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81.
Deborah Hart 《GeoJournal》1986,12(2):191-195
Humanist inspired literary geography offers one avenue of enquiry into the study of place. Its prime intention is to untangle the subjective, personalised construction and connotations of place meaning. African literature offers a rich source of information into the black urban experience. The presentation focuses upon the literary interpretation of Soweto, South Africa's largest black township. The Sowetan environment emerges as a landscape of placelessness in which the overwhelming emphasis by white and black writers alike is upon relating appalling conditions in an austere and hostile environment. 相似文献
82.
Robert C. Walter William K. Hart John A. Westgate 《Contributions to Mineralogy and Petrology》1987,95(4):462-480
The Cindery Tuff is an unusual tephra fall deposit that contains evidence for the mixing of basaltic and rhyolitic liquids prior to eruption. It contains clear rhyolitic glass shards together with brown basaltic glass spheres and a broadly bimodal phenocryst assemblage. Brown glasses are ferrobasaltic in composition and are similar to the voluminous Pliocene tholeiites of the surrounding west-central Afar volcanic field; both are enriched in the light rare earth and incompatible elements and possess higher 87Sr/86Sr and lower 143Nd/144Nd than MORB. Rhyolitic glasses are subalkaline and, compared to the basaltic glasses, are strongly depleted in the compatible elements and enriched in the incompatible elements. Both glass types have similar incompatible element and isotopic ratios, and with the rhyolite glass showing a 2-fold parallel enrichment in rare earth element abundances over the basaltic glass. These observations suggest that the two glasses are genetically related.Rare glasses with intermediate compositions occur as phenocryst melt inclusions, as mantles on phenocrysts and as free pumice clasts. Their major element contents do not point to an origin by simple hybrid mixing of the basaltic and rhyolitic melts. Rather, major element mixing calculations indicate formation of the intermediate and rhyolite melts by fractionation of the observed phenocryst assemblage, using a starting composition of the observed basaltic glass. Model calculations from trace element data, though lacking from the intermediate glasses, support fractional crystallization. The bimodal mineral assemblage argues against an immiscible liquid origin for the contrasting glass compositions. 相似文献
83.
The sources of reservoired liquid hydrocarbons in Australia differ substantially from their Northern Hemisphere counterparts. Not only are Australian source rocks largely of terrigenous origin but the concepts accepted as defining the hydrocarbon potential of source rocks have recently been challenged. Although isotopic measurements on Australian source rocks and liquid hydrocarbon products closely parallel those published from elsewhere, new interpretations of these data have been made, particularly with regard to D/H ratios in coals. As interesting as such results may be, the most important findings relate to the origins and histories of methane, the higher gaseous hydrocarbons and carbon dioxide, and the interpretation of these data in terms of hydrocarbon genesis. Simple Northern Hemisphere concepts which characterize gases as being biogenic, oil-associated, etc., on the bases of their isotopic and chemical compositions are clearly not applicable to the Australian scene. Indeed justification of such precise classifications in the Northern Hemisphere on the available evidence is also questioned.Isotopic and compositional data from gases from the Cooper, Bowen, Sydney and Gippsland Basins and from the North West Shelf (Australia) are reviewed, and assessed in terms of generation pathways. 相似文献
84.
Published data suggest that soil gas helium concentrations of 5.28–5.34 ppm v/v over uranium and hydrocarbon deposits are significantly anomalous compared to the ambient atmospheric background of 5.24 ppm. However, analyses for helium by mass spectrometers having constant-pressure inlet systems, from which most of these data are derived, are subject to errors of equivalent magnitude. These errors arise when the major component composition of unknown and standard gases differ, for the different gases have different flow rates through the inlet system — relative rates being O2 < dry air < water-saturated air < N2 < CO2 CH4. Soil gas compositions can vary greatly and, compared to a dry air standard, the flow-rate of a water-saturated gas containing 10% biogenic CO2 will increase, enhancing the apparent He content to 5.33 ppm. Accurate helium analyses can be achieved by using a constant-volume inlet and integrating the detector response over the period of the samples' passage through the detector. 相似文献
85.
86.
CASPIR is a near-infrared spectrometer/imager being built for the Mount Stromlo and Siding Spring Observatories' 2.3 m telescope. The instrument is based on a SBRC 256×256 InSb detector array and uses AR-coated Sapphire, MgO, CaF2, and BaF2 optics to produce two imaging focal plane scales with 0.5/pixel and 0.25/pixel. Spectral resolving powers of 500 will be achieved through a 1×128 slit with three grisms designed for the J, H, and K bands. IJ, JH, and HK cross-dispersed échelle grisms will achieve resolving powers of 1100 through a 1×15 slit. Coronograph and imaging polarimetry modes will also be available. The various observing configurations are selected via five remotely controlled wheels. The instrument design and system architecture are discussed, and preliminary detector performance figures reported. 相似文献
87.
Geographical Linked Data: The Administrative Geography of Great Britain on the Semantic Web 总被引:1,自引:0,他引:1
Ordnance Survey, the national mapping agency of Great Britain, is investigating how semantic web technologies assist its role as a geographical information provider. A major part of this work involves the development of prototype products and datasets in RDF. This article discusses the production of an example dataset for the administrative geography of Great Britain, demonstrating the advantages of explicitly encoding topological relations between geographic entities over traditional spatial queries. We also outline how these data can be linked to other datasets on the web of linked data and some of the challenges that this raises. 相似文献
88.
Matthew E. Brueseke Matthew T. Heizler William K. Hart Stanley A. Mertzman 《Journal of Volcanology and Geothermal Research》2007
The timing and petrogenesis of mid-Miocene flood basalt volcanism in the northwest United States has been extensively addressed, yet the chemical characteristics and temporal details of the Steens Basalt, exposed on the Oregon Plateau, are poorly defined. Steens Basalt volcanism has generally been accepted to have occurred at ∼ 16.6 Ma, coeval and/or just prior to the onset of Columbia River Basalt Group volcanism to the north. New major and trace element analyses and nine 40Ar/39Ar ages ranging from 15.51 ± 0.28 to 16.58 ± 0.18 Ma were obtained on Oregon Plateau flood basalt lava flows from stratigraphic sections in close proximity to Steens Mountain. Additionally, new 40Ar/39Ar ages were obtained on the uppermost and thirty-first lava flow down from the top of the ∼ 1 km section of Steens Basalt exposed at Steens Mountain and yield eruption ages of 16.59 ± 0.10 and 16.55 ±0.10 Ma, respectively. Field relations between these basalt sections suggest that multiple eruptive centers were present in the vicinity of Steens Mountain. 相似文献
89.
90.