Tephra layers in the Byrd Station ice core and the Dome C ice core, Antarctica and their climatic importance     

Philip R. Kyle  Peter A. Jezek  Ellen Mosley-Thompson  Lonnie G. Thompson 《Journal of Volcanology and Geothermal Research》1981,11(1)

Volcanic glass shards from tephra layers in the Byrd Station ice core were chemically analyzed by electron microprobe. Tephra in seven layers have similar peralkaline trachyte compositions. The tephra are believed to originate from Mt. Takahe, on the basis of their chemical similarity to analyzed rocks from Mt. Takahe and because dated rock samples from the volcano are younger than 250,000 years old. Glass shards from 726 m deep in the Dome C ice core, which is 2400 km from Byrd Station, are composed of peralkaline trachyte and may have also been derived from Mt. Takahe. The tephra could have resulted from eruptions which were triggered by increased ice loading during the late Wisconsin glaciation. Preliminary grain size data suggest the eruptions were only minor and they were unlikely to have instantaneously altered global climate as have explosive eruptions in the tropics. Nevertheless, the effect of this localized volcanic activity upon the Antarctic energy budget warrants further investigation.  相似文献   

Global radiation within corn     

W. J. Kyle  J. A. Davies  M. Nunez 《Boundary-Layer Meteorology》1977,12(1):25-35

Global and net solar radiation profiles were measured by traversing sensors at four heights in a square-sown plot and a row plot of field corn on four relatively cloudless days in August 1972. The fluxes and their vertical distributions are discussed. A numerical model of the short-wave radiation fluxes in a canopy is presented. Using leaf area index and fixed leaf radiative properties, calculated values of radiation are within 10% of measurements in most instances. The performance under predominantly beam or diffuse radiation is similar and model values of crop albedo compare well with values calculated from radiation measurements above the crops.  相似文献   

An Observational Study of Entraining Convection using Balloon-Borne Turbulence Probes and High-Power Doppler Radar     

S. G. Palmer  S. J. Caughey  K. W. Whyte 《Boundary-Layer Meteorology》1979,16(3):261-278

Features associated with the upper limit of convection, observed by turbulence probes supported by a tethered kite balloon and by high-power Doppler radar, are described. The observations illustrate the interaction of thermal plumes with the capping inversion (and stable air aloft) and confirm the existence of non-turbulent, intermittently turbulent and fully turbulent layers. Evidence is presented for entrainment processes occurring on scales ranging from a few metres to several hundred metres. Individual distortions of the inversion interface, tracked by the radar, have a lifetime of about 5 minutes. Other, larger scale (i.e., > 1 km) perturbations of the top of the boundary layer were observed over longer periods, and are thought to be due to topographical effects.  相似文献   

<Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating of the eruptive history of Mount Erebus,Antarctica: volcano evolution     

Richard?P.?EsserEmail author  Philip?R.?Kyle  William?C.?McIntosh 《Bulletin of Volcanology》2004,66(8):671-686

Mt. Erebus, a 3,794-meter-high active polygenetic stratovolcano, is composed of voluminous anorthoclase-phyric tephriphonolite and phonolite lavas overlying unknown volumes of poorly exposed, less differentiated lavas. The older basanite to phonotephrite lavas crop out on Fang Ridge, an eroded remnant of a proto-Erebus volcano and at other isolated locations on the flanks of the Mt. Erebus edifice. Anorthoclase feldspars in the phonolitic lavas are large (~10 cm), abundant (~30–40%) and contain numerous melt inclusions. Although excess argon is known to exist within the melt inclusions, rigorous sample preparation was used to remove the majority of the contaminant. Twenty-five sample sites were dated by the ⁴⁰Ar/³⁹Ar method (using 20 anorthoclase, 5 plagioclase and 9 groundmass concentrates) to examine the eruptive history of the volcano. Cape Barne, the oldest site, is 1,311±16 ka and represents the first of three stages of eruptive activity on the Mt. Erebus edifice. It shows a transition from sub-aqueous to sub-aerial volcanism that may mark the initiation of proto-Erebus eruptive activity. It is inferred that a further ~300 ky of basanitic/phonotephritic volcanism built a low, broad platform shield volcano. Cessation of the shield-building phase is marked by eruptions at Fang Ridge at ~1,000 ka. The termination of proto-Erebus eruptive activity is marked by the stratigraphically highest flow at Fang Ridge (758±20 ka). Younger lavas (~550–250 ka) on a modern-Erebus edifice are characterized by phonotephrites, tephriphonolites and trachytes. Plagioclase-phyric phonotephrite from coastal and flank flows yield ages between 531±38 and 368±18 ka. The initiation of anorthoclase tephriphonolite occurred in the southwest sector of the volcano at and around Turks Head (243±10 ka). A short pulse of effusive activity marked by crustal contamination occurred ~160 ka as indicated by at least two trachytic flows (157±6 and 166±10 ka). Most anorthoclase-phyric lavas, characteristic of Mt. Erebus, are less than 250 ka. All Mt. Erebus flows between about 250 and 90 ka are anorthoclase tephriphonolite in composition.Editorial responsibility: J. Donelly-Nolan  相似文献   

