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131.
Marian?B.?HolnessEmail author R.?Grant?Cawthorn James?Roberts 《Contributions to Mineralogy and Petrology》2017,172(11-12):102
The thickness of the crystal mush on magma chamber floors can be constrained using the offset between the step-change in the median value of dihedral angles formed at the junctions between two grains of plagioclase and a grain of another phase (typically clinopyroxene, but also orthopyroxene and olivine) and the first appearance or disappearance of the liquidus phase associated with the step-change in median dihedral angle. We determined the mush thickness in the Rustenburg Layered Suite of the Bushveld Complex at clinopyroxene-in (in Lower Main Zone) and magnetite-in (in Upper Zone). We also examined an intermittent appearance of cumulus apatite in Upper Zone, using both the appearance and disappearance of cumulus apatite. In all cases, the mush thickness does not exceed 4 m. These values are consistent with field observations of a mechanically rigid mush at the bases of both magnetitite and chromitite layers overlying anorthosite. Mush thickness of the order of a few metres suggests that neither gravitationally-driven compaction nor compositional convection within the mush layer is likely to have been important processes during solidification: adcumulates in the Bushveld are most likely to have formed at the top of the mush during primary crystallisation. Similarly, it is unlikely either that migration of reactive liquids occurs through large stretches of stratigraphy, or that layering is formed by mechanisms other than primary accumulation. 相似文献
132.
133.
Marian Ivan 《Journal of Seismology》2011,15(2):317-328
Crustal thickness (CT) in Vrancea region (Romania) and adjacent area is investigated using 1294 S to P converted waves from
the Moho discontinuity. A total of 269 local earthquakes in the depth range 99.8 to 171.1 km and recorded by 76 permanent
and 46 temporary stations of the Romanian Seismological Network are used. Time difference between the converted wave and the
direct P phase is corrected to a first order for epicentral distance and for the errors in focal depth, being finally inverted
to CT. Greatest values for the Moho depth are observed for stations located in the Carpathians molasse foredeep and smaller
values are observed in the Southern part of the Moesian Platform, for stations in the eastern part of Moldavian (East-European)
Platform and in Dobrogea area, close to the Black Sea shoreline. In Vrancea epicentral area, an important CT variation is
observed, from 42 km at MLR and 41.8 km at SIR, stations placed in the south-western part of the epicentral area, to 30.9 km
at VRI, located above north-eastern part of the seismogenic volume. Stations CVO and OZU, placed in Transylvanian Basin in
the proximity of the epicentral area, have CT values of 32.1 and 24.1 km, respectively. The results seem to support that a
mantle delamination process is responsible for Vrancea intermediate depth seismicity. 相似文献
134.
Copper has two naturally occurring stable isotopes of masses 63 and 65 which can undergo mass dependent fractionation during various biotic and abiotic chemical reactions. These interactions and their resulting Cu isotope fractionations can be used to determine the mechanisms involved in the cycling of Cu in natural systems. In this study, Cu isotope changes were investigated at the organismal level in the metal-accumulating desert plant, Prosopis pubescens. Initial results suggest that the lighter Cu isotope was preferentially incorporated into the leaves of the plant, which may suggest that Cu was actively transported via intracellular proteins. The roots and stems show a smaller degree of Cu isotope fractionation and the direction and magnitude of the fractionations was dependent upon the levels of Cu exposure. Based on this and previous work with bacteria and yeast, a trend is emerging that suggests the lighter Cu isotope is preferentially incorporated into biological components, while the heavier Cu isotope tends to become enriched in aqueous solutions. In bacteria, plants and animals, intracellular Cu concentrations are strictly regulated via dozens of enzymes that can bind, transport, and store Cu. Many of these enzymes reduce Cu(II) to Cu(I). These initial results seem to fit into a broader picture of Cu isotope cycling in natural systems where oxidation/reduction reactions are fundamental in controlling the distributions of Cu isotopes. 相似文献
135.
Application of the Engineering-Geological Conditions in Land-Use Plans in the Petrvald Region(Czech Republic) 总被引:3,自引:0,他引:3
Marian MARSCHALKO I??k YILMAZ Martin BEDNARIK Karel KUBE?KA Tomá? BOUCHAL 《《地质学报》英文版》2013,87(1):272-285
The objective of this paper is to demonstrate necessity to inform relevant parties about engineering-geological conditions for various practical purposes,especially including appropriate land-use planning.However,the relationship between relevant geological information and the geological environment is vital for foundation engineering purposes,especially where demanding structures are involved.This information is most conveniently structured when accumulated information concerning engineering-geological zones is utilized.This necessarily includes knowledge of rock workability and also of the pre-Quaternary bedrock,and these characteristics were then related to the current built-up area and future development according to the land-use plans in a case study are from the Petrvald Region(Czech Republic).The geological environment of area has been severely influenced by anthropogenic effects of deep black coal mining.Results of this research showed that future development should be founded on spoil banks,dumps,and settling basins. According to the land-use plan,this zone occupies 44.9%of the area of interest,and its materials predominantly emanate from mining in the Ostrava-Karvina Coal District.For future foundation structures planned there,it is imperative to consult detailed engineering-geological study.However, attention to and reliance on this necessity is not reflected in the existing land-use plan. 相似文献
136.
