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1.
Geochemical and isotopic studies have been undertaken to assess the origin of CO2‐rich waters issuing in the northern part of Portugal. These solutions are hot (76°C) to cold (17°C) Na–HCO3 mineral waters. The δ2H and δ18O signatures of the mineral waters reflect the influence of altitude on meteoric recharge. The lack of an 18O‐shift indicates there has been no high temperature water–rock interaction at depth, corroborating the results of several chemical geothermometers (reservoir temperature of about 120°C). The low 14C activity (up to 9.9 pmC) measured in some of the cold CO2‐rich mineral waters (total dissolved inorganic carbon) is incompatible with the presence of 3H (from 1.7 to 4.1 TU) in those waters, which indicates relatively short subsurface circulation times. The δ13C values of CO2 gas and dissolved inorganic carbon range between ?6‰ and ?1‰ versus Vienna‐Peedee Belemnite, indicating that the total carbon in the recharge waters is being diluted by larger quantities of CO2 (14C‐free) introduced from deep‐seated (upper mantle) sources, masking the 14C‐dating values. The differences in the 87Sr/86Sr ratios of the studied thermal and mineral waters seem to be caused by water–rock interaction with different granitic rocks. Chlorine isotope signatures (?0.4‰ < δ37Cl < +0.4‰ versus standard mean ocean chloride) indicate that Cl in these waters could be derived from mixing of a small amount of igneous Cl from leaching of granitic rocks.  相似文献   

2.
Offshore fresh or brackish groundwater has been observed around the globe and represents an interesting but unusual freshwater reserve. Formation waters in sedimentary basins evolve at geological time through fluid–rock interactions and water movements in aquifers. However, the mechanism and timing of freshwater displacing and mixing with pre‐existing formation water offshore under the seafloor has not been investigated in many cases. The growing need for developing freshwater resources in deeper parts of sedimentary basins that have not been economic or technically feasible in the past, may potentially lead to an increasing conflict with petroleum production or injection of carbon dioxide. For being able to assess and mitigate possible impacts of fluid production or injection on groundwater flow and quality, a better understanding of the natural history of the interaction between fresh meteoric water and deep basin formation water is necessary. A low‐salinity wedge of meteoric origin with less than 5000 ppm currently extends to about 20 km offshore in the confined Latrobe aquifer in the Gippsland Basin (Australia). The Latrobe aquifer is a freshwater resource in the onshore, hosts major petroleum reservoirs and has been considered for carbon dioxide storage in the offshore parts of the basin. The objective of this study is to constrain the evolution of formation water in the Latrobe aquifer by investigating the water naturally trapped in fluid inclusions during burial. The measured palaeo‐salinities from onshore and offshore rock samples have a minimum of about 12 500 ppm (NaCl equivalent) and a maximum of about 50 000 ppm. Most of the salinities are in the 32 000–35 000 ppm range. There is no evidence for freshwater in fluid inclusions and the variation in palaeo‐salinity across the basin is consistent with the palaeogeography of deposition of the sedimentary rocks. The current low‐salinity water wedge must have started to form recently after most of the diagenetic processes that led to the trapping of water in fluid inclusions happened. The minimum homogenisation temperatures (Th) recorded are consistent with current formation temperature. However, they are generally higher than present day suggesting that hotter temperatures were attained in the past. The Th and salinity data together suggest that the fluid inclusions record the diagenetic modification of connate water to higher salinities over a time period that was accompanied by an increase in temperature, consistent with a westward palaeo‐fluid flow from the deeper part of the basin through the aquifer. Subsequent pore‐water evolution from palaeo‐ to current day conditions is consistent with an influx of fresher and cooler meteoric water into the Latrobe Group. The meteoric recharge originates from the area of the Baragwanath anticline in the onshore part of the basin where the Latrobe Group subcrops at high elevations.  相似文献   

