bluuebunny/crossref_metadata_2025_split huggingface dataset:
Communication between overpressured compartments
Authors: Wangen M. 
Published: March 2003

AbstractOverpressure build‐up in compartments, and communication between overpressured compartments across faults are studied with simple analytical and numerical models. It is shown that the excess pressure in a (vertical) one‐dimensional, one‐compartment model can be written as the sum of the excess pressure generated in the seal above the compartment, and a second part, which is due to the expulsion of fluid from the compartment and the rocks below. The one‐compartment model is generalized to a two‐compartment model, which accounts for the fluid communication between the compartments through a fault zone. The volume rates of flow through the seals and the fault zone are shown to be the weighted mean of the volume rates of the one‐dimensional, one‐compartment model. The normalized weights are given by dimensionless numbers, called fault–seal numbers, which control the communication between the compartments. A fault–seal number much less than unity implies that the fault is a stronger barrier for the fluid flow than the seal. A fault–seal number larger than unity implies the opposite: that the seal is a stronger barrier than the fault. The conditions for isolated compartments and other regimes are identified in terms of the fault–seal numbers. It is discussed how the compartment fault–seal numbers can be computed when the permeability is given in the fault zone. The results given by the analytical compartment models are demonstrated and validated with two‐dimensional numerical (finite element) simulations.
FT‐IR measurements of petroleum fluid inclusions: methane, n‐alkanes and carbon dioxide quantitative analysis
Authors: Pironon J. , Thiery R. , Ayt Ougougdal M. , Teinturier S. , Beaudoin G. , Walgenwitz F. 
Published: March 2003

AbstractA recent advancement in petroleum geochemistry is to model fossil oil composition using microthermometric and volumetric data acquired from individual fluid inclusion analysis. Fourier transform infrared (FT‐IR) microspectroscopy can record compositional information related to gas (CH4 and CO2) and alkane contents of petroleum inclusions. In this study, a quantitative procedure for FT‐IR microspectrometry has been developed to obtain, from individual fluid inclusions, mol percentage concentrations of methane, alkanes and carbon dioxide as constraints to thermodynamic modelling. A petroleum inclusion in a sample from the Québec City Promontory nappe area was used as standard to record a reference spectrum of methane. The analytical procedure is based on the measurement of CH4/alkane and CH4/CO2 band area ratios. CH4/alkane infrared band area ratio is obtained after spectral subtraction of the reference methane spectrum. This area ratio, affected by absolute absorption intensities of methane, methyl and methylene, provides a molar CH4/alkane ratio. Methyl/methylene ratio (CH2/CH3) ratio is obtained following procedures established in previous work. CO2/CH4 concentration ratio is estimated from relative absolute absorption intensities. Application to natural inclusions from different environments shows good correlation between FT‐IR quantification and PIT (petroleum inclusion thermodynamic) modelling.
Fluids and halogens at the diagenetic–metamorphic boundary: evidence from veins in continental basins, western Norway
Authors: Svensen H. , Jamtveit B. , Banks D. A. , Karlsen D. 
Published: March 2003

AbstractSeven vein types are recognized in three continental Devonian molasse basins (the Hornelen, Kvamshesten and Solund basins) in western Norway. These include calcite‐, quartz‐ and epidote‐dominated veins. The salinities of fluid inclusions from quartz‐dominated veins in the Hornelen and Kvamshesten basins are close to or slightly higher than those for modern seawater, whereas the fluids from quartz‐ and calcite‐dominated veins in the Solund basin range from seawater values to 20 wt % NaCl equivalent. Minerals such as biotite, amphibole, titanite, chlorite and epidote are abundant in the latter veins, and are important constituents of the authigenic mineral assemblages. A combination of fluid inclusion and petrological data suggest that at least some of the veins formed at depths around 12–14 km. The Cl/Br ratios and the salinity of the fluid inclusions can be explained by interactions with evaporites, implying that the sedimentary environment forming the basin fill had the strongest influence upon low‐grade metamorphic fluid Cl and Br contents. Differences in the Cl/I and Na/Br ratios between the Solund basin and the Hornelen and Kvamshesten basins are best explained by local mass transfer between pore fluids and the surrounding rock matrix during burial and increasing temperatures.
Ancient hydrocarbon seeps from the Mesozoic convergent margin of California: carbonate geochemistry, fluids and palaeoenvironments
Authors: Campbell K. A. , Farmer J. D. , Des Marais D. 
Published: March 2003

