Hydrocarbons and fatty acids in two cores of Lake Huron sediments     

Philip A. Meyers  Richard A. Bourbonniere  Norishige Takeuchi 《Geochimica et cosmochimica acta》1980,44(8):1215-1221

Compositions of aliphatic hydrocarbons and of fatty acids were analyzed in two half-meter cores of postglacial Lake Huron sediment. One core represents a continuous record of the past 450 yr of sediment accumulation; the other consists of a surficial layer of modern sediment overlying 40 cm of 11,000–12,000 yr-old sediment. Concentrations of hydrocarbons are higher in the younger core than in the older one. Based upon n-alkane distributions, this reflects a smaller input of terrigenous material to Lake Huron 11,000 yr ago rather than diagenetic losses. Most of the hydrocarbons present in the 450 yr-old core are allochthonous while half are autochthonous in the older core. Fatty acids are primarily of aquatic character in both cores, and their concentrations decrease rapidly with depth. Unsaturated acids disappear more quickly than do their saturated analogs. Fatty acid degradation occurs mostly in the biologically active zone of these sediments, and little further alteration of fatty acids appears to happen over times as long as 12,000 yr.  相似文献   

Concentration of some platinum-group metals in coal     

Robert B. Finkelman  Philip J. Aruscavage 《International Journal of Coal Geology》1981,1(2):95-99

New data on some platinum group metals in coal indicate that the concentration of Pt is generally less than about 5 ppb, that of Pd is generally less than 1 ppb, and that of Rh is generally less than 0.5 ppb. No conclusive evidence was obtained concerning the mode of occurrence of these elements in coal.  相似文献   

FEM solution of the Navier-Stokes equations for vortex shedding behind a cylinder: experiments with the four-node element     

Philip M. Gresho  Robert L. Lee  Craig D. Upson 《Advances in water resources》1981,4(4):175-184

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On the calculation of cosmic-ray exposure ages of stone meteorites     

Philip J. Cressy  Donald D. Bogard 《Geochimica et cosmochimica acta》1976,40(7):749-762

Abundances of cosmic ray-produced noble gases and ²⁶Al, including some new measurements, have been compiled for some 23 stone meteorites with exposure ages of < 3 × 10⁶ yr. Concentrations of cosmogenic He, Ne, and Ar in these meteorites have been corrected for differences in target element abundances by normalization to L-chondrite chemistry. Combined noble gas measurements in depth samples of the Keyes and St. Séverin chondrites are utilized to derive equations for normalizing the production rates of cosmogenic ³He, ²¹Ne, and ³⁸Ar in chondrites to an adopted ‘average’ shielding: ${}^{22}\text{Ne}{}^{21}\text{Ne}\text{= 1.114.}$ The measured unsaturated ²⁶Al concentrations and the calculated equilibrium ²⁶Al for these meteorites are combined to estimate exposure ages. These exposure ages are statistically compared with chemistry- and shielding-corrected concentrations of cosmogenic He, Ne, and Ar to derive absolute production rates for these nuclides. For L-chondrites, at ‘average’ shielding, these production rates (in 10^?8 cm³/g 10⁶ yr) are: ³He = 2.45,²¹Ne = 0.47, and ³⁸Ar = 0.069, which are ~ 25% higher than production rates used in the past. From these production rates and relative chemical correction factors, production rates for other classes of stone meteorites are derived.  相似文献   

Structural analysis of the superficial deformation of the 1969 Pariahuanca earthquakes (Central Peru)     

H. Philip  F. Megard 《Tectonophysics》1977,38(3-4)

An analysis of the superficial structures related to the Huaytapallana fault is presented. This fault was formed during the Pariahuanca earthquakes of July 24 and October 1, 1969. The fault trends N120E and is 3.5 km long, the displacement is 0.70 m left-lateral slip and 1.6 vertical upthrust. At most places the fault appears as a steep flexure associated with open fractures and mostly gravity folds, all of them almost parallel to it. Oblique, “en échelon” shears, often associated with small folds, are developed in the turf which is partly detached from its substratum. The analysis of these fractures is consistent with a mean N65E shortening direction. The compressional and dilatational quadrants obtained by means of this analysis fit rather well with the focal-mechanism data. On the other hand, some of the en échelon fold and fault systems provide a model of similar features with a magnitude of several kilometers.  相似文献   

Trace element model studies of Nyanzian greenstone belts,western Kenya     

Philip A. Davis  Kent C. Condie 《Geochimica et cosmochimica acta》1977,41(2):271-277

