bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-resolution petrophysical characterization of samples from an aeolian sandstone: the Permian Penrith sandstone of NW England
Authors: Lovell M. A. , Jackson P. D. , Harvey P. K. , Flint R. C. 
Published: April 2008

Abstract

The Penrith Sandstone is an orange/red, mainly homogeneous, friable rock made up of well-rounded, highly spherical quartz grains, often showing euhedral overgrowths of quartz. Sandstone samples from Stoneraise Quarry, NW England, exhibit a remarkable degree of rounding and very high sphericity, along with frosted textures typical of aeolian deposits. Chemically, the rock is predominantly SiO
2
(>95%), with no evidence of carbonate cements. Quartz predominates with a small proportion (10%) of feldspar. The grain size across heterogeneous zones varies from very fine (100 µm) to coarse sand (700 µm). There is no evidence of the presence of clay minerals. Petrophysically, based on the measurements made in this study, the Penrith Sandstone is a typical clean sandstone characterized by moderate porosity (12%) and core-plug permeability (10
−14
−10
−12
m
2
), and Archie ‘
m
’ exponents between 1.90 and 1.91, suggesting a reasonably clean ‘Archie’ rock with no excess conductivity associated with clays or bound water. Capillary pressure curves for four samples demonstrate unimodal pore-size distributions with a single modal range that varies between 25–50 and 70–80 µm. Because of the relative simplicity of its petrophysics, the sandstone is thus potentially very useful in fundamental studies, and also in the trialling of new techniques.

We use imaging techniques to investigate the degree of heterogeneity and the fabric of the Penrith Sandstone. Conventional optical images are complemented by electrical resistivity, porosity and mini-permeametry images. These two-dimensional maps of resolution of approximately 5 mm show a spatial similarity determined by the rock fabric. The detailed images show a wider degree of variation and heterogeneity than the plug-averaged values. The success of the resistivity imaging method suggests that the technique could be used in deriving correlations that could be used to interpret borehole resistivity imaging logs. However, in the present study, correlations of property values derived from the imaging do show considerable scatter: this suggests that heterogeneity even below the scale of the imaging is also important, a conclusion supported by thin-section and electronmicroscope data.
Petrophysical characterization of the Sherwood Sandstone from East Yorkshire, UK
Authors: Pokar Magdeline , West L. J. , Odling N. E. 
Published: April 2008

Abstract

Petrophysical tests were conducted on core samples from the unsaturated zone of the Sherwood Sandstone Group in East Yorkshire. Tests were conducted to determine which physical parameters most influenced its hydraulic conductivity values. The main parameters analysed were grain-size distribution, pore-throat size distribution, clay content, mineralogy and porosity. A constant flow rate permeameter was used to measure saturated hydraulic conductivity values in the vertical direction (perpendicular to lamination),
K
v
, and horizontal direction (parallel to lamination),
K
h
. Hydraulic conductivity values in the vertical direction,
K
v
, ranged from 0.004 to 0.12 m day
−1
while values in the horizontal direction,
K
h
, ranged from 0.01 to 0.17 m day
−1
. Hydraulic conductivity anisotropy,
K
h
/
K
v
, varied from 0.6 to 35. Scanning electron microscope analysis showed this anisotropy to be caused mainly by millimetre-scale laminations. Representative bulk hydraulic conductivity values were estimated from the core data; bulk horizontal hydraulic conductivity,
K
hb
, was estimated as 0.1 m day
−1
, and bulk vertical hydraulic conductivity,
K
vb
, as 0.01 m day
−1
. Principal components analysis and multiple regression analysis were used to determine parameters that affect hydraulic conductivity most. Grain sorting is established to be the most important parameter to influence
K
v
values; samples with fine laminations have relatively low
K
v
.
Calcrete as a source of heterogeneity in Triassic fluvial sandstone aquifers (Otter Sandstone Formation, SW England)
Authors: Newell Andrew J. 
Published: April 2008

