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1.
Summary ?Results of experimental investigations in the dry system PtS-PdS-NiS at 1100°C, 1000°C, and 900°C are presented. The phases
observed at 1100°C are “cooperite” and a melt, at 1000°C “cooperite”, “braggite”, and a melt and at 900°C “cooperite”, “braggite”,
“vysotskite”, Ni1−xS, and a melt. At 1100°C the maximum solubility of Ni in ideal, Pd-free “cooperite” is 2.7 atomic per cent and the Pd-content
limit in Ni-free “cooperite” is 12.8 atomic per cent. At 1000°C the maximum solubility of Ni in ideal, Pd-free “cooperite”
is 3.3 atomic per cent and the Pd-content in Ni-free “cooperite” is 13.7 atomic per cent. The “braggite” composition ranges
from Pt0.56Pd0.38Ni0.06S and Pt0.59Pd0.41S in a Ni-saturated and Ni-free environment respectively to Pt0.18Pd0.80Ni0.02S and Pt0.14Pd0.86S respectively. At 900°C the maximum Ni-content in ideal Pd-free “cooperite” is 3.1 atomic per cent and the Pd-limit in Ni-free
“cooperite” is 12.5 atomic per cent. The “braggite” composition ranges from Pt0.59Pd0.29Ni0.12S and Pt0.60Pd0.40S for a Ni-saturated and Ni-free environment respectively, to Pd0.91Ni0.09S and PdS respectively. The Ni-content in “braggite” and “vysotskite” increases slightly with increasing Pt/Pd ratios and
is higher at 900°C than at 1000°C. Comparison of experimental trends with cooperite, braggite, and vysotskite analyses from
the literature implies high temperatures of formation for Pt-Pd-Ni sulphides in placers if Ni-saturation is assumed.
Received October 1, 1998;/revised version accepted September 7, 1999 相似文献
Zusammenfassung ?Synthetischer ,,Cooperit”, ,,Braggit” und “Vysotskit” im System PtS-PdS-NiS bei 1100°C, 1000°C und 900°C Ergebnisse experimenteller Untersuchungen im trockenen System PtS-PdS-NiS bei 1100°C, 1000°C und 900°C werden dargestellt. Bei 1100°C sind die Phasen “Cooperit” und Schmelze, bei 1000°C “Cooperit”, “Braggit” und Schmelze und bei 900°C “Cooperit”, “Braggit”, “Vysotskit”, Ni1−xS und Schmelze stabil. Bei 1100°C ist die maximale L?slichkeit von Ni in idealem, Pd-freiem “Cooperit” 2.7 Atomprozent und der Pd-Gehalt in Ni-freien “Cooperit” liegt bei maximal 12.8 Atomprozent. Bei 1000°C ist die maximale L?slichkeit von Ni in idealem, Pd-freien “Cooperit” 3.3 Atomprozent und der Pd-Gehalt in Ni-freien “Cooperit” liegt bei maximal 13.7 Atomprozent. Die Zusammensetzung des “Braggits” variiert zwischen Pt0.56Pd0.38Ni0.06S und Pt0.18Pd0.80Ni0.02S in einem Ni-ges?ttigtem und zwischen Pt0.59Pd0.41S und Pt0.14Pd0.86S in einem Ni-freien Umfeld. Bei 900°C liegt die maximale L?slichkeit von Ni in idealem Pd-freien “Cooperit” bei 3.1 Atomprozent und der Pd-Gehalt in Ni-freien “Cooperit” liegt bei maximal 12.5 Atomprozent. Die Zusammensetzung des “Braggits” variiert zwischen Pt0.59Pd0.29Ni0.12S und Pd0.89Ni0.08S in einem Ni-ges?ttigten und zwischen Pt0.59Pd0.40S und PdS in einem Ni-freien Umfeld. Der Nickelgehalt in “Braggit” und “Vysotskit” nimmt mit zunehmendem Pt/Pd Verh?ltnis zu und ist bei 900°C h?her als bei 1000°C. Ein Vergleich der experimentellen Trends mit Cooperit, Braggit und Vysotskit Analysen aus der Literatur weist auf eine Hochtemperaturbildung der Pt-Pd-Ni Sulfide in Seifenlagerst?tten hin, wenn man von Nickels?ttigung ausgeht.
Received October 1, 1998;/revised version accepted September 7, 1999 相似文献
2.
