共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
Catherine Hesse-Swain 《GeoJournal》2006,66(3):257-272
People living in the northeast of Thailand interchangeably label themselves and are labelled by others as Isan, Thai Isan,
Lao Isan, Thai or Lao, depending on the ethnic, political, social or familial nuances of any given situation. I use the term
Lao Isan to refer specifically to Isan people of Lao origin or ethnicity. Lao Isan are subject to complex and often competing notions
of Isan-ness, Lao-ness and Thai-ness by insiders and outsiders. Using data derived from an ethnographic study of popular Thai television and Lao Isan youth (aged
17–25) living in the city of Khon Kaen and the town of Mahasarakham in northeast Thailand in 2002, this paper explores contemporary
and co-existing interpretations of Isan identity or Khwampenisan among Lao Isan youth in relation to self-image and connections with national understandings of physical beauty as they are
perpetuated in Thai-produced television programs.
相似文献
Catherine Hesse-SwainEmail: |
3.
Myrl E. Beck Jr. 《Tectonophysics》1983,93(1-2)
4.
A redox profile of the Slave mantle and oxygen fugacity control in the cratonic mantle 总被引:4,自引:2,他引:4
The authors report a redox profile based on Mössbauer data of spinel and garnet to a depth of 210 km from mantle xenoliths of the northern (N) and southeastern (SE) Slave craton (northern Canada). The profile transects three depth facies of peridotites that form segments of different bulk composition, represented by spinel peridotite, spinel–garnet peridotite, low-temperature garnet peridotite, high-temperature garnet peridotite, and pyroxenite. The shallow, more depleted N Slave spinel peridotite records lower oxygen fugacities compared to the deeper, less depleted N Slave spinel–garnet peridotite, consistent with their different spinel Fe3+ concentrations. Garnet peridotites show a general reduction in log fO2 (FMQ)s with depth, where values for garnet peridotites are lower than those for spinel–garnet peridotites. There is a strong correlation between depletion and oxygen fugacity in the spinel peridotite facies, but little correlation in the garnet peridotite facies. The strong decrease in log fO2 (FMQ) with depth that arises from the smaller partial molar volume of Fe3+ in garnet, and the observation of distinct slopes of log fO2 (FMQ) with depth for spinel peridotite compared to spinel–garnet peridotite strongly suggest that oxygen fugacity in the cratonic peridotitic mantle is intrinsically controlled by iron equilibria involving garnet and spinel.
相似文献
C. McCammonEmail: Phone: +49-921-553709Fax: +49-921-553769 |
5.
6.
Quantifying the tectono-metamorphic evolution of pelitic rocks from a wide range of tectonic settings: mineral compositions in equilibrium 总被引:1,自引:0,他引:1
Commonly used thermometer and barometer calibrations are sensitive to mineral assemblage and, thus, bulk-rock composition.
Calculated mineral stabilities for an average pelitic rock over a pressure–temperature (PT) range appropriate for normal, thickened, heated and shallowly subducted continental crust (400–900°C at 0.1–3.0 GPa) reveal
more than one hundred possible assemblages. Individual phase compositions are dependent on the assemblage in which they belong
and combining isopleth sets to represent and reveals several PT-ranges where commonly used mineral thermobarometers are less effective. For example, the garnet-biotite thermometer becomes
increasingly P dependent in the absence of muscovite in high T melt-bearing assemblages, and biotite and plagioclase are not stable at pressures appropriate for lower thickened continental
crust. Compositional thermobarometers involving equilibration between alternative phases (namely garnet, phengite and omphacite)
are presented. Although the equilibrium compositions of phases at any P and T may change significantly as a function of bulk-rock composition, compositional-ratio thermobarometers are typically insensitive
to this, unless a pseudo-univariant reaction is crossed and the buffering assemblage is altered. Quantification of the limits
of efficacy of various thermobarometers allows the mineralogy of metapelites to be used to precisely determine segments of
PT paths and infer their likely tectonic controls.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Mark J. CaddickEmail: |
7.
