bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mud buildups on a Middle Devonian carbonate ramp (Algerian Sahara)
Authors: Wendt Jobst , Kaufmann Bernd 
Published: April 2008

Abstract
During sea-level highstand in late Mid-Devonian time, a carbonate ramp was established on the vast shelf of the Northwest African Craton, in the Ahnet and Mouydir Basins of southern Algeria. The ramp was at least 400 km wide and 700 km long and sloped, in front of a local shoal of rugose-tabulate-stromatoporoid dominated biostromes, towards the west into the Reggane Basin and towards the north into the Béchar Basin. Mid- and inner ramp zones were presumably situated in the area of the present Hoggar Massif and have been removed by erosion. Subsidence rates during Mid-Devonian time were considerably lower than during the preceding and subsequent periods of clastic sedimentation in Early and Late Devonian time. Spectacular mud buildups formed in an outer ramp setting and developed from small, lens-shaped, to steep, conical mounds, which eventually amalgamated into mud ridges and mud ‘atolls’. Orientation of mound rows and ridges matches older NW-SE and N-S tectonic lineaments, which were probably rejuvenated during Mid-Devonian time. Stable isotope values of early marine cements, composition of the buildup fauna, and the emplacement and orientation of neptunian dykes do not indicate, however, that buildup growth was triggered by hydrothermal activity or cold seeps.
A theory of the Earth: Hutton and Humpty Dumpty and Holmes
Authors: Anderson Don L. 
Published: April 2008

Abstract
Paradoxes can be viewed as a bother or as a rich source of information. Paradoxes, fallacies and logical inconsistencies, along with the unstated assumptions behind old worldviews often form the foundation for a new worldview. This is where science differs from myth and just-so stories.
Mantle dynamicists and geochemists have developed a worldview that, in many respects, is incompatible with modern theories of planetary accretion, geodynamics and geophysics, and with the geological context of volcanoes. A primordial undegassed mantle, as both the furnace and the fuel of midplate volcanoes, occupies a central role in the geochemical models. Although modern data alone are sufficient to overturn this view, it is interesting to address it in terms of its own assumptions, fallacies and inconsistencies, and the history of ideas. This is a vast field, so, in honour of James Hutton, I focus on volcanoes, their products, their causes and their sources.
The following axioms are developed which point toward a different kind of world from the pristine primordial worldviews and the plume paradigm.

•
Linear volcanic chains delineate the stress field, not the displacement field, of the lithosphere.

•
Lithospheric architecture, not the core-mantle boundary, dictates the planform of convection in the mantle.

•
Incipient melting is the normal state of the upper mantle.

•
The lower mantle is depleted in the heat producing elements compared to the crust, upper mantle and the bulk silicate Earth.

•
The Earth is depleted in volatile elements.

•

High
3
He/
4
He ratios in mantle materials imply a deficit of
4
He.

•
Primordial heat contributes a significant part of the Earth’s heat flow.

These axioms [
A
] are the inverse of the assumptions of the plume and primordial mantle paradigms [not-
A
] and the new and the old views are to each other as looking-glass worlds. An ‘axiom’ is a self-evident truth or an established rule. It is also an undemonstrated proposition concerning an undefined set of elements and relationships. The above ‘axioms’ [
A
] are not true axioms but [not-
A
] provide the axiomatic framework of the current world model. These [not-
A
] propositions are treated as self-evident truths so [
A
] can also be called axioms, even though they are falsifiable. The prevailing worldview, the ‘standard model’, attributes both melting and volcanic chains to deep mantle upwellings controlled by the bottom of the system with most of the original radioactivity and volatile inventory of the Earth in the deep mantle. This is not only inconsistent with modern data but also with the previous worldview embedded in the axioms. These axioms have not been pushed out by better ideas, or falsified; they have simply been overlooked or forgotten. Mantle dynamics is controlled from the top, not the bottom.
Hot little crucibles are pressured to reveal and calibrate igneous processes
Authors: Wyllie Peter J. 
Published: April 2008

