bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and tectonic evolution of the Armorican Massif
Authors: Roach R. A. 
Published: December 2007

Report of a meeting of the Tectonic Studies Group held at Burlington House, 14 March 1979. The meeting was organized by Dr A. J. Barber and Dr P. R. Cobbold.

The papers presented provided a timely review of the major advances during the last decade in understanding the structure and tectonic evolution of the Armorican Massif. Thestablishment of special research groups at the Universities of Rennes, Brest, Caen and Nantes, supported by the CNRS, has been the prime factor in this development. As a result, the geological evolution of this region is probably better understood than that of other Nercynian Massifs in central and western Europe.
The geological evolution of the Armorican Massif can be traced back more than 2000 Ma, beginning with the deposition of a Lower Proterozoic or late Archaean supracrustal sequence which was polyphase deformed, metamorphosed, and intruded by granitic and quartz-dioritic magmas between 2500 Ma and 1900Ma to produce the Pentevrian basement of the northern part of the Massif. Professor CognC portrayed the Pentevrian as a fragment of continental crust originally closely related to the W African Craton, which similarly exhibits magmatism around 2200 Ma to 1900 Ma (Eburnian event).
It was upon this basement and within adjacent oceanic domains that the Upper Proterozoic Brioverian Supergroup was deposited. The closure a portion of this ocean, the segment lying NW of Capdela Hague-Tregor Pentevrian axis and S continental crust represented by the Precambrian southern Britain, was, according to the model proposed by Auvray & Lefort, the result
Timing of thrusting in the southern Appalachians, USA: model for orogeny?
Authors: Hatcher R. D. , Odom A. L. 
Published: December 2007

Field and geochronological studies in the southern Appalachians reveal a space-time relationship of thrust and other large faults to their relative positions in the orogen, and their times of formation in relation to thermal-metamorphic peaks. Alleghanian thrusts of the Valley and Ridge-Cumberland Plateau are of the décollement type, resulting from compression of the foreland during the waning stages of mountain building.
At least one pre-metamorphic thrust is known in the Blue Ridge. Other pre-, syn-and late metamorphic thrusts have been recognized in the Blue Ridge, Chauga belt and Inner Piedmont, related to Taconic (450–480 Ma) metamorphism. Several later thrusts in the Blue Ridge and the Gold Hill–Silver Hill fault in the Piedmont have been dated as Devonian. Syn- to post-metamorphic faults in the eastern Piedmont are Hercynian. These were developed during or following the Hercynian metamorphism, which overprints earlier events.

Several large faults, notably the Brevard, record episodic movement histories spanning much of the Palaeozoic. The Brevard Fault had a pre- to syn-metamorphic (Taconic) movement history. Homogenization of Sr isotopes occurred in blastomylonites in the Brevard Fault after regional metamorphism, dated at 356 ± 20Ma. Both these early events involve ductile behaviour. Mylonites near the base of the Blue Ridge thrust sheet developed by 367 ± 20 Ma, yet elsewhere the allochthon locally overrides rocks as young as Carboniferous, indicating later (Alleghanian?) transport of the allochthon. Phyllonites in the Goat Rock–Bartlett Ferry fault zone are dated at
c
. 380±20Ma. One or more later events (Hercynian?) occur in the brittle realm. The Brevard Fault probably served as the root zone for early-to mid-Palaeozoic thrusts in the Blue Ridge. Later brittle deformation caused it to ramp over the rear of the Blue Ridge thrust sheet.

There is a space-time transgression of thrusting in the southern Appalachians, beginning with early pre-, syn- and late metamorphic (Taconic) thrusting in the metamorphic core. Devonian (Acadian) thrusting and high angle faulting also affected the metamorphic core. Later (Hercynian–Alleghanian) faults are restricted to the flanks of the orogen. This space-time relationship of faulting to thermal peaks and position in the orogen should be observable in other well-exposed orogenic belts and other portions of the Appalachian–Caledonide system.
Rb-Sr whole-rock isochron ages of late Precambrian to Cambrian igneous rocks from southern Britain
Authors: Patchett P. J. , Gale N. H. , Goodwin R. , Humm M. J. 
Published: December 2007

