Boundary-layer flow over topography: Impacts of the Askervein study   总被引：2，自引：0，他引：2  

John L. Walmsley  Peter A. Taylor 《Boundary-Layer Meteorology》1996,78(3-4):291-320

One of the objectives of the Askervein Hill Project was to obtain a comprehensive and accurate dataset for verification of models of flow and turbulence over low hills. In the present paper, a retrospective of the 1982 and 1983 Askervein experiments is presented. The field study is described in brief and is related to similar studies conducted in the early 1980s. Data limitations are discussed and applications of numerical and wind-tunnel models to Askervein are outlined. Problems associated with model simulations are noted and model results are compared with the field measurements.  相似文献   

A Controlled Field Test of Surfactant-Enhanced Aquifer Remediation   总被引：4，自引：0，他引：4  

John C. Fountain  Robert C. Starr  Thomas Middleton  Michael Beikirch  Craig Taylor  Dennis Hodge 《Ground water》1996,34(5):910-916

  相似文献   

Lower palaeozoic and precambrian petroleum source rocks and the coalification path of alginite     

Miryam Glikson  Dennis Taylor  Douglas Morris 《Organic Geochemistry》1992,18(6)

Organic-rich samples derived from a Middle Cambrian Formation in the Georgina Basin, and from the Middle Proterozoic of the McArthur Basin in northern and central Australia, yielded alginite ranging from immature oil shale material to overmature residue. A maturation scale has been developed based on the thermal evolution of alginite as determined from reflectance and fluorescence. The coalification path of alginite is marked by jumps in contrast to the linear path of wood-derived vitrinite. Six zones have been recognised, ranging from undermature (zone I), through the mature (zones II/III), followed by a stable stage of no change (zone IV) to the overmature (zones V and VI). The onset of oil generation in alginite as evident from the present study is at 0.3% R_{o Alg.} and is expressed in a change of fluorescence from yellow to brown, and a coalification jump from 0.3 to 0.6% R_o of Alg. In many boreholes zone III can be distinguished between 0.6 and 0.8% R_o of Alg. where subsequent oil generation occurs. Zones II and III represent the oil window.A zone of little or no change designated zone IV, at of alginite follows zones II/III. A marked coalification jump characterises zone V, where a pronounced change in reflectance occurs to >1.0% R_{o Alg.}, signifying peak gas generation. The border of oil preservation lies at the transition of zone V and VI, at 1.6% R_{o Alg.} In zone VI gas generation only occurs.Comparison of reflectance results with experimental and geochemical pyrolysis data supports high activation energies for hydrocarbon generation from alginite, and therefore a later onset of oil generation than other liptinite macerals (i.e. cutinite, exinite, resinite) as well as a narrow oil window.Transmission electron microscopy (TEM) confirms that alginite does not go through a distinct intermediate stage but that the percentage of unreacted organic matter decreases as maturation proceeds. A clear distinction can be made in TEM between immature alginite, alginite after oil generation, and alginite residue following gas generation. Alginite beyond 1.6% R_o acquires very high densities and the appearance of inertinite in TEM.Bitumens/pyrobitumens make a pronounced contribution to the organic matter throughout the basins and have been shown to effect pyrolysis results by suppressing T_max. The bitumens/pyrobitumens have been divided into four groups, based on their reflectance and morphology, which in turn appears to be an expression of their genetic history. Their significance is in aiding the understanding of the basins' thermal history, and the timing of oil and gas generation.  相似文献   

Barium- and LREE-rich, olivine-mica-lamprophyres with affinities to lamproites, Mt. Bundey, Northern Territory, Australia   总被引：1，自引：0，他引：1  