Damien Becker 《Swiss Journal of Geoscience》2009,102(3):489-504
Earliest rhinocerotoids from Switzerland are reviewed on the basis of dental remains from the earliest Oligocene north-central
Jura Molasse localities of Bressaucourt (MP21/22) and Kleinblauen (top MP22). The record in Bressaucourt is restricted to
Ronzotherium and Cadurcotherium, representing Switzerland’s oldest, well-dated post-“Grande Coupure” large mammal association, the only occurrence of Cadurcotherium, and the earliest occurrence of rhinocerotoids in Switzerland. The correlation with high-resolution stratigraphy of this
locality permitted a dating of the fauna to ca. 32.6 Ma, less than a million years after the “Grande Coupure” event. The rhinocerotoids
of Kleinblauen are represented by Epiaceratherium, Ronzotherium and Eggysodon. With the presence of Plagiolophus ministri, they are the only well-dated Swiss post-“Grande Coupure” large mammal assemblage with the persistence of an endemic pre-“Grande
Coupure” taxon. Moreover, the coexistence of Epiaceratherium magnum and E. aff. magnum could indicate a new speciation within the Epiaceratherium lineage around the top of MP22. The rhinocerotoid associations of Bressaucourt with Ronzotherium – Cadurcotherium on the western side of the southernmost Rhine Graben area, and Kleinblauen with Epiaceratherium – Ronzotherium – Eggysodon on the eastern side, respectively, reveal a possible environmental barrier constituted by the Early Oligocene Rhenish sea
and its eventual connection with the Perialpine sea. This one could have separated an arid area in central-eastern France
from a humid area in Switzerland and Germany. These results, combined with the repartition of similar rhinocerotoid associations
in Western Europe, also give new insights into an alternative earliest Oligocene dispersal route of rhinocerotoids from Asia
towards Western Europe via North Italy. 相似文献
3.
Chemodynamics of trace metal fractions in surface sediments of the Pandoh Lake,Lesser Himalaya,India
Anshumali A. L. Ramanathan Gurdeep Singh Gurmeet Singh Rajesh Ranjan Parijat Tripathi 《Environmental Geology》2009,57(8):1865-1879
The seasonal variation in the trace metals’ concentrations (Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) were investigated in surface
sediments of the Pandoh Lake. The horizontal distribution of TC, TN, and TP reflects spatial and temporal differences in sedimentary
organic production. The chemical sequential extraction of heavy metals was carried out by seven-step fractionation scheme
(Leleyter and Probst in Int J Environ Chem 73:109–128, 1999). The significant concentrations of Ni and Cd were associated with “water soluble (Eua)” fraction in the monsoon and winter,
respectively, while “exchangeable (Exch)” and “carbonate-bound (Carb)” fractions for Ni and Cd were abundant in winter and
summer. The Cd, Cu, and Pb associated with “Exch” fraction in the summer season support their availability on exchange sites
due to oxidized nature of surface sediments. Enrichment of Co, Fe, Mn, and Zn in “AFeO” fraction showed poor bioavailability,
while Cd, Cu, and Mn in the monsoon, Co in the winter and summer, and Zn in the winter season showed significant “organically
bound (Org)” fraction. The ANOVA was significant for chemical fractions of trace elements except “Carb” fraction of Pb and
Zn and “CFeO” fraction of Pb. Factor analysis revealed that the “Eua”, “Exch”, and “Carb” fractions together control the metal
enrichment of “MnO”, “AFeO”, and “CFeO” fractions in the summer season. 相似文献
4.