Rb-Sr age data are reported for late Precambrian to Cambrian igneous and metamorphic rocks from the border region of England and Wales. A felsic intrusion from Stanner Hill defines a good whole-rock isochron of 702 ±8 Ma. Uriconian pyroclastic rocks from the Wrekin area give a whole-rock age of 558± 16 Ma, while the late- or post-Uriconian Ercall granophyre from the same area gives a good whole-rock isochron of 533 ±13 Ma. A biotite cooling age from the nearby pre-volcanic Rushton Schist is consistent with these dates and suggests that the region cooled after the close of Uriconian magmatism at 536 ±8 Ma. All these results relate to widespread igneous/metamorphic activity in latest Precambrian to Lower Cambrian time.
The Ercall granophyre and Rushton schist are directly overlain by Lower Cambrian sediments and 533±13Ma is thus a maximum age for the deposition of these rocks.
A ground water resources databank in the Kingdom of Saudi Arabia
Authors: Marsh J. M. , Sagaby I. , Sooley R. R. 
Published: December 2007

In rapidly developing countries, one of the chief impediments to efficient assessment and planning of geologic resources is the frequent lack of awareness of existing data and difficulty of access to available information. Such problems can be reduced by employing a computerized data storage and retrieval system.
Such a system is being implemented by the Water Resources Development Department and Ministry of Agriculture and Water, Saudi Arabia, to store data of water resources and hydrogeology. The lack of an adequate system of data storage has impeded rationalization and adjudication of existing data; to enable the introduction of sophisticated data processing techniques, all available data are being input to a multiple database. So far only the well-site data file has been implemented and details of 23,000 wells have been entered. A further 6 files are planned to cover all aspects of water resources and the hydrochemistry and surface water data files are now in preparation.
The data are managed by SYSTEM 2000 software loaded on an IBM 370/158 computer housed in the National Computer Centre.
Sedimentary basin in-fill in the northernmost Natal Valley, hiatus development and Agulhas Current palaeo-oceanography
Authors: Martin A. K. , Goodlad S. W. , Salmon D. A. 
Published: December 2007

Sedimentation over large areas of a marginal plateau, the northernmost Natal Valley (NNV), is influenced by the tropical/sub-tropical Agulhas Current. Through mobilization of detritus and concentration of sedimentation into localized depo-centres, current action provides a mechanism for hiatus development both in on-shelf and off-shelf areas. Post-Gondwana break-up sedimentary basin in-fill is interrupted by several regional hiatuses. These correlate with coastal regressions, global sea-level low-stands, proposed phases of invigorated oceanic circulation and with global phases of slow deep-sea sedimentation. An assessment of these mechanisms indicates detritus supply related to sea-level changes cannot explain correlation of on-shelf and off-shelf hiatuses. Current action may have been a contributory factor in development of a Cenomanian/Turonian hiatus and facies change and a Cretaceous/Tertiary boundary hiatus.
An Early Oligocene hiatus clearly marks a change in the Agulhas Current regime. Current-moulded features, asymmetric sediment distributions and re-working attest to enhanced current action. Establishment of a cold bottom layer in the ocean at this time stimulated Indian Ocean surface/near-surface circulation. New circulation patterns were established after a Miocene/Pliocene boundary hiatus. Since then the main flow-paths have been fairly stable, although local depo-centre shifts late in the Pliocene–Recent sequence suggest eastward movement of a counter-current and cyclonic eddy off Maputo.
Petrochemistry and origin of sub-ophiolitic metamorphic and related rocks in the Oman Mountains
Authors: Searle M. P. , Malpas J. 
Published: December 2007