The Archean greenstone belts of the Nyanzian System in western Kenya are composed principally of andesite with minor tholeiitic basalt and siliceous volcanics. The Nyanzian tholeiite is an intermediate-K tholeiite with a flat REE pattern. There are two chemically-distinct andesites: a low-K andesite (Andesite I) and a high-K andesite (Andesite II). The REE pattern of the Andesite II is enriched in light REE and depleted in heavy REE relative to Andesite I.Major and trace element calculations indicate an origin for the Nyanzian tholeiite by 35–40% equilibrium melting of a lherzolite source followed by 10% shallow fractional crystallization. Similar calculations best explain Andesite I and Andesite II by 20 and 5% melting, respectively, of an ecologite or garnet amphibolite source of Nyanzian tholeiite composition. The rhyolite may have formed either by 20–30% partial melting of a siliceous granulite or by 20–30% fractional crystallization of a granodiorite parent magma.With respect to total exposure areas, the Nyanzian volcanics have significantly less tholeiite and more Andesite and siliceous volcanics than other Archean greenstone belts. If these abundances are representative, two models are proposed to explain the anomalous abundances of Andesite and siliceous volcanics. The first model involves an Archaen upper mantle with a relatively low geothermal gradient beneath Kenya, while the second model involves a relatively cool mantle plume. Both models inhibit ascent of a significant amount of primary tholeiite to the surface and prevent formation of secondary tholeiite. Other Archean greenstone terranes with higher mantle geotherms or hotter mantle plumes would receive higher proportions of mafic and ultramafic magmas.  相似文献   

International viewpoint and news     

Andrea Martin  Philip E. LaMoreaux 《Environmental Geology》2007,52(6):1223-1224

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PROFESSOR MICHAEL J BARNSLEY     

Adrian  Luckman 《The Geographical journal》2008,174(2):182-182

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Mass‐dependent fractionation of nickel isotopes in meteoritic metal     

David L. COOK  Meenakshi WADHWA  Robert N. CLAYTON  Nicolas DAUPHAS  Philip E. JANNEY  Andrew M. DAVIS 《Meteoritics & planetary science》2007,42(12):2067-2077

Abstract— We measured nickel isotopes via multicollector inductively coupled plasma mass spectrometry (MC‐ICPMS) in the bulk metal from 36 meteorites, including chondrites, pallasites, and irons (magmatic and non‐magmatic). The Ni isotopes in these meteorites are mass fractionated; the fractionation spans an overall range of ～0.4‰ amu^?1. The ranges of Ni isotopic compositions (relative to the SRM 986 Ni isotopic standard) in metal from iron meteorites (～0.0 to ～0.3‰ amu^?1) and chondrites (～0.0 to ～0.2‰ amu^?1) are similar, whereas the range in pallasite metal (～–0.1 to 0.0‰ amu^?1) appears distinct. The fractionation of Ni isotopes within a suite of fourteen IIIAB irons (～0.0 to ～0.3‰ amu^?1) spans the entire range measured in all magmatic irons. However, the degree of Ni isotopic fractionation in these samples does not correlate with their Ni content, suggesting that core crystallization did not fractionate Ni isotopes in a systematic way. We also measured the Ni and Fe isotopes in adjacent kamacite and taenite from the Toluca IAB iron meteorite. Nickel isotopes show clearly resolvable fractionation between these two phases; kamacite is heavier relative to taenite by ～0.4‰ amu^?1. In contrast, the Fe isotopes do not show a resolvable fractionation between kamacite and taenite. The observed isotopic compositions of kamacite and taenite can be understood in terms of kinetic fractionation due to diffusion of Ni during cooling of the Fe‐Ni alloy and the development of the Widmanstätten pattern.  相似文献   

A method for assessing local variation among scattered measurements     

G. M. Philip  D. F. Watson 《Mathematical Geology》1986,18(8):759-764

Automatic triangulation of scattered locations permits analysis of local variation in a dependent variable through calculation of a roughness index. This is approached by treating triangles of the triangulation (including the dependent variable) as vectorial structures, and accumulating at each data point the vector sum of the cluster of triangles surrounding it. The roughness index is defined as the complement of the ratio of the area of a triangle cluster to the area of component triangles as projected onto a gradient plane defined by their vector sum. The roughness index provides a measure of consistency of data values relative to surrounding observations and can be interpreted as a local index of reliability of interpolation.  相似文献