bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural influences on the occurrence of groundwater in SE Zimbabwe
Authors: Greenbaum D. 
Published: April 2008

Abstract
The Zimbabwe Craton is a heterogeneous assemblage of crystalline basement rocks in which the groundwater reservoirs are structurally controlled or confined to the weathered overburden. Lineaments, interpreted from Landsat imagery and aerial photographs, represent faults, joints and dykes of several ages. Such fissured rocks are more susceptible to deep weathering and are a main target for borehole siting. An analysis of borehole yields indicates that, although failure rates can be high, fractures of all trends are capable of providing an adequate hand-pump yield (0.25 l/s). Thus, despite their origin as compressional shears, many fractures now appear to provide open conduits for groundwater. It is concluded that within the near-surface zone of most importance to basement rock aquifers (40 to 80 m) fractures of all origins are in a state of tension probably as a result of recent uplift and erosional unloading.
Geomorphological controls on borehole yields: a statistical study in an area of basement rocks in central Malawi
Authors: McFarlane M. J. , Chilton P. J. , Lewis M. A. 
Published: April 2008

Abstract
Data from about 1500 boreholes in an area of African erosion surface in central Malawi were statistically analysed to attempt to correlate terrain characteristics, profiles and yields. The objectives were to seek terrain criteria which (a) allow regional evaluation of hydrogeological potential and (b) facilitate borehole site selection. From the 26 1:50 000 topographic maps analysed, a close map-by-map correlation was shown between extensive areas of dambo (seasonally waterlogged bottomland), low stream frequency and low relief as expressed by mean, median and modal values of the relative relief of individual km squares. Using this map-by-map approach no strong correlations were established between yield, profile and terrain characteristics.

There were only slight variations in mean yield of the two borehole types: those which finished in the regolith and those penetrating the underlying hard rock (55 1/min and 68 1/min respectively). Division of the total borehole data into relative relief subsets showed clear associations of low relative relief, thicker total and thicker saturated regolith and higher yields, where relative relief is <250 ft/km
2
. Subsetting the data with respect to the eight minor erosion surfaces which here comprise the African surface also showed significant variations in mean yield associated with these surfaces. Low relative relief emerged as the prime target for borehole siting, with sites at altitudes between the surfaces more likely to be higher yielding than comparably low relative relief sites within the altitudinal range of the minor surfaces. Sites close to the base of inselbergs yielded less well than those in the lowest relief category. The emergence of strong relationships between terrain and borehole performance, regardless of lithological variations, places the effects of rock type on borehole performance of secondary importance to those of geomorphology and leaching history in the study area.

This study allows regional assessment of hydrogeological potential in terms of terrain type. It also provides borehole site selection options within 1 km of a given site, using tabulated mean yields in the relative relief classes in various positions in relation to the minor erosion surfaces. Only the information available on the 1:50 000 topographic maps, i.e. altitude and relative relief as represented by the 50 ft contours, is necessary to apply the siting options.
Guillemot D: a successful appraisal through alternative interpretation
Authors: Banner J. A. , Chatellier J-Y. , Feurer J. R. , Neuhaus D. 
Published: April 2008

Abstract
Guillemot D is a small Tertiary oil accumulation situated at the edge of the Western Platform in the UK sector of the Central North Sea. This salt-induced dome was drilled as early as 1969 by the crestal well 21/30-1 which found thin oil-bearing sand stringers in the Palaeocene Forties and Eocene Rogaland Formations. The structure was re-evaluated in 1987 when additional potential was recognized at Forties level downflank to the north of the discovery wells. This concept was tested late 1988 by well 21/30-13 which found a 119 ft oil column in thick Forties sands of excellent reservoir quality (619 ft gross, net-to-gross 0.89) only 1 km away from well 21/30-1.
The 1989 mapping by Production Geology benefited from the availability of a new good quality 1987 2D seismic grid which allowed a better understanding of the subtle Lower Tertiary stratigraphy. Regional geochemical data significantly contributed to an alternative geological model which postulated additional potential in the Eocene Tay sands. Two appraisal wells, i.e. 21/30-14 and 15, were successful drilled, doubling the reserves.
This paper discusses the key structural, seismo-stratigraphical and geochemical considerations in this appraisal campaign.
Sequence architecture, facies development and carbonate-cemented horizons in the Troll Field reservoir, offshore Norway
Authors: Gibbons K. , Hellem T. , Kjemperud A. , Nio S. D. , Vebenstad K. 
Published: April 2008

