bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isotopic methods and their hydrogeochemical context in the investigation of palaeowaters
Authors: Loosli H. H. , Aeschbach-Hertig W. , Barbecot F. , Blaser P. , Darling W. G. , Dever L. , Edmunds W. M. , Kipfer R. , Purtschert R. , Walraevens K. 
Published: April 2008

Abstract

Isotope and geochemical techniques are the primary way in which the residence time, recharge conditions and subsequent evolution of palaeowaters can be determined. Isotopic species and noble gas concentrations are used as residence time and palaeoclimate indicators. Among the former,
14
C is pre-eminent in late Quaternary studies because of an age range which covers the Pleistocene-Holocene transition. However, its use is constrained by frequent difficulties in determining the dilution of dissolved
14
C due to water-rock interaction. A combination of
14
C data with
226
Ra and
4
He results may be useful for Holocene waters but they can also be used to validate the carbon systematics assumed for
14
C dating. For waters beyond the range of
14
C dating,
81
Kr,
36
Cl,
4
He and chemical tracers can be applied.

Stable isotope ratios and noble gas concentrations primarily reflect climatic conditions at the time of recharge. While the noble gases provide absolute values for recharge temperatures, stable isotopes are only relative indicators that vary regionally. The PALAEAUX programme has examined these aspects in some detail by looking at the δ
18
O shift between Pleistocene and Holocene waters on the European scale, and by calculating δ
18
O/Δ
T
ratios from δ
18
O v. recharge temperature plots for aquifers at different distances from the Atlantic Ocean. Indications are that the more positive δ
18
O value of ocean water during the Pleistocene dominates in the more westerly European countries over the negative δ
18
O shift during cooler conditions. There are also indications that air-mass circulation during the Pleistocene was similar to the present day.

The evolution of a palaeowater can best be studied by measuring chemical tracers; this is possible in freshwater aquifers, where a clear trend of geochemical reactions is observed, and in freshening marine aquifers. Chemical and isotopic tracers can also be used to study the movement of the front between palaeowater and younger components that must be identified in coastal aquifers to guarantee a sustainable water use.
Management of coastal palaeowaters
Authors: Custodio E. , Edmunds W. M. , Travi Y. 
Published: April 2008

Abstract
Coastal regions of Europe have special water supply problems due to the population pressure, competing demands and the ever-present risk of saline intrusion from modern and old sea water. This is especially the case in southern Europe where touristic demands exacerbate water supplies, often in semi-arid regions. Palaeowaters emplaced at times of lowered sea level offer potential high-quality, high-value reserves in many areas, although a lack of understanding of the nature of the resource, together with exploitation for non-drinking purposes and indiscriminate drilling, may already have damaged the underground reservoirs and the reserves within them. These aquifers may, however, offer sites that are attractive for seasonal water storage.
Palaeowaters generally are of high quality and are demonstrably free of human impacts. Good drilling practice and operation are required to avoid contamination, the mixing of palaeowaters with more saline waters and avoidance of marine intrusion. Two case studies illustrating the management practice in areas containing palaeowaters — in the French Mediterranean coast and the Llobregat Delta area of Catalonia, Spain — are given. These demonstrate, above all, the need for integrated development, observation and planning, which involves all the stakeholders, especially the beneficiaries and end-users. There is a need for improved regulation for the protection, use and management of aquifers containing palaeowaters at both the national and European scale, to consider the intrinsic value of uncontaminated palaeowaters as a unique, non-renewable source of drinking water. The value of such aquifers for subsequent freshwater storage and also for use as a brackish water source for desalination may also be considered.
European views on terrestrial chronology from Descartes to the mid-eighteenth century
Authors: Vaccari Ezio 
Published: April 2008

Abstract
The Theories of the Earth formulated by the English scholars Thomas Burnet, William Whiston and John Woodward at the end of the seventeenth century circulated widely within the continent of Europe during the first decades of the eighteenth century. These theories established a sequence of physical conditions of the Earth according to the chronology outlined in the Book of Genesis, emphasizing two main stages: the Creation and the Deluge. Although the authority of the Biblical account of the age and early history of the Earth was normally accepted at the beginning of the eighteenth century, the continental reception of English Theories of the Earth varied. This was due to the complexity of the European context which since the 1660s had produced the theories of René Descartes, Gottfried Wilhelm Leibniz and Athanasius Kircher, as well as Nicolaus Steno’s dynamic view on the development of the Earth’s surface. Steno emphasized the importance of the interpretation of rock strata in the field for reconstruction of the Earth’s history. He also carefully avoided contradicting the Biblical account and associated the Deluge with one of the geological stages identified in his history. Nevertheless, the Stenonian heritage stimulated some Italian scientists — such as Antonio Vallisneri, Luigi Ferdinando Marsili, and later Giovanni Targioni Tozzetti and Giovanni Arduino — to presuppose, within the results of their researches, an indefinitely great antiquity of the Earth. Theoretical models linked to Biblical chronology included those of Emanuel Swedenborg in Sweden and Johann Jakob Scheuchzer in Switzerland, while in France, Benoît De Maillet proposed a Theory of the Earth which was censured by the Church because of its possible implications regarding the eternity of matter. Among European scholars of the first decades of the eighteenth century, the Stenonian heritage (notably the necessity of fieldwork in a regional context) and the global Theories of the Earth were equally influential.
Buffon, Desmarest and the ordering of geological events in
époques
Authors: Taylor Kenneth L. 
Published: April 2008

