bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Cambrian period
Authors: Cowie J. W. 
Published: September 2007

Summary
Fifteen selected radiometric ages are used to construct a time-scale for the Cambrian System. Maximum thicknesses are not considered to be useful in constructing a Cambrian time-scale. Ages of 495 m.y. and 570 m.y. are suggested for the top and base of the system, with ages of 540 m.y. and 515 m.y. for the Lower-Middle and Middle-Upper Cambrian.
Surface Geochemical Exploration in the North Sea
Authors: Gevirtz J. L. , Carey B. D. , Blanco S. R. 
Published: September 2007

Summary
Tenneco Oil Company has conducted extensive bottom sampling programmes over several known but undeveloped oil and gas fields in the North Sea. Samples over one example, Beatrice Field in U.K. waters, were distributed on an approximate 2 × 2 km grid over the entire licence block containing the field. Shipboard samples were collected from the ocean floor using a modified gravity-coring device that delivered cores up to 2 m in length. Overall core lengths varied from 0.5 m in hard sand to 2 m in clay. For geochemical analysis, samples were taken from the lower 0.5 m of the core.

In the laboratory, samples were analysed for light gases using gas chromatography. These results are expressed as parts per billion (10
12
) dry weight of sample. Fluorescence intensity over two peaks was recorded from hexane extracts. These results were expressed as relative peak intensities.

Data were subjected to a variety of analytical techniques including mapping of both individual variables and specific ratios, cross-plotting and regression of variable pairs to determine subtle interrelationships, and to a battery of multivariate pattern recognition techniques to isolate recurrent, mappable geochemical signatures.
After an independent assessment of the geochemical data was completed, the resultant geochemical interpretation was integrated with geological and geophysical data. Comparison of the geochemical maps with those produced as a result of geophysical and geological interpretation revealed remarkable similarity between the structural and geochemical interpretations. This suggests focussing of upward movement of hydrocarbons by geologic structure.
This exercise demonstrates that geochemical data of this type can greatly aid in the evaluation of the hydrocarbon potential structures, but should not be used alone as a prospecting method.
Petroleum Offshore Sniffer Exploration
Authors: Sigalove J. 
Published: September 2007

Summary
The association of large-scale, visible (macro) seeps with oil and gas fields has been well known for many years. It is evident from the recent literature that developments in electronics and analytical techniques have been permitting more and more comprehensive geochemical analyses with a greater reliability and sensitivity. Low level, non-visible micro-seeps are now reliably detected and can be used to evaluate the hydrocarbon potential of a basin, to establish the association of hydrocarbons with individual structures, and to determine whether the reserves at depth are likely to be gas or oil prone.

Weisman at Gulf Oil Company describes a system which measures C
1
–C
4
hydrocarbons with a sensitivity of 5 × 10
−11
1 propane at STP 1
−1
seawater. The newest generation of ‘Sniffer’ systems manufactured and operated by Interocean Systems Inc. measures C
1
–C
8
hydrocarbons with resolution of the saturated and unsaturated isomers as well as resolutions of the straight chain, branch chain and cyclic isomers with a sensitivity of 5 × 10
−13
1
−1
octane at STP 1
−1
seawater. These advances in hardware in hardware coupled with new data processing techniques have permitted the establishment of a significant body of field data and experience over the years. It is evident from the data presented that these newer geochemical techniques and experience from field data have created the ability not only to detect the very low concentration micro-seeps, but also to interpret the data in a useful way. This is resulting in geochemistry playing a more significant role in exploration than ever before.
Some Geological Controls on Oil Composition in the U.K. North Sea
Authors: Cornford C. , Morrow J. A. , Turrington A. , Miles J. A. , Brooks J. 
Published: September 2007