Abstract
The Sognefjord Formation in the Troll Field area was deposited during a general rise in sea-level during the Late Callovian to Early Volgian. A detailed study including palynology, sedimentology, response modelling and petrography of carbonate cement has been performed on 15 wells primarily from the western part of the field. All wells have been extensively cored through the reservoir enabling detailed palynological and sedimentological study of the depositional sequences in the wells. The Sognefjord Formation is interpreted, in this study, as a shoreline-attached tidally-influenced shelf complex.

The study is based on the general consistency found between the eustatic sea-level curve published by Haq
et al.
in 1987 and the biostratigraphical zonation for the Troll Field described here. The response to sea-level fluctuations in a shallow marine environment is discussed and a response model is established. A theoretical assessment of the criteria for recognizing important events is presented. The maximum flooding surfaces (mfs) and sequence boundaries (sb) are easiest to recognize. Theoretically there is a higher probability of forming carbonate cements in connection with maximum flooding surfaces.

The stratigraphically important dinocysts on Troll are classified according to their relation to sea-level fluctuations. Most of the palynozone boundaries are related to maximum flooding surfaces, except for a few which coincide with sequence boundaries. A stratigraphical subdivision of the Troll Field reservoir is presented based on a comprehensive palynological study.
Lithofacies analysis in conjunction with palynofacies interpretation have been applied to delineate the depositional environment. As an aid to the interpretation a theoretical model was established. The predicted succession and variability of sequences and facies types outlined by the theoretical model could be recognized in all wells.
Petrographical analysis shows that early diagenetic, near-surface cementation has occurred in connection with maximum flooding surfaces and sequence boundaries on Troll.
With the help of the stratigraphical framework the presence or absence of sequence boundaries, transgressive systems tracts, maximum flooding surfaces, and highstand systems tracts in each cycle has been defined in each well. This has given the detailed geometry of the reservoir sands of the field, and also allowed correlation of carbonate cemented horizons which are associated with bounding surfaces of the systems tracts. Knowledge of the distribution and extent of these cemented horizons has considerable significance for oil production strategy, particularly the siting of horizontal wells.
A discussion on the use of analogues for reservoir geology
Authors: Alexander Jan 
Published: April 2008

Abstract
Whilst it may be easy to describe and quantify a sedimentary succession from outcrop or core, using these data to predict sedimentary facies, diagentic features and fracture distribution in unsampled areas still requires considerable intuition. Frequently, at the current state of geological knowledge, reservoir datasets must be supplemented by consideration of analogues. The aim of this paper is to sound caution on the indiscriminate use of analogues in reservoir geology.
Analogues used in reservoir geology fall into three main categories: comparisons with modern depositional processes, experimental simulations, and rock record analogues. All analogues used for reservoir geology suffer from limitations due to the physical and temporal scales at which the comparisons are made. Difficulty in selecting appropriate analogues results from the amount of interpretation of the nature of the reservoir required before an analogue may be selected, the large number of degrees of freedom in the processes of formation of reservoir rocks, and the limited numbers of well-documented analogues which are easily available.
Analogue dipmeter logs through a prograding deltaic sandbody
Authors: Cameron Gavin I. F. , Collinson John D. , Rider Malcolm H. , Xu Li 
Published: April 2008

