High-temperature deformation during continental-margin subduction & exhumation: The ultrahigh-pressure Western Gneiss Region of Norway     

Bradley R. Hacker  Torgeir B. Andersen  Scott Johnston  Andrew R.C. Kylander-Clark  Emily M. Peterman  Emily O. Walsh  David Young 《Tectonophysics》2010,480(1-4):149-171

A new dataset for the high-pressure to ultrahigh-pressure Western Gneiss Region allows the definition of distinct structural and petrological domains. Much of the study area is an E-dipping homocline with E-plunging lineations that exposes progressively deeper, more strongly deformed, more eclogite-rich structural levels westward. Although eclogites crop out across the WGR, Scandian deformation is weak and earlier structures are well preserved in the southeastern half of the study area. The Scandian reworking increases westward, culminating in strong Scandian fabrics with only isolated pockets of older structures; the dominant Scandian deformation was coaxial E–W stretching. The sinistrally sheared Møre–Trøndelag Fault Complex and Nordfjord Mylonitic Shear Zone bound these rocks to the north and south. There was moderate top-E, amphibolite-facies deformation associated with translation of the allochthons over the basement along its eastern edge, and the Nordfjord–Sogn Detachment Zone underwent strong lower amphibolite-facies to greenschist-facies top-W shearing. A northwestward increase in exhumation-related melting is indicated by leucosomes with hornblende, plagioclase, and Scandian sphene. In the western 2/3 of the study area, exhumation-related, amphibolite-facies symplectite formation in quartzofeldspathic gneiss postdated most Scandian deformation; further deformation was restricted to slip along biotite-rich foliation planes and minor local folding. That the Western Gneiss Region quartzofeldspathic gneiss exhibits a strong gradient in degree of deformation, implies that continental crust in general need not undergo pervasive deformation during subduction.  相似文献   

Jupiter’s South South Temperate Zone vortices: Observations and simulations     

Raúl Morales-Juberías  Emily S. Brindle 《Icarus》2010,206(2):747-754

The region in Jupiter’s atmosphere with the highest density of anticyclonic spot-like vortices is the region known as the South South Temperate Zone (SSTZ), which is located between the eastward jet at ≈−42.9° latitude and the westward jet at ≈−39.2° latitude. We present a characterization of the spots found in this region based on ground-based and Hubble Space Telescope observations from the years 1993 to 2007. Mergers have been reported between spots in this region, similar to those observed for the White Ovals in the latitudinal domain immediately equatorward (northward). We use a multilayer model to perform numerical simulations that capture the details of a well-observed merger event involving multiple interacting vortices. We find that the vertical stratification has an important effect in the outcome of the interaction between spots. In particular it can play a determining role on whether or not a cyclone embedded between two approaching anticyclones can inhibit their merging. From our simulations we conclude that the background static stability of the atmosphere in the SSTZ is better characterized by an average value of .  相似文献   

Carbon dioxide and carbon monoxide photoproduction quantum yields in the Delaware Estuary     

Emily M. White  David J. Kieber  Jane Sherrard  William L. Miller  Kenneth Mopper 《Marine Chemistry》2010,118(1-2):11-21

Photochemical mineralization of dissolved organic matter (DOM) plays an important role in the cycling of carbon in estuarine systems. A key to modeling this process is knowledge of apparent quantum yields (AQYs) for the photochemical products. Here we determined spectral AQYs for carbon dioxide (CO₂) and carbon monoxide (CO), the main products of DOM photomineralization, along the main axis of the Delaware Estuary. Apparent quantum yields for CO₂ photoproduction were determined shipboard using a multi-spectral irradiation system. Carbon monoxide AQYs were determined in stored samples by employing a narrow band spectral irradiation system. A single AQY spectrum described carbon dioxide photochemical production within the estuary whereas CO AQY spectra varied with salinity, suggesting different precursors and mechanisms for the production of these two species. CO₂ AQYs were used along with shipboard measurements of DOM absorbance and solar irradiance to calculate photoproduction rates. Calculated CO₂ photoproduction rates agreed with directly measured rates (2 to 4 μM CO₂ d^? 1) within experimental error, supporting the further development and use of AQYs to calculate regional-scale photochemical fluxes.  相似文献   