Monika Koch-Müller Stanislav S. Matsyuk Dieter Rhede Richard Wirth Natasha Khisina 《Physics and Chemistry of Minerals》2006,33(4):276-287
The incorporation of hydrogen in mantle olivine xenocrysts from the Udachnaya kimberlite pipe was investigated by Fourier-transform infrared spectroscopy and secondary ion mass spectrometry (SIMS). IR spectra were collected in the OH stretching region on oriented single crystals using a conventional IR source at ambient conditions and in situ at temperatures down to −180°C as well as with IR synchrotron radiation. The IR spectra of the samples are complex containing more than 20 strongly polarized OH bands in the range 3,730–3,330 cm−1. Bands at high energies (3,730–3,670 cm−1) were assigned to inclusions of serpentine, talc and the 10 Å phase. All other bands are believed to be intrinsic to olivine. The corresponding point defects are (a) associated with vacant Si sites (3,607 cm−1 E || a, 3,597 E || a, 3,571 cm−1 E || c, 3,567 E || c, and 3,556 E || b), and (b) with vacant M1 sites (most of the bands polarized parallel to a). From the pleochroic behavior and position of the OH bands associated with the vacant M1 sites, we propose two types of hydrogen—one bonded to O1 and another to O2, so that both OH vectors are strongly aligned parallel to a. The O2–H groups may be responsible for the OH bands at higher wavenumbers than those for the O1–H groups. The multiplicity of the corresponding OH bands in the spectra can be explained by different chemical environments and by slightly different distortions of the M1 sites in these high-pressure olivines. Four samples were investigated by SIMS. The calculated integral molar absorption coefficient using the IR and SIMS results of 37,500±5,000 L mol H2O cm−2 is within the uncertainties slightly higher than the value determined by Bell et al. (J Geophys Res 108(B2):2105–2113, 2003) (28,450±1,830 L mol H2O cm−2). The reason for the difference is the different distributions of the absorption intensity of the spectra of both studies (mean wavenumber 3,548 vs. 3,570 cm−1). Olivine samples with a mean wavenumber of about 3,548 cm−1 should be quantified with the absorption coefficient as determined in this study; those containing more bands at higher wavenumber (mean wavenumber 3,570 cm−1) should be quantified using the value determined by Bell et al. (J Geophys Res 108(B2):2105–2113, 2003).
相似文献
Monika Koch-MüllerEmail: Phone: +49-331-2881492 |
8.
9.
Jaap S. Sinninghe Damst Stefan Schouten W. Irene C. Rijpstra Ellen C. Hopmans Harry Peletier Winfried W. C. Gieskes Jan A. J. Geenevasen 《Organic Geochemistry》1999,30(12):918
2,6,10,14-tetramethyl-7-(3-methylpent-4-enyl)-pentadeca-2,5E,9E,13-tetraene I possessing a C25 highly branched isoprenoid skeleton has been isolated from the marine diatom Rhizosolenia setigera and identified by 1H and 13C NMR spectroscopy. 相似文献
10.
Moment tensors of the January 1997 earthquake swarm in NW Bohemia (Czech Republic): double-couple vs. non-double-couple events 总被引:1,自引:0,他引:1
We investigated moment tensors (MTs) of 70 events of the earthquake swarm which occurred in January 1997 in NW Bohemia. A refined location using the master-event procedure shows that all the foci clustered in a volume of less than 0.5 km3 comprising two compact clusters—the southern and northern ones. The results of single-source, absolute-moment tensor inversion of the P- and SH-peak amplitudes reveal two types of the source mechanisms, A and B in our denotation, which dominated in the swarm. Type A implies an oblique normal faulting with a nearly pure double-couple (DC) source. For the B type, an oblique-thrust faulting and a combined source [double-couple combined with the isotropic (ISO) and compensated linear-vector dipole (CLVD) components] are typical. Magnitudes of the non-double-couple components of MT appear unrelated to the ML magnitude of the event. The proximity of hypocentres of A and B events guarantees the non-double-couple source mechanisms of the B events not to be an artefact of a mismodelling of the medium. To exclude finiteness of the focus or station-site effects as possible causes of spurious non-double-couple components of MTs of the B events, the residuals of the peak amplitudes across the set of the B events were analysed and the jack-knife test was applied. The A and B events separate in time and space. Consequently, three major phases of swarm activity can be distinguished. In the first, only the southern cluster was active and A events prevailed, while B events dominated in the northern cluster in the third phase. Both A and B events occurred (the former in the southern cluster, the latter in the northern one) during the second phase. The initiation of the B events in the northern cluster are reflected in a pronounced increase in the non-double-couple components of the MTs, which points to tensile-source mechanisms as a consequence of a hypothesised fluid injection. 相似文献
11.