Indrajit Pal Sankar Kumar Nath Khemraj Shukla Dilip Kumar Pal Abhishek Raj K. K. S. Thingbaijam B. K. Bansal 《Natural Hazards》2008,45(3):333-377
An earthquake hazard zonation map of Sikkim Himalaya is prepared using eight thematic layers namely Geology (GE), Soil Site
Class (SO), Slope (SL), Landslide (LS), Rock Outcrop (RO), Frequency–Wavenumber (F–K) simulated Peak Ground Acceleration (PGA),
Predominant Frequency (PF), and Site Response (SR) at predominant frequencies using Geographic Information System (GIS). This
necessitates a large scale seismicity analysis for seismic source zone classification and estimation of maximum earthquake
magnitude or maximum credible earthquake to be used as a scenario earthquake for a deterministic or quasi-probabilistic seismic
scenario generation. The International Seismological Center (ISC) and Global Centroid Moment Tensor (GCMT) catalogues have
been used in the present analysis. Combining b-value, fractal correlation dimension (Dc) of the epicenters and the underlying tectonic framework, four seismic source zones
are classified in the northeast Indian region. Maximum Earthquake of M
W 8.3 is estimated for the Eastern Himalayan Zone (EHZ) and is used to generate the seismic scenario of the region. The Geohazard
map is obtained through the integration of the geological and geomorphological themes namely GE, SO, SL, LS, and RO following
a pair-wise comparison in an Analytical Hierarchy Process (AHP). Detail analysis of SR at all the recording stations by receiver
function technique is performed using 80 significant events recorded by the Sikkim Strong Motion Array (SSMA). The ground
motion synthesis is performed using F–K integration and the corresponding PGA has been estimated using random vibration theory
(RVT). Testing for earthquakes of magnitude greater than M
W 5, a few cases presented here, establishes the efficacy and robustness of the F–K simulation algorithm. The geohazard coverage
is overlaid and sequentially integrated with PGA, PF, and SR vector layers, in order to evolve the ultimate earthquake hazard
microzonation coverage of the territory. Earthquake Hazard Index (EHI) quantitatively classifies the terrain into six hazard
levels, while five classes could be identified following the Bureau of Indian Standards (BIS) PGA nomenclature for the seismic
zonation of India. EHI is found to vary between 0.15 to 0.83 quantitatively classifying the terrain into six hazard levels
as “Low” corresponding to BIS Zone II, “Moderate” corresponding to BIS Zone III, “Moderately High” belonging to BIS Zone IV,
“High” corresponding to BIS Zone V(A), “Very High” and “Severe” with new BIS zones to Zone V(B) and V(C) respectively. 相似文献
5.
We use an analytical model for the post-injection spreading of a plume of CO2 in a saline aquifer under the action of buoyancy and capillary trapping to show that the spreading behavior is at all times
strongly influenced by the shape of the plume at the end of the injection period. We solve the spreading equation numerically
and confirm that, at late times, the volume of mobile CO2 is given by existing asymptotic analytical solutions. The key parameters governing plume spreading are the mobility ratio,
M, and the capillary trapping number, Γ—the former sets the shape of the plume at the end of the injection period, and the latter sets the amount of trapping. As
a quantitative measure of the dependence of the spreading behavior on the initial shape, we use a volume ratio. That is, we
evolve the plume from a true end-of-injection initial shape and also from an idealized “step” initial shape, and we take the
ratio of these mobile plume volumes in the asymptotic regime. We find that this volume ratio is a power-law in M, where the exponent is governed exclusively by Γ. For conditions that are representative of geologic CO2 sequestration, the ratio of mobile volumes between “true” and “step” initial plume shapes can be 50% or higher. 相似文献
6.
The probability of landslide volume, V
L
, is a key parameter in the quantitative hazard analysis. Several studies have demonstrated that the non-cumulative probability
density, p(V
L
), of landslide volumes obeys almost invariably a negative power law scaling of p(V
L
) for landslides exceeding a threshold volume and a roll-over of small landslides. Some researchers attributed the observed
roll-over to under-sampling of data, while others relate it to a geo-morphological (physical) property of landslides. We analyzed
15 sets of a complete landslide inventory containing shallow debris slides (2 ≤ V
L
≤ 3.6 × 103 m3) with sources located on cut slopes along a 17-km-long railroad corridor. The 15 datasets belong to individual years from
1992 to 2007. We obtained the non-cumulative probability densities of landslide volumes for each dataset and analyzed the
distribution pattern. The results indicate that for some datasets the probability density exhibits a negative power law distribution
for all ranges of volume, while for others, the negative power scaling exists only for a volume greater than 10 m3, with scaling exponent β varying between 0.96 and 2.4. When the spatial distribution of landslides were analyzed in relation to the terrain condition
and triggering rainfall, we observed that the number of landslides and the range and the frequency of volumes vary according
to the changes in local terrain condition and the amount of rainfall that trigger landslides. We conclude that the probability
density distribution of landslide volumes has a dependency on the local morphology and rainfall intensity and the deviation
of small landslides from power law, i.e., the roll-over is a “real effect” and not an artifact due to sampling discrepancies. 相似文献
7.