Abstract
The fires of Hutton’s (1726–1797) Plutonists could not be quenched by the oceans of Werner’s (1750–1817) Neptunists. Hall (1761–1832) was convinced that Hutton’s theory could be proved by experiments, but he deferred to the fears of his older colleague that failed experiments might discredit the theory (which needed no further proof), and completed the experiments only after Hutton’s death. Hutton censured those who ‘judge of the great operations of the mineral kingdom, from having kindled a fire, and looked into the bottom of a little crucible’. Hall believed that ‘the imitation of the natural process is an object which may be pursued with rational expectation of success’. Following many discussions between Hutton and Hall, three topics were pursued in Hall’s experiments: 1790, the magmatic origin of granites, younger than schists; 1798, whinstones/dolerites are as magmatic as known lavas; 1805, powdered calcite is transformed to marble and melted by the effects of compression (and water) in modifying the action of heat. The latter involved the first high-pressure, high-temperature apparatus and earned Hall the title ‘Father of Experimental Petrology’. Subsequent development of these topics is outlined, with reference to debates about primary basalts, granitization, and carbonatites.
Impacts from space: the implications for uniformitarian geology
Authors: Marvin Ursula B. 
Published: April 2008

AbstractThe geological implications of the Earth’s collisions with other bodies in space have become fully evident only since the opening of the Space Age. In the early eighteenth century, most western natural philosophers accepted the view, inherited from Aristotle and confirmed on mechanistic grounds by Isaac Newton, that interplanetary space is empty of solid matter. In the final decade of that century, two books, one by Ernst F. F. Chladni of Wittenberg and one by James Hutton of Edinburgh, contributed to the rise of meteorite studies and uniformitarian geology, respectively. Although they arose almost simultaneously, these two branches of science, one of which postulated the fall to Earth of solid bodies from space while the other endorsed only strictly endogenous processes acting upon the Earth, evolved separately over the next 200 years. This paper traces the long estrangement between mainstream geology and the science of meteorites. The two disciplines collided head-on in 1980 when a team of scientists headed by the physicist, Luis Alvarez, of the University of California, hypothesized that the massive extinctions at the end of the Cretaceous were triggered by the hypervelocity impact of a large body from space. Many geologists rejected outright such an exotic cause. More recently, as evidence has accumulated for the K-T impact as well as for many other crater-forming impacts, we are beginning to realize that unpredictable collisions have played a role of fundamental importance throughout the history of the solar system.
Vestiges of a beginning and the prospect of an end
Authors: Dalziel Ian W. D. 
Published: April 2008

Abstract
‘No vestige of a beginning, …’ In one sense the first half of James Hutton’s famous statement of 1788 holds true today — the oldest parts of Earth’s crust identified in two centuries of ‘modern’ study look not unlike those being formed at present. Yet the age of the planet can now be determined as close to 4.5 billion years, and radiometric ages of vestigial rocks and minerals approach 90 per cent of that value. The history of the planet is becoming clearer. We can now accurately reconstruct the geography of Pangea in early Mesozoic times. Remnants of older rifted continental margins suggest the existence of previous supercontinents for which hypothetical reconstructions have been proposed — a global-scale Huttonian process of tectonic renewal. Their mode of fragmentation and comparison with the other terrestrial planets suggest a functional connection between surficial plates and deep-seated mantle plumes, which may extend back to the Archaean. The fossil record, geochemistry, and molecular biology provide a timeline for life on Earth which does extend to the Archaean, almost as far as the oldest rocks and minerals. The history of endogenic tectonism, environmental change and biological evolution was punctuated, and to some extent at least influenced, by bolide impacts.