3.
Geologic carbon capture and storage (CCS) is an option for reducing CO2 emissions, but leakage to the surface is a risk factor. Natural CO2 reservoirs that erupt from abandoned oil and gas holes leak to the surface as spectacular cold geysers in the Colorado Plateau, United States. A better understanding of the mechanisms of CO2‐driven cold‐water geysers will provide valuable insight about the potential modes of leakage from engineered CCS sites. A notable example of a CO2‐driven cold‐water geyser is Crystal Geyser in central Utah. We investigated the fluid mechanics of this regularly erupting geyser by instrumenting its conduit with sensors and measuring pressure and temperature every 20 sec over a period of 17 days. Analyses of these measurements suggest that the timescale of a single‐eruption cycle is composed of four successive eruption types with two recharge periods ranging from 30 to 40 h. Current eruption patterns exhibit a bimodal distribution, but these patterns evolved during past 80 years. The field observation suggests that the geyser's eruptions are regular and predictable and reflect pressure and temperature changes resulting from Joule–Thomson cooling and endothermic CO2 exsolution. The eruption interval between multiple small‐scale eruptions is a direct indicator of the subsequent large‐scale eruption.  相似文献   

4.
G. Etiope  A. Ionescu 《Geofluids》2015,15(3):438-452
Metal‐catalysed CO2 hydrogenation is considered a source of methane in serpentinized (hydrated) igneous rocks and a fundamental abiotic process germane to the origin of life. Iron, nickel, chromium and cobalt are the catalysts typically employed in hydrothermal simulation experiments to obtain methane at temperatures >200°C. However, land‐based present‐day serpentinization and abiotic gas apparently develop below 100°C, down to approximately 40–50°C. Here, we document considerable methane production in thirteen CO2 hydrogenation experiments performed in a closed dry system, from 20 to 90°C and atmospheric pressure, over 0.9–122 days, using concentrations of non‐pretreated ruthenium equivalent to those occurring in chromitites in ophiolites or igneous complexes (from 0.4 to 76 mg of Ru, equivalent to the amount occurring approximately in 0.4–760 kg of chromitite). Methane production increased with time and temperature, reaching approximately 87 mg CH4 per gram of Ru after 30 days (2.9 mgCH4/gru/day) at 90°C. At room temperature, CH4 production rate was approximately three orders of magnitude lower (0.003 mgCH4/gru/day). We report the first stable carbon and hydrogen isotope ratios of abiotic CH4 generated below 100°C. Using initial δ13CCO2 of ‐40‰, we obtained room temperature δ13CCH4 values as 13C depleted as ?142‰. With time and temperature, the C‐isotope separation between CO2 and CH4 decreased significantly and the final δ13CCH4 values approached that of initial δ13CCO2. The presence of minor amounts of C2‐C6 hydrocarbons is consistent with observations in natural settings. Comparative experiments at the same temperatures with iron and nichel catalysts did not generate CH4. Ru‐enriched chromitites could potentially generate methane at low temperatures on Earth and on other planets.  相似文献   

5.
Human skeletal remains from the Neolithic sites BHS18 in the interior of the Sharjah Emirate and the Neolithic shell midden UAQ2 (Umm al‐Quwain) on the coast of the Persian Gulf (United Arab Emirates, UAE) were analysed for their isotope ratios of strontium (87Sr/86Sr) and oxygen (18O/16O). The results are not in agreement with earlier assumptions about a Neolithic nomadism between inland regions and the south‐eastern coast of the Persian Gulf. Existing evidence of nomadic movements of the people from BHS18 most possibly refers to transhumance within the mountains in the hinterland. The strontium isotope measurements on human skeletons from UAQ2 on the contrary indicate uninterrupted residence of this population on the coast. Nevertheless, evidence was found of individual mobility between inland regions and the coast.  相似文献   

6.
A. SAEEDI  R. REZAEE  B. EVANS 《Geofluids》2012,12(3):228-235
During a geo‐sequestration process, CO2 injection causes an increase in reservoir pore pressure, which in turn decreases the reservoir net effective stress. Changes in effective stress can change all the reservoir and cap‐rock properties including residual saturations. This article presents the results of an experimental work carried out to understand the potential change in the volumes of residually trapped CO2, while the porous medium tested underwent change in the net effective stress under in‐situ reservoir conditions of pore pressure and temperature. The experimental results obtained show that an initial 1725 psi (11.9 MPa) decrease in the net effective pressure caused 1.4% reduction in the volumes of residually trapped CO2, while another 1500 psi (10.3 MPa) reduction caused a further 3.2% drop in the residual saturation of CO2.  相似文献   

