‘Think globally,act locally’: sustainable communities,modernity and development     

Fred Powell 《GeoJournal》2012,77(2):141-152

This article sets out to explore the political relationship between the global and the local through the prism of the sustainable development. The ideal of sustainable communities is explored in the context of evolving political fictions that define alternative conceptions of modernity. While the article uses Ireland (reputedly the most globalised society in the world) as a microcosm of development, the context is firmly located within the wider sphere of European and planetary politics. It is argued that the ideal of sustainable communities offers the opportunity of reviving the civic republican tradition of democracy (the Ancient Greek agora) as a metaphor for the public sphere in the conditions of late modern society. The agora in Ancient Greece provided a site of political assembly, based upon participation (citizens’ engagement in decision-making) and deliberation (a process of reached argument). Today, concepts such as ‘participatory civility’ and ‘discursive democracy’ seek to revive these classical ideals, as the basis for building sustainable communities in a transforming modernity that searches for a new logic of development.  相似文献   

Tectonic Relationship between the Late Ordovician and Late Silurian palaeogeographies of southeastern Australia     

C. McA. Powell 《Australian Journal of Earth Sciences》2013,60(3-4):353-373

The Ordovician palaeogeography of southeastern Australia was an east‐facing mafic volcanic island arc separated from the Gondwanan continent by a marginal sea, probably floored by oceanic crust. By mid‐Silurian the palaeogeography had changed to an almost wholly ensialic configuration, with meridional horsts and grabens east of the Wagga Metamorphic Belt and widespread silicic magmatism. By extending a previously postulated match between the modern Andaman Basin and parts of southeastern Australia in the Late Ordovician, the transition from the Late Ordovician to Late Silurian palaeogeography can be explained. The entire Ordovician and Silurian interval can be understood in terms of a relatively simple and constant plate geometry involving southeastern Australia in regional dextral shear.  相似文献   

A thermodynamic model for silicate melt in CaO–MgO–Al2O3–SiO2 to 50 kbar and 1800 °C     

T. J. B. Holland  R. Powell 《Journal of Metamorphic Geology》2012,30(6):579-597

A fully thermodynamic model for mafic melt in CaO–MgO–Al₂O₃–SiO₂ (CMAS) has been calibrated, for calculation of melting equilibria in the pressure range 0–50 kbar. It is intended as a preliminary step towards a large‐system melt model, suitable for exploring melting, melt loss and crystallization processes in a wide range of natural rock compositions. Calibration was performed with attention to the model's behaviour in its compositional subsystems, as a rigorous test of model structure and parameterization. The model is consistent with the latest Holland & Powell thermodynamic data set, and can therefore be used to calculate phase relations in conjunction with the many solid‐phase activity–composition models written for the data set. Model calculations successfully reproduce experimental melting reactions in CMAS spinel lherzolite and garnet lherzolite assemblages, as well as sapphirine‐ and kyanite‐bearing assemblages, at moderate to high pressure. Thermodynamically sensitive features, such as thermal divides are also recovered. However, some changes to the model structure will be required before the model can describe the full range of mafic and ultramafic melt compositions known from experiment at low pressures.  相似文献   

Garnet and spinel lherzolite assemblages in MgO–Al2O3–SiO2 and CaO–MgO–Al2O3–SiO2: thermodynamic models and an experimental conflict     

T. J. B. Holland  R. Powell  R. W. White 《Journal of Metamorphic Geology》2012,30(6):561-577

The recent publication of an updated thermodynamic dataset for petrological calculations provides an opportunity to illustrate the relationship between experimental data and the dataset, in the context of a new set of activity–composition models for several key minerals. These models represent orthopyroxene, clinopyroxene and garnet in the system CaO–MgO–Al₂O₃–SiO₂ (CMAS), and are valid up to 50 kbar and at least 1800 °C; they are the first high‐temperature models for these phases to be developed for the Holland & Powell dataset. The models are calibrated with reference to phase‐relation data in the subsystems CaO–MgO–SiO₂ (CMS) and MgO–Al₂O₃–SiO₂ (MAS), and will themselves form the basis of models in larger systems, suitable for calculating phase equilibria in the crust and mantle. In the course of calibrating the models, it was necessary to consider the reaction orthopyroxene + clinopyroxene + spinel = garnet + forsterite in CMAS, representing a univariant transition between simple spinel and garnet lherzolite assemblages. The high‐temperature segment of this reaction has been much disputed. We offer a powerful thermodynamic argument relating this reaction to the equivalent reaction in MAS, that forces us to choose between good model fits to the data in MAS or to the more recent data in CMAS. We favour the fit to the MAS data, preserving conformity with a large body of experimental and thermodynamic data that are incorporated as constraints on the activity–composition modelling via the internally consistent thermodynamic dataset.  相似文献   

Near real-time ocean circulation assimilation and prediction in the Intra-Americas Sea with ROMS   总被引：2，自引：0，他引：2  

B.S. Powell  A.M. Moore  H.G. Arango  E. Di Lorenzo  R.F. Milliff  R.R. Leben 《Dynamics of Atmospheres and Oceans》2009,48(1-3):46