Abstract

Carbonate is not generally considered as a potential source of large-scale heterogeneity in Permo-Triassic sandstone aquifers. This study shows that carbonate, in the form of early diagenetic calcrete, forms an abundant component of the Triassic Otter Sandstone Formation in south Devon. Three types of calcrete are described from the outcrop of this fluvial sandstone dominated aquifer: rhizocretions; calcrete sheets; and calcrete conglomerates. Data obtained from core plugs show that calcrete reduces sandstone permeability to less than 10
−15
m
2
and porosity to less than 12%. Calcrete can be sufficiently abundant to produce a significant (up to 30%) reduction in the total effective porosity of the aquifer. Moreover, calcrete conglomerates can form laterally extensive (up to 1 km) low-permeability sheets that will represent major baffles to vertical flow.
Investigating rising nitrate concentrations in groundwater in the Permo-Triassic aquifer, Eden Valley, Cumbria, UK
Authors: Butcher Andrew , Lawrence Adrian , Jackson Chris , Cullis Emma , Cunningham Jennifer , Hasan Kamrul , Ingram John J. A. 
Published: April 2008

Abstract

Groundwater nitrate concentrations in the Permo-Triassic aquifer of the Eden Valley vary from less than 4 mg l
−1
to in excess of 100 mg l
−1
(as NO
3
). A significant number of boreholes exhibit rising trends in nitrate concentration that either approach or exceed the CEC Directive 80/778 Maximum Admissible Concentration (MAC) of 50 mg l
−1
. The main source of the nitrate is believed to be the nitrogen applied to grassland, both as slurry and as inorganic fertilizers.

The variability in groundwater nitrate concentrations is thought to be due in part to land use, particularly where low-yielding boreholes derive their water from a limited/localized area, and in part due to the variability in the travel times for water and solutes to migrate from the soil to the water table and then to the borehole. This variability in travel times is a function of surficial geology, depth to water table, depth of borehole and superficial deposit thickness, amongst other factors.

It is surprising, given the considerable storage within the saturated zone of the aquifer and the slow groundwater movement, that some relatively deep boreholes pump groundwater with nitrate concentrations in excess of 20 mgl
−1
. Simple numerical modelling suggests that the fraction of modern water pumped is sensitive to the presence of fissures close to the abstraction boreholes and the location of the boreholes relative to superficial deposits. For some scenarios, using realistic superficial deposit geometries and aquifer hydraulic parameters, the proportion of modern water (water that is derived from infiltration that reached the water table since pumping started) could exceed 40% within 15 years of pumping.
Investigation and management of a kerosene leakage into a Permo-Triassic sandstone aquifer in the UK
Authors: Rees S. B. 
Published: April 2008

Abstract

Leakage over a 35-year period, starting in the 1960s, of approximately 9 × 10
6
l of kerosene from an industrial complex located above fractured Permo-Triassic sandstone aquifer resulted in the potential for a significant dissolved phase. However, a phased, risk-based approach identified no significant risks in terms of dissolved-phase petroleum hydrocarbons, BTEX, or volatile or semi-volatile organic compounds. This is considered to be due to biodegradation of potential contaminants via metabolic pathways using electron acceptors primarily provided by the groundwater recharge (oxygen, nitrate and sulphate). Contaminant concentrations have remained below regulatory limits for protection of the receptor since monitoring was initiated in 2000. This case study demonstrates the potential for biodegradation within the Permo-Triassic sandstone aquifer of the UK: the risk-based approach described and the management plan developed could be applicable at other sites.
Compositional data and their analysis: an introduction
Authors: Pawlowsky-Glahn V. , Egozcue J. J. 
Published: April 2008

Abstract

Compositional data are those which contain only relative information. They are parts of some whole. In most cases they are recorded as closed data, i.e. data summing to a constant, such as 100% — whole-rock geochemical data being classic examples. Compositional data have important and particular properties that preclude the application of standard statistical techniques on such data in
raw
form. Standard techniques are designed to be used with data that are free to range from − ∞ to + ∞. Compositional data are always positive and range only from 0 to 100, or any other constant, when given in closed form. If one component increases, others must, perforce, decrease, whether or not there is a genetic link between these components. This means that the results of standard statistical analysis of the relationships between
raw
components or parts in a compositional dataset are clouded by spurious effects. Although such analyses may give apparently interpretable results, they are, at best, approximations and need to be treated with considerable circumspection. The methods outlined in this volume are based on the premise that it is the relative variation of components which is of interest, rather than absolute variation. Log-ratios of components provide the natural means of studying compositional data. In this contribution the basic terms and operations are introduced using simple numerical examples to illustrate their computation and to familiarize the reader with their use.
On stability of compositional canonical variate vector components
Authors: Reyment R. A. 
Published: April 2008

