Differentiation in South African and Indian Cities     

Sophie Oldfield 《Geoforum》2004,35(2):143-144

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Charles D. Walcott in England and Wales (1888): A crucial visit in the resolution of Taconic-Cambrian-Ordovician questions     

Michael G. Bassett 《Proceedings of the Geologists' Association. Geologists' Association》2004,115(1):63-75

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Some mineralogical applications of synchrotron radiation     

G. Calas  W. A. Bassett  J. Petiau  M. Steinberg  D. Tchoubar  A. Zarka 《Physics and Chemistry of Minerals》1984,11(1):17-36

Synchrotron radiation offers several advantages over the conventional X-ray sources, among which the most important are its high intensity, broad spectral range and natural collimation. Among the numerous techniques which have been recently developed we present a review of the results concerning more specifically mineralogical systems: X-ray absorption spectroscopy concerning high-resolution edge spectra and Extended X-ray absorption fine structure (EXAFS), X-ray diffraction under high P-high T conditions, small-angle scattering, X-ray microanalysis and X-ray topography. For each technique the basic principles are described together with the experimental devices used, before mineralogical examples are given. Two main applications may be pointed out: chemical and structural characterization of disordered systems and kinetic studies (phase transitions and evolution). Many other techniques (photoelectron spectroscopy, X-ray fluorescence analysis ...) which are actually under development as a result of the rapid increase of the use of storage rings are not covered in the present review but will possibly also be used in the near future in Earth Sciences.  相似文献   

Experimental determination of the effects of pressure and temperature on the stoichiometry and phase relations of wüstite     

William A Bassett 《Geochimica et cosmochimica acta》1983,47(4):773-778

When quenched metastable wüstite (Fe_.924O and Fe_.947O) is held at 300°C at pressures up to 200 kbar in a diamond anvil cell, a mixture of magnetite, metallic iron and wüstite is found. We interpret this to indicate that magnetite plus metallic iron constitute the stable phase assemblage at pressures and temperatures below this boundary is stoichiometric FeO ($\text{a}{}_0\text{= 4.332 ± 0.001}\text{A}\text{?}$) at pressures below 110 kbar at 300°C. However, just below the boundary in the pressure range 110 kbar to 200 kbar at 300°C, the residuál wüstite is non-stoichiometric ($\text{a}{}_0\text{< 4.332}\text{A}\text{?}$). Data collected at pressures and temperatures above the boundary indicate that non-stoichiometric wüstite (Fe_xO) plus metallic iron constitute the stable phase assemblage and that the value of x in Fe_xO increases as pressure is increased isothermally to 100 kbar and then decreases as pressure is increased above 100 kbar.  相似文献   

Volcanic facies architecture of an intra-arc strike-slip basin, Santa Rita Mountains, Southern Arizona     

Cathy J. Busby  Kari N. Bassett 《Bulletin of Volcanology》2007,70(1):85-103

The three-dimensional arrangement of volcanic deposits in strike-slip basins is not only the product of volcanic processes, but also of tectonic processes. We use a strike-slip basin within the Jurassic arc of southern Arizona (Santa Rita Glance Conglomerate) to construct a facies model for a strike-slip basin dominated by volcanism. This model is applicable to releasing-bend strike-slip basins, bounded on one side by a curved and dipping strike-slip fault, and on the other by curved normal faults. Numerous, very deep unconformities are formed during localized uplift in the basin as it passes through smaller restraining bends along the strike-slip fault. In our facies model, the basin fill thins and volcanism decreases markedly away from the master strike-slip fault (“deep” end), where subsidence is greatest, toward the basin-bounding normal faults (“shallow” end). Talus cone-alluvial fan deposits are largely restricted to the master fault-proximal (deep) end of the basin. Volcanic centers are sited along the master fault and along splays of it within the master fault-proximal (deep) end of the basin. To a lesser degree, volcanic centers also form along the curved faults that form structural highs between sub-basins and those that bound the distal ends of the basin. Abundant volcanism along the master fault and its splays kept the deep (master fault-proximal) end of the basin overfilled, so that it could not provide accommodation for reworked tuffs and extrabasinally-sourced ignimbrites that dominate the shallow (underfilled) end of the basin. This pattern of basin fill contrasts markedly with that of nonvolcanic strike-slip basins on transform margins, where clastic sedimentation commonly cannot keep pace with subsidence in the master fault-proximal end. Volcanic and subvolcanic rocks in the strike-slip basin largely record polygenetic (explosive and effusive) small-volume eruptions from many vents in the complexly faulted basin, referred to here as multi-vent complexes. Multi-vent complexes like these reflect proximity to a continuously active fault zone, where numerous strands of the fault frequently plumb small batches of magma to the surface. Releasing-bend extension promotes small, multivent styles of volcanism in preference to caldera collapse, which is more likely to form at releasing step-overs along a strike-slip fault. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Montagne Pelée volcano (Martinique,in the French Lesser Antilles) hydrogeological system revealed by high-resolution helicopter-borne electromagnetic imagery     