7.
Petrography, Eh‐pH calculations and the stable isotope composition of oxygen are used to interpret geochemical processes that occurred during iron oxide mineralization and dolomitization along the Menuha Ridge segment of the Paran Fault, southern Israel, adjacent to the Dead Sea Transform (DST). Iron mineralization is strongly localized in the fault zone as ferruginous lenses, whereas Fe dolomitization spreads laterally into the Cenomanian‐Turonian carbonate host rock as stratabound beds. The average oxygen isotope fractionation between syngenetic quartz and iron oxides in the ferruginous lenses gives a temperature of 50 ± 10°C and δ18O SMOW water = ?3.5‰; consistent with an origin from metalliferous groundwater flow in the sedimentary basin. Ferroan dolomite initially formed under strongly reducing conditions, but this was followed by oxidation and pseudomorphic replacement of the dolomite by a mesh of fine‐grained iron oxides (simple zoned dolomites). This cycle of ferroan dolomite formation and replacement by iron oxides was repeated in complex zoned dolomites. Dolomite oxygen isotope compositions fall into two groups: a high δ18O group corresponding to the simple zoned dolomites and non‐ferroan dolomites and a low δ18O group corresponding to the complex zoned dolomites. Water‐rock calculations suggest that the epignetic dolomites formed under fluid‐buffered conditions: the high δ18O group are indicated to have formed at temperatures of ca. 25°C for waters with δ18O = ?4 to 0‰; the low δ18O complex zoned dolomites at 50–75°C for waters with the same isotopic composition. A kinetic calculation for a complex zoned dolomite‐bearing bed indicates that dolomitization must have occurred at high values of the dolomite saturation index. This requirement for high Mg supersaturation and the indication that epigenetic dolomitization is more protracted in stratigraphically deeper formations located closer to the DST is consistent with models proposing that Mg‐rich solutions originated in the Dead Sea Rift.  相似文献   

8.
L. Wang  Y. Cheng  W. Li 《Geofluids》2014,14(4):379-390
This study assesses the displacement of coalbed methane by CO2 migration along a fault into the coal seam in the Yaojie coalfield. Coal and gas samples were collected continuously at various distances in NO.2 coal seam from F19 fault. Vitrinite reflectance, maceral, and pore distributions and proximate analysis of fourteen coal samples were performed. Gas components, concentrations, carbon isotopes of 28 gas samples were determined. We examined the coal–gas trace characteristics of coalbed methane displaced away from the fault by CO2 injection after geological ages. From east to west, away from the F19 fault, the CO2 concentration decreased, whereas the CH4 concentration increased gradually. The δ13C values for CO2 varied between ?9.94‰ and 1.12‰, suggesting a metamorphic origin. A wider range of values (from ?9.94‰ to 20‰) was associated with the mixing of microbial carbon dioxide, isotopic fractionation during CO2 migration through the microporous structures of coals, and/or carbon isotope fractionation during gas–water exchange and dissolution of CO2. Away from the F19 fault, the volumes of micropores, mesopores and macropores decrease gradually. The Dubinin–Radushkevich (DR) micropore volume decreased from 0.0059 to 0.0037 cmg‐1, and the mesopore and macropore volumes decreased from 0.066 to 0.026 cmg‐1. The CO2 injection can mobilize aromatic hydrocarbons and mineral matter from coal matrix, resulting in the decrease in the absorption peak intensity for coal samples after supercritical CO2 treatment, which indicates that chemical reactions occur between coal and CO2, not only physical adsorption.  相似文献   

9.
This article explores the use of a revised conception of social evolutionary theory towards an understanding of nationalism. First, I review the debate between ethno‐symbolism and modernism, through the lens of the Warwick Debate between Gellner and Smith, arguing that both are partly right. Secondly, I outline what the revised conception of social evolution is looking first at its traditional conception before outlining a Darwinian view of social evolutionary theory. Finally, I examine how Darwinian social evolutionary theory can help fruitfully bring the ethno‐symbolic and modernist perspectives together. This is done by a sustained engagement primarily with the theories of Anthony Smith and Ernest Gellner pointing to how Darwinian social evolutionary theory can provide a link between the two theories that makes them mutually supportive rather than opposed.  相似文献   