Abstract
Detailed analogue dipmeter measurements have been made along a 430 m roadcut in the Upper Namurian Rough Rock at Elland in Yorkshire. A series of 21 vertical sections were measured with dip and azimuth (dip-log) readings taken every 0.2 m, which were calibrated to previously described sedimentological sections and recordings of surface natural gamma ray profiles.
The inter-relationship between the scale of sedimentary structures and dipmeter processing parameters is shown by dip-log measurements in medium scale, crossbedded sedimentary structures. The analysis of grouped dip-log data is seen to give palaeocurrents very similar to those measured by traditional methods at outcrop. The relationship between sedimentological facies and ‘dip-log facies’ is applied to reservoir characterization, and statistical analysis of dip-log data is demonstrated to be an aid to inter-well comparisons.
Analysis techniques, mainly computer based and applicable in the subsurface, are applied to the outcrop data and the implications for subsurface dipmeter studies are stressed.
Eocene-Miocene high latitude biostratigraphy
Authors: Radford Sally S. , Qianyu Li 
Published: April 2008

Abstract
Studies of high-latitude planktonic foraminiferal faunas indicate that certain biostratigraphic problems may be resolved by the application of bioevents among the three microperforate families, Guembelitriidae, Chiloguembelinidae and Tenuitellidae. With the aid of the scanning electron microscope, these small tests appear to be useful stratigraphic markers in the condensed sequences of deep-sea cores, where their evolution can be correlated with magnetostratigraphy.

In the early-mid-Eocene, the
Jenkinsina-Cassigerinelloita
lineage assists the recognition of zones based on the larger, muricate
Acarinina
. Four zones are proposed in a revised lineage zonation of the tenuitellids, presented as a complementary biostratigraphic scheme for differentiating the Eocene-Oligocene boundary interval in high latitudes: (1) the Praetenuitella insolita Zone in the late Eocene; (2) the Tenuitella gemma Zone in the early Oligocene; (3) the Tenuitella munda Zone in the mid-Oligocene; (4) the Tenuitellinata angustiumbilicata Zone in the late Oligocene.
Ostracoda as biostratigraphical indices in Cenozoic deep-sea sequences
Authors: Whatley R. C. 
Published: April 2008

Abstract
Some of the disadvantages inherent in the use of benthonic deep-sea Ostracoda such as their lack of pelagic larval stages and the extent to which relative paucity in deeper abyssal environments is prejudicial to diversity, are balanced against the advantages of being pandemic in distribution and independent of latitudinal and surface current temperature controls. The application of Ostracoda to the biostratigraphy of the deep water Cenozoic of the North Atlantic is outlined in some detail and it is shown that podocopid Ostracoda can be used to determine the various nannofossil zones.
Strontium isotope stratigraphy for the Late Cretaceous: a new curve, based on the English Chalk
Authors: McArthur J. M. , Thirlwall M. F. , Gale A. S. , Kennedy W. J. , Burnett J. A. , Mattey D. , Lord A. R. 
Published: April 2008

Abstract

Marine
87
Sr/
86
Sr decreases from 0.70775 in the Cenomanian to 0.70730 in the middle Turonian before increasing in a near-linear manner to >0.70775 in the early Maastrichtian. This variation has been defined using samples from the English Chalk that are closely integrated with the macrofossil and microfossil biostratigraphy of northwestern Europe. With this new isotope curve a stratigraphic resolution is attainable in correlation that is typically ±0.8 Ma for the Santonian and Campanian stages. Isotopic and biostratigraphic correlations between Dorset and Norfolk, in the UK, agree within the limit of analytical error in
87
Sr/
86
Sr.
Transatlantic correlations in the Campanian-Maastrichtian stages by eustatic changes of sea-level
Authors: Hancock Jake M. 
Published: April 2008

AbstractThere is good evidence that high sea-levels peaked simultaneously during the Late Albian to Turonian in the USA and northwest Europe. Therefore, it is to be expected that the principal peaks during the Campanian-Maastrichtian, now well dated in northwest Europe, should be detectable in the USA. Of the four main peaks in Europe, no. 3, low in the Zone ofBelemnitella langei, is the most prominent, and can be recognized with confidence in the Western Interior, New Jersey, Alabama-Mississippi and probably in Texas. The other peaks can be identified with various degrees of confidence, but the sea did not persist long enough in the Western Interior for the last peak, early in the Late Maastrichtian, to be developed there. The results change the generally assumed position of the Campanian-Maastrichtian boundary on the foraminiferal scale: the base of the Maastrichtian on the belemnite scale is a considerable distance above the top of the Zone ofGlobotruncanita calcarata, possibly as high as the base of the Zone ofGansserina gansseriin north temperate regions. On the ammonite scale in the western interior of the USA the boundary is probably at the base of the Zone ofBaculites baculusat 70.7 Ma, but could be at the base of the Zone ofB. eliasi.
High resolution biostratigraphy
Authors: Cope John C. W. 
Published: April 2008

