Resource-based development in the Russian Far East: Problems and prospects     

Michael J. Bradshaw  Nicholas J. Lynn 《Geoforum》1998,29(4):375-392

The paper examines the prospects for resource-based development in the Russian Far East. It adopts a critical perspective on the potential for resource-based development by examining problems with Far East resource industries, specifically by looking at the experience of the other resource economies more generally. In particular, it highlights the new geo-economic context for resource development in the Far East of Russia as the world economy approaches the much touted, and now questioned, ‘Pacific Century’.  相似文献   

Gold in “primitive” Archaean volcanics     

C.R. Anhaeusser  K. Fritze  W.S. Fyfe  R.C.O. Gill 《Chemical Geology》1975,16(2):129-135

Gold concentrations have been determined by neutron activation in sixteen samples of komatiites and related rocks from Barberton, South Africa. All the rocks give Au values in the ranges 1–1.5 ppb with no evidence for anomalously high values in such old primitive igneous types. As the rocks are extensively hydrated, it is possible that Au has been leached from the rocks during later hydration processes.  相似文献   

Computer-composite mapping for geologists     

J. Nicholas van Driel 《Environmental Geology》1980,3(3):151-157

A computer program for overlaying maps has been tested and evaluated as a means for producing geologic derivative maps. Four maps of the Sugar House Quadrangle, Utah, were combined, using the Multi-Scale Data Analysis and Mapping Program, in a single composite map that shows the relative stability of the land surface during earthquakes. Computer-composite mapping can provide geologists with a powerful analytical tool and a flexible graphic display technique. Digitized map units can be shown singly, grouped with different units from the same map, or combined with units from other source maps to produce composite maps. The mapping program permits the user to assign various values to the map units and to specify symbology for the final map. Because of its flexible storage, easy manipulation, and capabilities of graphic output, the composite-mapping technique can readily be applied to mapping projects in sedimentary and crystalline terranes, as well as to maps showing mineral resource potential.  相似文献   

A diagnostic model using ashfall data to determine eruption characteristic and atmospheric conditions during a major volcanic event     

Joseph B. Knox  Nicholas M. Short 《Bulletin of Volcanology》1964,27(1):3-24

A model is developed for estimating location of a volcano relative to sample points in an associated ashfall, cloud height during eruption, and mean wind velocity during ash deposition. The ash deposit must cover a large area and have an elongate axis. The model appears to be applicable both to recent and to unobserved ashfalls in the past, provided adequate and representative ash samples are available. The opportunity to test the diagnostic model on volcanic ashfalls is limited by sparsity of the necessary input data. From more than 20 ashfalls described in the literature, the 1947 Hekla (Iceland) eruption is the only one which includes suitable particle size analyses taken from samples related to a well-defined axis. The application of the model to the Hekla ashfall is discussed.  相似文献   

The Ameralik dykes of West Greenland,the earliest known basaltic rocks intruding stable continental crust     

R.C.O. Gill  D. Bridgwater 《Earth and Planetary Science Letters》1976,29(2):276-282

The pre-3100 m.y. old Ameralik dykes from West Greenland show a range in primary composition from primitive low-K, low-Ti tholeiites virtually identical in composition to ridge basalts of modern ocean crust, to more differentiated basaltic rocks similar to some present-day continental tholeiites. Primary variations are distinguished from secondary metasomatism using REE patterns, Ni, Sr, Ti and Zr contents and Mg number as a guide to the stage of differentiation reached by a particular sample and comparing this to the amount of alkalis present. The chemistry of the dykes is compared to that of metabasalts from Archaean greenstone belts and the use of chemistry alone to distinguish the crustal environment under which Archaean basic rocks were formed is questioned.  相似文献   

Moon—An albite depleted giant Skaergaard?     

Surendra K. Saxena  Alan Benimoff  Nicholas E. Pingitore Jr. 《Contributions to Mineralogy and Petrology》1977,60(1):77-90

The chemical composition of 2188 terrestrial igneous rocks ranging from ultrabasic to granitic composition was analyzed statistically using the method of factor analysis (principal components). The resultant first and second factors were: $$\begin{gathered} {\text{ }}F_1 = 0.933{\text{ Na}}_{\text{2}} {\text{O + 0}}{\text{.143 SiO}}_{\text{2}} + 0.206{\text{ K}}_{\text{2}} {\text{O}} - 0.346{\text{ CaO}} - 0.263{\text{ MgO}} - \hfill \\ .203{\text{ FeO}} \pm \cdot \cdot \cdot \hfill \\ {\text{ }}F_2 = 0.979{\text{ Al}}_{\text{2}} {\text{O}}_{\text{3}} - 0.269{\text{ MgO}} - 0.151{\text{ SiO}}_{\text{2}} - 0.112{\text{ FeO}} \pm \cdot \cdot \cdot \hfill \\ \end{gathered} $$ where oxides are in weight percent. A plot of the first factor against the second results in a useful igneous variation diagram. When the compositions of the 2188 terrestrial rocks and 604 lunar rocks are plotted on this diagram, the two groups of rocks are clearly separated within an albite-anorthite-forsterite-fayalite-quartz polygon. None of the terrestrial differentiation trends are significant for lunar rocks. The major difference in the chemistry of lunar and terrestrial rocks lies in the former being albite poor. Removal of most of the albite from the compositions of terrestrial layered intrusives such as the Skaergaard results in an excellent match between the compositions of the two groups of rocks. Albite subtracted compositions of Skaergaard rocks in particular cover the entire range of chemical variation in the lunar rocks. The statistical results prompt us to speculate further on the similarity of the moon and Skaergaard. We note that the average composition of the moon (Wanke et al., 1974) is similar to the albite subtracted composition of the Skaergaard magma. The lunar crust and a significant part of the lunar interior may match the albite subtracted and somewhat Mg enriched Skaergaard magma.  相似文献   

