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181.
Summary The effect of secular sea level variations on coastal levelling nets was considered for some parts of the North West European Lowlands levelling. On neglecting local geological influences a simplified global model was used for treating the following problems: (1) Magnitude of secular tilt effects in NWELL due to possible sea level variations; (2) Levelling errors due to sea tide loadings.  相似文献   
182.
125 whole rock samples from the productive Marysville, Montana, granodiorite and the surrounding metamorphic rocks were analyzed by neutron activation analysis for gold and silver, and by atomic absorption for copper, lead and zinc. In the vicinity of known gold veins, anomalous values for gold and silver were found in both types of bedrock. Anomalies for the base metals were much less pronounced. The results indicate that systematic analysis of igneous bodies could be useful in exploration for hydrothermal ore deposits.
Zusammenfassung 125 Gesteinsproben des sogenannten produktiven Granodiorits in Marysville (Montana) wurden durch Neutronenaktivierungsanalyse auf Gold und Silber und mittels Atomabsorptionsanalyse auf Kupfer, Blei und Zink analysiert. In der Nähe bekannter Goldadern wurden in beiden Gesteinsarten ungewöhnlich hohe Gold- und Silber-Werte gefunden. Anomale Werte für Kupfer, Blei und Zink waren seltener. Die Ergebnisse zeigen, daß eine systematische Untersuchung magmatischer Gesteinskomplexe bei der Suche nach hydrothermalen Erzlagerstätten von Nutzen sein kann.
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183.
Shabogamo gabbro, an olivine gabbro, intrudes the metamorphosed sedimentary rocks in the Wabush Lake map area, southern part of the Labrador geosyncline. In close spatial relation to this intrusive is an amphibolite schist that appears conformable with these meta-sediments. Field evidence is by itself insufficient to demonstrate whether this amphibolite schist is a metamorphosed sediment or whether it is genetically related to this olivine gabbro. Since large amphibolite schist bands occur in the Smallwood Mine, determination of the origin and relation of the amphibolite schist to the olivine gabbro is of special importance because this will determine ore potential at depth in this mine.Initial ratios of Sr87/Sr86 (0.704±0.001) in these two rock types are singularly not conclusive to demonstrate a common origin. Until recently, geologists associated the Shabogamo gabbro with igneous activities of the Grenville orogeny, but a minimum age of 1,600±130 m. y. of biotite in this intrusive shows that it should be associated with an earlier orogeny. Moreover the minimum biotite age of 1,050±140 m. y. of the amphibolite schist also approximates the time since the Grenville orogeny in this area.On the strength of all investigations on these two rock types, it is concluded that the amphibolite schist is a metamorphic derivative of the olivine gabbro.
Zusammenfassung Durch geologische Felduntersuchungen ist es nicht möglich, eine genetische Verwandtschaft zwischen einem Amphibolitschiefer und einem Olivingabbro im südlichen Labrador-Trog (Wabush Lake) festzustellen.Da Amphibolitschiefer-BÄnder auch in der Smallwood Mine vorkommen, ist es von ökonomischer Bedeutung, festzustellen, ob beide Gesteinsarten genetisch verwandt sind oder ob die Schiefer sedimentÄrer Herkunft sind. Im ersten Fall könnte diese Annahme Erzreserven im Untertageabbau vermindern. Im zweiten Fall — also einer syngenetischen Ablagerung mit der Eisenformation — wÄre der Amphibolitschiefer viel Älter als der Olivingabbro, wobei sich das Problem der Erzreserven anders stellt, da die Smallwood Mine in einer Synklinale liegt.Ein Ergebnis dieser Forschung deutet an, da\ die IsotopenverhÄltnisse (Sr87/ Sr86: 0,704±0,001 Gesamtgestein in beiden Gesteinsarten) allein nicht die Felduntersuchungen bekrÄftigen oder entkrÄften können. Zugleich ergibt das Alter des Biotit im Amphibolitschiefer einen unteren Grenzwert der Grenville Orogenese von 1,050±140 Millionen Jahren und das Alter des Biotit im Olivingabbro einen unteren Grenzwert seiner Intrusion von 1,600±130 Millionen Jahren in diesem Gebiet.Die Schlu\folgerungen aus den Ergebnissen dieser Untersuchung laufen darauf hinaus, da\ der Amphibolitschiefer ein metamorphes Produkt aus dem Olivingabbro ist.