Validating a Tsunami Vulnerability Assessment Model (the PTVA Model) Using Field Data from the 2004 Indian Ocean Tsunami 总被引:2,自引:1,他引:2
The “PTVAM” tsunami vulnerability assessment model [Papathoma and Dominey-Howes: 2003, Nat. Hazards Earth Syst. Sci. 3, 733–744; Papathoma et al.: 2003, Nat. Hazards Earth Syst. Sci. 3, 377–389], like all models, requires validation. We use the results from post-tsunami surveys in the Maldives following the
December 26, 2004 Indian Ocean tsunami to ‘evaluate’ the appropriateness of the PTVAM attributes to understanding spatial
and temporal vulnerability to tsunami damage and loss. We find that some of the PTVAM attributes are significantly important
and others moderately important to understanding and assessing vulnerability. Some attributes require further investigation.
Based upon the ground-truth data, we make several modifications to the model framework and propose a revised version of the
PTVAM (PTVAM 2). 相似文献
8.
N. P. Laverov S. V. Yudintsev T. S. Livshits S. V. Stefanovsky A. N. Lukinykh R. C. Ewing 《Geochemistry International》2010,48(1):1-14
Complex oxides of the pyrochlore (space groups Fd3m, [8]A2
[6]B2O7) and garnet (Ia3d, [8]A3
[6]B2
[4]T3O12) structures (“A” = Ca2+, Ln3+/4+, An3+/4+; “B” = (Ti, Sn, Hf, and Zr)4+ in pyrochlore, and Al3+, Ga3+, and Fe3+ in garnet alone; “T” = (Al3+, Ga3+, and Fe3+) are promising matrices for actinide-bearing wastes. In order to identify optimal compositions of these phases, their isomorphic
capacity with respect to REE, actinides, and other components of wastes was examined. The long-term behavior of the matrix
at a repository was predicted based on data obtained on the behavior of pyrochlores and garnets under ion irradiation and
244Cm decay and on the determined leaching rates of REE from the matrices because of their interaction with aqueous solutions,
including that after amorphization. In order to propose efficient synthesis techniques, samples prepared with the use of various
methods were studied. The possibility of incorporating long-lived decay products of 99Tc into the crystalline matrices was analyzed. 相似文献
9.
Comparison of Mathematical Methods of Potential Modeling 总被引:1,自引:0,他引:1
Helmut Schaeben 《Mathematical Geosciences》2012,44(1):101-129
Various attempts are known to turn the “catalogue” of mineral deposit models compiled by Cox and Singer (1986) operational, and have initiated activities called “potential mapping”, “potential modeling”, or “targeting”. The common
ultimate objective is to estimate the probability for a given location that a mineralization of a given type occurred. The
mathematics range from “weights of evidence” and others featuring a Bayesian approach to logistic regression by maximum likelihood,
and include other realizations by means of fuzzy methods, genetic programming, and artificial neural nets. Once developed
and coded, applications are not restricted to mineral prospection and exploration but include any kind of occurrences and
their estimated probabilities, e.g., risk assessment of land slides and many others. 相似文献
10.
Timotej Verbovšek 《Environmental Geology》2008,53(6):1173-1182
Diagenetic effects upon the hydraulic parameters of dolomite aquifers were examined. Results indicate that dolomites affected
only by late (burial) diagenesis are economically more interesting to exploit than those formed first by early and then also
affected by late diagenesis, as the values of most studied hydraulic parameters (transmissivity, specific capacity, linearized
specific capacity and maximum yields) are higher in the former group. Data were collected from the hydrogeological reports
of 298 wells in dolomites from Permian to Cretaceous age in Slovenia, classified in a relational hydrogeological database
and analyzed by statistical methods. The studied parameters are hydraulic conductivity K, transmissivity T, specific capacity q (=Q/s), linearized specific capacity Ql (=q/d) and maximum yields Q
max. Values of the studied parameters are distributed log-normally according to most normality tests and span several orders
of magnitude. Statistical tests show significant differences between the “late” and “early + late” groups for parameters q, Ql and T, and non-significant differences for K and Q
max. 相似文献
11.