The Semail ophiolite complex of the northern Oman Mountains was obducted during Cenomanian to Campanian (Upper Cretaceous) times onto the Arabian continental margin. During this time span, schistose metamorphic rocks of amphibolite and greenschist facies exhibiting polyphase deformation were formed and accreted below the ophiolite slice. Whole-rock and mineral analyses confirm that the amphibolites were originally tholeiitic basalts comparable to present day occurrences at mid-ocean ridges. A comparison of trace element geochemistries, however, suggests that the protoliths were not equivalent to the Haybi alkaline and transitional tholeiites found in the underlying structural slice, or to the Semail ophiolite volcanic rocks which lie structurally higher in the sequence. It is therefore suggested that the amphibolites may have been derived from Jurassic or Lower Cretaceous oceanic basalts not recognized elsewhere in the Oman Mountains.
Structurally beneath the amphibolites within the metamorphic sheet, greenschist facies metasedimentary rocks, including quartzites and marbles, are interbanded with metabasite horizons containing actinolite and, less commonly, blue crossitic amphiboles.
It is suggested that the sedimentary and volcanic protoliths were metamorphosed in a subduction zone environment during initial ophiolite displacement, and were accreted to the base of the ophiolite during progressive underthrusting.
Variations in fluvial style on the Eocene–Oligocene alluvial fan of the Scala Dei Group, SE Ebro Basin, Spain
Authors: Allen P. A. , Cabrera L. , Colombo F. , Matter A. 
Published: December 2007

The Scala Dei Group represents one of several coarse clastic wedges along the eastern margin of the Tertiary Ebro Basin. This group, of Eocene–Oligocene age, is partly concealed by faulted and locally overthrust older sediments, but a segment of Oligocene age is spectacularly exposed for about 15 km along the newly constructed A2 motorway.
Near the edge of the basin multistorey conglomerate channel-bodies are composed of large scale foresets up to 3 m high, representing side bars or possibly point bars. Smaller (up to 40 cm) normally graded beds with imbricated clasts represent diagonal or transverse bars, and horizontally-stratified sheets may be longitudinal bars. Flow was highly variable. The multistorey conglomerate bodies are restricted to several crudely radiating axes representing major feeder systems and give rise to a ‘goose-foot’ depositional palaeomorphology.
Towards the basin centre and in quiet zones between the main feeder axes single-storey channel-bodies of conglomerate and sandstone are common. Some plug-like conglomerate and sandstone channel-bodies are ribbons which are essentially straight in plan, and other, generally asymmetrical, sandstone channel-bodies preserve the point bars of channel bends where limited lateral migration took place.
Many channel-bodies possess extremely well-developed wings representing levees and locally amalgamated crevasse splay sequences. Conspicuous crevasse channels cut through the levees. The wings and crevasse channel-bodies contain carbonate-rich palaeosols.
This sequence is interpreted as an essentially distributive but ephemeral fluvial system.
Petrogenesis of Dalradian albite porphyroblast schists
Authors: Watkins K. P. 
Published: December 2007

A linear belt of schists within which abundant albite porphyroblasts are developed outcrops over approximately 2000 km
2
of the SW Scottish and NE Irish Dalradian. Other features which characterize these rocks are chloritization, the common occurrence of magnetite and development of quartz segregations. The albite porphyroblast schists occur in the biotite and garnet Barrovian metamorphic zones and occupy the crests of regional F3 antiforms.

Textural, mineralogical and petrological data indicate that retrogression of original (Barrovian) metamorphic assemblages and concomitant hydrogen metasomatism occurred. As a consequence of these reactions pH gradients were induced between quartz-albite and mica-garnet-rich bands in the rocks which resulted in redistribution and recrystallization of albite as porphyroblasts. No input of sodium on a regional scale is necessary to explain porphyroblast growth.
An influx of water was responsible for these processes. It is likely that the water was a product of Barrovian regional metamorphism and accumulated in the crests of F3 antiforms as a result of restricted fluid flow.
Pressure solution in nature, theory and experiment
Authors: Rutter E. H. 
Published: December 2007

Some of the features of water enhanced deformation of rocks by diffusive mass transfer (pressure solution) in nature which are pertinent to the rate controlling mechanism of the deformation are reviewed, and it is inferred that (a) the diffusion of matter in an aqueous intergranular film which can support shear stress is an essential part of the process, and (b) the diffusion is driven by stress induced chemical potential gradients, together with gradients due to local chemical reactions.
The theoretical approach to the derivation of constitutive flow laws for creep by diffusive mass transfer is outlined, and a simplified flow law proposed. Crucial to the absolute rate of deformation predicted by the flow law is the estimation of the phenomenological coefficient which links diffusive flux to chemical potential gradient. It is argued that this should be several orders of magnitude less in thin, stressed aqueous films than for solutions of ions in large water volumes.
Some simple experiments are described to address the question of (a) the existence of thin intergranular aqueous films which can support shear stress, and(b) the magnitude of the above phenomenological coefficient. The results obtained are consistent with the inferences made from the study of microstructures in naturally deformed rocks, and this is illustrated by means of extrapolation of theoreticallv derived relationships to conditions of natural rock deformation and sediment compaction by pressure solution.
The ending of the Caledonian orogeny in Scotland
Authors: Watson Janet 
Published: December 2007