Summary

The U.K. North Sea contains a wide variety of reservoired oils, ranging from the biodegraded heavy oils, via mid-gravity crudes to light oils and condensates. Statistical data from a suite of U.K. North Sea oils gives an average API gravity of 36°, an average asphaltene content of 1.4% and an average saturate/aromatic ratio of 2.02. Averages for pristane/phytane, pristane/n-C
17
and phytane/n-C
18
are 1.24, 0.63 and 0.56 respectively. It is possible to explain the ocurrence of the vast majority of the U.K. North Sea crudes in terms of generation over a range of maturities from single source rock horizons (the Kimmeridge Clay Formation hot shales), followed by alteration during migration or within the reservoir. The source rocks are shown to be immature below 175°F (80°C); early mature between 175–225°F (80–107°C); mid-mature between 225–265°F (107–130°C) and late mature above 265°F (130°C). Early mature, full maturity spectrum and late mature oils are identified using maturity-controlled sterane and triterpane ratios established from the source rock studies, and are related to bulk properties such as API gravity and saturate/aromatic ratios.

Bacterial degradation in shallow cool reservoirs (less than 6000 ft; below 140°F (60°C)) is responsible for the majority of the heavy oil in the U.K. North Sea, while asphaltene enrichment is another mechanism for producing heavy oils.

Though the Kimmeridge Clay Formation hot shales are fairly homogeneous over the U.K. North Sea, molecular ratios such as the pristane/phytane ratio, the abundance of a C
28
hopane and a C
27
moretane can be used to correlate oils with specific facies of the generally homogeneous source rock.
Isotope Geochemistry of Natural Gases in Central Europe
Authors: Schoell M. , Whiticar M. J. 
Published: September 2007

Summary

Three parameters of natural gases, i.e. the 13C/12C and D/H ratio of methane and the C
2
+ content have been arranged in new diagrams for the genetic characterisation of natural gases. The principal gas provinces of Central Europe are discussed with regard to the various processes of gas formation. Three gas producing geological ‘Stockwerke’ can be distinguished:

(1)
Palaeozoic: Producing mostly gases from coal measures (southern North Sea, the Netherlands, NW Germany)

(2)
Mesozoic: Predominantly gases associated with oils (northern North Sea, NW Germany, S Germany, Italy)

(3)
Tertiary: Bacterial gases reservoired in Tertiary basins and thermogenic or mixed gases accumulated in Tertiary and pre-Tertiary basins (S Germany, Austria, Italy).

Isotopic and molecular changes found in all gases investigated can be explained by processes during formation of the gases (‘primary gases’) and simple process of mixing of primary gases. Specifically, isotope patterns in young sedimentary basins argue against diffusion as a dominant process that controls compositional variations in natural gases.
Geochemical Observations and Oil Genesis in the German Alps and their foreland
Authors: Kuckelkorn K. , Wehner H. , Hufnagel H. 
Published: September 2007

Summary
Currently attempts are being made to follow migration paths ‘upstream’ to deeply buried autochthonous Tertiary and Mesozoic source rocks below the Alpine over-thrusts using routine and geochemical exploration.
In the east the oil window probably lies much deeper to the south, however thermally mature strata rise westwards towards Lake Constance.
In the Eastern Molasse region, the basal Tertiary and Gault oils have a much higher maturity than the associated Tertiary source rocks, and also differ from the humic kerogen of the underlying Cretaceous. Their source may lie in Jurassic bituminous rocks, deeper and to the south.
In the Western Molasse region, oils in Tertiary and Mesozoic reservoirs form two families which can be correlated with source rocks of corresponding age occurring further south.
Pyrolysis-Mass Spectrometry in Coal Chemistry: a study of the coalification of vitrites and the typification of Australian Brown Coals
Authors: Schenck P. A. , de Leeuw J. W. , Viets T. C. , Haverkamp J. 
Published: September 2007

Summary
Curie-point pyrolysis-mass spectrometry and Curie-point pyrolysis-gas chromatography-mass spectrometry have been applied to analyse a series of vitrites of different degrees of coalification and a number of samples taken from Australian brown coal seams (La Trobe Valley, Victoria).
The relationship between mass spectral data and degree of coalification for the first series and biochemical precursors for the second series can be established.
Spectral Correlation of Spore Coloration Standards
Authors: Smith P. M. R. 
Published: September 2007