An incomplete skull of the leptonectid ichthyosaur Eurhinosaurus longirostris found in the Rietheim Member (previously “Posidonienschiefer”; Toarcian, Early Jurassic) of Staffelegg, Canton Aargau, is
the first record from Switzerland of this taxon and supports the status of Eurhinosaurus longirostris as a palaeobiogeographic very widespread ichthyosaur species in the Early Toarcian of Western Europe. Being from either the
Bifrons or Variabilis zone, it is one of the youngest records of Eurhinosaurus and one of the few diagnostic ichthyosaur finds from this time interval. The partial skull is well articulated and preserved
three-dimensionally in a carbonate concretion. Both the mode of preservation of the ichthyosaur and an associated ammonoid
(Catacoeloceras raquinianum) provided the age of the concretion, which had been collected from scree. Taphocoenosis and taphonomy show the C. raquinianum to be one of few non re-worked fossils recorded from the Early to Late Toarcian boundary (Bifrons/Variabilis zone) of northern
Switzerland in general and of this ammonite species in particular. The Toarcian section at Staffelegg differs from other localities
where strata of the same age are exposed with respect to facies variations of the Rietheim Member (previously “Posidonienschiefer”,
Early Toarcian) and the extraordinarily high thickness of the Gross Wolf Member (previously “Jurensis-Mergel”, Late Toarcian). 相似文献
12.
Strontium and oxygen isotopic variations in Mesozoic and Tertiary plutons of central Idaho 总被引:2,自引:0,他引:2
Regional variations in initial 87Sr/86Sr ratios (r
i) of Mesozoic plutons in central Idaho locate the edge of Precambrian continental crust at the boundary between the late Paleozoic-Mesozoic
accreted terranes and Precambrian sialic crust in western Idaho. The r
i values increase abruptly but continuously from less than 0.704 in the accreted terranes to greater than 0.708 across a narrow,
5 to 15 km zone, characterized by elongate, lens-shaped, highly deformed plutons and schistose metasedimentary and metavolcanic
units. The chemical and petrologic character of the plutons changes concomitantly from ocean-arc-type, diorite-tonalite-trondhjemite
units to a weakly peraluminous, calcic to calcalkalic tonalite-granodiorite-granite suite (the Idaho batholith). Plutons in
both suites yield Late Cretaceous ages, but Permian through Early Cretaceous bodies are confined to the accreted terranes
and early Tertiary intrusions are restricted to areas underlain by Precambrian crust. The two major terranes were juxtaposed
between 75 and 130 m.y. ago, probably between 80 and 95 m.y.
Oxygen and strontium isotopic ratios and Rb and Sr concentrations of the plutonic rocks document a significant upper-crustal
contribution to the magmas that intrude Precambrian crust. Magmas intruding the arc terranes were derived from the upper mantle/subducted
oceanic lithosphere and may have been modified by anatexis of earlier island-arc volcanic and sedimentary units.
Plutons near the edge of Precambrian sialic crust represent simple mixtures of the Precambrian wall-rocks with melts derived
from the upper mantle or subducted oceanic lithosphere with r
i of 0.7035. Rb/Sr varies linearly with r
i, producing “pseudoisochrons” with apparent “ages” close to the age of the wall rocks. Measured δ
18O values of the wall rocks are less than those required for the assimilated end-member by Sr-O covariation in the plutons,
however, indicating that wall-rock δ
18O was reduced significantly by exchange with circulating fluids. Metasedimentary rocks of the Belt Supergroup are similarly
affected near the batholith, documenting a systematic depletion in 18O as much as 50 km from the margin of the batholith.
Plutons of the Bitterroot lobe of the Idaho batholith are remote from the accreted terranes and represent mixtures of Precambrian
wall-rocks with melts dominated by continental lower crust (r
i>0.708) rather than mantle. “Pseudoisochrons” resulting from these data are actually mixing lines that yield apparent “ages”
less than the true age of the wall rocks and meaningless “ri”. Assimilation/ fractional-crystallization models permit only insignificant amounts of crystal fractionation during anatexis
and mixing for the majority of plutons of the region. 相似文献
13.
Joseph Palis 《GeoJournal》2009,74(3):227-234
My paper aims to ask what space characterizes the various constructs of orientalism and othering in the early short films
of Thomas Edison. Using Lefebvre’s concept that social space “subsumes things produced, and encompasses their interrelationships
in their coexistence and simultaneity” in these early shorts, I will look at three Biograph actualities found at the Library
of Congress-American Memory page to show how space is manifested and negotiated onscreen. I will examine Edison’s “Filipinos
Retreat From Trenches”, “Capture of Trenches at Candaba” and “U.S. Troops and Red Cross in the Trenches Before Caloocan” which
were all released in 1899. These reenacted short films were shot during the tumultuous years of the Spanish-American War.