A commented translation of the paper by C.W. Correns and W. Steinborn on crystallization pressure 总被引:1,自引:0,他引:1
Crystallization of salts is recognized to be a major factor of the degradation of porous materials such as stone and concrete.
On the theoretical side, there is now general acceptance about the thermodynamic origin of this phenomenon. However, on the
experimental side, there are only scarce quantitative data. In this respect, the reference work par excellence is that of Correns (Discuss Faraday Soc 5:267–271, 1949) who shows a good correlation between calculated and measured crystallization pressures. However, concerns about both the
thermodynamic derivation and the experimental conditions raise the question about why Correns could have obtained such a good
correlation. This issue is discussed extensively in this paper which is organized as a commented translation of a former paper
by Correns, co-authored by Steinborn, and that is much richer in experimental details.
相似文献
Robert J. FlattEmail: |
12.
We focus on Swiss earthquakes in antiquity and the early medieval period before A.D. 1000. We have information on less than
half a dozen earthquakes within this era, since written records for the first half of the first millennium A.D. are minimal,
and there is little hope of finding more written evidence for earthquakes. Furthermore, interpreting the documents at hand
is somewhat complex. For the 6th century Gregory of Tours in Historia Francorum gives hints of a rockslide near the castle Tauredunum (Le Grammont) in the Swiss canton Valais, an event that has been considered in the literature as caused by an earthquake. The Carolingian period (ca. 750–950) included the rise of some very important cultural centers in various parts of today’s Switzerland. For
instance, the ecclesiastical culture in St. Gallen generated a remarkable number of written records, which survived for our
use in a unique manner. From the 9th and 10th centuries, we have evidence for earthquakes in the years 849, 867, 902, and
944. However, information on them remains so scarce that their location and intensity are generally difficult to assess. Nevertheless,
the finding of a new document - a memoir written by the abbot of Reichenau - offers some insight into the A.D. 849 event and
its reportedly aftershocks.
相似文献
Monika GislerEmail: |
13.
Using density functional simulations, within the generalized gradient approximation and projector-augmented wave method, we study structures and energetics of CaSiO3 perovskite in the pressure range of the Earths lower mantle (0–150 GPa). At zero Kelvin temperature the cubic
CaSiO3 perovskite structure is unstable in the whole pressure range, at low pressures the orthorhombic (Pnam) structure is preferred. At 14.2 GPa there is a phase transition to the tetragonal (I4/mcm) phase. The CaIrO3-type structure is not stable for CaSiO3. Our results also rule out the possibility of decomposition into oxides.
相似文献
Daniel Y. JungEmail: Phone: +41-44-6323744Fax: +41-44-6321133 |
14.
A Double Solid Reactant Method was elaborated from a suggestion of Marini (Geological sequestration of carbon dioxide: Thermodynamics,
kinetics, and reaction path modeling. Developments in Geochemistry, Elsevier, Amsterdam, 2007) to simulate the release of
trace elements during the progressive dissolution of solid phases. The method is based on the definition, for each dissolving
solid, of both an entity whose thermodynamic and kinetic properties are known (either a pure mineral or a solid mixture) and
a special reactant, that is, a material of known stoichiometry and unknown thermodynamic and kinetic properties. The special
reactant is utilised to take into account the concentrations of trace elements in the dissolving solid phase. In this communication,
the influence of several trace elements on the ΔG
f
o, ΔG
r
o and log K of the minerals considered by Lelli et al. (Environ Geol, 2007) and Accornero and Marini (Geobasi, 2007a; Proceedings of
IMWA symposium, Cagliari, 27–31 May 2007b) was evaluated assuming ideal mixing in the solid state. These effects were found
to be negligible for albite and the leucite–latitic glass, limited for muscovites and chlorites, and slightly more important
for apatites. These influences become progressively higher with increasing concentration of trace elements in these minerals.
Based on these deviations in thermodynamic parameters, special reactants should not include oxide components with molar fractions
higher than 0.003.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Luigi MariniEmail: |
15.
G. R. Dargahi-Noubary 《Mathematical Geology》1981,13(2):119-133
Stochastic models are derived for two source formulations for explosions. Using this kind of model, a comparison is made between source time functions due to Blake, Haskell, Mueller and Murphy, and Von Seggern and Blandford, for explosions, and between -square (Aki, Brune)and -cube (Aki, Haskell)models for earthquakes. When seeking a stochastic model for records of Rayleigh waves from atmospheric explosions, the k-model corresponding to Haskell's time function was found to be an appropriate choice. 相似文献
16.