Summary
The optical examination of kerogen using transmitted light microscopy reveals a progressive and irreversible colour change with increasing thermal maturity. Such observations have resulted in various workers producing individual colour index scales, using diverse components of kerogen concentrates.
Three colour index scales are commonly quoted in the literature, namely Staplin’s Thermal Alteration Index (TAI), Robertson Research Spore Coloration Index (SCI), and Batten’s Colour Scale, which is also spore based.
Transmitted light spectra have been produced from the above mentioned sets of standard material, and a correlation of the different indices obtained.
The Use of Computerized Information in Britoil, Exploration Division
Authors: Baxter G. G. 
Published: September 2007

Summary
The Geodata Group of the Exploration Division of Britoil plc maintains six computerized information systems on behalf of the explorationists in the Company. These systems contain data about wells, licences, field studies, well exchange, shotpoint locations and 3-D grids. The wells system contains basic reference data and drilling summaries. The licence system consists of complete licence details as well as co-ordinate information for plotting purposes. The field studies system contains pairs of files, geological/petrophysical data and deviation survey data, for all wells in each field covered. The well exchange system is a list of what wells were ‘given’ for those wells ‘obtained’. The shotpoint locations system consists of navigation data obtained during seismic surveys from which shotpoint basemaps are directly produced. The 3-D grids are generated by the Radian Corporation package CPS-1 and contain two-way seismic times, seismic velocities or structural depth surfaces over fields or prospects. All the systems have developed in response to specific requirements of geologists or geophysicists. A database requirements review was undertaken during 1982 and the results of this will be built in to a proposed integrated information system. Because of this transition only an abstract of the paper is presented here.
Diapiric ascent and cooling of a sillimanite gneiss dome revealed by40Ar/39Ar thermochronology: the Kigluaik Mountains, Seward Peninsula, Alaska
Authors: Calvert Andrew T. , Gans Phillip B. , Amato Jeffrey M. 
Published: September 2007

AbstractThe upper amphibolite to granulite facies Kigluaik gneiss dome cooled rapidly in late Cretaceous time as it rose through the crust and was emplaced against the older blueschist-greenschist facies Nome Group.40Ar/39Ar data from metamorphic rocks reveal prolonged moderately rapid cooling histories that vary somewhat with structural depth and geographical position. Hornblende ages (Tcc.535°C) range from 86 to 82 Ma, mica ages (Tcc.300–400°C) range from 85 to 83 Ma, and K-feldspar spectra yield age gradients that record cooling fromc.300° toc.150°C between 82 and 65 Ma. These high-precision cooling ages on hornblende, white mica and biotite, and detailed temperature-time curves obtained from diffusion modelling of K-feldspar age spectra allow us to reconstruct the 3D geometry of isotherms during cooling and local reheating of the gneiss dome. Isotherms were parallel to lithological contacts during high-temperature cooling, then became subhorizontal in present-day coordinates as layering was domed byc.84 Ma. Low-temperature cooling (300–150°C) of the gneiss dome is asymmetrical, with the north side cooling several million years before the south side. The contact between high-grade gneisses of the Kigluaik Mountains and surrounding lower-grade rocks is not a fault, but rather a steep metamorphic field gradient where closely spaced Barrovian isograds and partially reset mica ages document progressive thermal overprint of the older blueschist-greenschist facies Nome Group rocks. These combined geological and thermochronological data are most compatible with a model wherein the Kigluaik gneiss dome rose diapirically from mid-crustal levels between 91 Ma andc.82 Ma and cooled through low temperatures differentially as it was tilted gently southward between 83 and 65 Ma.
Exposure of deep, dense rocks: interplay between erosion and sinking
Authors: Glazner Allen F. 
Published: September 2007

Abstract

A numerical model of the interplay between viscous sinking and erosion predicts that the ultimate fate of dense rock bodies in the crust is a sensitive function of erosion rate and of the body’s radius, density, and initial depth of emplacement. If all of these variables save one are held constant, the trajectories taken by the body on a depth-time plot diverge widely about a critical value of the remaining variable. For example, if erosion rate, depth, and density are held constant, there is a critical value of the body’s radius below which it will be carried to the Earth’s surface by erosion and above which it will plummet to neutral buoyancy in the deep crust. This critical sensitivity may explain, for example, why dense plutons larger than a few kilometres in diameter are rare in plutonic terranes. The calculations indicate that exceptionally high erosion or tectonic denudation rates, on the order of 10 km Ma
−1
or more, may be necessary to bring dense bodies to the surface before they sink through less dense crust.
Thermal and mechanical models for the structural and metamorphic evolution of the Zanskar High Himalaya
Authors: Searle M. P. , Waters D. J. , Dransfield M. W. , Stephenson B. J. , Walker C. B. , Walker J. D. , Rex D. C. 
Published: September 2007