Like Hutton, in the rocks we can still read ‘no prospect of an end’, though astrophysical evidence indicates the demise of the Earth, or at least of its biosphere, will inevitably come 5000 million years into the future when our Sun will become a red giant, enveloping all its planets in a gaseous holocaust. Detection of complex organic molecules in the comas of comets that recently traversed the inner Solar System has shown, however, that the basic chemical building blocks of life are present in interstellar space. Evidence is steadily building up for the existence of planets around other stars of the Milky Way. Hence life need not be limited in either space or time by the existence of the Earth itself. Indeed, contemporary cosmology entertains possibilities that the entire universe that we recognize may be boundless, permanently expanding, or perhaps even part of a continuum of evolving universes. In this ultimate sense, therefore, the concluding sentence of the
Theory of the Earth
by the ‘founder of modern geology’ can be considered as valid today as it was 200 years ago.
The Dynamic Earth project and the next millennium
Authors: Monro S. K. , Crosbie A. J. 
Published: April 2008

Abstract

Two hundred and fifty years ago Edinburgh was a focus of intellectual ferment. The Enlightenment fired concern for an understanding of the science of the natural world. Hutton’s
Theory of the Earth
not only provided a comprehensive view of the planet and its processes but also altered the perception of time. The next millennium will see a new global Englightenment. The communications revolution is extending an awareness of science, but there is also an increased responsibility on scientists to make the results of their work understandable and accessible to the general public. Edinburgh’s ‘Dynamic Earth’ exhibition will play a major part in delivering a better public understanding of the planet, generating that same sense of excitement felt by Hutton and his colleagues when first they looked into ‘the abyss of time’. It will demonstrate that the Earth is a dynamic system, and show how landscapes are formed by a complex interaction between the geosphere, atmosphere, hydrosphere and biosphere and that these processes continue today. The challenge of Hutton’s concept that ‘the present is the key to the past’ lies in what it implies about the future. The presentation within the Dynamic Earth will help visitors make up their own mind about what the future may hold.
Acquisition of anhysteretic remanence and tensor subtraction from AMS isolates true palaeocurrent grain alignments
Authors: Borradaile Graham J. , Fralick Philip W. , Lagroix France 
Published: April 2008

Abstract
Anisotropy of magnetic susceptibility (AMS) is commonly used to detect subtle palaeocurrent directions. A Proterozoic subarkose shows extreme anomalous inverse AMS fabrics that cannot be attributed to the well-known effect of single-domain magnetite. This was confirmed by anisotropy of anhysteretic remanent magnetization (AARM). Further, by subtracting increasing proportions of the AARM tensor from the AMS tensor the paramagnetic/diamagnetic response of the silicate fabric was isolated. This reveals an inverse quartz fabric but analysis of the results shows that two grain alignments are present. A prominent inverse magnetic fabric is due to quartz long axes aligning with current flow revealed by the difference [AMS]-[AARM]. This is due to the avalanche flow of concentrated sand dispersions down the slip-face of cross-stratified units. Dispersive pressure caused by grain interactions and shear within the fluid produces a subhorizontal resultant force that aligns grains by frictional freezing during deposition. In some samples AARM isolates a secondary feeble alignment of magnetite nearly perpendicular to bedding. This is due to suspension rainout and sweeping by the reverse circulation separation eddy that supplies additional material to the top of the sand laminae. It particularly affects fine grains such as magnetite that infiltrate the framework’s pores to produce a secondary population of vertically oriented grains.
Sequence stratigraphic subdivision of the Humber Group in the Outer Moray Firth area (UKCS, North Sea)
Authors: Duxbury S. , Kadolsky D. , Johansen S. 
Published: April 2008