Abstract

During the eighteenth century many naturalists and philosophers became persuaded of the great antiquity of the Earth, and of the promise that knowledge of the Earth’s past and development could be built up through investigations of natural terrestrial features. In common with most geological issues of the time, these opinions rose to prominence to a considerable degree in connection with the so-called Theories of the Earth. This paper discusses some interconnections between Theories of the Earth and the emerging enterprise of geological field investigation, as they related to efforts toward establishing relative ages of geological phenomena. It considers in particular the two rather different Theories of the Earth offered by Buffon in 1749 and 1778, respectively. While the earlier one (
Théorie de la Terre
) emphasized principles for extracting physical knowledge of the Earth’s configuration through empirical investigation, the latter theory (
Époques de la Nature
) drew attention to the project of organizing knowledge about the Earth around a directional sequence of periods. The central impulses of Buffon’s two conceptions of the Earth were combined in actualistic field investigations by geologists of the late eighteenth century, Nicolas Desmarest in particular, which contributed significantly to the establishment of methods for determining distinct stages or sequences of the Earth’s past.
Timeless order: William Smith (1769–1839) and the search for raw materials 1800–1820
Authors: Torrens Hugh S. 
Published: April 2008

Abstract

Smith first described himself as ‘land surveyor and drainer’ in his 1801
Prospectus
but then as ‘engineer and mineralogist’ in his first book of 1806. His several careers are discussed with an attempt to shed new light on his pioneering career as ‘mineral surveyor’ (a term invented by his pupil, John Farey, in 1808). The trials for coal with which he was involved can be divided into two: those in which he used his new stratigraphic knowledge in positive searches for new coal deposits; and those where his stratigraphic science could often negatively demonstrate that many such searches were doomed to failure. These latter attempts were being made in, and misled by, repetitious clay lithologies, which resembled, but were not, Coal Measures. Smith was the first to show how unfortunate it was for such coal hunters that the British stratigraphic column abounded in repetitious clay lithologies. It was also unfortunate for Smith that many of the founding fathers of the Geological Society were unconvinced of the reality or the utility of Smith’s discoveries. Its leaders at first did not believe he had uncovered anything of significance and then simply stole much of it. The development of Smith’s stratigraphic science in the world of practical geology remains poorly understood, but the legacy of his method for unravelling relative geological time and space was one of the most significant of the nineteenth century.
The age of the Earth in the United States (1891–1931): from the geological viewpoint
Authors: Yochelson Ellis L. , Lewis Cherry L. E. 
Published: April 2008

Abstract
In North America, prior to the Second World War, discussions on the age of the Earth were a minuscule part of the geological literature, as demonstrated by the small number of papers indexed to the subject in bibliographies. Indeed, during the first quarter of the twentieth century, there were few general papers on this topic circulating among those geologists who dealt with sedimentary rocks and fossils; nevertheless, evidence is provided that many geologists were aware of the ‘debate’ going on in Britain.
As the methodology for determining the length of geological time dramatically changed during the four decades represented here, so too did the evolution of ideas about the age of the Earth. These can conveniently be divided into three time periods: before, during and after the discovery that radioactivity could be applied to the dating of rocks. The first section reviews the attitudes of geologists in America to the age of the Earth in the 1890s. It is followed by their reactions to the discovery of radioactivity. The third part discusses two major publications on the age of the Earth which reflect the ultimate acceptance, by geologists, of the long timescale revealed by radioactivity. Because much of the early work on radioactivity was being done in Europe, American geologists were marginally later than their British counterparts in accepting the concept of radiometric dating, but by the end of the period under consideration they led the field in geochronology.
The oldest rocks on Earth: time constraints and geological controversies
Authors: Kamber Balz S. , Moorbath Stephen , Whitehouse Martin J. 
Published: April 2008

Abstract
Ages in the range 3.6–4.0 Ga (billion years) have been reported for the oldest, continental, granitoid orthogeneisses, whose magmatic precursors were probably formed by partial melting or differentiation from a mafic, mantle-derived source. The geological interpretation of some of the oldest ages in this range is still strongly disputed.