AbstractThe regional Barrovian facies metamorphic rocks of the High Himalayan Slab in Zanskar are bounded along the base by the southwest vergent Main Central Thrust (MCT) with its characteristic zone of inverted isograds, and along the top of the slab by the northeast dipping Zanskar Shear Zone (ZSZ), part of the South Tibetan Detachment (STD) System of normal faults. Summarized here are the results of systematic mapping combined with detailedP-T-tdata from the Zanskar Himalaya, and models for the thermal and mechanical evolution of the middle and deep crustal rocks of the Himalaya are discussed. Temperatures and pressures increase dramatically up-structural section across the MCT Zone from biotite through garnet, staurolite and kyanite grade to sillimanite + muscovite, and decrease along the top of the stab beneath the ZSZ normal faults. In Zanskar, peakP-Tconditions of the M1 kyanite-grade rocks are 550–680°C and 9.5–10.5kbar, and M2 sillimanite-grade gneisses were formed at 650–770°C and 4.5–7 kbar. The core of the High Himalayan Zone is a 30 km wide zone of sillimanite + K-feldspar-grade gneisses, migmatites and anatectic leucogranites with a right way-up isograd sequence above and an inverted sequence below.Thermal models of thrusting a hot slab over a cold slab and frictional heating along the MCT are not supported by the structural and thermobarometric data. Mechanical models of post-metamorphic structural disruption by folding and thrusting of a pre-existing, right way-up metamorphic sequence are compatible with structural andP-Tdata. Ductile shearing along the MCT Zone has structurally condensed the isograds, and final motion along the ZSZ postdated leucogranite crystallization (21.5-19.5 Ma; U-Pb monazite ages) and emplacement in the footwall. Crustal shortening and thickening, resulting in prograde metamorphism, lasted from the time of India-Asia collision at 54-50Ma until at least 30-25 Ma. Crustal melting is constrained at 20.8-19.5 Ma along the core of the stab. Late stage out-of-sequence thrusting within the High Himalayan Slab effectively maintained the crustal thickening process enablingP-Tconditions to remain high for 10-5 Ma. Rapid exhumation between 21-18.5 Ma was accompanied by removal of 18–25 km of overburden by erosion at exhumation rates of 6–10 mm yr−1. This early Miocene period of high exhumation rates, rapid erosion and exhumation of rocks buried at τ25 km depth is interpreted to indicate the uplift of high mountains and erosion of deep valleys, probably with high precipitation during that time.
The Influence of Strain Rate on the Mode III Interlaminar Fracture of Composite Materials
Authors: Pennas D. , Cantwell W.J. , Compston P. 
Published: September 2007

The Mode III interlaminar fracture toughness, GIIIc, of composite materials based on both thermoplastic and thermosetting-matrices have been investigated using the edge crack torsion (ECT) test geometry. Tests were undertaken at room temperature and over a range of crosshead displacement rates to study the influence of strain rate on the interlaminar fracture properties of these materials. Further information concerning the crack tip loading conditions was obtained by undertaking a finite element analysis of the ECT specimen geometry. The experimental results show that the value of GIIIc depends on initial crack length, increasing steadily with increasing crack length for both types of material. It has been shown that the interlaminar fracture toughness of the glass fiber/epoxy-based system was superior to that offered by its thermoplastic counterpart, an effect that may be due to the fact that the glass fiber-reinforced polypropylene composite was slow-cooled from its processing temperature. The interlaminar fracture toughness of both types of composite remained roughly constant over the range of crosshead displacement rates considered here suggesting that they do not exhibit any rate-sensitive fracture behavior. The finite element analysis of the ECT specimens showed that the specimen is subjected to pure Mode III loading over the central part of the test specimen whereas regions of locally-high Mode II loading were observed over the region in which the load was applied. The Mode III strain energy release rate profile does not depend on specimen thickness or the displacement of the ECT test geometry.
Measured and predicted energy demand of a low energy building: important aspects when using Building Energy Simulation
Authors: Karlsson F. , Rohdin P. , Persson M.-L. 
Published: September 2007