Abstract

The Humber Group (Late Oxfordian-Ryazanian) in the Outer Moray Firth has been subdivided into 19 depositional sequences, which are firmly related to a newly defined, consistent biostratigraphic framework. Each sequence has been defined by core sedimentology (where possible), biostratigraphy and electric log patterns. In non-marine to shallow-marine environments (e.g. Piper Formation
sensu lato
), well-defined transgressive and highstand (or regressive) systems tracts are recognized, which are extensively cored in the area due to their importance as reservoirs of major fields. In younger sections, sequence recognition is based on the presence of submarine fans and maximum flooding surfaces; sequences so defined are to some extent supported by the cyclicity of equivalent shallowmarine sand sequences near the basin margins. The sequence stratigraphy approach has clarified the lateral stratigraphic relationships of reservoir sand units within the Tartan Field, and the relationships between the reservoir sand units in the Tartan, Highlander and Petronella fields. The main causes of the observed cyclic sedimentation are interpreted as the complex interplay between sediment supply, subsidence rates and eustasy. Although the relative importance of the last two remains unclear, the sequence stratigraphic approach followed here has allowed rigorous description and consistent interpretation of vertical and lateral facies associations.
Well-site biostratigraphy of Danish horizontal wells
Authors: Shipp D. J. 
Published: April 2008

Abstract
The number of horizontal and subhorizontal wells drilled has significantly increased over the last decade, especially during the last five years, and the use of horizontal wells in oil-field production and development is now routine. In 1987 Maersk Olie and Gas AS drilled the first horizontal well on the Dan Field. Since that time biostratigraphers at Robertson Research International Limited have been involved in Maersk’s pioneering work on the development of steering techniques for horizontal wells in the Danish sector of the North Sea. Well-site biostratigraphy has been successfully used to aid in the steering of these horizontal wells.
The background studies leading to the erection of highly detailed local biozonal schemes capable of detecting changes over vertical distances as little as 1 foot are described. The logistics of how well-site biostratigraphy is carried out at the well site is explained. In addition to Dan, well-site biostratigraphy has been successfully applied to development wells from several other Danish North Sea carbonate fields operated by Maersk Olie og Gas AS on behalf of the Danish Underground Consortium (a joint venture between Shell, Texaco and AP Møller). These fields include Harald, Kraka, Gorm, Roar, Skjold, Svend, Tyra and Valdemar. Over 100 wells from Danish fields have to date been effectively steered using high-resolution biostratigraphy. Vertical targets of 10–20 feet or less have been successfully followed over distances of several thousand feet.
Forties Field (North Sea) revisited: a demonstration of the value of historical micropalaeontological data
Authors: Jones R. W. 
Published: April 2008

Abstract
The history of the discovery, appraisal and development of the Forties Field and the evolution of the reservoir model are briefly reviewed.
The process of integrated reservoir description (IRD) is still ongoing, iterating with the acquisition of new analytical or (re)interpreted biostratigraphic or sedimentological or other static (seismic, well) or dynamic data. IRD has already made a significant impact on the ongoing infill production drilling programme.
Even in the absence of newly acquired high-resolution palynostratigraphic and three-dimensional (3D) seismic data, historical high-resolution micropalaeontological data can be used to identify eight main sands in the reservoir system, separated vertically and/or laterally by shales (production barriers).
Historical micropalaeontological and sedimentological data can also be used to refine the interpretation of the depositional environment of the reservoir section. It indicates the development of both high-density channel-axis turbidite and low-density channel and overbank turbidite facies in pay zones, and interturbidite facies (with low potential as production barriers) and hemipelagite facies (with high potential as production barriers) in non-pay zones. The progressive elimination of infaunal and epifaunal benthonic foraminifera during the time the reservoir section was deposited indicates a progressive deterioration of the physics or chemistry of the benthonic environment (ultimately resulting in the development of a non-bioturbated laminite facies).
Constraints on the application of palynology to the correlation of Euramerican Late Carboniferous clastic hydrocarbon reservoirs
Authors: McLean D. , Davies S. J. 
Published: April 2008