AbstractMore than a dozen hydrocarbon seep‐carbonate occurrences in late Jurassic to late Cretaceous forearc and accretionary prism strata, western California, accumulated in turbidite/fault‐hosted or serpentine diapir‐related settings. Three sites, Paskenta, Cold Fork of Cottonwood Creek and Wilbur Springs, were analyzed for their petrographic, geochemical and palaeoecological attributes, and each showed a three‐stage development that recorded the evolution of fluids through reducing–oxidizing–reducing conditions. The first stage constituted diffusive, reduced fluid seepage (CH4, H2S) through seafloor sediments, as indicated by Fe‐rich detrital micrite, corroded surfaces encrusted with framboidal pyrite, anhedral yellow calcite and negative cement stable isotopic signatures (δ13C as low as −35.5‰ PDB; δ18O as low as −10.8‰ PDB). Mega‐invertebrates, adapted to reduced conditions and/or bacterial chemosymbiosis, colonized the sites during this earliest period of fluid seepage. A second, early stage of centralized venting at the seafloor followed, which was coincident with hydrocarbon migration, as evidenced by nonluminescent fibrous cements with δ13C values as low as −43.7‰ PDB, elevated δ18O (up to +2.3‰ PDB), petroleum inclusions, marine borings and lack of pyrite. Throughout these early phases of hydrocarbon seepage, microbial sediments were preserved as layered and clotted, nondetrital micrites. A final late‐stage of development marked a return to reducing conditions during burial diagenesis, as implied by pore‐associated Mn‐rich cement phases with bright cathodoluminescent patterns, and negative δ18O signatures (as low as −14‰ PDB). These recurring patterns among sites highlight similarities in the hydrogeological evolution of the Mesozoic convergent margin of California, which influenced local geochemical conditions and organism responses. A comparison of stable carbon and oxygen isotopic data for 33 globally distributed seep‐carbonates, ranging in age from Devonian to Recent, delineated three groupings that reflect variable fluid input, different tectono‐sedimentary regimes and time–temperature‐dependent burial diagenesis.
Fluidized sandstone intrusions as an indicator of Paleostress orientation, Santa Cruz, California
Authors: Boehm A. , Moore J. C. 
Published: March 2003

AbstractThe late Miocene sandstone intrusions of northern Santa Cruz County, California, are the largest subaerial exposures of clastic intrusions on earth. The intrusions are sourced from a sandstone, underlying mudstone, accumulated in an outer shelf to upper slope environment. Dikes are the most frequent intrusion type, reach the greatest thickness and tend to strike north‐east and dip steeply. One giant dike is more than 150 m wide. Sills are least frequent, locally > 8 m thick and have no clear preferred geographical distribution. Clustered intrusions are commonly < 10 cm thick and mostly composed of dikes of various attitudes. The majority of the intrusions probably were injected shallowly as some extrude onto the seafloor. The local seafloor extrusion also indicates injection during the deposition of the Santa Cruz Mudstone (7–9 Ma). The intrusions are concentrated at the basin margin. Fluid pressure at the centre of the basin and perhaps hydrocarbons were communicated to the basin margin through the then sand, causing fluid overpressures that contributed to the fluidization and intrusion into the overlying mudstone.Primarily north‐east‐striking, steeply dipping dikes and secondarily, shallowly dipping sills are most significant in terms of regional connectivity of intrusions and physical dilation of the formation. The orientation of the dikes and sills indicates a regional stress field with a horizontal NE–SW maximum and a NW–SE minimum compressive direction. The simultaneous development of dikes and sills suggests similar magnitudes of the minimum and intermediate principal stresses. Preferential weakness along bedding contributed to the development of sills. Palaeomagnetic data indicate no significant block rotation around a vertical axis. The maximum principal stress direction indicated by the intrusions is about 55° to the San Gregorio Fault and about 70° to the San Andreas Fault during the late Miocene. This stress field is similar to the modern stress field and suggests moderate fault weakness.
Fracture‐fill calcite as a record of microbial methanogenesis and fluid migration: a case study from the Devonian Antrim Shale, Michigan Basin
Authors: Budai J. M. , Martini A. M. , Walter L. M. , Ku T. C. W. 
Published: March 2003

