Major and trace elements in igneous rocks from apollo 15     

Philip A. Helmke  Douglas P. Blanchard  Larry A. Haskin  Karen Telander  Charles Weiss  Jeffrey W. Jacobs 《Earth, Moon, and Planets》1973,8(1-2):129-148

The concentrations of major and trace elements have been determined in igneous rocks from Apollo 15. All materials analyzed have typical depletions of Eu except for minerals separated from sample 15085. Four samples have concentrations of trace elements that are similar to those of KREEP. The samples of mare basalt from Apollo 15 have higher concentrations of FeO, MgO, Mn, and Cr and lower concentrations of CaO, Na₂O, K₂O, and rare-earth elements (REE) as compared to the samples of mare basalt from Apollos 11, 12, and 14. The samples can be divided into two groups on the basis of their normative compositions. One group is quartz normative and has low concentrations of FeO while the other is olivine normative and has high concentrations of FeO. The trace element data indicate that the samples of olivine normative basalt could be from different portions of a single lava flow. At least two and possible three parent magmas can be identified from the samples of the quartz normative group on the basis of their concentration ratios of Sm to Eu. Within each group, the compositions of the samples appear to be related by crystallization of olivine or pyroxene. Significant variations of the ratio of concentration of Sm to Eu cannot be produced without plagioclase-liquid equilibrium. The source material of mare basalt may be depleted in Eu. Alternatively, the magmas may have assimilated a small volume of material similar to KREEP.Paper dedicated to Prof. Harold C. Urey on the occasion of his 80th birthday on 29 April 1973.  相似文献   

Relationship of manganese-iron oxides and associated heavy metals to grain size in stream sediments     

Philip R. Whitney 《Journal of Geochemical Exploration》1975,4(2):251-263

The distribution of ammonium citrate-leachable lead, zinc and cadmium among size fractions in stream sediments is strongly influenced by the presence of hydrous Mn-Fe oxides in the form of coatings on sediment grains. Distribution curves showing leachable metals as a function of particle size are given for eight samples from streams in New York State. These show certain features in common; in particular two concentrations of metals, one in the finest fractions, and a second peak in the coarse sand and gravel fraction. The latter can be explained as a result of the increasing prevalence and thickness of oxide coatings with increasing particle size, with the oxides serving as collectors for the heavy metals. The distribution of Zn and Cd in most of the samples closely parallels that of Mn; the distribution of Pb is less regular and appears to be related to Fe in some samples and Mn in others. The concentration of metals in the coarse fractions due to oxide coatings, combined with the common occurrence of oxide deposition in streams of glaciated regions, raises the possibility of using coarse materials for geochemical surveys and environmental heavy-metal studies.  相似文献   

Dissolved chromium in the St. Lawrence estuary     

John A. Campbell  Philip A. Yeats 《Estuarine, Coastal and Shelf Science》1984,19(5):513-522

A study of dissolved chromium in the St. Lawrence estuary and Gulf of St. Lawrence has been carried out. A chromium concentration of 0·7 μg l^?1 was found in the St. Lawrence River. In the turbidity maximum of the upper estuary, chromium is removed from solution onto fine-grained resuspended sediments and internally produced organic-rich floccules. A simple flux calculation shows that these processes remove ～50% of the total dissolved chromium input of the river. At salinities greater than 5‰ dissolved chromium mixes conservatively.  相似文献   

    

William R. Normark  Neal E. Barnes 《Geo-Marine Letters》1984,3(2-4):223-224

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The concentrations of the noble metals in Southern African flood-type basalts and MORB: implications for petrogenesis and magmatic sulphide exploration   总被引：4，自引：0，他引：4  

Wolfgang D. Maier  Sarah-Jane Barnes  Julian S. Marsh 《Contributions to Mineralogy and Petrology》2003,146(1):44-61

