Phase relations in the system KAlSi3O8-NaAlSi 3O8 have been examined at pressures of 5–23 GPa and temperatures of 700–1200° C. KAlSi3O8 sanidine first dissociates into a mixture of wadeite-type K2Si4O9, kyanite and coesite at 6–7 GPa, which further recombines into KAlSi3O8 hollandite at 9–10 GPa. In contrast, NaAlSi3O8 hollandite is not stable at 800–1200° C near 23 GPa, where the mixture of jadeite plus stishovite directly changes into the assemblage of calcium ferrite-type NaAlSiO4 plus stishovite. Phase relations in the system KAlSi3O8-NaAlSi3O8 at 1000° C show that NaAlSi3O8 component gradually dissolves into hollandite with increasing pressure. The maximum solubility of NaAlSi3O8 in hollandite at 1000° C was about 40 mol% at 22.5 GPa, above which it decreases with pressure. Unit cell volume of the hollandite solid solution decreases with increasing NaAlSi3O8 component. The hollandite solid solution in this system may be an important candidate as a host mineral of K and Na in the uppermost lower mantle 相似文献
Boron samples from 40 fumarolic condensates from volcanoes in the Ryukyu arc (Satsuma Iwo-jima and Shiratori Iwo-yama) and the North-east Japan arc (Usu-shinzan, Showa-shinzan, Esan and Issaikyo-yama) all have ratios close to 4.07. Higher values, from 4.09 to 4.13, were only observed in condensates from volcanoes in the southernmost end of the North-east Japan arc (Nasu-dake), the northern part of the Izu-Bonin arc (Hakone), and the North Mariana arc (Ogasawara Iwo-jima). These higher values suggest geological interaction of the magmas with sea-water enriched in 11B. 相似文献
Experiments were conducted to estimate heaving pressures of saturated soil partially frozen in a closed system. Temperatures at both ends of a specimen were kept constant, i.e., positive at the top and negative at the bottom. When the overburden pressure P was maintained at a constant value, the pore-water pressure Pw, which showed a certain value before freezing, decreased gradually as freezing progressed, finally attaining a specific value, whereafter the specimen ceased taking water into it. The pressure difference between P and Pw, at this stage was defined as the upper limit of heaving pressure σu, which evidently depended on the temperature θc of the cooling end, in accordance with the relation: σu = −11.4 θc (kg/cm2)
It corresponds to the modified Clausius-Clapeyron's formula, which gives the freezingpoint depression of an ice—water system, where the pressure acting on the ice differs from that on the water. This is the same as the value obtained by Radd and Oertle (1973). It is considered, however, that, when θc lowers, the value of θu reaches finally a constant value smaller than the one obtained by the above equation. Denoted by σu max, it was defined as a maximum heaving pressure. The value of σu max depended on soil type. 相似文献
Analytical data compiled on nine Geological Survey of Japan (GSJ) reference samples, "Sedimentary rock series" received by February 1996 are reported. After excluding outliers and examining critically the analytical procedures employed, the data were evaluated statistically. Recommended or preferable values for fifteen major and sixty minor and trace elements are proposed. 相似文献
Abstract A radiolarian zonal scheme for the entire Jurassic and Lower Cretaceous using biostratigraphic data from both Japanese Island sections and the western Pacific seafloor is documented. The zonation is applicable to low and middle paleolatitude portions of the Paleo-Pacific ocean. Radiolarian bio-events such as the evolutionary first appearance biohorizon, first occurrence biohorizon, and last occurrence biohorizon were used to define zones. The 11 zones proposed are, in ascending order, Parahsuum simplum, Trillus elkhornensis, Laxtorum(?) jurassicum, Tricolocapsa plicarum, Tricolocapsa conexa, Stylocapsa(?) spiralis, Hsuum maxwelli, Pseudodictyomitra primitiva, Pseudodictyomitra carpatica, Cecrops sep-temporatus, and Acanthocircus carinatus zones. Preliminary age assignments for these zones are presented. 相似文献
This paper presents a numerical study of mitigation for liquefaction during earthquake loading. Analyses are carried out using
an effective stress based, fully coupled, hybrid, finite element-finite differences approach. The sandy soil behavior is described
by means of a cyclic elastoplastic constitutive model, which was developed within the framework of a nonlinear kinematic hardening
rule. In theory, the philosophies of mitigation for liquefaction can be summarized as two main concepts, i.e. prevention of
excess pore water pressure generation and reduction of liquefaction-induced deformations. This paper is primarily concerned
with the latter approach to liquefaction mitigation. Firstly, the numerical method and the analytical procedure are briefly
outlined. Subsequently, a case-history study, which includes a liquefaction mitigation technique of cement grouting for ground
improvement of a sluice gate, is conducted to illustrate the effectiveness of liquefaction countermeasures. Special emphasis
is given to the computed results of excess pore water pressures, displacements, and accelerations during the seismic excitation.