The geological evolution of the metamorphic Caledonides during the 100-million-year period from the phase of crustal thickening initiated by the Grampian orogeny to the emplacement of late granites at
c.
400 Ma is reviewed. Shortening and westward transport associated with the Grampian orogeny were diachronous; deformation began in the weak Dalradian basin and extended north-westward into the area of crystalline Moine rocks. An important change in tectonic regime, coinciding roughly with the closing of the Iapetus Ocean, was recorded at
c.
425 Ma by the onset of sinistral transcurrent motions on NE–SW lines parallel to the Caledonian belt. Regional uplift of the thickened crustal welt, accompanied by deep erosion, led to the removal of 20–30 km of overburden from the Highlands, mainly in Ordovician and Silurian times. Known Lower Palaeozoic deposits of Scotland cannot account for the volume of sediment so produced and it is suggested that other basins were located in a major transform zone beneath the northern North Sea.

The onset of late Caledonian magmatism coincided with the start of the post-collisional regime of strike-slip motion. The distribution of granites and appinites was influenced by transverse (NW–SE) dislocations in the lower crust and the emplacement of individual intrusions was often fault-controlled. The deep transverse lineaments acted as conduits for both sub-crustal and crustal melts over periods of up to 25 million years. It is suggested that mantle rocks metasomatized by fluids generated at an underlying subduction zone were the main source of the sub-crustal melts, and that magmatism was triggered from above by vertical and horizontal block movements.
This paper is a contribution to IGCP Project 27.
The geotectonic environment of Zambian copper-cobalt mineralization
Authors: Annels A. E. 
Published: December 2007

Suggestions that the Ore-Shale of the Lower Roan Group is part of a series of sedimentary fades produced by the north-easterly transgression of the sea over dominantly arenaceous strata of littoral, deltaic, lacustrine and continental origin have been viewed with scepticism by the author. The lack of proven transition facies from silty carbonaceous argillites, of the type found close to the south-western limits of the Ore-Shale in the Zambian Copperbelt, to dolomites found further to the SW, has tended to accentuate this feeling. The intensity of exploration drilling in these areas must imply that, whatever the cause, the cut-out of the Ore-Shale is rapid. At the same time a 'normal' Lower Roan succession of the Chambishi type suddenly becomes attenuated and dolomites and dolomitic/chloritic schists are found immediately overlying argillaceous gritty sandstones, conglomerates and arkosic quartzites characteristic of Footwall Formations. Locally this contact may be reddened, porous and brecciated. Amphibolite bodies of the type normally found at a much higher stratigraphic level in the Upper Roan Group are present a short distance above this contact. It is thus proposed that this feature represents a hiatus in the succession and that all rocks from the Ore-Shale to the top of the Lower Roan, and possibly into the base of the Upper Roan, are missing due to non-deposition and/or erosion. This interruption of the succession coincides with the western cut-out of the Ore-Shale from the Konkola Dome in the NW, down to the western end of the Roan Basin in the S.
In view of various authors' contention that the Zambian Copperbelt is the site of an ancient aulacogen, the above observations take on an important genetic significance. The present paper thus reviews the location of copper-cobalt mineralization in relation to sedimentary facies changes and cut-outs, structural features and amphibolitic bodies, and proposes a geotectonic model for the Copperbelt which, it is hoped, provides a more satisfactory and comprehensive explanation for the facts. This model also provides a source for the metals which were converted to sulphides by diagenetic processes. It is believed that the complex mineral chemistry of the Ore-Shale associated ores and, in particular, the presence of localized concentrations of Mo, Co, Ag, As, Bi and Te-bearing phases, is best explained by high level seepage of magmatically enriched hydrothermal solutions along Precambrian rift systems and associated fractures. These metals were either dispersed by wave and current action in the sedimentary environment or were concentrated by porosity and physico-chemical and bacteriogenic controls in the diagenetic environment.
Uplift patterns and orogenic evolution in the Scottish Dalradian
Authors: Dempster T. J. 
Published: December 2007