Geographical indications and the South Africa–European Union free trade agreement     

Emily Craven  & Charles Mather 《Area》2001,33(3):312-320

Geographical indications, as a form of intellectual property, are becoming increasingly important in global trade. In South Africa's trade and cooperation agreement with the European Union, problems over the use of names such as 'port' and 'sherry' provided an important obstacle to the conclusion of the trade deal. This paper argues that the conflict over geographical indications in this trade agreement must be seen in the context of broader initiatives to establish a system of protecting this form of intellectual property through the World Trade Organisation.  相似文献   

Multi-source spatial data-based invasion risk modeling of Striga (Striga asiatica) in Zimbabwe     

Bester Tawona Mudereri  Elfatih Mohamed Abdel-Rahman  Timothy Dube  Tobias Landmann  Zeyaur Khan  Emily Kimathi 《地理信息系统科学与遥感》2020,57(4):553-571

ABSTRACT

Monitoring of destructive invasive weeds such as those from the genus Striga requires accurate, near real-time predictions and integrated assessment techniques to enable better surveillance and consistent assessment initiatives. Thus, in this study, we predicted the potential ecological niche of Striga (Striga asiatica) weed in Zimbabwe, to identify and understand its propagation and map potentially vulnerable cropping areas. Vegetation phenology from remote sensing, bioclimatic and other environmental variables (i.e. cropping system, edaphic, land surface temperature, and terrain) were used as predictors. Six machine learning modeling techniques and the ensemble model were evaluated on their suitability to predict current and future Striga weed distributional patterns. The mentioned predictors (n = 40) were integrated into six models with “presence-only” training and evaluation data, collected in Zimbabwe over the period between the 12^th and 28^th of March 2018. The area under the curve (AUC) and true skill statistic (TSS) were used to measure the performance of the Striga modeling framework. The results showed that the ensemble model had the strongest Striga occurrence predictive power (AUC = 0.98; TSS = 0.93) when compared to the other modeling algorithms. Temperature seasonality (Bio4), the maximum temperature of the warmest month (Bio5) and precipitation seasonality (Bio15) were determined to be the most dominant bioclimatic variables influencing Striga occurrence. “Start of the season” and “season minimum value” of the “Enhanced Vegetation Index base value” were the most relevant remote sensing-based variables. Based on projected climate change scenarios, the study showed that up to 2050, the suitable area for Striga propagation will increase by ~ 0.73% in Zimbabwe. The present work demonstrated the importance of integrating multi-source data in predicting possible crop production restraints due to weed propagation. The results can enhance national preparedness and management strategies, specifically, if the current and future risk areas can be identified for early intervention and containment  相似文献   

Melt structural control on olivine/melt element partitioning of Ca and Mn     

Bjorn O. Mysen  Emily V. Dubinsky 《Geochimica et cosmochimica acta》2004,68(7):1617-1633

Relationships between mineral/silicate melt partition coefficients and melt structure have been examined by combining Ca and Mn olivine/melt partitioning data with available melt structure information. Compositions were chosen so that melts with olivine on their liquidii range in degree of polymerization, NBO/T, from ∼0.5 to ∼2.5 under near isothermal conditions (1350-1400°C). Olivine/melt Ca-Mn exchange coefficients, Ca(olivine)/CaO(melt)/MnO(olivine)/MnO(melt) (K_{D Ca-Mn}^olivine/melt), as a function of melt NBO/T have a parabolic shape with a minimum K_{D Ca-Mn}^olivine/melt-value at NBO/T near 1. Notably, published K_{D Fe2⁺-Mg}^olivine/melt versus NBO/T functions are also parabolic with a maximum in K_{D Fe2⁺-Mg}^olivine/melt near 1 (Kushiro and Mysen, 2002).The olivine/melt partitioning data are modeled in terms of structural units (Qⁿ-species) in the melt. The NBO/T-value corresponding to the minimum K_{D Ca-Mn}^olivine/melt is near that where the abundance ratio of Qⁿ-species, X_Q3/X_Q2, has its largest value. Therefore, the activity coefficient ratio in the melt, γ_Ca2⁺(melt)/γ_Mn2⁺(melt), attains a minimum where the abundance ratio of X_Q3/X_Q2 is at maximum. It is inferred from this relationship that Ca²⁺ in the melts is dominantly bonded to nonbridging oxygen (Ca-NBO) in Q³-species, whereas Mn²⁺ is bonded to nonbridging oxygen (Mn-NBO) in less polymerized Qⁿ-species such as Q².  相似文献   

