Chemical and isotopic signatures of Na/HCO3/CO2‐rich geofluids,North Portugal

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.     

Experimental study of the effect of variation in in‐situ stress on capillary residual trapping during CO2 geo‐sequestration in sandstone reservoirs

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.     

Iron mineralization and dolomitization in the Paran Fault zone,Israel: implications for low‐temperature basinal fluid processes near the Dead Sea Transform

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.     

Origin of palaeo‐waters in the Ordovician carbonates in Tahe oilfield,Tarim Basin: constraints from fluid inclusions and Sr,C and O isotopes

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.     

Drought is normal: the socio-technical evolution of drought and water demand in England and Wales, 1893–2006

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.     

‘The Party Hack,and Tool of the British Government’: T.P. O'Connor,America and Irish Party Resilience at the February 1918 South Armagh By‐Election

The common view of Irish electoral politics for the 1916 to 1918 period is one of major decline for the traditional nationalist representatives, the Irish Parliamentary Party (IPP), and the meteoric rise of the newly reconstituted Sinn Féin party; culminating in the latter's overwhelming victory at the December 1918 general election. By examining the February 1918 South Armagh by‐election campaign, this article argues that the Irish Parliamentary Party, which won the contest, was much more resilient than is often acknowledged. Through detailed analysis of election pamphlets, newspaper articles, private correspondence and committee minutes, it considers the significance of the grass‐roots strength of both in the form of their local organisations, the role of the Roman catholic church, and the election strategies of the two parties; in particular Sinn Féin's vilification of the IPP member, T.P. O'Connor, who was in America at the time of the contest.     

The ‘Society’ at Bora Ceremonies: A Manifestation of a Body of Traditional Law and Custom in Aboriginal Australia relevant to Native Title Case Law

Anthropologists working on native title cases in Australia are commonly asked to identify the Aboriginal ‘society’ that holds the body of laws and customs that confer land ownership rights on certain groups of people. In this paper I investigate how the early documentation of bora initiation ceremonies is relevant to understanding contemporary Aboriginal societies and the normative laws and customs that give rise to rights and interests in land. The vast ethnographic oeuvre of R.H. Mathews (1841–1918) includes detailed documentation of bora gatherings, which allows the reconstruction of the wider social reaches of people's networks in the lower Darling Downs of eastern Australia, and can in turn be understood as the ‘society’ so often sought in current native title case law.     

The Determinants of Policy Introduction and Bill Adoption: Examining Minimum Wage Increases in the American States, 1997–2006

Faced with long intervals between federal minimum wage increases in recent years, state legislatures are increasingly likely to take action. Motivated by the relative dearth of empirical work on minimum wages in the American states, this article considered various explanations to determine which factors are associated with legislative efforts to pass wage increases. Taking seriously the view that disagreements over the effects of minimum wage increases enhances the influence of political factors, we drew on the policy adoption and diffusion literature to examine how internal determinants (political and economic variables) and regional diffusion pressures relate to both the introduction and adoption of minimum wage legislation in the American states in the years between the last two federal minimum wage increases (1997–2006). Employing negative binomial regression to analyze annual bill introductions, we found that a number of political variables are related to the consideration of minimum wage increases. However, using event history analysis to examine annual adoptions of minimum wage increases, we found few of the same variables matter. We concluded with a discussion of the empirical results within the context of the broader policy literature and cautioned future scholars to consider seriously whether political factors exert distinct influences at different stages of the policy process.