In the Biograph shorts, the privileged positions of both Spanish and American forces in relation to the annexation of a foreign
land in world history books is indicative of the tendency to de-emphasize the contribution of the native population in the
war. Manthia Diawara has said that “space is related to power and powerlessness, insofar as those who occupy the center of
the screen are usually more powerful than those in the background or completely absent from the screen.” The spatial hierarchies
and spatially situated images in Edison’s short films show how historically configured power relations encrypted oppression
to its external “others” through the cinematic apparatus.
相似文献
Joseph PalisEmail: |
14.
Hualing Wei Nianqiao Fang Xuan Ding Lanshi Nie Xiuming Liu 《Frontiers of Earth Science》2008,2(2):162-169
This paper presents pelagic records of planktic foraminifera, as well as data of stable isotope stratigraphy and carbonate
stratigraphy since 3.5 Ma B.P. from site ODP758 in the Ninetyeast Ridge of the Indian Ocean. Based on these data, manifestations
and related mechanisms of major tectonic and environmental events such as the rapid uplift of the Himalaya Mountains, “middle
Pleistocene climatic transition” and “mid-Brunhes dissolution event” in the region are discussed. According to the analysis
and comparison of various indices and changes in terms of foraminifera assemblage, paleotemperature, paleosalinity and themocline
from site ODP758, the authors deduce that the paleoclimatic changes might correlate with the mid-Pleistocene transition at
1.4–1.7 Ma B.P. The changes of CaCO3, mass accumulation rates (MAR) of CaCO3 and non- CaCO3 MAR indicate that the loaded terrigenous sediments increased at 1.7 Ma, which is in agreement with the uplift history of
the Qinghai-Tibet plateau as shown by the available data. The last two changes coincide with the uplift of the Qinghai-Tibet
plateau, hence they are called “Qinghai-Tibet movement” (1.7 Ma), and the “Kunlun-Yellow River movement” (1.2–0.6 Ma). The
changes of the CaCO3 content, coarse fraction (> 150 μm) content and planktonic foraminifera biostratigraphy show that strong dissolution of abyssal
CaCO3 occurred in the study region during 0.5–0.4 Ma. The event was consistent with the “mid-Brunhes dissolution event” in the
sedimentary records of the Atlantic Ocean, Pacific Ocean, Indian Ocean and Nansha sea area of the South China Sea.
__________
Translated from Geological Bulletin of China, 2007, 26(12): 1627–1632 [译自: 地质通报] 相似文献
15.
Martin R. Lee Kim A. Waldron I. Parsons William L. Brown 《Contributions to Mineralogy and Petrology》1997,127(3):291-304
Braid microperthitic alkali feldspars in the Klokken, South Greenland and Coldwell, Ontario syenite intrusions have bulk-compositional
variations along grain boundaries called pleated rims. These, together with vein microperthites in aplites which cross-cut the syenites, have been investigated by SEM and TEM.
We distinguish two main types of pleated rims, “arched ” and “parallel-sided ”, consisting of alternating Ab- and Or-rich areas on (001), which are 0.5–300 μm in length normal to (010) and 0.2–20 μm
in width along (010). The smallest pleats, which occur on intracrystalline boundaries in Klokken feldspars, are fully coherent
and composed of low albite and low microcline. Above the heads of some of the coarser pleats, braid microperthite grades into
a film crypto- and micro-perthite and antiperthite microtexture called a “transitional zone” containing roughly planar lamellae of low albite and tweed orthoclase. During pleat development, local alternating volumes
form in which the proportions of the phases differ ( phase separation) and the morphology of the intergrowths changes from braided to straight in response to this change in local bulk composition.
Straightening is also accompanied by transformation of low microcline to tweed orthoclase. The coarsest pleats, which occur
along grain boundaries in feldspars from the Coldwell syenite, are semi- or in-coherent and have a thick coherent and semicoherent
transitional zone. Coarsening of pleats and development of the transitional zone has been facilitated by diffusion of “water”
into grain interiors. In many cases, pleated rims have suffered deuteric alteration, by dissolution–reprecipitation processes,
through the action of a water-rich fluid from the grain boundary, in which tweed orthoclase was transformed into irregular
microcline and micropores developed. Vein microperthites in aplites from Klokken, and by extension the vein microperthites
almost universal in most alkali granites, are interpreted to have formed by propagation of pleat heads across entire crystals
during pervasive interaction with water.