Vittecoq  Benoit  Reninger  Pierre-Alexandre  Bellier  Vincent  Taïlamé  Anne-Lise  Nacimento  Laureen  Gros  Emile  Violette  Sophie 《Hydrogeology Journal》2023,31(5):1331-1352

Montagne Pelée, on the French island of Martinique, eastern Caribbean Sea, has been one of the deadliest volcanoes in the world, with 30,000 victims following the 1902 eruption. Thousands of people still live nearby, and this volcano is a strategic “water tank” for Martinique Island, providing 40% of the island’s water supply. This research aimed to better understand its hydrogeological functioning and the relationship with its complex volcanological evolution, taking advantage of a high-resolution helicopter-borne geophysical survey correlated with hydrogeological data from the boreholes and springs databases. Electromagnetic data, correlated with hydrogeological data, allowed for the identification of unsaturated zones, aquifers, and seawater intrusions, as well as the main geological units. In addition, data synthesised from pumping tests revealed that the older the unconsolidated pyroclastic deposits, the lower their hydraulic conductivity. The structural asymmetry between the northeastern and southwestern volcano flanks impacts its hydrogeological functioning. Consequently, the Montagne Pelée hydrogeological conceptual model is marked by several distinguishable aquifers. The upper perched aquifer within recent lava domes is directly involved in, and impacted by, phreatic eruptions, and it supports low flowrate springs. The remaining effective rainfall infiltrates to depth and recharges the hydrothermal system through vertical fractures. The other aquifers are categorized into three groups: northeastern, southeastern and southwestern flank aquifers. This research is a new step toward a better understanding of the Lesser Antilles volcanoes and more broadly of the central and proximal parts of the andesitic active volcanoes.

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Gardening at the edge: Documenting the limits of tropical Polynesian kumara horticulture in southern New Zealand     

Kari N. Bassett  Hamish W. Gordon  David C. Nobes  Chris Jacomb 《Geoarchaeology》2004,19(3):185-218

An Erratum has been published for this article in Geoarchaeology 19(6) 2004, 613. Kumara (Ipomoea batatus), a major food source for Maori, was brought to New Zealand from tropical Eastern Polynesia ∼700 years ago. Maori successfully adapted their cultivation techniques to grow kumara in New Zealand's cooler, seasonal climate, although most kumara cultivation was limited to the warmer North Island, with cultivation becoming more marginal southward. Banks Peninsula area is considered to be the southernmost limit for kumara gardening. The Okuora Farm archeological site on the southern side of Banks Peninsula has five pits that appear to be of the raised‐rim type used for over winter storage of kumara tubers. We conducted a preliminary investigation into the nature of the pits and surrounding 1 km² area using nondestructive techniques in accordance with Maori designation of food storage sites as tapu. Ground penetrating radar (GPR) investigation of two of the pits revealed subsurface disturbances consistent with postholes and drains, typical of raised rim kumara storage pits. Soil modification typical of kumara gardening was identified on a 1 ha area on a warm north‐northwest facing hillside. Several large borrow pits were identified as the likely source of the gravel added to the modified soil, possibly to retain heat and moisture. A plant phytolith study of soil samples identified several that appear to be from kumara. The combination of results strongly suggests this site was one of the southernmost Maori kumara gardening sites yet identified in New Zealand. © 2004 Wiley Periodicals, Inc.  相似文献   