AbstractThe Devonian Antrim Shale is an organic‐rich, naturally fractured black shale in the Michigan Basin that serves as both a source and reservoir for natural gas. A well‐developed network of major, through‐going vertical fractures controls reservoir‐scale permeability in the Antrim Shale. Many fractures are open, but some are partially sealed by calcite cements that retain isotopic evidence of widespread microbial methanogenesis. Fracture filling calcite displays an unusually broad spectrum of δ13C values (+34 to −41‰ PDB), suggesting that both aerobic and anaerobic bacterial processes were active in the reservoir. Calcites with high δ13C values (>+15‰) record cementation of fractures from dissolved inorganic carbon (DIC) generated during bacterial methanogenesis. Calcites with low δ13C values (<−32‰) are solely associated with outcrop samples and record methane oxidation during cement precipitation. Fracture‐fill calcite with δ13C values between −10 and −30‰ can be attributed to variable organic matter oxidation pathways, methane oxidation, and carbonate rock buffering. Identification of13C‐rich calcite provides unambiguous evidence of biogenic methane generation and may be used to identify gas deposits in other sedimentary basins.It is likely that repeated glacial advances and retreats exposed the Antrim Shale at the basin margin, enhanced meteoric recharge into the shallow part of the fractured reservoir, and initiated multiple episodes of bacterial methanogenesis and methanotrophic activity that were recorded in fracture‐fill cements. The δ18O values in both formation waters and calcite cements increase with depth in the basin (−12 to −4‰ SMOW, and +21 to +27‰ PDB, respectively). Most fracture‐fill cements from outcrop samples have δ13C values between −41 and −15‰ PDB. In contrast, most cement in cores have δ13C values between +15 and +34‰ PDB. Radiocarbon and230Th dating of fracture‐fill calcite indicates that the calcite formed between 33 and 390 ka, well within the Pleistocene Epoch.
Equations of state for basin geofluids: algorithm review and intercomparison for brines
Authors: Adams J. J. , Bachu S. 
Published: March 2003

ABSTRACTPhysical properties of formation waters in sedimentary basins can vary by more than 25% for density and by one order of magnitude for viscosity. Density differences may enhance or retard flow driven by other mechanisms and can initiate buoyancy‐driven flow. For a given driving force, the flow rate and injectivity depend on viscosity and permeability. Thus, variations in the density and viscosity of formation waters may have or had a significant effect on the flow pattern in a sedimentary basin, with consequences for various basin processes. Therefore, it is critical to correctly estimate water properties at formation conditions for proper representation and interpretation of present flow systems, and for numerical simulations of basin evolution, hydrocarbon migration, ore genesis, and fate of injected fluids in sedimentary basins. Algorithms published over the years to calculate water density and viscosity as a function of temperature, pressure and salinity are based on empirical fitting of laboratory‐measured properties of predominantly NaCl solutions, but also field brines. A review and comparison of various algorithms are presented here, both in terms of applicability range and estimates of density and viscosity. The paucity of measured formation‐water properties at in situ conditions hinders a definitive conclusion regarding the validity of any of these algorithms. However, the comparison indicates the versatility of the various algorithms in various ranges of conditions found in sedimentary basins. The applicability of these algorithms to the density of formation waters in the Alberta Basin is also examined using a high‐quality database of 4854 water analyses. Consideration is also given to the percentage of cations that are heavier than Na in the waters.
Infiltration of basinal fluids into high‐grade basement, South Norway: sources and behaviour of waters and brines
Authors: Gleeson S. A. , Yardley B. W. D , Munz I. A. , Boyce A. J. 
Published: March 2003

