tanner Geoff 
Published: December 2007

Report of a meeting of the Tectonic Studies Group held at the University of Glasgow, 18–21 December 1983. The meeting was organized by Drs P. W. G. Tanner and C. Farrow (Glasgow), I. Allison (Strathclyde) and A. D. Gibbs (Britoil).

After a decade of sustained growth, the Tectonic Studies Group has acquired international status and the 14th Annual Meeting attracted nearly 300 participants, many of whom were from the European continent and North America. Papers on any structural topic were invited and for the first time the number of contributions (92) far exceeded the number of papers (51) which could be given in two days. The organizers were faced with the unwelcome task of selecting speakers and also had to reduce discussion time to less than was desirable. John Underhill was awarded the prize for the best postgraduate contribution.
The meeting began with a 2-day workshop (18 and 19 December) on the interpretation of seismic reflection sections, organized by G . K. Westbrook (Durham) and J. Hall (Glasgow). A basic course in the techniques of reflection seismology was followed by a series of presentations by researchers from the universities and from industry on applications to different tectonic environments.
On 19 December, three field excursions were held. P. R. Thomas (Paisley) led an excursion to look at structures in the Central Highland Moine as exposed in new road cuttings on the A9; W. G. Henderson (BGS) led a party to North Glen Sannox on the Isle of Arran to examine
Upper Palaeozoic successions and nappe structures in north Cornwall
Authors: SELWOOD E. B. , THOMAS J. M. 
Published: December 2007

For many years the geology of north Cornwall has been interpreted in terms of a south-facing overfold model, which predicts a major confrontation at Padstow with the north-facing structures of south Cornwall. New evidence indicates the existence of contrasting successions separated by flat-lying thrusts. In upward succession the Port Isaac, Tredorn and Boscastle nappes are identified; the first appears to have been emplaced by gravity sliding in late Viséan times, followed by the Tredorn and Boscastle nappes in the early Namurïan. Strata represented in the inverted limb of the Port Isaac Nappe, not previously distinguished, are described as the Jacket's Point Slate Formation.
Throughout the nappe pile there is consistent evidence of north-facing and northward transport for distances measured in tens of kilometres. Not more than 3 km of south-facing strata may now exist at the Padstow confrontation, and this feature is unlikely to be of great regional significance. The allochthon extends northwards to the Rusey Fault Zone where the autochthon was locally backfolded over the allochthon in late Westphalian times; this appears to be the only significant confrontation of facing directions in north Cornwall.
Volcanological and petrological evolution of San Pedro volcano, Provincia EI Loa, North Chile
Authors: O'CALLAGHAN L. J. , FRANCIS P. W. 
Published: December 2007

The 6163 m high volcano San Pedro in the Western Cordillera of the central Andes of North Chile, is a composite of two cones, each representing a different structural and chemical stage in the evolution of the volcano. Eruption of thin lavas and scoria, dominantly of basaltic andesite composition, built up an older cone, which was subsequently modified by both glacial erosion and a major collapse event, akin to that of Mt. St. Helens in May 1980. A younger cone has subsequently grown within the crater, obscuring much of the detailed structure of the older cone. The younger cone was built up in four distinct phases of eruption which produced andesite and dacite lavas and pyroclastic flow deposits. The latter include both pumice flows and hot avalanche deposits. All of these products from the younger cone are chemically distinct from those of the older cone.
Whilst much of the whole rock geochemistry can be explained by simple crystal-liquid fractionation involving the observed phenocryst phases, this process cannot adequately account for the petrographic textures and mineralogical variations, which show evidence for considerable thermal and chemical disequilibrium. Textural, mineralogical and chemical variations are consistent with models of late stage mixing between magmas of the same fractionation series, with chemical and thermal inputs from hot dense basalt or basaltic andesite injected into the base of the magma chamber.
The British Geological Survey Database
Authors: LUMSDEN G. I. , HAWORTH R. T. 
Published: December 2007

The British Geological Survey is a component body of the Natural Environment Research Council, through which it is funded by government to assemble, manage, interpret and communicate the National Geosciences Database for the benefit of the nation. On the 150th Anniversary of the founding of the Geological Survey of Great Britain, set up in 1835, the Geological Society has honoured the Survey by dedicating this issue of its Journal to the reporting of some of the Survey's activities. This issue is not meant to be a compendium of papers covering the full range of BGS activities. That is impossible in an organization currently dominated by a financial need to respond rapidly to the demands of customers (including Government). Instead it represents a snapshot of those activities that reached publication stage during the summer of 1985. Some papers offered for inclusion had to be withdrawn pending their release from confidential status. Others submitted could not be revised in time because of customer demands on the author’s time. They all, however, emanate from a broadly based programme of strategic research responding to the immediate demands of modern industrialized society while contributing to the on-going and long-term assembly of the National Geosciences Database.
The objective of the Survey, 150 years ago, was to assemble and interpret a geological database for the whole country, and initially the only tool available was geological surveying. Geological surveying is carried out by field geologists observing and sampling strata to identify rock type, composition and age, observing topographical features