10.
H. Chu  G. Chi  I‐M. Chou 《Geofluids》2016,16(3):518-532
Fluid inclusions of the H2O‐NaCl‐CaCl2 system are notorious for their metastable behavior during cooling and heating processes, which can render microthermometric measurement impossible or difficult and interpretation of the results ambiguous. This study addresses these problems through detailed microscopic examination of synthetic solutions during cooling and warming runs, development of methods to enhance nucleation of hydrates, and comparison of microthermometric results with different degrees of metastability with values predicted for stable conditions. Synthetic H2O‐NaCl‐CaCl2 solutions with different NaCl/(NaCl + CaCl2) ratios were prepared and loaded in fused silica capillaries and glass‐sandwiched films for microthermometric studies; pure solutions were used with the capillaries to simulate fluid inclusions, whereas alumina powder was added in the solutions to facilitate ice and hydrate crystallization in the sandwiched samples. The phase changes observed and the microthermometric data obtained in this study have led to the following conclusions that have important implications for fluid inclusion studies: (i) most H2O‐NaCl‐CaCl2 inclusions that appear to be completely frozen in the first cooling run to ?185°C actually contain large amounts of residual solution, as also reported in some previous studies; (ii) inability of H2O‐NaCl‐CaCl2 inclusions to freeze completely may be related to their composition (low NaCl/(NaCl + CaCl2) ratios) and lack of solid particles; (iii) crystallization of hydrates, which is important for cryogenic Raman spectroscopic studies of fluid inclusion composition, can be greatly enhanced by finding an optimum combination of cooling and warming rates and temperatures; and (iv) even if an inclusion is not completely frozen, the melting temperatures of hydrohalite and ice are still valid for estimating the fluid composition.  相似文献   

11.
One of the most important questions at the 1919 Paris Peace Conference was what to do about the newly re‐created state of Poland. The Paris peacemakers realised the importance of the settlement, thanks in part to dire warnings about Poland's future, and the leaders spent much time discussing the territorial settlement. Yet discussions of this important question regularly strayed from debates about policy to incorporate understandings of Polish national character. In particular, the leaders of the so‐called Big Three, Britain, France, and the United States, connected expert opinion and the broader political landscape to stereotyped understandings of national character, among other factors. With reference to scholarship on stereotyping, this article analyses how developing attitudes on Polish national character became integrated into the complex settlement of Poland's borders. The peacemakers' decisions, which were a compromise between different points of view, reflected interconnected understandings of the Polish settlement.  相似文献   

12.
K. LI  C. CAI  H. HE  L. JIANG  L. CAI  L. XIANG  S. HUANG  C. ZHANG 《Geofluids》2011,11(1):71-86
Petrographic features, isotopes, and trace elements were determined, and fluid inclusions were analyzed on fracture‐filling, karst‐filling and interparticle calcite cement from the Ordovician carbonates in Tahe oilfield, Tarim basin, NW China. The aim was to assess the origin and evolution of palaeo‐waters in the carbonates. The initial water was seawater diluted by meteoric water, as indicated by bright cathodoluminescence (CL) in low‐temperature calcite. The palaeoseawater was further buried to temperatures from 57 to 110°C, nonluminescent calcite precipitated during the Silurian to middle Devonian. Infiltration of meteoric water of late Devonian age into the carbonate rocks was recorded in the first generation of fracture‐ and karst‐filling dull red CL calcite with temperatures from <50°C to 83°C, low salinities (<9.0 wt%), high Mn contents and high 86Sr/87Sr ratios from 0.7090 to 0.7099. During the early Permian, 87Sr‐rich hydrothermal water may have entered the carbonate rocks, from which precipitated a second generation of fracture‐filling and interparticle calcite and barite cements with salinities greater than 22.4 wt%, and temperatures from 120°C to 180°C. The hydrothermal water may have collected isotopically light CO2 (possibly of TSR‐origin) during upward migration, resulting in hydrothermal calcite and the present‐day oilfield water having δ13C values from ?4.3 to ?13.8‰ and showing negative relationships of 87Sr/86Sr ratios to δ13C and δ18O values. However, higher temperatures (up to 187°C) and much lower salinities (down to 0.5 wt%) measured from some karst‐filling, giant, nonluminescent calcite crystals may suggest that hydrothermal water was deeply recycled, reduced (Fe‐bearing) meteoric water heated in deeper strata, or water generated from TSR during hydrothermal water activity. Mixing of hydrothermal and local basinal water (or diagenetically altered connate water) with meteoric waters of late Permian age and/or later may have resulted in large variations in salinity of the present oilfield waters with the lowest salinity formation waters in the palaeohighs.  相似文献   