AbstractQuartz veins hosted by the high‐grade crystalline rocks of the Modum complex, Southern Norway, formed when basinal fluids from an overlying Palaeozoic foreland basin infiltrated the basement at temperatures of c. 220°C (higher in the southernmost part of the area). This infiltration resulted in the formation of veins containing both two‐phase and halite‐bearing aqueous fluid inclusions, sometimes with bitumen and hydrocarbon inclusions.Microthermometric results demonstrate a very wide range of salinities of aqueous fluids preserved in these veins, ranging from c. 0 to 40 wt% NaCl equivalent. The range in homogenization temperatures is also very large (99–322°C for the entire dataset) and shows little or no correlation with salinity.A combination of aqueous fluid microthermometry, halogen geochemistry and oxygen isotope studies suggest that fluids from a range of separate aquifers were responsible for the quartz growth, but all have chemistries comparable to sedimentary formation waters. The bulk of the quartz grew from relatively low δ18O fluids derived directly from the basin or equilibrated in the upper part of the basement (T < 200°C). Nevertheless, some fluids acquired higher salinities due to deep wall‐rock hydration reactions leading to salt saturation at high temperatures (>300°C).The range in fluid inclusion homogenization temperatures and densities, combined with estimates of the ambient temperature of the basement rocks suggests that at different times veins acted as conduits for influx of both hotter and colder fluids, as well as experiencing fluctuations in fluid pressure. This is interpreted to reflect episodic flow linked to seismicity, with hotter dry basement rocks acting as a sink for cooler fluids from the overlying basin, while detailed flow paths reflected local effects of opening and closing of individual fractures as well as reaction with wall rocks. Thermal considerations suggest that the duration of some flow events was very short, possibly in the order of days. As a result of the complex pattern of fracturing and flow in the Modum basement, it was possible for shallow fluids to penetrate basement rocks at significantly higher temperatures, and this demonstrates the potential for hydrolytic weakening of continental crust by sedimentary fluids.
Creating new product concepts for foodservice – the role of conjoint measurement to identify promising product features
Authors: Moskowitz Howard 
Published: March 2003

AbstractIn the early stage of product development, the marketer and developer have many options available to them. This paper presents an overview to conjoint measurement, one approach to identifying the best of those options, and determining the customer‐relevant impact of each option. The paper explains how conjoint analysis fits into the emerging need for customer knowledge, and into the goal of fact‐based decision making. The paper tells how to conceptualize, execute, analyze and use the conjoint measurement technique for a burger product.
To everything there was a season: deconstructing UK food availability
Authors: Colquhoun Anne , Lyon Phil 
Published: March 2003

AbstractFor a considerable period of time, the UK has had a largely inflexible relationship between the seasons and the availability of many foods. Plants, with their constituent fruits, foliage and roots, provide numerous examples of seasonality in diet. In this, both plant and seasonal meat/fish variability, gives a cadence to the year as well as the potential for problems of glut and famine. Historically, at one extreme, the problem has been to preserve excesses to avoid starvation when food supply is predictably problematic. As an adjunct, people were also able to extend the pleasures of particular foods for a greater part of the year. Now, at the start of a new millennium, the effectiveness of food preservation and distribution techniques is such that most food commodities are available most of the time. In this paper, we map the progress of attempts to ensure food security and ask, by reference to food availability in the UK, if this has not been at the expense of novelty and the appreciation of seasonality.
Survival of Clostridium botulinum in hot‐fill meals
Authors: Rodgers Svetlana 
Published: March 2003

AbstractSous‐vide technology poses a risk of botulism. Twenty‐six catering and retail cook‐chill meals were challenged with non‐proteolytic Clostridium botulinum (103 spores/g) and incubated for 10 days at 10 °C. C. botulinum populations were enumerated on salicin tryptic soy agar and background microflora – on plate count agar. Botulinal toxin was detected using the enzyme‐linked immunoassay. Only ten of the products supported the active growth of this pathogen. C. botulinum populations were static in another ten products which had a low pH except for two vegetable‐based soups. In the remaining six products, C. botulinum populations reduced to undetectable levels. Although the predictive models described the general growth pattern of C. botulinum in the products supporting the active growth and the products with low pH values, they did not predict the spontaneous decline of this pathogen and the static populations in high pH vegetable soups.
Population dynamics of the lichen genus Bulbothrix Hale as potential bioindicators of ‘time‐since‐last‐fire’ in the cerrado of the Distrito Federal, central Brazil
Authors: Mistry Jayalaxshmi 
Published: March 2003

