Erratum     

F. David  L. Walker 《Contributions to Mineralogy and Petrology》1991,107(1):135-135

  相似文献   

Partitioning of siderophile elements in the FeNiS system: 1 bar to 80 kbar     

J.H. Jones  D. Walker 《Earth and Planetary Science Letters》1991,105(1-3)

Partition coefficients for Au, Ni, P and Ge between solid FeNi metal and sulfur-bearing metallic liquids have been measured at 7,27 and 80 kbar. To our knowledge, these are the only such data for Au, P and Ge at high pressure. Comparison of our partitioning results to those obtained at 1 bar indicate that only the 80 kbar Ge data differ significantly from the 1-bar experiments. Thus, many low-pressure partitioning experiments in the FeNiSP system may have applicability to the greater portion of the Earth's upper mantle or, alternatively, the entire mantle of Mars.  相似文献   

THE NEW DECADE: DIGITS AND DIVERSITY     

I. Newton  J. D. Leatherdale    J.-P. Muller  M. Sowton  A. S. Walker 《The Photogrammetric Record》1991,13(78):877-888

The President of the Photogrammetric Society, Mr. I Newton, chaired a panel discussion concerned with those developments in photogrammetry which may take place during the 1990s.  相似文献   

A numerical investigation of the JASIN atmospheric boundary layer     

David P. Rogers  Joost A. Businger  Henry Charnock 《Boundary-Layer Meteorology》1985,32(4):373-399

A numerical model of the cloudy marine boundary layer is described and used to investigate the role of entrainment instability on the developing boundary layer. In general, previous studies have been limited to boundary layers capped by convectively stable inversions or have described only cumulus fields. Here we extend a stratus-capped boundary-layer model to consider the transition to a convectively unstable cloud layer capped by an inversion across which there is a rapid decrease in wet-bulb or equivalent potential temperature. In this case, the inversion is very active and the entrainment rate is determined by the active instability at the interface, in contrast to the mean turbulent motion within the boundary layer.The model is used to interpret the observed boundary layer from the JASIN experiment. Cool, dry air is modified by prolonged passage over increasingly warmer ocean which leads to the development of a convectively unstable cloud layer.  相似文献   

PHOTOGRAMMETRIC SOCIETY COUNCIL ACTIVITIES     

S. Walker 《The Photogrammetric Record》1985,11(66):755-758

  相似文献   

Petroleum isoprenoid hydrocarbons derived from catagenetic degradation of archaebacterial lipids     

J. Albaigés  J. Borbón  W. Walker 《Organic Geochemistry》1985,8(4):293-297

The three GC coeluting C₄₀ bis-phytanes with head-to-tail, tail-to-tail and head-to-head linkages considered to be archaebacterial markers, have been recognized in petroleum by enhanced mass-fragmentography. Supporting evidence has been obtained by the simultaneous occurrence of two C₂₁–C₂₄ series of isoprenoid and quasi-isoprenoid hydrocarbons that are supposedly formed during the catagenetic degradation of the isomeric C₄₀ isoprenoids. The C₂₁–C₂₄ quasi-isoprenoid hydrocarbons have been identified conclusively for the first time by comparison with authentic standards.  相似文献   

Tarawera 1886, New Zealand — A basaltic plinian fissure eruption     

George P.L. Walker  Stephen Self  Lionel Wilson 《Journal of Volcanology and Geothermal Research》1984,21(1-2)

New Zealand's biggest and most destructive volcanic eruption of historical times was that of Tarawera in 1886. The resulting scoria fall has a dispersal very similar in extent to that of the Vesuvius A.D. 79 pumice fall and is one of the few known examples of a basaltic deposit of plinian type. A new estimate of the volume (2 km³) is significantly greater than previous estimates. The basalt came mainly from a 7-km length of fissure, and emission and exit velocity were fairly uniform along at least 4 km of it, this is one of the few documented examples of a plinian eruption from a fissure vent. Primary welding of the scoria fall resulted where the accumulation rate exceeded about 250 mm min⁻¹. A model of the eruption dynamics is proposed which leads to an estimate of 28 km for the height of the eruption cloud and implies a magma volatile fraction of 1.5–3%. Violent phreatic explosions occurred in the southwestern extension of the fissure across the Rotomahana geothermal field, and it is thought that some of the water responsible for the power of the plinian eruption came from this source, though its amount was not sufficient to turn the eruption into a phreatoplinian one.  相似文献   