Résumé Le gabbro Shabogamo de la région du lac Wabush a envahi les roches métasédimentaires de la fosse du Labrador. Un schiste à amphibole, l'une des gangues de la mine de fer Smallwood, a une étroite association spatiale avec cet intrusif mais semble interstratifié avec les métasédiments. Cependant seules les relations de terrain ne peuvent permettre de démontrer si ce schiste est un métasédiment ou s'il est un facies altéré du gabbro à olivine. L'origine du schiste amphibolitique est importante à reconnaÎtre puisqu'elle permettra de prédire le potentiel économique en profondeur de l'exploitation.Contrairement à ce qui avait été conclu précédemment, le gabbro Shabogamo n'a pas été mis en place durant l'orogénie Grenville. En effet le rapport isotopique Sr87/Sr86 (0.704±0.001) de la biotite indique que le gabbro a un âge minimum de 1,600±130 millions d'années. Par contre la biotite du schiste à amphibole donne à la roche un âge de 1,050±140 millions d'années. De plus, l'analyse pétrographique et chimique des deux roches indique qu'elles sont génétiquement reliées. On croit donc que le gabbro Shabogamo appartient probablement au système orogénique Hudsonien mais qu'il fut métamorphisé localement en schiste amphibolitique durant l'orogénie Grenville. Il faudra alors s'attendre, à la mine Smallwood, à une baisse considérable du tonnage du minerai avec la profondeur.

- — Wabush Lake — - .. . Smallwood, - , . . -, . . , , , Smallwood . , Sr87/Sr86: 0,704±0,001 , . (1,050±140 ), - 1,600±130 . , -.
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184.
Vorwort     
Ohne Zusammenfassung  相似文献   
185.
Generally, oxidative regeneration of phosphate from anoxic sediments is by microbially mediated sulfate reduction processes. Stoichiometric modelling of such reactions takes into consideration varying proportions of ‘decomposable’ organically bound P to account for the ratios among nutrients in depth-concentration profiles of near-surface sediments. New results of interstitial water composition from sediments underlying the water masses influenced by coastal upwelling of the eastern boundary current system off Peru indicate that dissolution of phosphatic fish debris represents a mechanism for remineralization of phosphate comparable to or larger in magnitude than that by oxidative regeneration of organically bound P.Dissolved interstitial phosphate from fish debris is revealed by an excess amount of phosphate over that predicted from a simple stoichiometric oxidative regeneration model and by anomalously high dissolved interstitial fluoride concentrations. Phosphate flux estimates based on diffusion from the sediment suggest that this mechanism may generate up to 10% of the nutrient pool in the waters of the Peru undercurrent. Partitioning of P among the two sources reveals further that fish debris phosphate is about four times more important than organically bound P in nutrient generation from sediments of the Peru continental margin. Not only does this mechanism of regeneration affect the nutrient cycling but may also control widespread phosphorite formation in this area.  相似文献   
186.
Chow  Jun Kang  Wang  Yu-Hsing  Lui  Hoi Lun  Huang  Erwin 《Acta Geotechnica》2020,15(9):2665-2680

In this study, the U-oedometer, a novel modified oedometer cell equipped with tailor-made needle probes, is developed to easily and accurately measure the excess pore water pressure (\(\Delta u\)) during 1D consolidation tests and to determine the coefficient of consolidation (\(c_{\text{v}}\)). The 3D printing technique is applied to make simple yet robust modifications to the conventional oedometer cell for facilitating the installation of the needle probes. The tailor-made needle probes are designed in such a way that the volumetric compliance is lowered to avoid measurement bias. Subsequently, the \(\Delta u\)-based method is proposed to determine \(c_{\text{v}}\), with the target of avoiding the intervention of human judgement and therefore minimizing the degree of subjectivity. The experimental results demonstrate that the measured \(\Delta u\) matches the theoretical values of the Terzaghi 1D consolidation theory, showing that the estimated \(c_{\text{v}}\) is sufficiently reliable. In addition to the determination of \(c_{\text{v}}\), the U-oedometer allows additional measurements of other soil properties during consolidation, including the coefficient of permeability (\(k\)) and the coefficient of earth pressure at rest (\(K_{0}\)). It is observed that k decreases with the reduction in void volume, due to the increase in the effective vertical stress (\(\sigma_{\text{v}}^{'}\)). Further, the secondary compression seems to be a continuation of the primary consolidation, where the soil sample continues to deform at a relatively slower rate, associated with the slight decrease in \(k\). A constant value of \(K_{0}\) is observed at any value of \(\sigma_{\text{v}}^{'}\) in the loading path, while during secondary compression, \(K_{0}\) slightly increases with time.

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187.
正The Qaidam Basin in the NE Tibetan Plateau has contributed the largest amount of potash in China.However,how the potash was formed has long been a subject of debate.Here we carried out a deep drilling  相似文献   
188.
More than two years of almost continuous polar motion data (obtained by reprocessing GPS-Observations) have been used to analyse the daily/subdaily variations in Earth rotation based on the complex Wavelet-Technique. Systematic and spectral analytical investigations of the degree of variability of periods including tidal have been carried out. Relevant indications of oceanic effects, besides atmospheric components, have been observed.  相似文献   
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