Received: 10 June 1996 / Accepted: 12 December 1996 相似文献
16.
Method for Quantification of Wear of Sheared Joint Walls Based on Surface Morphology 总被引:4,自引:2,他引:2
Roughness and wear evolution of three different joint wall surfaces were characterized using surface roughness and surface
wear parameters. Parameters were defined by considering the two components of morphology: waviness (“primary” roughness) and
surface roughness (“secondary” roughness). Two surface roughness parameters are proposed: joint interface (or single wall)
specific surface roughness coefficient SR
s
(0 ≤ SR
s
≤ 1) for quantifying the amount of “pure” roughness (or specific roughness), and degree of joint interface (or single wall)
relative surface roughness DR
r
(0 ≤ DR
r
≤ 0.5). Two further parameters are also proposed in order to quantify the wear of wall surface: joint interface (or single
wall) surface wear coefficient Λinterface, and the degree of joint interface (or single wall) surface wear D
w(interface). The three test specimens were: man-made granite joints with hammered surfaces, man-made mortar joints with corrugated surfaces,
and mortar joints prepared from natural rough and undulated schist joint replicas. Shearing under monotonic and cyclic shearing
was performed using a computer-controlled bidirectional and biaxial shear apparatus. Joint surface data were measured using
a noncontact laser sensor profilometer prior to and after each shear test. Calculation of specific surface roughness coefficient
SR
s
, and degree of surface wear D
w
, indicated that the hammered joint interface with predominant interlocking wears much more (>90%) than the corrugated (27%)
and the rough and undulated (23%) joint interfaces having localized interlocking points. The proposed method was also successfully
linked to the classical wear theory. 相似文献
17.
Jishu-bosai-soshiki, or Jishubo for short, with a literal meaning of “autonomous organization for disaster reduction”, is a neighborhood association for
disaster preparedness and rescue activity. In this paper, the role of Jishubo in the context of participatory disaster management in Japan is discussed. Although the formation of Jishubo is not legally mandated, local governments exercise a great deal of persuasion on the inhabitants of their community to organize
and participate in disaster management activities. Therefore, participants in Jishubo activities tend to be guided and mobilized with a soft touch by local governments rather than being truly self-motivated,
with the objective of reducing disaster risks in their residential areas. There have been several studies on community participatory
management conducted in a number of countries, including New Zealand, the USA and Europe, which will serve as a reference
in our study. However interesting, the cultural comparison of the “Western” and “Japanese” approaches to community disaster
management, is beyond the scope of this paper, the aim of which is to determine a case of community disaster management in
Japan. This paper addresses the background behind the development of Jishubo and discusses the uniqueness and limits of this softly mobilized participatory movement in Japan. Based on a case study in
Kishiwada City, Osaka, the motivations driving people to participate in disaster management activities organized for Jishubo members is examined. In conclusion, we derive some policy implications and suggest possible approaches for improving the
effectiveness of Jishubo and increasing the motivation of people to participate. We also propose that the roles of administrative bodies in Japan,
such as non-profit organizations, be better incorporated into community’s participatory disaster reduction activities. 相似文献
18.
During the late Early Cretaceous, the shallow-water domains of the western Tethys are characterized by the widespread deposition
of Urgonian-type carbonates rich in rudists, corals and other oligotrophic, shallow-marine organisms. In the Helvetic Alps,
the Urgonian occurrences have been dated by ammonite biostratigraphy as Late Barremian and Early Aptian. For the more proximal
occurrences in the western Swiss Jura, a recent age model based on bio-, chemo- and sequence stratigraphy has been proposed,
which allows for an improved correlation with the Helvetic counterparts. In order to corroborate the recently proposed age
model for the Jura, a set of well-preserved rhynchonellids collected from five different lithostratigraphical formations and
members (“Marnes bleues d’Hauterive”, “Marnes d’Uttins”, basal marly layers within the “Urgonien Jaune”, “Marnes de la Russille”,
“Urgonien Blanc”) has been analysed for its strontium–isotope ratios (87Sr/86Sr). In addition, K–Ar dating was performed on well-preserved glauconite grains from two different levels (“Marnes d’Uttins”
and a basal layer within the “Urgonien Jaune”). The correlation of the Sr–isotope data set with a belemnite-based, ammonite-calibrated
reference curve provides an age model which is coherent with recently published ages based on calcareous nannofossil biostratigraphy
and the correlation of trends in chemo- and sequence stratigraphy. K–Ar dating on well-preserved glauconite grains from the
“Marnes d’Uttins” and lowermost part of the “Urgonien Jaune” delivered ages of 127.5 ± 2.3 and 130.7 ± 2.6 Ma, respectively.