Saturn's auroral/polar H₃ infrared emission: I. General morphology and ion velocity structure     

Tom Stallard  Steve Miller  Makenzie Lystrup  Nicholas Achilleos 《Icarus》2007,189(1):1-13

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First cosmogenic 10Be age constraint on the timing of Younger Dryas glaciation and ice cap thickness,western Scottish Highlands     

Nicholas R. Golledge  Derek Fabel  Jeremy D. Everest  Stewart Freeman  Steven Binnie 《第四纪科学杂志》2007,22(8):785-791

We use cosmogenic ¹⁰Be surface exposure age techniques at a locality close to Rannoch Moor, western Scottish Highlands, in order to establish the age and chronology of its most recent glaciation. Glacial erratics and an in situ bedrock quartz vein sampled from this site—the summit of Beinn Inverveigh—have yielded zero‐erosion exposure ages of 12.9 ± 1.5 ka to 11.6 ± 1.0 ka, implying complete ice cover of the mountain during the Younger Dryas, or Loch Lomond Stadial. These results fit closely with published ¹⁴C dates that bracket the maximum (lateral) extent of ice cap outlet glaciers, and are the first internally consistent ages to specifically address this period of glaciation in Scotland. Furthermore, the dates imply that previous palaeoglaciological reconstructions for this area may have underestimated both the thickness of the former ice cap and, by implication, its volume. © British Geological Survey/Natural Environment Research Council copyright 2007. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd.  相似文献   

A multiproxy climate record from a raised bog in County Fermanagh,Northern Ireland: a critical examination of the link between bog surface wetness and solar variability     

Graeme T. Swindles  Gill Plunkett  Helen M. Roe 《第四纪科学杂志》2007,22(7):667-679

A proxy climate record from a raised bog in County Fermanagh, Northern Ireland, is presented. The record spans the interval between 2850 cal. yr BC and cal. yr AD 1000 and chronological control is achieved through the use of tephrochronology and ¹⁴C dating, including a wiggle‐match on one section of the record. Palaeoclimatic inferences are based on a combination of a testate amoebae‐derived water table reconstruction, peat humification and plant macrofossil analyses. This multiproxy approach enables proxy‐specific effects to be identified. Major wet shifts are registered in the proxies at ca. 1510 cal. yr BC, 750 cal. yr BC and cal. yr AD 470. Smaller magnitude shifts to wetter conditions are also recorded at ca. 380 cal. yr BC, 150 cal. yr BC, cal. yr AD 180, and cal. yr AD 690. It is hypothesised that the wet shifts are not merely local events as they appear to be linked to wider climate deteriorations in northwest Europe. Harmonic analysis of the proxies illustrates statistically significant periodicities of 580, 423–373, 307 and 265 years that may be related to wider Holocene climate cycles. This paper illustrates how the timing of climate changes registered in peat profiles records can be precisely constrained using tephrochronology to examine possible climatic responses to solar forcing. Relying on interpolated chronologies with considerable dating uncertainty must be avoided if the climatic responses to forcing mechanisms are to be fully understood. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

On the iron interpretation of the 6.4 keV emission line from SGR 1900+14     

Alaa I. Ibrahim  Hisham Anwer  Mohamed H. Soliman  Nicholas Mackie-Jones  Kalvir S. Dhuga  William C. Parke  Jean H. Swank  Tilan Ukwatta  M. T. Hussein  T. El-Sherbini 《Astrophysics and Space Science》2007,308(1-4):535-539

A 6.4 keV emission line was discovered in an unusual burst from the soft gamma repeater SGR 1900+14 with the Rossi X-ray Timing Explorer (RXTE). The line was detected in part of a complex multipeak precursor that preceded the unusual burst of 1998 August 29, i.e. two days after the giant flare of August 27 from the source. The origin of the line was not firmly identified and two possible interpretations were equally plausible including (a) Kα fluorescence from a small iron rich material that was ejected to the magnetosphere during the August 27 flare, and (b) proton or α-particle cyclotron resonance. If the iron scenario was correct, we expect to find evidence for the line during the intervening interval between the flare and the August 29 burst, i.e. on August 28. Here we present the results of the August 28 burst observation, taken with RXTE. We detect a total of seven bursts whose individual and joint spectra do not show evidence for spectral lines. We also investigated a sample of nine bursts before and after the August 29 burst (from 1998 June to December) that do not reveal evidence for a spectral line near 6.4 keV or elsewhere. These results disfavor the iron scenario and make the proton/α-particle cyclotron resonance interpretation more plausible. The appearance of the emission line in part of a complex burst and its absence from the studied sample indicate that the line is likely due to a transient phenomenon that may depend on the burst morphology, energetics and the properties of the emission region.   相似文献