A REVIEW OF MAP REVISION BY PHOTOGRAMMETRY     

A. S. Walker 《The Photogrammetric Record》1984,11(64):395-405

Revision has become a task equally as important as new mapping. Photogrammetric methods, however, have developed around the latter rather than the former. Modern instrumentation rejects this growth process. This paper examines the efficacy of various photogrammetric approaches for revision with respect to both detection and plotting of change.  相似文献   

Chromian spinel as a petrogenetic indicator in abyssal and alpine-type peridotites and spatially associated lavas   总被引：70，自引：0，他引：70  

Henry J. B. Dick  Thomas Bullen 《Contributions to Mineralogy and Petrology》1984,86(1):54-76

The composition of chromian spinel in alpine-type peridotites has a large reciprocal range of Cr and Al, with increasing Cr# (Cr/(Cr+Al)) reflecting increasing degrees of partial melting in the mantle. Using spinel compositions, alpine-type peridotites can be divided into three groups. Type I peridotites and associated volcanic rocks contain spinels with Cr#<0.60; Type III peridotites and associated volcanics contain spinels with Cr#>0.60, and Type II peridotites and volcanics are a transitional group and contain spinels spanning the full range of spinel compositions in Type I and Type II peridotites. Spinels in abyssal peridotites lie entirely within the Type I spinel field, making ophiolites with Type I alpine-type peridotites the most likely candidates for sections of ocean lithosphere formed at a midocean ridge. The only modern analogs for Type III peridotites and associated volcanic rocks are found in arc-related volcanic and intrusive rocks, continental intrusive assemblages, and oceanic plateau basalts. We infer a sub-volcanic arc petrogenesis for most Type III alpine-type peridotites. Type II alpine-type peridotites apparently reflect composite origins, such as the formation of an island-arc on ocean crust, resulting in large variations in the degree and provenance of melting over relatively short distances. The essential difference between Type I and Type III peridotites appears to be the presence or absence of diopside in the residue at the end of melting.Based on an examination of co-existing rock and spinel compositions in lavas, it appears that spinel is a sensitive indicator of melt composition and pressure of crystallization. The close similarity of spinel composition fields in genetically related basalts, dunites and peridotites at localities in the oceans and in ophiolite complexes indicates that its composition reflects the degree of melting in the mantle source region. Accordingly, we infer from the restricted range of spinel compositions in abyssal basalts that the degree of mantle melting beneath mid-ocean ridges is generally limited to that found in Type I alpine-type peridotites. It is apparent, therefore, that the phase boundary OL-EN-DI-SP +meltOL-EN-SP+melt has limited the degree of melting of the mantle beneath mid-ocean ridges. This was clearly not the case for many alpine-type peridotites, implying very different melting conditions in the mantle, probably involving the presence of water.  相似文献   

Pollen analysis and quaternary research in Scotland     

M.J.C. Walker 《Quaternary Science Reviews》1984,3(4):369-404

The development of pollen analysis in Scotland and its role in present-day Quaternary studies are examined. Methodological advances in field and laboratory techniques, in the treatment and interpretation of pollen analytical data and in palaeoecological investigations involving pollen analysis are considered in the context of research in Scotland. The applications of pollen analysis in specific areas of Scottish Quaternary research are then discussed. These include the reconstruction of interglacial, interstadial and Late Devensian Lateglacial environments, Flandrian plant migrations and forest history, man and landscape change in the mid- and late Flandrian, the dating of geomorphological events, and the study of land and sea-level changes.  相似文献