Whereas the age of the glauconitic level near the base of the “Urgonien Jaune” is chronostratigraphically meaningful, the
K–Ar age of the “Marnes d’Uttins” appears too young relative to the presently used time scale. This may be related to rejuvenation
of the K–Ar chronometer due to post-depositional Ar loss, most likely during hardground formation. The ages obtained here
confirm the Late Barremian age for the onset of the Urgonian platform, an age which is conform with ages obtained in the Helvetic
Alps and elsewhere along the northern Tethyan margin. 相似文献
19.
H. L. Vacher Larry D. Seale Lee J. Florea Robert Brinkmann 《Environmental Geology》2008,54(5):1007-1015
We apply the logic of clinical epidemiological studies to quantify the accuracy of mapping sinkholes by ALSM in the 750 km2 Pinellas County. By such studies, a new diagnostic procedure is tested by comparing the diagnoses in a clinical trial to
diagnoses on the same patients from a more reliable, but more elaborate and expensive procedure (“gold standard” in epidemiological
context). A relatively undeveloped, 65 km2 focus area where we have aerial photographs that are effectively contemporaneous with the ALSM flights serves as the “clinical
trial”. The xy-locations in the focus area are the “patients” in the trial. The “diagnostic test” for having “sinkhole disease” is inclusion
in a database of sinkhole polygons delimited by ALSM contours (“ALSM-alone”), as detailed in Part 1. The standard of comparison
(“gold standard” would be an overstatement in the absence of geophysical testing) is inclusion in a database of sinkhole outlines
derived by best judgment of conjunctive interpretation of ALSM and aerial photography. GIS intersections that indicate the
sensitivity and specificity of the test (ALSM-alone) are 43 and 98.3%, respectively, and, in the focus area where the prevalence
of “sinkhole disease” is 4.7%, the positive and negative predictive values are 55.5 and 97.2%, respectively. Over much of
the rest of the county, where only the test can be applied, the prevalence of sinkholes is sufficiently small that it cannot
be determined to be any different from zero given the paucity of interpreted sinkholes (positive diagnoses) and the low specificity
of the test method. The conclusion, therefore, is that contemporaneous aerial photography is essential to compile an ALSM-derived
database that aims to state that the given xy-points lay inside or outside of topographic depressions in the covered karst of west-central Florida. 相似文献
20.
Wu Chonglong Li Shaohu Wang Genfa Liu Gang Kong Chunfang 《Frontiers of Earth Science》2007,1(1):97-105
An extra-thick high-quality brown coal was found to have accumulated in the Xianfeng basin in Yunnan Province, China. There
are also abundant sedimentary marks of allochthonous genesis in the extra-thick coalbeds. These genesis indicators reveal
a new submodel about allochthonous accumulation, which is: the long-distance river transportation of detrital plant and inorganic
matter → the sedimentation of detrital plant fan delta + the hypautochthony accumulation of local lakeshore swamp peat → the
autochthonous accumulation of local lacustrine peat + the sedimentation of fine inorganic matter → the mixing and transportation
by flood current or weak storm flow or underwater gravity flow → the mechanical differentiation and their resedimentation
between detrital plant and inorganic matter. This submodel can be called “the double accumulation of lacustrine detrital plant
fan delta and underwater gravity flow” or “Xianfeng submodel”, which supplements the “allochthonous-hypautochthony lacustrine
combination accumulation model” of the extra-thick coalbeds. The combination accumulation model is based on the Fuxin submodel
and Fushun submodel in the Chinese Mesozoic and Cenozoic intarcontinental fault basin.
Translated from Acta Sedimentologica Sinica, 2006, 24(1): 1–9 [译自: 沉积学报] 相似文献