The oldest known supracrustal (i.e. volcanic and sedimentary) rocks, with an age of 3.7–3.8 Ga, occur in West Greenland. They were deposited in water, and several of the sediments contain
13
C-depleted graphite microparticles, which have been claimed to be biogenic.

Ancient sediments (
c.
3 Ga) in western Australia contain much older detrital zircons with dates ranging up to 4.4 Ga. The nature and origin of their source is highly debatable. Some ancient (magmatic) orthogneisses (
c.
3.65–3.75 Ga) contain inherited zircons with dates up to
c.
4.0 Ga. To clarify whether zircons in orthogneisses are inherited from an older source region or cogenetic with their host rock, it is desirable to combine imaging studies and U-Pb dating of single zircon grains with independent dating of the host rock by other methods, including Sm-Nd, Lu-Hf and Pb/Pb.

Initial Nd, Hf and Pb isotopic ratios of ancient orthogneisses are essential parameters for investigating the degree of heterogeneity of early Archaean mantle. The simplest interpretation of existing isotopic data is for a slightly depleted, close-to-chondritic, essentially homogeneous early Archaean mantle; this does not favour the existence of a sizeable, permanent continental crust in the early Archaean.

By analogy with the moon, massive bolide impacts probably terminated on Earth by
c.
3.8–3.9 Ga, although no evidence for them has yet been found. By
c.
3.65 Ga production of continental crust was well underway, and global tectonic and petrogenetic regimes increasingly resembled those of later epochs.
Lead isotopes and the age of the Earth — a geochemical accident
Authors: Hofmann Albrecht W. 
Published: April 2008

Abstract
The assumptions underlying the models used in the literature for obtaining the age of the Earth from terrestrial lead isotopes are severely violated by the complex evolution of the Earth, particularly the extreme chemical fractionation occurring during crust-mantle differentiation. Young conformable lead deposits are isotopically very similar to young sediments, the erosion products derived from the Earth’s most highly fractionated large-scale reservoir, the upper continental crust. Therefore, ancient conformable lead deposits are also likely to track continental compositions rather than the composition of any truly primitive reservoir.
Although the specific enrichment mechanisms during crust formation are both extreme and quite different for U and Pb, the net enrichments in the crust, as well as the corresponding depletions in the residual mantle, are on average very similar for the two elements. It is because of this geochemical coincidence that the time-integrated U/Pb ratios of conformable lead deposits, which integrate and average large volumes of crustal lead, are very close to average mantle values. For the same reason, the isotopic evolution of these conformable lead deposits follows an apparently (nearly) closed system evolution path of a 4.4 to 4.5 Ga-old U-Pb system rather closely, even though that system was actually very far from remaining chemically closed during its history. From these considerations I conclude that terrestrial Pb isotopes do not furnish a suitable tool for determining a refined estimate of the age of the Earth within the broad bounds of 4.4 and 4.56 Ga limits, which are given by other types of evidence, such as the ages of meteorites, the Moon, and the formation intervals of the Earth’s core and atmosphere derived from the decay products of short-lived, now-extinct nuclides.
Understanding the beginning and the end
Authors: Rees Martin J. 
Published: April 2008

Abstract
This paper attempts to set the Earth in a cosmic perspective. It discusses the Sun’s life cycle in the context of stellar evolution, and the ideas of stellar nucleosynthesis, as an explanation of the origin of the atoms on the Earth. Current ideas on how planetary systems form are mentioned, along with data on recently discovered planets around other stars. The origin of matter itself can be traced back to a ‘Big Bang’: corroboration of this model comes from the microwave background and from observed helium and deuterium abundances. There is now a concordance between stellar ages and the cosmic evolutionary timescale inferred from cosmology, from which we derive an age for the universe. Recent progress brings into focus a new set of questions about the ultra-early universe. Until these can be answered, it will remain a mystery why the universe is expanding in the observed fashion, and why it contains the measured mix of atoms, radiation and dark matter.
Compaction creep of quartz-muscovite mixtures at 500°C: Preliminary results on the influence of muscovite on pressure solution
Authors: Niemeijer A. R. , Spiers C. J. 
Published: April 2008