Abstract

Canonical variate analysis (aka discriminant coordinates) is viewed from the aspect of Aitchisonian compositional data analysis and the concept of stability in canonical vectors examined in relation to their refication (i.e. providing canonical vector components with a practical interpretation). The log-ratio transformation was found to have computational and interpretational advantages over the centred log-ratio transformation. The
ad hoc
application of N. A. Campbell’s application of the method of shrinkage estimators to multiple discrimination, and the optimal retention of discrimination power, is exemplified by two cases, one drawn from quantitative sedimentology, the other from biomolecular palaeontology, with the intention of probing the effect of instability on interpreting the relative importance of standardized canonical variate coefficients in relation to the suppression of near-redundant directions of within-groups variation. Pronounced instability in canonical vectors may endanger the validity of an analysis.
Detailed guide to CoDaPack: a freeware compositional software
Authors: Thió-Henestrosa S. , Martín-Fernández J. A. 
Published: April 2008

Abstract
Suitable statistical methods for compositional data based on log-ratio methodology are not included in standard statistical packages. This work presents a detailed guide to freeware Excel for Windows-based package, named CoDaPack, which implements most of the basic statistical methods of this methodology. The web site Data Package contains this freeware package and to install it users need only to have Excel installed on their computers. The guide starts with an example in order to show how to work with this software and ends with a description of all features of CoDaPack.
Visualization of three- and four-part (sub)compositions with R
Authors: Bren M. , Batagelj V. 
Published: April 2008

Abstract

In 2003 the MixeR (Mixtures with R) project was started and work began to develop a library of functions written in R to support the analysis of compositional data, i.e. mixtures. This paper presents the ‘mix’ object in R, reading different data file formats and some MixeR routines for graphical presentation of three- and four-part (sub)compositions in ternary diagrams and tetrahedrons. Additional graphical features and use of parameters are applied on real data — a glacial dataset and dataset of the researcher’s daily activities, both from Aitchison’s (1986) book. All these routines and datasets are available at
http://vlado.fmf.uni-lj.si/pub/MixeR
Frequency distributions and natural laws in geochemistry
Authors: Buccianti A. , Mateu-Figueras G. , Pawlowsky-Glahn V. 
Published: April 2008

Abstract
The chemical composition of natural waters is derived from many different sources of solutes, including gases and aerosols from the atmosphere, weathering and erosion of rocks and soil, solution or precipitation reactions occurring below the land surface, and effects resulting from human activities. The chemical composition of the crustal rocks of the Earth, as well as the composition of the ocean and the atmosphere, are important in evaluating sources of solutes. Data used in the investigation of natural and non-natural contributions are obtained usually from chemical analysis of water samples, which may be statistically evaluated with the aim of summarizing the contained information. However, as these data are compositional and thus constrained to move in the simplex, application of usual statistical methodologies may lead to incorrect evaluations and/or interpretations. This paper focuses on how to draw information on natural processes by modelling univariate and multivariate frequency distributions using water data. The chemical composition of 977 samples collected in wells from Vulcano island (Italy) are used as a case study. The methodological approach can be transferred to the investigation of other geochemical or constrained data.
Is the simplex open or closed? (some topological concepts)
Authors: Barrabés E. , Mateu-Figueras G. 
Published: April 2008

Abstract

The simplex is the natural space to work with when compositional data are considered. Sometimes, the concepts of
open
simplex and
closed
simplex are used, although most of the time they are not well defined. The objective of this contribution is to expose some of the mathematical concepts related to the simplex and its structure in order to make clear when the terms
open
and
closed
are mathematically appropriate. Moreover, these concepts sometimes generate discussion about the proper representation of the simplex. It will be shown that this discussion makes no sense when considering the simplex as a Euclidean vector space.
Non-marine Permian biostratigraphy and biochronology: an introduction
Authors: Lucas Spencer G. , Schneider Joerg W. , Cassinis Giussepe 
Published: April 2008