Landslide hazard or susceptibility assessment is based on the selection of relevant factors which play a role on the slope instability, and it is assumed that landslides will occur at similar conditions to those in the past. The selected statistical method compares parametric maps with the landslide inventory map, and results are then extrapolated to the entire evaluated territory with a final product of landslide hazard or susceptibility map. Elements at risk are defined and analyzed in relation with landslide hazard, and their vulnerability is thus established. The landslide risk map presents risk scenarios and expected financial losses caused by landslides, and it utilizes prognoses and analyses arising from the landslide hazard map. However, especially the risk scenarios for future in a selected area have a significant importance, the literature generally consists of the landslide susceptibility assessment and papers which attempt to assess and construct the map of the landslide risk are not prevail. In the paper presented herein, landslide hazard and risk assessment using bivariate statistical analysis was applied in the landslide area between Hlohovec and Sered?? cities in the south-western Slovakia, and methodology for the risk assessment was explained in detail. 相似文献
137.
Evaluation of engineering-geological conditions for conurbation of Ostrava (Czech Republic) within GIS environment 总被引:4,自引:4,他引:0
The main aim of the presented study was to create a new type of engineering-geological maps for relative costs for foundation engineering. The newly proposed map in this paper can replace the formerly used maps of the suitability for foundation engineering which shows only the suitable and/or unsuitable sites and suggests the use of suitable areas for construction only. However, there are developed technologies that they can overcome the potential problems in unsuitable areas by relatively high costs. It means that unsuitable areas can also be used as construction areas. Therefore, the use of the newly proposed map of relative costs, which reflects the complexity of geo-factors by proportional category of larger, or smaller relative costs is satisfactory. Another part of this research was to assess various geo-factors (engineering-geological zones, workability of rocks, pre-Quaternary bedrock, flood land, radon hazard, mining subsidence and slope movements), which affect the foundation of future buildings. This study was carried out in the large industrial city of Ostrava in the Czech Republic with complicated engineering geological conditions and high anthropogenic influence factors including undermining. The use of complicated relationships is also generally difficult to be taken into account by the planners. Therefore, the use of the newly created synthetic map by planners is simple; even planners who are not geologists will be able to apply it easily. 相似文献
138.
Oksana Sytar Marian Brestic Abhay Kumar M. N. V. Prasad Nataliya Taran Iryna Smetanska 《洁净——土壤、空气、水》2013,41(11):1129-1137
In this study, Fagopyrum esculentum (common buckwheat) sprayed with nickel (Ni) (0, 0.5, 1.0, 3.0, and 5.0 mM) for different duration has been investigated for Ni accumulation, malondialdehyde (MDA), total phenolics, and phenolic acids. Ni accumulation significantly increased in dose‐dependent manner. Plants exposed for 72 h, showed visible damages as chlorosis and irreversible necrosis. The MDA and total phenolic contents increased at 24 h of Ni treatments. HPLC data revealed that phenolic acids are in good correlation with concentration and durations of treatments. After 24 and 48 h the contents of chlorogenic, p‐hydroxybenzoic, hesperetic, p‐anisic, and caffeic acids increased in Ni treated leaves. On the other hand, p‐hydroxybenzoic, hesperetic, p‐anisic, p‐coumaric, caffeic acids contents decreased after 72 h of Ni exposure. Vanillic and cinnamic acid followed same pattern and increased significantly at 3.0 and 5.0 mM after 48 h of Ni exposure. It may suggest that buckwheat can be possible hyperaccumulators of Ni, because of high Ni accumulation in tissues through foliar treatment. Furthermore, the analyzed phenolic acids have potential role as antioxidants, which provide tolerance to buckwheat against Ni treatment. 相似文献
139.
This study presents the first preliminary U–Pb zircon data on tin-bearing S-type granites from the Gemeric unit of the Western Carpathians (Slovakia). U–Pb single zircon dating controlled by cathodoluminescence suggests crystallization of the Gemeric granites during Permian to Early Triassic (303–241 Ma) time. Post-crystallization, low-temperature metamorphic overprint is reflected by partial Pb loss in zircons. These Gemeric granites are younger than the highly fractionated, S-type, tin- and rare-element-bearing leucogranites in the European Variscides. They may have resulted from partial melting, triggered by increased heat flow from the mantle below the continental crust, and most probably intruded during the post-collisional extension and initial rifting of the Variscan orogenic belt. During Alpine orogeny, the Gemeric granites were affected by a low-temperature deformation and metamorphism. 相似文献
140.
Infiltration in Soils with Fractal Permeability Distribution 总被引:1,自引:0,他引:1