Comparison of polynomial chaos and Gaussian process surrogates for uncertainty quantification and correlation estimation of spatially distributed open-channel steady flows   总被引：1，自引：1，他引：0  

Pamphile?T.?RoyEmail authorView author&#;s OrcID profile  Nabil?El Mo?ayd  Sophie?Ricci  Jean-Christophe?Jouhaud  Nicole?Goutal  Matthias?De Lozzo  Mélanie?C.?Rochoux 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(6):1723-1741

Data assimilation is widely used to improve flood forecasting capability, especially through parameter inference requiring statistical information on the uncertain input parameters (upstream discharge, friction coefficient) as well as on the variability of the water level and its sensitivity with respect to the inputs. For particle filter or ensemble Kalman filter, stochastically estimating probability density function and covariance matrices from a Monte Carlo random sampling requires a large ensemble of model evaluations, limiting their use in real-time application. To tackle this issue, fast surrogate models based on polynomial chaos and Gaussian process can be used to represent the spatially distributed water level in place of solving the shallow water equations. This study investigates the use of these surrogates to estimate probability density functions and covariance matrices at a reduced computational cost and without the loss of accuracy, in the perspective of ensemble-based data assimilation. This study focuses on 1-D steady state flow simulated with MASCARET over the Garonne River (South-West France). Results show that both surrogates feature similar performance to the Monte-Carlo random sampling, but for a much smaller computational budget; a few MASCARET simulations (on the order of 10–100) are sufficient to accurately retrieve covariance matrices and probability density functions all along the river, even where the flow dynamic is more complex due to heterogeneous bathymetry. This paves the way for the design of surrogate strategies suitable for representing unsteady open-channel flows in data assimilation.  相似文献   

More water: The rise of a singular vision for rural development     

Amanda Thomas  Sophie Bond  Gradon Diprose  Andrew McGregor 《New Zealand geographer》2020,76(2):106-116

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Connecting Coronal Mass Ejections to Their Solar Active Region Sources: Combining Results from the HELCATS and FLARECAST Projects     

Sophie A. Murray  Jordan A. Guerra  Pietro Zucca  Sung-Hong Park  Eoin P. Carley  Peter T. Gallagher  Nicole Vilmer  Volker Bothmer 《Solar physics》2018,293(4):60

Coronal mass ejections (CMEs) and other solar eruptive phenomena can be physically linked by combining data from a multitude of ground-based and space-based instruments alongside models; however, this can be challenging for automated operational systems. The EU Framework Package 7 HELCATS project provides catalogues of CME observations and properties from the Heliospheric Imagers on board the two NASA/STEREO spacecraft in order to track the evolution of CMEs in the inner heliosphere. From the main HICAT catalogue of over 2,000 CME detections, an automated algorithm has been developed to connect the CMEs observed by STEREO to any corresponding solar flares and active-region (AR) sources on the solar surface. CME kinematic properties, such as speed and angular width, are compared with AR magnetic field properties, such as magnetic flux, area, and neutral line characteristics. The resulting LOWCAT catalogue is also compared to the extensive AR property database created by the EU Horizon 2020 FLARECAST project, which provides more complex magnetic field parameters derived from vector magnetograms. Initial statistical analysis has been undertaken on the new data to provide insight into the link between flare and CME events, and characteristics of eruptive ARs. Warning thresholds determined from analysis of the evolution of these parameters is shown to be a useful output for operational space weather purposes. Parameters of particular interest for further analysis include total unsigned flux, vertical current, and current helicity. The automated method developed to create the LOWCAT catalogue may also be useful for future efforts to develop operational CME forecasting.  相似文献