Stephen Sheppard  Wayne R. Taylor 《Lithos》1992,28(3-6):303-325

Primitive olivine-mica-K-feldspar lamprophyre dykes, dated at 1831 ± 6 Ma, intrude lower greenschist facies rocks of the Early Proterozoic Pine Creek Inlier, of northern Australia. They are spatially, temporally and probably genetically associated with a post-tectonic composite granite-syenite pluton (Mt. Bundey pluton). The dykes have unusually high contents of large-ion-lithophile (LILE) and LREE elements (e.g. Ba up to 10,000 ppm, Ce up to 550 ppm, K₂O up to 7.5 wt. %) that resemble the concentrations found in the West Kimberley olivine and leucite lamproites. However, mineralogically the Mt. Bundey lamprophyres resemble shoshonitic lamprophyres and lack any minerals diagnostic of lamproites; leucite or leucite-pseudomorphs are absent. Mineral compositions are also unlike those in lamproites: micas contain higher Al₂O₃ than lamproitic mica; amphiboles are secondary actinolites after diopside; and oxides consist of zincian-chromian magnetite and groundmass magnetite. Heavy mineral concentrates contain mantle-derived xenocrysts of magnesiochromite, pyrope, Cr-diopside and rutile indicating a depth of sampling > 70 km. The Mt. Bundey lamprophyres are non-peralkaline to borderline peralkaline (molar (K + Na)/Al = 0.8 − 1.0) and potassic rather than ultrapotassic (molar K/Na < 2.5). They have distinctive major element compositions (≈46−49 wt. % SiO₂, ≈1.5−2 wt. % MgO, ≈7 wt. % CaO), and element ratios (e.g. molar Al/Ti ≈10, K/Na ≈2) that indicate they are best classified amongst transitional lamproites, i.e. potassic rocks such as cocites, jumillites and Navajominettes, that have geochemical characteristics transitional between Groups I and III. (Foley et al., 1987). The Mt. Bundey lamprophyres have LILE enrichment patterns that resemble the W. Kimberley pamproites but have moderate negative Ta---Nb---Ti anomalies and HREE abundances that are closely similar to the jumillites of southeastern Spain and Mediterranean-type lamproites. Single-stage modelling of Rb---Sr data is consistent with enrichment of the source-region of the Mt. Bundey lamprophyres ≈ 120–170 Ma before partial melting; i.e. at 1.95–2.10 Ga. Source enrichment does not appear to be associated with subduction processes, but may instead relate to incipient rifting of the Archaean basement. Negative Ta---Nb---Ti anomalies in the Mt. Bundey dykes may, therefore, relate to stability of residual titanate minerals in an oxidized subcontinental mantle source. This view is supported by high Fe³⁺/ΣFe ratios of mantle-derived magnesiochromite xenocrysts which indicate oxidized mantle conditions (ƒ_o2 ≈ FMQ + 1 long units), and by the presence of xenocrystic Cr-bearing rutile. Although the Mt. Bundey dykes have sampled upper mantle material, the oxidized nature of the magma source-region, and of the magma itself, suggests that conditions may not be favourable for diamond survival at depth nor for diamond transport in transitional lamproite magmas of this kind.  相似文献   

Wind profile development above a locally adjusted sea surface     

P. A. Taylor 《Boundary-Layer Meteorology》1972,2(3):381-389

Results are presented from a numerical experiment of wind and shear stress profile development away from a shore line; the water surface is assumed to obey the Charnock-Ellison relation between surface roughness and friction velocity. In typical cases the upwind, land surface is rough relative to the sea and the velocity and shear stress results are qualitatively similar to those for flows from relatively rough to relatively smooth solid surfaces. In the present case, however, the downwind surface roughness and friction velocity vary with position and we find that wind profile development may play a significant role in the relationship between sea surface roughness and fetch.  相似文献   

Temperatures of serpentinization of ultramafic rocks based on O18/O16 fractionation between coexisting serpentine and magnetite     

David B. Wenner  Hugh P. Taylor Jr. 《Contributions to Mineralogy and Petrology》1971,32(3):165-185

Five lizardite-chrysotile type serpentinites from California, Guatemala and the Dominican Republic show oxygen isotope fractionations of 15.1 to 12.9 per mil between coexisting serpentine and magnetite (O¹⁸ magnetite=–7.6 to –4.6 per mil relative to SMOW). Nine antigorites (mainly from Vermont and S. E. Pennsylvania) show distinctly smaller fractionations of 8.7 to 4.8 per mil (O¹⁸ magnetite=–2.6 to +1.7 per mil). Two lizardite and chrysotile serpentinites dredged from the Mid-Atlantic Ridge exhibit fractionations of 10.0 and 12.4 per mil (O¹⁸ magnetite=–6.8 and –7.9 per mil, respectively), whereas an oceanic antigorite shows a value of 8.2 per mil (O¹⁸ magnetite=–6.2). These data all clearly indicate that the antigorites formed at higher temperatures than the chrysotilelizardites. Electron microprobe analyses of magnetites from the above samples show that they are chemically homogeneous and essentially pure Fe₃O₂. However, some magnetites from certain other samples that show a wide variation of Cr content also give very erratic oxygen isotopic results, suggesting non-equilibrium. An approximate serpentine-magnetite geothermometer curve was constructed by (1) extrapolation of observed O¹⁸ fractionations between coexisting chlorites and Fe-Ti oxides in low-grade pelitic schists whose isotopic temperatures are known from the quartz-muscovite O¹⁸ geothermometer, and (2) estimates of the O¹⁸ fractionation factor between chlorite and serpentine (assumed to be equal to unity). This serpentine-magnetite geothermometer suggests approximate equilibrium temperatures as follows: continental lizardite-chrysotile, 85° to 115° C; oceanic lizardite and chrysotile, 130° C and 185° C, respectively; oceanic antigorite, 235° C; and continental antigorites, 220° to 460° C.Contribution No. 2029 of the Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91109.  相似文献   