Abstract
Palynology represents the standard tool for subsurface biostratigraphical correlation of Euramerican Late Carboniferous sequences. While palynomorphs are usually absent from sandstone lithologies, they form diverse and abundant assemblages in fine-grained sediments and coals. The occurrence of inter- and intrasandstone horizons that contain distinctive palynological assemblages forms the basis for the correlation and discrimination of sandstone reservoirs, and the application of palynology to development drilling programmes. The successful application of development palynology is contingent upon many factors related to geology (sandstone-body type, occurrence and lateral consistency of distinctive horizons, nature of intrareservoir units, degree of reservoir incision, etc.) and to practical constraints (such as the nature of databases, sampling strategies with ditch cuttings, standardization of preparation and data acquisition techniques, and time and cost limitations). The development palynologist needs to be critically aware of the existence of such constraints, and should limit the confidence attached to interpretations and predictions made accordingly.
The Mesozoic denudation history of the Atlantic margins of southern Africa and southeast Brazil and the relationship to offshore sedimentation
Authors: Gallagher Kerry , Brown Roderick 
Published: April 2008

Abstract
A new interpretation of regional apatite fission track data suites from western southern Africa (South Africa, Namibia) and southeast Brazil, in terms of the post-break-up denudation chronologies, is presented. The data reveal that although significant denudation occurs parallel to the present-day margin (associated with the inland escarpment) there are regional variations along-strike and with time. Moreover, the data reveal a significant amount of post-break-up denudation from within the continental interior of southern Africa. The data indicate relatively little post-rift denudation but the rates increase dramatically in both regions in the late Cretaceous-Early Tertiary, more than 50 Ma after initial rifting. The inferred denudation chronologies are broadly consistent with the sedimentary record in the offshore basins, which can show increases in sedimentation rate, contemporaneous unconformities and major changes in depositional character.
The distribution of petroleum reserves in basins of the South Atlantic margins
Authors: Coward M. P. , Purdy E. G. , Ries A. C. , Smith D. G. 
Published: April 2008

Abstract
The opening of the South Atlantic created a series of passive margin basins on both sides of the new ocean. This paper reviews the distribution of petroleum reserves in these basins in terms of their tectono-stratigraphic position within the framework of the rift-drift succession. Seven megasequences are recognized. Three are in the drift succession, three are in the rift succession and one comprises the pre-rift succession. Ninety-three per cent of the presently discovered recoverable hydrocarbons are reservoired in the drift succession, 6% are located in the rift succession and 1% is associated with the pre-rift units. The basins group geographically into seven sectors within which both margins share some common features. Sixty-five per cent of the reserves are contained in Sector V which is dominated by the Niger Delta, and 28% are positioned in Sector III, which includes the Campos and Lower Congo Basins. The new deepwater giant discoveries of Angola, which are located in Sector III, are the Africa counterparts of the earlier deepwater Campos Basin discoveries. In general sectors III–V, located between the Walvis Ridge and the Equatorial Atlantic transforms, are most favourable as they are characterized by the most prolific source rocks at all horizons.
Tectonics and hydrocarbon distribution along the Brazilian South Atlantic margin
Authors: Davison Ian 
Published: April 2008

Abstract
Break-up of the Brazilian margin produced a wide variety of structural styles depending on opening kinematics and thermal configuration of the lithosphere. Wide margins developed in Santos and Campos, where stretched continental crust extends for up to 600 km from the shoreline; whereas narrow margins may be only 40 km wide. The wide margins host the largest oil fields, such as those discovered in the Campos Basin. Wide margins have good hydrocarbon potential in the post-rift sequence, but narrow margins probably have the better unknown syn-rift plays which have still to be drilled in deepwater. Little is known of the narrow margins, such as the Jacuípe and Pernambuco-Cabo Basin area, as most of the prospective hydrocarbon structures lie in water depths > 1500 m.
Hydrocarbons are hosted by reservoirs ranging from fractured Neocomian volcanics to Miocene turbidites, with over 80% of the reserves trapped in the Campos Basin turbidite sandstones. These sandstones occur as constrained channel-fills on the upper platform and slope, and as unconstrained lobes up to 30 km in long dimension on the mid to lower continental slope which are situated in 500+ m water depths at the present day. The wide margins will continue to be the most productive in Brazil, but deepwater production technology has advanced enough to make the deeper parts of the narrower margins attractive exploration areas.