To constrain the amount and rate of crustal contamination that is possible in basaltic and jotunitic magma, and to gain an insight into the physical and thermal processes of assimilation in crustal magma chambers, we have modelled published Sr and Nd isotopic data from three layered intrusions. Well-exposed sequences of cumulates with no evidence of magma recharge provide direct records of concurrent assimilation and fractional crystallization (AFC). The key to the modelling is that F, the mass fraction of magma remaining in the chamber, can be estimated from the thicknesses of the studied cumulate sequences. This allows AFC model curves to be fitted to the isotopic data by varying r, the ratio of the rate of mass assimilated to the rate of mass crystallized. The results of modelling show that r is nearly constant in 800 to 2000 m thick sequences of cumulates displaying up-section decreases in anorthite content of plagioclase, increases in whole-rock Sr0 (initial 87Sr/86Sr) and decreases in whole-rock εNd0 (initial εNd). The r-values of the layered sequences range from 0.12 in the Fongen–Hyllingen Intrusion, over 0.20 in the Bjerkreim–Sokndal Intrusion, to 0.27 in the Hasvik Intrusion. The total amount of assimilation, the bulk crust/magma ratio, reaches values of 0.08, 0.19 and 0.28 at the level of the most contaminated samples after 60% to 80% crystallisation, whereas the instantaneous crust/magma ratio of the most contaminated magmas were respectively 0.14, 0.46, and 0.70, for the three intrusions.Innumerable country rock xenoliths occur in the three layered intrusions and played a crucial role in the assimilation process. The xenoliths spalled off the roofs of the magma chambers during magma emplacement and their initial temperature and composition relate to r in the intrusions. In the Hasvik Intrusion (r = 0.27), the initial temperature of the country rocks was 450 °C and the xenoliths were fusible metasediments and therefore produced a high fraction of partial melt that could be assimilated. In the Bjerkreim–Sokndal Intrusion (r = 0.20), the country rocks were initially at temperatures of 640–880 °C but included both refractory massif-type anorthosite and fusible gneisses. In the Fongen–Hyllingen Intrusion (r = 0.12), the country rocks were cooler (300 °C) and the xenoliths include refractory metabasalt (dominant) and fusible metapelite. We argue that the refractory metabasalt and anorthosite xenoliths acted mainly as heat sinks, resulting in reduced r-values in Fongen–Hyllingen and Bjerkreim–Sokndal Intrusions.Heating of refractory and fusible xenoliths, and melting of fusible xenoliths absorbed sensible and latent heat of the magma. Energy-balanced modelling shows that up to 75% of the heat available was absorbed by xenoliths within the magma chambers, promoting higher rates of cooling and crystallisation than would have resulted from loss of heat to the envelope of country rocks alone. The high r-values reflect the amount of heat absorbed by heating and melting country rock within the magma chambers themselves, and their constancy reflects the ready availability of fusible xenoliths. 相似文献
17.
Giorgio Hadi Curti 《GeoJournal》2009,74(3):201-208
Ostensibly, subtitles in films serve as linguistic approximations of meaning. Expectedly then, much of the debate surrounding
subtitling has been concerned with representational accuracy, fidelity and authenticity. In this article I argue that by encountering
subtitles as affective bodily expressions, as opposed to approximate representations of pre-existent meanings or intentions,
filmic experiences may be(come) transformed and differently transformational. As a result, meaning and accuracy in subtitles
as superimposed signifiers or static representations become secondary to subtitles as spatially affective- and expressive-movements
intimately part of filmic scapes. The creative use of subtitling in Bekmambetov’s Russian language film Night Watch (Nochnoy dozor; 2006 [2004]) is discussed.
相似文献
Giorgio Hadi CurtiEmail: |
18.