Bradford Sturtevant, 1933-2000     

Youxue Zhang  Heidy Mader  Emily Brodsky  Hiroo Kanamori  Sue Kieffer  Jeremy Phillips  Joe Shepherd  Steve Sparks 《Bulletin of Volcanology》2002,63(8):569-571

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The Oxford–Dartmouth Thirty Degree Survey – II. Clustering of bright Lyman break galaxies: strong luminosity-dependent bias at z= 4     

Paul D. Allen  Leonidas A. Moustakas  Gavin Dalton  Emily MacDonald  Chris Blake  Lee Clewley  Catherine Heymans  Gary Wegner 《Monthly notices of the Royal Astronomical Society》2005,360(4):1244-1256

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Women and seed management: A study of two villages in Bangladesh     

Emily Oakley  Janet Henshall Momsen 《Singapore journal of tropical geography》2007,28(1):90-106

Seed management has until recently been neglected in agrobiodiversity research. Gender dimensions in seed selection, processing, storage and exchange embody critical task areas in the human management of diverse crop species and varieties. This paper focuses on women's roles in seed management in field and homegarden crops in Bangladesh and reports on the findings of a study in two villages in Tangail District. Seventy-five women were surveyed with a questionnaire and subsets interviewed in-depth; focus groups conducted for women and men provided a means of cross-checking responses. Three distinct areas of agrobiodiversity were addressed: the gendered divisions of labour among agricultural tasks; the pervasiveness of seed saving among respondents; and seed management practices and techniques. The results indicate that while men have greater authority over field activities, homegarden production is the exclusive domain of women. Seed management is seen as an extension of women's domestic duties: women are responsible for all seed processing, storage and exchange for field as well as homegarden crops. The vast majority of seeds sown are saved on-farm by women, revealing important cultural, economic and environmental implications for agrobiodiversity conservation and local differences.  相似文献   

The 9th of July 1998 Faial Island (Azores,North Atlantic) seismic sequence   总被引：2，自引：0，他引：2  

L. Matias  N. A. Dias  I. Morais  D. Vales  F. Carrilho  J. Madeira  J. L. Gaspar  L. Senos  A. B. Silveira 《Journal of Seismology》2007,11(3):275-298

The Faial earthquake (M _L 5.8) that occurred on the 9th of July, 1998, in the Azores region (north Atlantic), caused nine casualties and severe destruction affecting more than 5,000 people. The main shock was located at sea, 10 km NE of the Faial Island, and triggered a seismic sequence that lasted for several weeks and was characterized by an unusual high p-value of 1.40 for the modified Omori law. We present here the results of a joint inversion of hypocenters and 1D velocity model performed on the data collected by the permanent network complemented with a temporary network installed shortly after the occurrence of the main event. The 1D velocity model shows a heterogeneous upper crust, testified by the observed differences in site effects at the stations, while the middle crust from ∼2.5 to 8 km in depth is quite homogeneous. The Moho is located at a depth of about 12–13 km and the Vp/Vs ratio is found to be around 1.78. The events at depth are mainly concentrated in the middle-lower crust (8–12 km), while their spatial distribution shows a main cluster, visible after relocation, SSE trending. This direction of elongation is consistent with one of the fault planes (N151°E) of the centroid moment tensor (CMT) solution for the main shock. The same plane is the preferred main shock fault plane inferred after a Coulomb failure function analysis on the aftershock distribution. The main event relocation points to a focal depth shallower than 5 km. The aftershocks pattern shows that several fault systems were reactivated by the stress perturbation induced by the main shock. Besides the two main tectonic directions, trending WNW–ESE and NNW–SSE, observed in the tectonics of Faial, Pico, and S. Jorge, there is also evidence of a new tectonic direction trending WSW–ENE.  相似文献