Trace element geochemistry of the rhyolitic volcanic rocks,Central North Island,New Zealand. Phenocryst data     

A. Ewart  S. R. Taylor 《Contributions to Mineralogy and Petrology》1969,22(2):127-146

Data are presented for K, Ba, Sr, Rb, Li, Ga, Mg, Mn, and Fe for twelve rhyolitic plagioclases (An₂₈-An₄₆), one dacitic (An₅₃), and three andesitic plagioclases (An₆₈-An₈₁). Additional data are presented for Ga, Gr, V, Ni, Co, Sc, Y, La, Sr, and Ba for two augites, nine hypersthenes, and five hornblendes separated from the same rocks. Distribution factors have been calculated, using these data, and previously published results for coexisting groundmass compositions (=liquids).The plagioclases show a positive correlation between, and a progressive increase in K and Ba (range 0.09–0.58% and 61–610 p.p.m. respectively) with increasing Ab-content. Sr (range 465–880 p.p.m.) shows a well defined maximum between An₄₀-An₅₅. The plagioclases have extremely high K/Rb ratios (mostly > 1,000).This volcanic series is characterised by relatively Mg-rich pyroxenes and hornblendes. The augites contain higher Sc, Cr, Y, Sr, and Y relative to their coexisting hypersthenes, while the hornblendes exhibit higher Sc, V, Ba, Sr, Y, and La relative to coexisting hypersthenes. Very marked differences in concentrations of these elements exist between the rhyolitic and andesitic ferromagnesian phenocrysts. There is also evidence of a systematic distribution of Sc, V, Cr, Y, Co, and Ni between coexisting hypersthenes and hornblendes, and between these minerals and their coexisting whole rock and groundmass compositions.The data are discussed from a petrological viewpoint, as they are interpreted to indicate that the phenocrysts crystallised in the magmas in which they are found, and are not xenocrystic. No evidence of hybridisation or contamination, subsequent to the onset of crystallisation, is found.  相似文献   

The oxygen isotope geochemistry of igneous rocks   总被引：34，自引：0，他引：34  

Hugh P. Taylor Jr. 《Contributions to Mineralogy and Petrology》1968,19(1):1-71

Oxygen isotope analyses have been obtained for 443 igneous rock and mineral samples from various localities throughout the world. Detailed studies were made on the Medicine Lake, Newberry, Lassen, Clear Lake, S. E. Guatemala, Hawaii and Easter I. volcanic complexes and on the Bushveld, Muskox, Kiglapait, Guadalupe, Duluth, Nain, Egersund, Lac St. Jean, Laramie, Skaergaard, Mull, Skye, Ardnamurchan and Alta, Utah plutonic complexes, as well as upon several of the zoned ultramafic intrusions of S. E. Alaska. Basalts, gabbros, syenites and andesites are very uniform in O¹⁸/O¹⁶, commonly with δ-values of 5.5 to 7.0 per mil. Many rhyolite obsidians, particularly those from oceanic areas and the Pacific Coast of the United States, also lie in this range; this indicates that such obsidians are differentiates of basaltic or andesitic magma at high temperatures (about 1,000° C). They cannot represent melted sialic crust. The only plutonic granites with such low δ-values are some of the hypersolvus variety, suggesting that these also might form by fractional crystallization. Obsidians from the continental interior, east of the quartz-diorite line, have higher δ-values. This is compatible with their having assimilated O¹⁸-rich sialic crust. A correlation generally exists between the O¹⁸/O¹⁶ ratios of SiO₂-rich differentiates and the chemical trends in volcanic complexes. High O¹⁸/O¹⁶ ratios accompany those trends having the lower Fe/Mg ratios, while ferrogabbro trends are associated with depletion in O¹⁸. Variations in oxygen fugacity may be responsible for these effects, as abundant early precipitation of magnetite should lead to both O¹⁸-enrichment and Fe-depletion in later differentiates. Plutonic granites have higher O¹⁸/O¹⁶ ratios than their volcanic equivalents, because (a) their differentiation occurred at much lower temperatures, or (b) they are in large part derived from O¹⁸-rich sialic crust by partial melting or assimilation. Also, the oxygen isotope fractionations among coexisting minerals are distinctly larger in plutonic rocks than in volcanic rocks. This is in keeping with their lower crystallization temperatures and their longer cooling history, which promotes post-crystallization oxygen isotope exchange. Hydrated obsidians and perlites have δO¹⁸-values that are much different from their primary, magmatic values. A correlation exists between D/H and O¹⁸/O¹⁶ ratios in hydrated volcanic glass from the western U.S.A., proving that the isotopic compositions are a result of exchange with meteoric waters. The O¹⁸ contents of the glasses appear to be about 25 per mil higher than their associated waters; hence, these hydrated glasses have not simply absorbed H₂O, but they have exchanged with large quantities of it. The igneous rocks from Mull, Skye, Ardnamurchan and the Skaergaard intrusion are all abnormally depleted in O¹⁸ relative to “normal” igneous rocks. This is a result of their having exchanged at high temperatures with meteoric water that was apparently abundant in the highly jointed plateau lavas into which these igneous rocks were intruded. In part, this exchange occurred with liquid magma and in part with the crystalline rock; in the latter case the feldspar was more easily exchanged and has become much more depleted in O¹⁸ than has coexisting quartz or pyroxene. The later differentiates of the Muskox intrusion are markedly O¹⁸-rich, but this is not a result of fractional crystallization. It is in large part a result of deuteric exchange between feldspars and an oxygen-bearing fluid (H₂O ?) that was either O¹⁸-rich or had a relatively low temperature. This phenomenon was also observed in a number of granophyres from other localities, particularly those containing brick-red alkali feldspar. The exchanged feldspars in all these examples are turbid or cloudy, and may be filled with hematite dust. It is concluded that most such feldspar in nature is the result of deuteric exchange and is probably drastically out of oxygen isotopic equilibrium with its coexisting quartz.  相似文献   