We present the feasibility of a prototype, near real-time assimilation and ensemble prediction system for the Intra-Americas Sea run autonomously aboard a ship of opportunity based on the Regional Ocean Modeling System (ROMS). Predicting an ocean state depends upon numerical models that contain uncertainties in their modeled physics, initial conditions, and model state. An advanced model, four-dimensional variational assimilation, and ensemble forecasting techniques are used to account for each of these uncertainties. Every 3 days, data from the previous 7 days period were assimilated to generate an estimate of the circulation and to create an ensemble of 2 weeks forecasts of the ocean state. This paper presents the methods and results for a multi-resolution assimilation system and ensemble forecasts of surface fields and dominant surface circulation features. When compared to post-processed science quality observations, the state estimates suffer from our reliance on real-time, quick-look satellite observations of the ocean surface. Despite a number of issues, the ensemble forecast estimate is often superior to observational persistence. This proof-of-concept prototype performed well enough to reveal deficiencies, provide useful insights, valuable lessons, and guidance for future improvements in real-time ocean forecasting.  相似文献   

Syn-deformational remanent magnetization of the Mount Eclipse Sandstone, central Australia     

Z. X. Li  C. McA. Powell  P. W. Schmidt 《Geophysical Journal International》1989,99(1):205-222

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Geochemical studies related to the occurrence of oil and gas in the dampier sub-basin,Western Australia     

T.G. Powell 《Journal of Geochemical Exploration》1975,4(4):441-466

An organic geochemical study has been made of sediments from five petroleum exploration wells and liquid hydrocarbons from seven oil and gas condensate discoveries in the offshore Dampier Sub-basin. Hydrocarbon generation has occurred between 3000 and 4250 m and the probable source rocks have been identified. Oils and condensates in the basin are of two types; a paraffinic-naphthenic type derived from Jurassic source beds and a naphthenic type coming from Cretaceous source sediments. Mixing of the two oil types appears to have occurred in the Egret reservoir.  相似文献   

Preliminary Results on the 3-dimensional Seismic Structure of the Lithosphere under the USGS Central California Seismic Array     

Eystein S. Husebye  ers Christoffersson  Keiiti Aki  Christine Powell 《Geophysical Journal International》1976,46(2):319-340

About 1500 readings of teleseismic P -time residuals obtained from the US Geological Survey seismograph network in central California have been used to obtain a three-dimensional image of seismic velocity anomalies for this area by the method of Aki, Christoffersson & Husebye We found that the California network is less suitable than the LASA and NORSAR arrays for this kind of studies because of its greater proportion of peripheral blocks in which the resolution is very poor for the stochastic inverse solution and the random error effect is severe for the generalized inverse solution. Nevertheless, the resultant velocity anomalies show a remarkable correlation with the San Andreas fault zone to a depth of 75 km. The anomaly pattern changes drastically as the depth exceeds 75 km, suggesting that the asthenosphere has been reached.  相似文献   

Orthopyroxene–sillimanite–quartz assemblages: distribution, petrology, quantitative P–T–X constraints and P–T paths     

D. E. Kelsey  R. W. White  R. Powell 《Journal of Metamorphic Geology》2003,21(5):439-453

Granulite facies magnesian metapelites commonly preserve a wide array of mineral assemblages and reaction textures that are useful for deciphering the metamorphic evolution of a terrane. Quantitative pressure, temperature and bulk composition constraints on the development and preservation of characteristic peak granulite facies mineral assemblages such as orthopyroxene + sillimanite + quartz are assessed with reference to calculated phase diagrams. In NCKFMASH and its chemical subsystems, peak assemblages form mainly in high‐variance fields, and most mineral assemblage changes reflect multivariant equilibria. The rarity of orthopyroxene–sillimanite–quartz‐bearing assemblages in granulite facies rocks reflects the need for bulk rock X_Mg of greater than approximately 0.60–0.65, with pressures and temperatures exceeding c. 8 kbar and 850 °C, respectively. Cordierite coronas mantling peak minerals such as orthopyroxene, sillimanite and quartz have historically been used to infer isothermal decompression P–T paths in ultrahigh‐temperature granulite facies terranes. However, a potentially wide range of P–T paths from a given peak metamorphic condition facilitate retrograde cordierite growth after orthopyroxene + sillimanite + quartz, indicating that an individual mineral reaction texture is unable to uniquely define a P–T vector. Therefore, the interpretation of P–T paths in high‐grade rocks as isothermal decompression or isobaric cooling may be overly simplistic. Integration of quantitative data from different mineral reaction textures in rocks with varying bulk composition will provide the strongest constraints on a P–T path, and in turn on tectonic models derived from these paths.  相似文献   

The PUMA experiment west of Lewis, U.K.     

C.M.R. Powell  M.C. Sinha 《Geophysical Journal International》1987,89(1):259-264

Summary. In August-September 1984 a 165 km long, reversed, wide-angle, seismic line was shot along part of the BIRPS WINCH deep seismic reflection profile west of Lewis in the Outer Hebrides. The experiment was recorded using a new type of sea-bottom receiver, the PUMA (Pull-Up Multichannel Array). This consists of an 1100 m long array of hydrophones connected to a sea-bottom recording package. Airgun and explosive shots recorded by the PUMA provide a densely sampled record section, allowing even low amplitude arrivals to be traced across the section. An initial, 1-D interpretation of the data reveals a crustal thickness of 27 km, and confirms that a band of reflectors seen at around 8.6 s TWT on the normal incidence data, and interpreted as the 'reflection Monol, coincide with the Moho determined by wide-angle reflections and refractions.  相似文献