Abstract
The Permian time scale based on marine rocks and fossils is well defined and of global utility, but non-marine Permian biostratigraphy and chronology is in an early phase of development. Non-marine Permian strata are best known from western Europe and the western United States, but significant records are also known from Russia, South Africa, China and Brazil. Global time terms based on non-marine Permian strata, such as Rotliegend, Zechstein, Autunian, Saxonian and Thuringian, are either inadequately defined or poorly characterized and should only be used as lithostratigraphic terms. Macro- and microfloras have long been important in non-marine Permian correlations, but are subject to limitations based on palaeoprovinciality and facies/climatic controls. Charophytes, conchostracans, ostracodes and freshwater bivalves have a potential use in non-marine Permian biostratigraphy but are limited by their over-split taxonomy and lack of well-established stratigraphic distributions of low-level taxa. Tetrapod footprints provide poor biostratigraphic resolution during the Permian, but tetrapod body fossils and insects provide more detailed biostratigraphic zonations, especially in the Lower Permian. Numerous radioisotopic ages are available from non-marine Permian sections and need to be more precisely correlated to the global time scale. The Middle Permian Illawarra reversal and subsequent magnetic polarity shifts are also of value to correlation. There needs to be a concerted effort to develop non-marine Permian biostratigraphy, to correlate it to radio-isotopic and magnetostratigraphic data, and to cross-correlate it to the marine time scale.
Tetrapod footprint ichno-associations from French Permian basins. Comparisons with other Euramerican ichnofaunas
Authors: Gand Georges , Durand Marc 
Published: April 2008

Abstract
In order to take into account the studies of the European and American (USA) collections carried out by one of the authors, and of the recent nomenclatural revisions from new footprint discoveries, which have occurred during the last decade, the authors present a critical review of the French Permian palichnofauna. The distribution of the ichnospecies in the stratigraphy of the Lodève Basin, taken as a reference, is outlined. The ichno-associations are then compared with those of other French (Provence), European (Italy, Germany) and USA basins. Based on the ages of different ichnofossiliferous formations, three successive ichnofaunal units can be distinguished in the Permian of Europe. The first developed in the Cisuralian (Asselian to Kungurian). The second is found in the south of France in Kazanian to Lower Tatarian strata, equivalent to the Roadian-Wordian. The third and youngest, dated as Lopingian, is only found in Italy, in the Bolzano Basin. Because of sedimentary gaps, limited observations, sometimes erroneous determinations, and ichnospecies with great vertical distribution, it currently appears that footprints have a low utility for biochronological resolution. Nevertheless, they allow us to discriminate three time intervals in the Permian, as is also the case for skeletal remains.
Permian tetrapod footprints: biostratigraphy and biochronology
Authors: Lucas Spencer G. , Hunt Adrian P. 
Published: April 2008

AbstractPermian tetrapod footprints are known from localities in North America, South America, Europe and Africa. These footprints comprise four ichnofacies, theChelichnusichnofacies from aeolianites and theBatrachichnus, BrontopodusandCharacichnosichnofacies from water-laid (mostly red-bed) strata. Permian track assemblages of theChelichnusichnofacies are of uniform ichnogeneric composition and low diversity, range in age from Early to Late Permian, and thus are of no biostratigraphic significance. Footprints of theBatrachichnusandBrontopodusichnofacies represent two biostratigraphically distinct assemblages: (1) Early Permian assemblages characterized byAmphisauropus, Batrachichnus, Dimetropus, Dromopus, Hyloidichnus, LimnopusandVaranopus; and (2) Middle to Late Permian assemblages characterized byBrontopus, Dicynodontipus, Lunaepes, Pachypes, Planipes, and/orRhynchosauroides. Few Permian footprint assemblages are demonstrably of Middle Permian (Guadalupian) age, and there is a global gap in the footprint record equivalent to at least Roadian time. Permian tetrapod footprints represent only two biostratigraphically distinct assemblages, an Early Permian pelycosaur assemblage and a Middle to Late Permian therapsid assemblage. Therefore, footprints provide a global Permian biochronology of only two time intervals, much less than the ten time intervals that can be distinguished with tetrapod body fossils.
Carboniferous-Permian actinopterygian fishes of the continental basins of the Bohemian Massif, Czech Republic: an overview
Authors: Štamberg Stanislav 
Published: April 2008