Abstract
The degree of stratigraphical resolution obtainable from biostratigraphical data provides, for most parts of the Phanerozoic, a finer discrimination than that obtained by other means. The full potential of biostratigraphy has not yet been realised in many parts of the geological column and much time and effort, in many cases including primary taxonomic work, is needed, in a field which is currently considered unfashionable. Examples are selected from the Phanerozoic to illustrate the degree of resolution currently achievable.
Devonian goniatite biostratigraphy and timing of facies movements in the Frasnian of the Canning Basin, Western Australia
Authors: Becker R. Thomas , House Michael R. , Kirchgasser William T. 
Published: April 2008

Abstract

As part of an international study of Devonian facies movements against cratonic areas an investigation has been undertaken of the timing of facies movements associated with the Frasnian and Famennian reef complexes of the Canning Basin, Western Australia. This led to the discovery of rich goniatite faunas which enable significant improvements to be made to the high resolution ammonoid time scale. A new goniatite classification for the Frasnian is proposed for international use based on the entry of particular genera; this gives 12 divisions. A much more detailed regional zonation is proposed for the Canning Basin. As part of this, a description is given of the following new genera of the Gephuroceratidae:
Gogoceras, Playfordites, Serramanticoceras
and
Mixomanticoceras
. The genus
Probeloceras
is used in a restricted sense and recognised as the first member of the Beloceratidae;
Acanthoclymenia
is used for forms previously assigned loosely to
Probeloceras
.

The new zonation provides a framework for analysis of facies movements. Occasions of anoxic or hypoxic events are indicated by rich, hematized goniatite faunas. Reef backstepping associated with deepening is dateable by goniatites in associated marginal slope deposits. Several of the international eustatic sea-level changes are recognised, noticeably those correlative with the Genundewa, Middlesex and Rhinestreet deepenings of New York. No evidence has been found for the internationally widespread ‘Kellwasserkalk’ facies in the late Frasnian, but a succession of terminal Frasnian sea-level changes is recognized. The ‘Irtidium Anomaly’ level lies well above the Frasnian/Famennian boundary and hence provides no confirmation of a bolide to explain Frasnian/Famennian boundary extinctions. In the Famennian, evidence for the European Condroz regression and Annulata deepening is presented.
Towards a carbon isotope stratigraphy of the Cambrian System: potential of the Great Basin succession
Authors: Brasier M. D. 
Published: April 2008

Abstract

The Cambrian spans a time of major biosphere change, during which the major invertebrate groups appeared and radiated. Recent discoveries of major carbon isotope excursions in carbonate rocks around the world have stimulated a working group on ‘Late Precambrian-Cambrian Event Stratigraphy’ to explore their potential for correlation (IGCP Project 303). Bioevents, sequence boundaries and trace element markers may also be used for calibration. A major impediment to this objective has been the endemicity and diachroneity of many polymeroid trilobites and early skeletal microfossil taxa associated with shallow water carbonates. The use of deeper-water carbonates, bearing more widely-distributed agnostoids and polymeroids should, however, provide an opportunity to test independently the correlative value of carbon isotope excursions on a global scale. Studies on the Cambrian of the Great Basin, western USA, show that such facies can bear similar δ
13
C signatures to contemporaneous shallow-water carbonates with more endemic trilobites. Hence ‘agnostoid facies’ do have the potential to provide a global and integrated carbon isotope and fossil stratigraphy. A test case is provided by a major positive carbon excursion in the late Dresbachian (or Steptoean) Stage, coincident with shoaling and emergence at the top of the Sauk II sequence across the Laurentian craton. If global, this distinctive marker should be traceable into other Cambrian carbonate successions since it lies between two of the most widely correlatable biohorizons: above the last occurrence of
Glyptagnostus reticulatus
and below the first appearance of
Irvingella
spp.
Analogue sandbox modelling of Miocene extensional faulting in the Outer Moray Firth
Authors: Higgs W. G. , McClay K. R. 
Published: April 2008