Three different simulation tools were used to simulate a low energy terraced house in the south of Sweden. The software tools all use dynamic models to calculate, for example, the energy demand for heating and the indoor temperatures. The aim of this paper is to discuss the relative importance to the annual energy demand of different energy aspects of a Swedish low-energy house. Both measured and simulated values are considered and compared. The focus is on the impact of choice of software, the habits of the tenants, and the relative impact of different design parameters such as ventilation rates. The measured values for total electricity demand range from about 6000 kWh to over 12 000 kWh, the average demand being 8020 kWh. The annual predicted total energy demand using three different simulation software tools deviated by about 2%. The energy use deviation due to airflow control was about 10%, and the deviation due to differences in heat exchanger efficiency was about 20% and the deviation in annual energy use due to differences in internal gains due to differences in tenant habits, assumed in the models, was 7%. Furthermore, when comparing the predicted energy use during the design process of the low-energy building with actual measurements after the tenants have moved in, these differ about 50% in average for this specific case. Practical application: Building energy simulation software is often used to make predictions of how different construction materials, design principles and operation influence the energy balance and indoor thermal comfort. It is therefore important that the output of these software tools is trustworthy and accurate. This paper discusses the importance of accurate input data during the design process in order to achieve a valid prediction of energy use with emphasis on tenants' behaviour. It was shown that the deviations in a parametric study were larger than the deviations in the comparison between the results from the three simulation tools. This indicates a need for more accurate models for modelling tenant behaviour and habits rather than more accurate building component models.
New algorithm for generating hourly temperature values using daily maximum, minimum and average values from climate models
Authors: Chow D.H.C. , Levermore Geoff J. 
Published: September 2007

The use of building simulation programmes for predicting building performance is increasing all the time especially with the advent of cheap, fast computers. Hourly weather data, in particular outdoor dry bulb temperature (DBT) and solar radiation values, are required for simulation programmes for building performance. When hourly values are not available there are algorithms for generating hourly temperature values from daily values. These use the daily maximum temperature TMAX, and daily minimum temperature, TMIN. However, climate prediction models, such as HadCM3 and HadRM3 also provide the daily average dry-bulb temperature TAVE as well as the daily maximum and minimum. The average temperature is important for selecting weather years and also because the average temperature is often different from the average of the maximum and minimum, assumed in the simpler algorithms. Buildings being designed now will need to perform under future weather conditions with climate change, so the downscaling of daily values from climate prediction models to hourly values is required. This paper describes a new, more accurate algorithm for generating hourly temperature values in the UK that uses all three temperature parameters from climate change models, and demonstrates the improvement of the quality of the generated values against traditional algorithms that use just the daily maxima and minima. Practical application: The proposed algorithm for generating hourly DBT values from daily maximum, minimum and average values is intended primarily for deriving hourly data for running building simulation programmes, as some weather stations and future climate prediction models only provide daily values of weather parameters. Climate change is affecting all aspects of human life, and as well as being affected by climate change, buildings can also affect the degree of climate change, since well-designed buildings will require less energy to run, thus minimising the amount of carbon dioxide emitted. As the climate is predicted to change significantly in the next 100 years, if buildings are designed to last, it is important for designers to know how buildings will respond and perform then. Building simulation programmes are useful for this, but they require hourly weather data which are not provided by most climate prediction models. By having a quality-assured algorithm for down-scaling the raw daily values to hourly values, data from climate prediction models, such as HadCM3 and HadRM3 can be used for building simulations for any location in the world. The hourly DBTs derived from using the algorithm suggested in this paper may also be used in conjunction with other hourly weather data, such as wet-bulb temperature, solar irradiance, cloud cover and wind speed, derived from the same dataset.