Concentrations of the platinum-group elements have been determined in several suites of southern African flood-type basalts and mid-ocean ridge basalt (MORB), covering some 3 Ga of geologic evolution and including the Etendeka, Karoo, Soutpansberg, Machadodorp, Hekpoort, Ventersdorp and Dominion magmas. The magmas cover a compositional range from 3.7 to 18.7% MgO, 26–720 ppm Ni, 16–250 ppm Cu, and <1–255 ppb total platinum-group elements (PGE). The younger basalts (Etendeka, Karoo) tend to be depleted in PGE relative to Cu, while most of the older basalts (Hekpoort, Machadodorp, Ventersdorp, Dominion) show no PGE depletion relative to Cu. Further, the younger basalts tend to have lower average Pt/Pd ratios than the older basalts, and the MORBs have lower average Pt/Pd than the continental basalts within the broad groupings of "old" and "young" basalts. This may reflect (1) a decreasing degree of mantle melting through geologic time, and (2) source heterogeneity, in that the MORBs are derived from predominantly asthenospheric mantle, whereas the continental basalts also contain a lithospheric mantle component enriched in Pt. In addition to these factors, some PGE fractionation also occurred during differentiation of the magmas, with Pd showing incompatible behaviour and the other PGE variably compatible behaviour. The examined southern African flood-type basalts and MORB appear to offer limited prospects for magmatic sulfide ores, largely because they show little evidence for significant chalcophile metal depletion that could be the result of sulphide extraction during ascent and crystallization.Editorial responsibility: I. Parsons  相似文献   

Geophysical response of filled sinkholes,soil pipes and associated bedrock fractures in thinly mantled karst,east-central Illinois     

Shawkat?Ahmed  Philip?J.?CarpenterEmail author 《Environmental Geology》2003,44(6):705-716

Karst aquifers are often protected by a thin mantle of unconsolidated sediment. Soil pipes and sinkholes may breach this natural protective barrier and open pathways for contaminants to quickly reach bedrock aquifers. Geophysical surveys offer a quick and noninvasive way to identify these features; such surveys may also be sequenced to reveal increasing detail in critical areas. At a study site in east-central Illinois, electromagnetic (EM) surveys mapped high conductivity anomalies over filled sinkholes and soil pipes that penetrated the unconsolidated cover. Two-dimensional inverted resistivity sections, made over these anomalies, depict filled sinkholes and soil pipes as conductive zones above deeply weathered bedrock fractures. Borings verified the geophysical models and suggest high conductivities associated with the filled sinkholes are the result of enhanced moisture near active soil pipes. EM surveys also identified conductive zones in the overburden above a probable bedrock fracture linking sinkhole areas 0.5 km apart. Resistivity and EM methods, used in a phased and sequential manner, thus proved useful in mapping filled sinkholes and in delineating the vertical and lateral connections between soil pipes and hydraulically active bedrock fractures.  相似文献   

Chemical Mechanism Development: Laboratory Studies and Model Applications     

Harald Geiger  Ian Barnes  Karl H. Becker  Birger Bohn  Theo Brauers  Birgit Donner  Hans-Peter Dorn  Manfred Elend  Carlos M. Freitas Dinis  Dirk Grossmann  Heinz Hass  Holger Hein  Axel Hoffmann  Lars Hoppe  Frank Hülsemann  Dieter Kley  Björn Klotz  Hans G. Libuda  Tobias Maurer  Djuro Mihelcic  Geert K. Moortgat  Romeo Olariu  Peter Neeb  Dirk Poppe  Lars Ruppert  Claudia G. Sauer  Oleg Shestakov  Holger Somnitz  William R. Stockwell  Lars P. Thüner  Andreas Wahner  Peter Wiesen  Friedhelm Zabel  Reinhard Zellner  Cornelius Zetzsch 《Journal of Atmospheric Chemistry》2002,42(1):323-357

Within the German Tropospheric Research Programme (TFS) numerous kinetic and mechanistic studies on the tropospheric reaction/degradation of the following reactants were carried out: oxygenated VOC, aromatic VOC, biogenic VOC, short-lived intermediates, such as alkoxy and alkylperoxy radicals.At the conception of the projects these selected groups were classes of VOC or intermediates for which the atmospheric oxidation mechanisms were either poorly characterised or totally unknown. The motivation for these studies was the attainment of significant improvements in our understanding of the atmospheric chemical oxidation processes of these compounds, particularly with respect to their involvement in photooxidant formation in the troposphere. In the present paper the types of experimental investigations performed and the results obtained within the various projects are briefly summarised. The major achievements are highlighted and discussed in terms of their contribution to improving our understanding of the chemical processes controlling photosmog formation in the troposphere.  相似文献   