Abstract

It is widely claimed that the presence of phyllosilicates in sandstones increases intergranular pressure solution (IPS) rates in these rocks. However, this has not been experimentally confirmed. This study reports the results of isostatic hot-pressing compaction experiments at a temperature of 500°C and an effective pressure of 100 MPa on mixtures of quartz and muscovite. Previous work has shown that under these conditions dissolution is rate controlling in pure quartz. No acceleration of compaction rates of quartz by the addition of muscovite was observed. Instead, a modest decrease in compaction rates was observed (factor 3–10), which we infer was due to a decrease in IPS rate. The effect of muscovite in slowing IPS may be due to the influence of dissolved aluminum (Al
3+
) dominating over any accelerating effects of alkali-metal cations. From the geochemical literature, Al
3+
in solution is expected to decrease the solubility, dissolution rates and precipitation rates of quartz. However, the effect of the addition of muscovite on IPS rates in quartz when controlled by diffusion or precipitation may be different. Experiments should be conducted on quartz sand under conditions where diffusion or precipitation is rate controlling to investigate these possible effects.
The origin of fibrous veins: constraints from geochemistry
Authors: Elburg Marlina A. , Bons Paul D. , Foden John , Passchier Cees W. 
Published: April 2008

Abstract
Several recent studies have suggested that antitaxial fibrous veins may form without fracturing, and not by the commonly invoked crack-seal mechanism. It has also been suggested that such veins would derive their nutrients locally by diffusional transport. This hypothesis was tested on carbonaceous shale-hosted antitaxial fibrous calcite veins from Oppaminda Creek in the northern Flinders Ranges, South Australia. Apart from their fibrous texture, these veins lack the classical features of crack-seal veins, such as wallrock-parallel inclusion bands.
Diffusional transport of locally derived calcite cannot explain all major and trace element data of the veins and their adjacent wallrock and indicate that part of the calcite was transported over distances of at least >decimetres, probably ≫100m. Sr isotopic fingerprinting shows that an external fluid that carried radiogenic Sr must have percolated through the system. Fluid flow was pervasive as there is no evidence that this fluid preferentially percolated through the veins. Our data support the view that antitaxial fibrous veins of the type found at Oppaminda Creek grew in the absence of fractures, but show that such veins do not necessarily indicate local diffusional transport. Our data confirm a recently postulated basin-wide fluid flow event around 586 Ma that is probably related to copper mineralization in the area.
Textures and microstructures of naturally deformed amphibolites from the northern Cascades, NW USA: methodology and regional aspects
Authors: Leiss Bernd , Gröger Heike R. , Ullemeyer Klaus , Lebit Hermann 
Published: April 2008

Abstract

Neutron texture analyses of quartz-bearing and quartz-free amphibolite mylonites from the Windy Pass thrust, Cascades Crystalline Core (Washington/USA) reveal pronounced textures of plagioclase and clino-amphiboles (hornblende, cummingtonite) but no preferred orientation of quartz. A reliable strategy for amphibolite fabric analysis is presented by a systematic analytical approach to the experimental diffraction data processing. Clino-amphiboles show transitional textures between ideal single crystal orientations and axial symmetric great circle distributions. Plagioclase reveals
a
-axes distributions scattering along a great circle approximating the foliation plane as well as
a
-axes maxima close to the macroscopic lineation. Correlation of the textures with grain shape anisotropies of horn-blende and plagioclase and comparison with data from the literature suggest that the texture variations are due to different strain regimes rather than due to different crystallographic reorientation mechanisms. The kinematic directions deduced from the microfabric correlate well with the regional tectonic interpretations. In contrast, individual deformation paths are not yet established for the different tectonic units, as the significance of the separating Windy Pass thrust requires further structural analysis and fabric studies.
GPR in sediments: advice on data collection, basic processing and interpretation, a good practice guide
Authors: Jol Harry M. , Bristow Charlie S. 
Published: April 2008

Abstract
Within sedimentological studies, ground penetrating radar (GPR) is being used with increasing frequency because it yields images of the shallow subsurface that cannot be achieved by any other non-destructive method. The purpose of this paper is to provide an introduction to the collection, processing and interpretation of GPR data so that future sedimentary studies can be improved. With GPR equipment now being lightweight, robust and portable, proper data collection and survey design methods need to be followed in order to acquire high resolution, subsurface digital data. Various factors are discussed including: reflection profiling, velocity soundings, test surveys, topography, logistics, data quality and extreme environments. Basic data processing and visualization are then reviewed, followed by a discussion on GPR interpretation strategies including a background to radar stratigraphy. For the sedimentary geologist or geomorphologist, GPR offers unique data of the shallow subsurface including stratigraphy, geometry, architecture and structure.