Abstract

The actinopterygian fishes from the continental Westphalian to the Lower Permian basins in the Czech Republic are reviewed and compared with those of deposits of equivalent age in some central and western European Basins. Nine genera of actinopterygians belonging to eight families are known from the Westphalian-Stephanian sediments, and five genera belonging to four families are known from the Early Permian sediments of the Bohemian Massif. The new family Sceletophoridae is erected for the genus
Sceletophorus
from the Westphalian D. Very close relationships of the actinopterygian fauna between the Bohemian Massif and especially the basins of the French Massif Central are discussed.
Late Permian to Early Triassic transition in central and NE Spain: biotic and sedimentary characteristics
Authors: Arche Alfredo , López-Gómez Jose 
Published: April 2008

Abstract
The Late Permian to Early Triassic (P/T) transition represents one of the most important Phanerozoic mass extinction episodes. Data from this transitional period are very scarce in continental basins, and reliable correlation with marine series is still a matter of debate. In this paper, information on the P/T transition in the continental series of central and NE Spain and the Balearic Islands is presented and compared with some coeval western European basins. The Iberian Ranges sections contain detailed information on the P/T transition, with sediments interpreted as alluvial fans, sandy and gravelly braided rivers and high sinuosity rivers with extensive floodplains, dated by means of pollen and spore assemblages. However, the fossil record contains two barren intervals throughout the study area, one in the Late Permian (Thuringian) and another during the latest Permian to Early Triassic. The possible causes of these gaps include the very likely relationship with the emplacement of the basaltic large igneous provinces (LIP) of SE China and western Siberia during this period of time.
The problem of the transition from the Permian to the Triassic Series in southeastern France: comparison with other Peritethyan regions
Authors: Durand Marc 
Published: April 2008

Abstract
In the French sedimentary basins, widespread alluvial deposits sealing narrow Permian troughs are referred to as ‘Buntsandstein’. An Early Triassic age is generally put forward despite a lack of any Scythian biochronological elements. In Provence (Southeast Basin) some doubts remain about the age of the latest Permian deposits, and the oldest Triassic fossils (Anisian palynomorphs) appear in the upper ‘Buntsandstein’. Three types of contact occur: disconformity overlain by a quartz-conglomerate, apparent transition, and angular unconformity, according to an increasing basal incompleteness of the ‘Buntsandstein’. Whereas the conglomerate was deposited under arid conditions, the overlying fluvial deposits indicate a marked climate change. A transect from France up to the Germanic Basin centre shows that the ‘French Buntsandstein’ cycle might begin considerably before the end of the Permian; the Early Triassic arid ‘event’ is Dienerian/Smithian in age; and the Provençal ‘basal’ conglomerate corresponds to the uppermost part of a coeval subordinate cycle, and thus the underlying sub-Triassic unconformity represents a hiatus estimated at 10–15 Ma. Works in progress confirm that sedimentary climate indicators constitute powerful tools for correlations within non-marine formations devoid of biostratigraphical marker that straddle the Permian-Triassic boundary, at least on the scale of the Western European Plate.
The Eagle III BKA system, a novel sediment core X-ray fluorescence analyser with very high spatial resolution
Authors: Haschke M. 
Published: April 2008

Abstract
Sediment cores contain valuable information on geological history and palaeoclimate, and it is necessary to study cores at high spatial resolution to recover useful palaeoenvironmental data. This paper describes an innovative micro-X-ray fluorescence spectrometer that can measure spot sizes in the range of 50 μm, with incremental step sizes down to 10 μm. The analysis is non-destructive so the sediment core is preserved and available for other investigations. This paper describes the new instrument, the Eagle III BKA system, which employs some novel features such as a polycapillary lens, moveable sample stage and X-ray head, a Varispot focusing system and an environmental sample cabinet. Some examples of recent applications are described.