Isotope and trace element evidence for depleted lithosphere in the source of enriched Ko’olau basalts 总被引:1,自引:0,他引:1
Vincent J. M. Salters Janne Blichert-Toft Zuzana Fekiacova Afi Sachi-Kocher Michael Bizimis 《Contributions to Mineralogy and Petrology》2006,151(3):297-312
We have measured the Hf and Nd isotopic compositions of 38 basalts from the Ko’olau drill hole, Hawai’i. The basalts show
limited variations in both 176Hf/177Hf and 143Nd/144Nd (ε
Nd varies from +4.2 to +7.3 and ε
Hf from +8.0 to +12.3). Their correlated variation has an R
2 of 0.86. The data form an array with a slope of 1.2 on an ε
Hf–ε
Nd isotope correlation diagram, while the slope of all Hawai’ian basalt data is 0.98. Both slopes are significantly shallower
than that of the mantle array of 1.4 defined by ocean island basalts. Previous studies have shown that a shallow slope in
Hf–Nd isotope space can be related to ancient pelagic sediments in the mantle source (Blichert-Toft et al. 1999; Salters and White 1998). However, the combined variations in Ko’olau basalts of Hf–Nd–Pb–Os isotopic compositions and trace element ratios, such
as La/Nb, Th/La and Sr/Nd, are not consistent with the simple addition of a sediment component to the mantle. We instead propose
that the shallow slope on the Hf–Nd isotope correlation diagram for Ko’olau shield stage basalts can be better explained if
the enriched endmember contains either an ancient oceanic lithosphere component or the high-176Hf/177Hf component observed in the Salt Lake Crater (SLC) peridotite xenoliths (which also have a depleted lithosphere origin).
Since Ko’olau basalts have high 187Os/188Os (0.135–0.160) and the SLC xenoliths have 187Os/188Os up to 0.13 (Lassiter et al. 2000) Os-isotopes are consistent with the latter being a component in the enriched Ko’olau source.
相似文献
Vincent J. M. SaltersEmail: |
19.
Crack Coalescence in Molded Gypsum and Carrara Marble: Part 1. Macroscopic Observations and Interpretation 总被引:8,自引:5,他引:3
Cracking and coalescence behavior has been studied experimentally with prismatic laboratory-molded gypsum and Carrara marble
specimens containing two parallel pre-existing open flaws. This was done at both the macroscopic and the microscopic scales, and the results are presented in two separate papers. This paper (the first of two) summarizes the macroscopic experimental
results and investigates the influence of the different flaw geometries and material, on the cracking processes. In the companion
paper (also in this issue), most of the macroscopic deformation and cracking processes shown in this present paper will be
related to the underlying microscopic changes. In the present study, a high speed video system was used, which allowed us
to precisely observe the cracking mechanisms. Nine crack coalescence categories with different crack types and trajectories
were identified. The flaw inclination angle (β), the ligament length (L), that is, intact rock length between the flaws, and the bridging angle (α), that is, the inclination of a line linking up the inner flaw tips, between two flaws, had different effects on the coalescence
patterns. One of the pronounced differences observed between marble and gypsum during the compression loading test was the
development of macroscopic white patches prior to the initiation of macroscopic cracks in marble, but not in gypsum. Comparing
the cracking and coalescence behaviors in the two tested materials, tensile cracking generally occurred more often in marble
than in gypsum for the same flaw pair geometries.
相似文献
H. H. EinsteinEmail: |
20.
Social vulnerability and seismic risk perception. Case study: the historic center of the Bucharest Municipality/Romania 总被引:3,自引:2,他引:1
Iuliana Armaş 《Natural Hazards》2008,47(3):397-410
Social vulnerability is as much a part of risk as building damage, hazard magnitude, and economic loss. Social vulnerability refers to the capacity of a human community exposed during the impact of a natural hazard event (in this case, an earthquake)
to resist, cope with, and recover from that impact. In the perspective of the 3rd millennium, we come to understand that the
most efficient and accessible way to reduce the pressure of natural risks is to reduce the vulnerability level of the human
communities exposed to that certain hazard. This study aims to test, in an exposed and vulnerable area, the relationship between
social vulnerability and the perception of the seismic risk. The research focuses only on the first level of social vulnerability,
defined as the ability of an individual within a household to recover from a natural hazard impact (Dwyer et al. 2004). A prevailing assumption was that social vulnerability influences the level of perception of the seismic risk, in an exposed, vulnerable area. To this end, two samples were used, different under the aspect of social vulnerability, in the context of the same residential
area. Social vulnerability was computed as a normalized composed index that includes the poverty ratio and the demographic
vulnerability ratio (depending on the age, gender, and education level indicators). The statistical processing has indicated
a significant difference in the high perception level for the two samples that were compared, in the sense that in the context
of an increased level of social vulnerability, people generally better acknowledge the seismic risk.
相似文献
Iuliana ArmaşEmail: |