Rb-Sr and K-Ar mineral ages from the Dalradian rocks of Angus and Perthshire indicate considerable diachronism of cooling, following the Caledonian regional metamorphism. The oldest mineral ages (~515 Ma) are similar to the independent estimates of peak metamorphic age, and hence indicate very rapid cooling; they occur in the highest grade samples of the Angus region and are associated with localized uplift. Regional rapid uplift events at 460–440 Ma and 410–390 Ma may also be recognized and correlated with structural and igneous activity and metamorphic age dates within the Scottish Highlands.
Thermal models show the importance of localized and discontinuous uplift in determining both the timing of metamorphism and the shape of the P–T paths. They suggest that the major diachronous metamorphism (and granite production) in the Scottish Highlands is depth controlled rather than representing major lateral diachronism of thickening or heat sources.
Localized uplift may exercise considerable control on mineral facies variation within orogenic belts. The local uplift in Angus introduces hot, high-pressure Tarfside Nappe rocks into higher level Tay Nappe rocks. Thus, the uniform block uplift models frequently used in the interpretation of metamorphic and structural phenomena in orogenic belts are an oversimplification of the real events.
Storm sedimentation
Authors: Allen P. A. , Pound C. J. 
Published: December 2007

Report on a meeting of the British Sedimentological Research Group held on 5 May 1984 at University College, Cardiff. The meeting was organized by P. A. Allen and C. J. Pound.

This meeting was arranged to reflect the recent resurgence of interest in the dynamics and sedimentation of continental shelves. To some extent this has been stimulated by advances in physical oceanography which reveal exceedingly complex patterns of water motion on the continental shelf. Yet there still remains enormous uncertainty as to the response of a mobile substrate to these complex water motions. As if to fill this scientific vacuum, hummocky cross-stratification has become an obsessional focus of attention amongst clastic sedimentologists. It was thought timely to consolidate our knowledge of storm sedimentation as a whole and in particular, first, to evaluate critically the palaeohydraulic constraints on the formation of hummocky cross-stratification (HCS) and second, to document its context within marine sedimentary sequences.
The contributions to the meeting fall into two themes: (1) insights into the genetic significance of storm deposits, particularly HCS, and (2) documentation of the geometry and anatomy of storm-generated sedimentary sequences.

Physical significance of storm deposits

J. R. L. Allen (Reading) provided the general physical implications of storms. Storms cause changes in water level resulting from barometric effects and from wind drag on the water surface creating a water surface slope or set-up. They also induce currents in the affected water body; these currents are created by wind drag, flowing as a surface layer in the
Computer education in geology
Authors: Howarth Richard 
Published: December 2007

Report of a joint meeting of the Geological Information and Earth Science Education Methods Groups of the Geological Society, held at the Department of Earth Sciences, University of Cambridge, on 22 May 1984. The meeting was organized by P. Hill.

The aim of the meeting was to examine the requirements of employers of geology graduates and the present provision for the education of undergraduates with respect to computing and computer-based skills and applications. It consisted of presentations on the viewpoints of academic,industrial,and government bodies, plus discussion.
G. Y. Craig opened the meeting with an account of the use of computing and statistical teaching in the Geology Department at the University of Edinburgh. All geology students take a course in statistics as part of the coursework.They are also encouraged to take an optional l-year course in Computer Science.
One major problem theDepartment has found is the rapidly increasing cost of acquiring and maintaining capital equipment. There is not enough money to provide sufficient student workstations at present, and this applies to all departments. The last 10 years have seen the computing costs rise from 10% to 37% of the equipment budget. Annual maintenance charges for computing have been found to be very much higher than that for other major equipment,and paying an hourly rate for maintenance can be cheaper.The problem of where to draw the balance between the costs of data analysis and that of acquisition of hardware with which to obtain original data is an increasing one.
A. D. M. Burwell (BP Research Centre, Sunbury) drew a contrast between the way computers are being used by geologists in the petroleum industry