13.
The aim of this study was to determine the process–structure–property relationships between the pre‐ and post‐CO2 injection pore network geometry and the intrinsic permeability tensor for samples of core from low‐permeability Lower Triassic Sherwood Sandstone, UK. Samples were characterised using SEM‐EDS, XRD, MIP, XRCT and a triaxial permeability cell both before and after a three‐month continuous‐flow experiment using acidic CO2‐rich saline fluid. The change in flow properties was compared to those predicted by pore‐scale numerical modelling using an implicit finite volume solution to the Navier–Stokes equations. Mass loss and increased secondary porosity appeared to occur primarily due to dissolution of intergranular cements and K‐feldspar grains, with some associated loss of clay, carbonate and mudstone clasts. This resulted in a bulk porosity increase from 18 to 25% and caused a reduction in mean diameter of mineral grains with an increase in apparent pore wall roughness, where the fractal dimension, Df, increased from 1.68 to 1.84. All significant dissolution mass loss occurred in pores above c. 100 μm mean diameter. Relative dilation of post‐treatment pore area appeared to increase in relation to initial pore area, suggesting that the rate of dissolution mass loss had a positive relationship with fluid flow velocity; that is, critical flow pathways are preferentially widened. Variation in packing density within sedimentary planes (occurring at cm‐scale along the ‐z plane) caused the intrinsic permeability tensor to vary by more than a factor of ten. The bulk permeability tensor is anisotropic having almost equal value in ‐z and ‐y planes but with a 68% higher value in the ‐x plane (parallel to sedimentary bedding planes) for the pretreated sample, reducing to only 30% higher for the post‐treated sample. The intrinsic permeability of the post‐treatment sample increased by one order of magnitude and showed very close agreement between the modelled and experimental results.  相似文献   

14.
This article asks how, when, and why people came to mobilize en masse in the name of the Tunisian nation against French Protectorate rule. Rather than taking anti‐colonial nationalism as an inevitable response to the imposition of colonial rule, the account offered here insists that it is an outcome to be explained. Building on more recent theoretical directions that stress the processual, relational, and eventful dynamics of nationalism, the article shows that nationalism and nationalist mobilization cannot be attributed simply to the workings of nationalist intellectuals, to long‐standing grievances, or to larger macro‐level transformations. Rather, seeing nationalism as part of struggle and as a domain in which various forms of contentious politics are played out, I show how attention to a particular contentious event in the anti‐naturalization campaign can help us to understand how a certain version of the nation becomes salient as a mobilizing rubric for mass‐level mobilization and how various forms of contention coalesce to produce nationalist outcomes.  相似文献   

15.
Karen Bakker 《对极》2007,39(3):430-455
Abstract: In response to the growth of private sector involvement in water supply management globally, anti‐privatization campaigns for a human right to water have emerged in recent years. Simultaneously, alter‐globalization activists have promoted alternative water governance models through North‐South red‐green alliances between organized labour, environmental groups, women's groups, and indigenous groups. In this paper, I explore these distinct (albeit overlapping) responses to water privatization. I first present a generic conceptual model of market environmentalist reforms, and explore the contribution of this framework to debates over ‘neoliberalizing nature’. This conceptual framework is applied to the case of anti‐privatization activism to elucidate the limitations of the human right to water as a conceptual counterpoint to privatization, and as an activist strategy. In contrast, I argue that alter‐globalization strategies—centred on concepts of the commons—are more conceptually coherent, and also more successful as activist strategies. The paper concludes with a reiteration of the need for greater conceptual precision in our analyses of neoliberalization, for both academics and activists.  相似文献   