Abstract
The Palaeogene sequence of the Outer Moray Firth in the UK sector of the North Sea consists of a series of stacked submarine-fans and associated shelf deltaic deposits. The sequence was derived from the elevated Shetland Platform to the northwest. The clastic material was transported southeastwards along the axis of the Witch Ground Graben towards the basin low in the Central Graben.
Towards the top of the Palaeogene submarine-fan slope deposits, there is a disturbed sequence, Oligocene in age, which is interpreted to have been deformed by Miocene age extensional faulting. A semi-regional study of Quadrants 15, 16, 21 and 22 has revealed that the faults, which cut the Eocene to Lower Miocene section, terminate at the Middle Miocene unconformity. Fault activity coincided with a Middle Miocene tilting event indicated by the onlap of Upper Miocene sequences higher on the shelf slope. This tilting event acted as a trigger for extensional fault movement.
Detailed study of the extensional fault geometries illustrates the complex nature of the deformation. The dominant fault trend is northeast-southwest, commonly with the downthrown side towards the northwest. The faults do not exhibit a marked listric geometry nor do they have a common detachment horizon. A common feature is the decrease in observed brittle deformation with depth.
Analogue sandbox modelling illustrates the development of extensional faults associated with the gravitational collapse of a tilted sequence. Deformation within the sandbox models is dominated by non-rigid block rotation.
The Miocene-aged faulting in the Outer Moray Firth is interpreted to be a result of the gravitational collapse of the Palaeogene slope sequence. Fault dip towards the shelf was probably controlled by shear stresses within the deforming sequence and a downslope resistance to deformation. A non-rigid block rotation model is proposed as a possible mechanism for the deformation. A basal detachment is not a requirement of this model.
Seismic sequence stratigraphy and tectonics offshore Namibia
Authors: Light M. P. R. , Maslanyj M. P. , Greenwood R. J. , Banks N. L. 
Published: April 2008

Abstract
High quality seismic data recently acquired offshore Namibia have revealed the complex interplay between sedimentation and rifting that accompanied the breakup of Gondwanaland. Seismic sequence analysis has demonstrated a complex series of superimposed phases of rifting.
Jurassic early-rift sediments were deposited in a Basin & Range setting with marine embayments. Mid- to Late Jurassic extension probably culminated in acidic to intermediate volcanicity. Subsequently, late-rift fill sedimentary accumulations were terminated locally by a major period of plateau-forming effusive activity. This was coincident with the start of Early Cretaceous spreading in the South Atlantic. Shelf, slope and basinal facies are clearly defined in the post-rift succession.
Although virtually undrilled, the area is considered to have very considerable petroleum potential. Seismic stratigraphy will continue to play a vital role in defining the critical juxtapositions of source rock, reservoir and seal.
Sand transport by wind: a review of the current conceptual model
Authors: McEwan Ian K. , Willetts Brian B. 
Published: April 2008

Abstract
Rapid progress has been made in the last decade towards a more comprehensive model of wind blown sand transport extending and sharpening Bagnold’s classic model in significant aspects. This paper reviews the current physical model and attempts to indicate future directions of research.
The currently accepted physical model of aeolian sand transport reduces the sand transport system to four distinct sub-processes: aerodynamic entrainment; the trajectory of the wind driven sand grains; the grain/bed collision; and the modification of the wind by the driven sand. The isolation and separate treatment of these sub-processes has been an important factor in the recent rapid development of aeolian sand transport mechanics. It is, however, their interaction that produces the rich behaviour of the system. Anderson & Haff (1991) and McEwan & Willetts (1991) have synthesized the four sub-processes and constructed full saltation models which follow the system from incipience to steady-state saltation. These computer simulations provide a stern test for the physical model as the results calculated can be compared to experimental observations from field and wind tunnel. The models compare well with available data; thus we can have some confidence that the physical model is realistic. Moreover, these computer simulations have become a powerful investigative tool and have highlighted areas where our understanding is deficient.