Mode Mixing by a Shallow Sunspot     

Barnes  G.  Cally  P.S. 《Solar physics》2000,193(1-2):373-382

Sunspots are strong absorbers of f and p modes. A possible absorption mechanism is direct conversion to slow magnetoacoustic waves. Calculations based on vertical magnetic field models show that this works well for f modes, but is inadequate for p modes. Using a very simple shallow spot model, in which the effects of the magnetic field are accounted for solely by a surface condition, we investigate the possibility that p modes first scatter into f modes inside the spot, which are then more susceptible to conversion to slow modes. We find that the coupling between an incident p mode and the internal f mode is unlikely to be strong enough to account for the observed absorption, but that the incident modes do couple strongly to the acoustic jacket in some cases, leading to a region immediately around the sunspot where a significant fraction of the surface velocity is due to the jacket modes.  相似文献   

Wide-Field Camera for Gravitational Microlensing Survey: MOA-cam2     

Toshifumi Yanagisawa  Yasushi Muraki  Yutaka Matsubara  Fumio Abe  Kimiaki Masuda  Sachiyo Noda  Takahiro Sumi  Yuji Kato  Mitsuaki Fujimoto  Shuji Sato  Ian Bond  Nicholas Rattenbury  Philip Yock  Pam Kilmartin  John Hearnshaw  Micheal Reid  Denis Sullivan  Brian Carter  Richard Dodd  Garry Nankivell  Noiman Rumsey  Morihiro Honda  Maki Sekiguchi  Masanori Yoshizawa  Takashi Nakamura  Humitaka Sato  Seiji Kabe  Makoto Kobayashi  Yoshiyuki Watase  Jun Jugaku  Toshiharu Saito  Barbel Koribalsky 《Experimental Astronomy》2000,10(4):519-535

We have constructed a large, mosaic CCD camera called MOA-cam2 which has 4096 × 6144-pixelsto search for gravitational microlensing events. MOA-cam2 has three4096 × 2048-pixel SITe CCD chips, which have a very high quantum efficiency (nearly 80% in the wave region 500 to 800 nm),and three buttable sides. We have placed the threechips side by side with 100 m dead space. MOA-cam2 has been installed on the 61 cm Boller and Chivens telescope of the MOA collaboration at the Mt. John University Observatory (MJUO) in NewZealand since July 1998. The field coverage is 0.92° × 1.38° per exposure. The technical details of MOA-cam2 and the first images obtained with the Boller and Chivens telescope are presented. MOA-cam2 introduces a second phase of research on gravitational microlensing by the MOA collaboration.  相似文献   

Influence of wave groups on SSC patterns over vortex ripples     

Paul V. Villard  Philip D. Osborne  Christopher E. Vincent 《Continental Shelf Research》2000,20(17):1

Estimates of spatial and temporal variations in suspended sand concentrations (SSC) made with a multi-transducer Acoustic Backscatter Sensor (ABS) under a repeated wave group over a mobile rippled bed in the wave research flume at the National Hydraulics Laboratory in Ottawa, Canada, reveal an number of complex and intriguing patterns. Ensemble averages of 8 nearly identical wave groups provided much more robust estimates of SSC and allowed a detailed examination of the wave group effects. The largest SSC near the bed (< 0.10 m) occurs in phase with the largest waves in the group. Above approximately 0.10 m elevation, SSC lags behind the near bed SSC by as much as 2–3 waves; introducing significant curvature (on a semi-log plot) to the SSC profile. The log linear segments of the SSC profile grow and decay systematically on the scale of the wave group. The range in lengths of log-linear profile segments ( 0.03–0.355 m) suggest that the boundary layer thickness also fluctuates throughout the passage of the wave group. Furthermore, there are significant variations in the patterns of SSC, which occur under the largest and smallest waves in the group. Under the largest waves vertical bands of alternating high and low SSC produce an intra-wave modulation in the upper water column ( 0.075–0.30 m). The equivalent horizontal excursion of these bands scales to the ripple length. Under the smaller waves the intra-wave modulation of the SSC disappears and is replaced by temporally homogenous suspension that expands vertically through several individual wave cycles. The former pattern of homogenous suspension appears to be associated with growth of a boundary layer due to the persistent uni-directional horizontal flow during this part of the group together with the persistence of antecedent bed generated turbulence and vorticity which maintains the suspension. The latter pattern of bands of high and low SSC indicates a strong temporal and spatial constraint on the SSC (phase coupling) induced by the presence of the bedforms which may be enhanced by strong reversals in both flow and vorticity under the large waves in the group.  相似文献