Geochemistry of the pantellerites of Mayor Island,New Zealand     

A. Ewart  S. R. Taylor  A. C. Capp 《Contributions to Mineralogy and Petrology》1968,17(2):116-140

Recent pantelleritic lavas comprise the whole of the isolated and outlying volcano of Mayor Island. Mineralogically, they are characterised by phenocrystic anorthoclase-sodic27 sanidine, quartz, sodic ferrohedenbergite, and cossyrite. Nine new chemical analyses of the lavas are presented (including one residual glass), confirming their strongly sodic and peralkaline nature. One analysis is also given of trachybasalt, which occurs as common inclusions in the mantling pumice deposits. These inclusions are characterised by abundant feldspar phenocrysts. Detailed trace element data is presented for five of the lava samples, representing the mam volcanic phases and the trachybasalt inclusions. The following conclusions are presented:

1. The lavas exhibit a marked enrichment (relative to “average” granitic compositions) of the alkalis; rare earths; highly charged cations (e.g. Nb, Zr, Hf, Mo, U, Th); Ga, Be, and Cl. In contrast, they show a spectacular depletion of Sr, Ba, and Mg, and a less intense depletion of Ca, Sc, V, and Cr.
2. The pantelleritic rare earth patterns show a similar degree of fractionation to the sedimentary pattern, and are dominated by a very strong Eu depletion. This suggests feldspar subtraction. The trachybasalt pattern shows a similar degree of fractionation, but exhibits enrichment of Eu.
3. The trachybasalt inclusions are characterised by a trace element assemblage comparable to alkali basalts, except for higher Ba and exceedingly high K/Rb and K/Cs ratios. The chemical and mineralogical data suggest that they represent partial feldspar accumulate rocks.
4. There is a progressive enrichment of nearly all trace and minor elements in the youngest lavas. This includes those elements that show an overall depletion in the lavas. The younger lavas are also enriched in Na and Fe, but further depleted in Al.

The data is interpreted to indicate that the pantellerites were derived by crystal differentiation from a postulated mildly alkali olivine basalt parent — feldspar fractionation is considered to have been extremely important in this process. It is shown that the element enrichment occurring in the younger lavas may not be wholely explained by crystallisation differentiation alone — it is possible that some additional process is required. It is also shown that the observed enrichment of sodium in the youngest lavas can only occur during crystal fractionation if quartz, as well as anorthoclase, separate from the magma. This is due to the higher alkali abundances of the anorthoclase phenocrysts, relative to the pantellerite compositions. There is limited evidence that post-eruptive devitrification of some of the lavas has resulted in some modification of the lava chemistry, notably sodium loss.  相似文献   

Photogrammetric survey of the structural geology of the Sudbury-McGregor Bay District,Ontario, Canada     

R. D. Dallmeyer  W. E. G. Taylor 《International Journal of Earth Sciences》1973,62(2):350-356

New information is presented regarding the structural geology of the Huronian rocks (Middle Precambrian) of the Sudbury-McGregor Bay district of Ontario, Canada. Using standard photogrammetric techniques a base map of the area was prepared from photographs taken at a height of about 11,000 m. Extrapolation from the work ofYoung &Church (1966) together with the evidence deduced from the aerial photographs facilitated the construction of a lithological map at the scale of 1∶187,500 (Fig. 2). From this map large scale type 2 interference pattern is recognised (seeRamsay, 1967) and a tentative structural history is suggested for the area.  相似文献