SummaryThis paper investigates the potential use of the corticolous lichen genus Bulbothrix Hale as a bioindicator of ‘time‐since‐last‐fire’ in the cerrado (savannas) of central Brazil. Work was carried out at the Reserva Ecológica do IBGE and the Jardim Botãnico de Brasilia, 33 km outside Brasilia D.F., in plots of cerrado denso with known fire histories within the ‘Fire Project’ area. Measurements of abundance and thallus size were taken of all Bulbothrix individuals encountered up to 2 m on the trunks of three phorophyte species. The results show that abundances and thalli sizes of the Bulbothrix populations can be correlated with the ‘time‐since‐last‐fire’ that had occurred in each of the plots. This study shows that is is possible to use characteristics of specific lichen populations as bioindicators of fire history.
The history, distribution and rate of spread of the invasive alien plant, bridal creeper, Asparagus asparagoides (L.) Wight, as determined from a questionnaire survey of landholders in south‐western Australia
Authors: Stansbury C. D. , Scott J. K. 
Published: March 2003

SummaryThe distribution and rate of spread of the introduced weed bridal creeper, Asparagus asparagoides (L.) Wight, were calculated from the results of a questionnaire that was distributed to landholders in the south‐west of Western Australia. The weed was associated with regions that receive more than 350 mm of annual rainfall. There was a weak association between properties that had a longer history of disturbance through clearing of native vegetation and the presence of A. asparagoides. On a local scale, the questionnaire indicated that the rate of spread of A. asparagoides peaked at 0.6 m/yr of radial spread for patches of 10 m2. The rate of spread of A. asparagoides on a regional scale was calculated as 0.09 postcode regions per year. While 50% of respondents indicated that they attempted to control the weed, only 20% of land managers on neighbouring properties (usually roadside reserves) were involved in some type of weed control. The level of weed control also influenced rates of spread calculated for weed patches for the two groups. Asparagus asparagoides was not ranked highly as a weed by landholders, whereas government officials surveyed considered it the most important environmental weed.
Genic diversity, genetic structure, and biogeography of Pinus sabiniana Dougl.
Authors: Ledig F. Thomas 
Published: March 2003

Summary Pinus sabiniana Dougl. (grey pine) forms savanna forests in the foothills surrounding California's Great Central Valley. However, its fossil record, which dates from the late Miocene through the Pliocene and Pleistocene, is found exclusively in southern California, south of the species’ present range. A total of twenty‐nine isozyme loci, representing eighteen enzyme systems, was assayed to analyse the genetic structure in eight populations of grey pine and attempt to track its migration history from southern to northern California. Expected heterozygosity in the two southernmost samples was 0.128 and 0.150, and heterozygosity tended to decrease with increasing latitude, suggesting the loss of diversity as grey pine dispersed northward. However, genetic distances between populations were very small, even on opposite sides of the treeless Great Central Valley; and estimated time since divergence was 900 to 9000 years at a maximum. Wright's FST, the proportion of total genetic diversity among populations, was only 0.057, which is similar to values found in many conifers with continuous distributions. Nm, the number of migrants among populations per generation, was 4.1 to 6.7, depending on estimator, and indicates that gene flow is extensive, or was so in the recent past. In every population, observed heterozygosity was less than expected heterozygosity, and the fixation index, FIS, for the progeny was 0.128, which indicates a fairly high rate of inbreeding. The genetic similarity of disjunct populations, in combination with paleogeographic and paleoclimatic evidence, suggests that grey pine formed a continuous population throughout the Great Central Valley, perhaps between 12,000 and 8000 yrs
BP. Its range became fragmented during the Xerothermic, when it ascended into the foothills. Gaps in its range correlate with late Pleistocene–early Holocene lakes in adjacent basins and with the Sacramento–San Joaquin Delta.