Generally, the distinctive patterns of seismic response are accurately reproduced by the numerical simulation. The proposed
numerical method is thus considered to capture the fundamental aspects of the problems investigated, and yields results for
design purposes. From the results in the case, excess pore water pressures eventually reach fully liquefied state under the
input earthquake loading and this cannot be prevented. However, liquefaction-induced lateral spreading of the foundation soils
can be effectively reduced by the liquefaction mitigation techniques.
An erratum to this article can be found at 相似文献
The paper presents a computationally efficient meta-modeling approach to spatially explicit uncertainty and sensitivity analysis in a cellular automata (CA) urban growth and land-use simulation model. The uncertainty and sensitivity of the model parameters are approximated using a meta-modeling method called polynomial chaos expansion (PCE). The parameter uncertainty and sensitivity measures obtained with PCE are compared with traditional Monte Carlo simulation results. The meta-modeling approach was found to reduce the number of model simulations necessary to arrive at stable sensitivity estimates. The quality of the results is comparable to the full-order modeling approach, which is computationally costly. The study shows that the meta-modeling approach can significantly reduce the computational effort of carrying out spatially explicit uncertainty and sensitivity analysis in the application of spatio-temporal models. 相似文献
Climate engineering has received increasing attention, but its discussion has remained on the sidelines of mainstream climate policy. The policy relevance of this previously exotic option is poised to rise because of the gap between the temperature goals of the Paris Agreement and slow global mitigation efforts. It is therefore crucial to understand the risks and benefits of the proposed schemes, and the social implications of policy choices. Assessment of the risks and benefits of solar geoengineering strongly depends on scenarios, but previous scenarios have not reflected the full range of social choices. In light of concerns over risks, a newer set of scenarios is desirable, which represents both uncertainties and social choices more fully. Borrowing and extending lessons from recent literature on the new community climate scenario process, we envision a possible scenario-building process that combines interdisciplinary scholarship with the involvement of stakeholders and citizens. The resultant scenarios would better characterize uncertainties of, and policy choices for, solar geoengineering, and foster critical appraisal of its risks and benefits. Such societal choices might include not only total ban and large-scale deployment, but also limited deployment, which has received less attention in the scenario literature. The interaction between scenario and governance research would be able to highlight the central issues at stake, including ethical, social, and political dimensions.
Key policy insights
A more comprehensive assessment of solar geoengineering is necessary to evaluate its risks and benefits, necessitating new scenario research
It is crucial to reflect the full span of policy choices and uncertainties with interdisciplinary collaboration in such scenarios
Such societal choices might include not only total ban and large-scale deployment, but also limited deployment, which has received less attention in the scenario literature
Participatory scenario research would enable incorporating the concerns and opinions of stakeholders and citizens in scenario creation
The Permian planktonic distribution is not well known, in contrast to other fossil distributions of nekton and benthos. Radiolaria are representative microfossils of plankton in the Permian palaeocean. This study compares both correlated radiolarian occurrences (Pseudotormentus De Wever et Caridroit and Quadriremis Nazarov et Ormiston) in literature data from the Pacific Rim and quantitative data from the Liuhuang and Gujingling sections in South China. Pseudotormentus distributions are concentrated in the Panthalassa, whereas Quadriremis occurrences are distributed over both the Panthalassa and the Palaeotethys. The uneven distribution of Pseudotormentus seems to have been controlled by a difference in the oceanic basins, indicating the presence of faunal differences in Permian planktonic microorganisms between the Panthalassa and the Palaeotethys. In other words, this study infers the provincialism of Permian planktonic microorganisms. The uneven distribution is explainable by a hypothesis that Pseudotormentus was strongly affected by a Panthalassan equatorial current. 相似文献