16.
Water stress is becoming a permanent feature of life in Britain and other developed societies, and attempts to change ‘consumer behaviour’ are at the forefront of strategies for sustainability. This paper combines historical, geographical and sociological perspectives on the evolution of drought and water demand in modern England and Wales. Droughts have natural properties but their course, size and distribution is also the result of an interplay between governance, social norms and everyday practices. Focusing on seven significant droughts between 1893 and 2006, this article traces changing understandings of ‘normal’ water consumption and ‘rational’ demand and relates them to the evolving socio-technical management of water and identities of ‘the consumer’. We challenge the idea of a watershed between private supply (associated with passive ‘customers’) and public ownership (associated with active ‘citizens’). While private systems facilitated self-organised civic action more easily than public supply, the ideal of a citizen-contract blinded systems of public provision to the problem of expanding water use. An interdisciplinary analysis of droughts in the past offers lessons for the debate about sustainable consumption today.  相似文献   

17.
18.
X. R. Ming  L. Liu  M. Yu  H. G. Bai  L. Yu  X. L. Peng  T. H. Yang 《Geofluids》2016,16(5):1017-1042
This study investigates the Wangfu Depression of the Songliao Basin, China, as a natural analogue site for Fe migration (bleaching) and mineralization (formation of iron concretions) caused by reducing CO2‐bearing fluids that leak along fractures after carbon capture, utilization, and storage. We also examined the origin of fracture‐filling calcite veins, the properties of self‐sealing fluids, the influence of fluids on the compositions of mudstone and established a bleaching model for the study area. Our results show that iron concretions are the oxidative products of precursor minerals (pyrite and siderite) during uplift and are linked to H2S and CO2 present in early stage fluids. The precipitation of calcite veins is the result of CO2 degassing and is related to CO2, CH4, and minor heavy hydrocarbons in the main bleaching fluids. In our model, fluids preferentially enter high‐permeability fracture systems and result in the bleaching of surrounding rocks and precipitation of calcite veins. The infilling of calcite veins significantly decreases the permeability of fractures and forces the fluids to slowly enter and bleach the mudstone rocks. The Fe2+ released during bleaching migrates to elsewhere with the solutions or is reprecipitated in the calcite veins and iron concretions. The formation of calcite veins reduces the fracture space and effectively prevents fluid flow. The fluids have an insignificant effect on minerals within the mudstone. In terms of the chemistry of the mudstone, only the contents of Fe2O3, U, and Mo change significantly, with the content of U increasing in the mudstone and the contents of Fe2O3 and Mo decreasing during bleaching.  相似文献   

19.
Federico Ferretti 《对极》2016,48(3):563-583
This paper addresses the work of early critics of colonialism and Eurocentrism within Italian geography in the Age of Empire. At that time, a minority but rather influential group of Italian scholars, influenced by the international debates promoted by the anarchist geographers Reclus, Kropotkin and Me?nikov, fumed publicly at Italy's colonial ambitions in Africa. Their positions assumed, at least in the case of Arcangelo Ghisleri, the character of a radical critique of both political and cultural European hegemony. These approaches were linked to a similar critique of “internal colonialism”, both Austrian in the Italian‐speaking regions of Trento and Trieste, and Piedmontese in southern Italy. Based on primary sources, and drawing on the international literature on imperial geography and colonial and postcolonial sciences, this paper conjures up the Italian example to discuss how some European geographers of the Age of Empire were also early critics of racism, colonialism and chauvinism, and how these historical experiences can serve current debates on critical, radical and anarchist geographies.  相似文献   

20.
There are growing concerns over current and future incarnations of routine work, based on the rise of technology and its perceived impact on skill requirements in the labour market. Drawing on Autonomist Marxist (AM) literature, the following article demonstrates how and why workers are likely to play a role in maintaining meaningful forms of work. Complimenting labour process research, which focuses on the role of worker “resistance” in the workplace, we develop a more nuanced perspective on worker agency and the human potential to create meaning through self‐governance in even the most unlikely service work encounters. Taking resilience and reworking agencies as subtle forms of “self‐valorisation”, we show how different spaces of routine work are mobilised for reproducing human connections and values in ways which act in opposition to management’s control and the evolution of unpleasant work environments.  相似文献   

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