Three-dimensional outlier detection for GPS networks and their densification via the BLIMPBE approach     

Kyle?B.?SnowEmail author  Burkhard?Schaffrin 《GPS Solutions》2003,7(2):130-139

This article discusses outlier detection based on Baarda's theory, but applied to three-dimensional GPS baseline vectors, as compared to the traditional approach of investigating the vector components individually (one-dimensional). In addition, Schaffrin's recently proposed estimator of type BLIMPBE is discussed and contrasted with a minimum constrained least-squares adjustment, specifically Partial-MINOLESS. A more detailed discussion of these topics, which includes additional formulas and derivations, can be found in the first author's Master of Science thesis, hereinafter referred to as Report 465.  相似文献   

Estimating tectonic history through basin simulation-enhanced seismic inversion: geoinfomatics for sedimentary basins     

Kush Tandon †  Kagan Tuncay  Kyle Hubbard  John Comer  Peter Ortoleva 《Geophysical Journal International》2004,156(1):129-139

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Lithostratigraphy of the Mérida (Wisconsinan) glaciation and Pedregal interstade, Mérida Andes, northwestern Venezuela     

Randy W. Dirszowsky  William C. Mahaney  Kyle R. Hodder  Michael W. Milner  Volli Kalm  Maximiliano Bezada  Roelf P. Beukens 《Journal of South American Earth Sciences》2005,19(4):525-536

At Pedregal, more than 40 m of sediments are exposed within a ‘fan complex’ formed between lateral moraines of the adjacent Mucuchache and El Caballo valleys. Early and late Mérida (Wisconsinan) glaciations are represented by till and till plus proglacial sediments, respectively. A middle Wisconsinan interstadial event, here termed the Pedregal interstade, began at the end of the Early Mérida glaciation at approximately 60 ka BP. Following the retreat of ice from the small Pedregal Basin, a lake formed when the local drainage was blocked due to movement of the Mesa de Caballo along the Boconó Fault. Shallow lake or no-lake phases lasted approximately a few hundred to, at most, 2000 years, and each lake phase was marked by peat accumulation. Four of seven peats identified formed during sufficiently long intervals for soil profiles (incipient to mature Spodosols) also to develop. The Spodosol with the strongest development (Eb/Bsb/Coxb/Cub horizons) is found adjacent to the lowest peat and reflects ongoing early Mérida stadial (MIS 3) conditions; the youngest peats, associated with weak podzolic soils (Eb/Bsb horizons), formed under slightly warmer interstadial conditions, presumably with less soil water. Cyclic lacustrine deposition is related to lake level and relative depth fluctuations, due in part to variable shoreline/delta progradation and shallowing as the lake deepened in general. Whereas final drainage of the lake is related to movement of the Boconó Fault and breach of the moraines that form the Mesa de Caballo, earlier lake level fluctuations appear related to climate change. Radiocarbon dating of the peats suggests they are related to warmer periods and may tentatively correlate with small ‘interstadials’ or ‘D-O events’ detected in the oxygen-isotope record of Greenland ice cores and North Atlantic marine sediments.  相似文献   

Book reviews     

W. R. Stanley  H. Tietze  C. P. Lo  B. Hartung-Kagi  R. O. Whyte  W. U. Ehrmann  A. G. Koestler  A. Wallner 《GeoJournal》1987,14(2):277-280

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Geochemical alteration associated with the Selbaie copper-zinc-silver deposit     

J.B. Whyte  I. Nichol 《Journal of Geochemical Exploration》1987,28(1-3)

The object of this study is to establish the nature of geochemical alteration in the wall rocks of the Selbaie Cu-Zn-Ag deposit, and to ascertain whether bedrock geochemistry could be applied in exploration for deposits of this type. The Selbaie Cu-Zn-Ag deposit, in northwestern Quebec, is atypical of base-metal deposits in the Canadian Shield, as mineralization occurs in epigenetic veins and as disseminations in volcanic wall rocks, rather than as syngenetic massive sulfide bodies which have been the focus of extensive comparable studies in the past. The deposit comprises three mineralized zones in felsic tuffs and quartz porphyry. Two of these, the A1 and A2 zones, which are the focus of the present study consist of quartz-carbonate veins containing chalcopyrite, sphalerite, and pyrite, and accessory sulfide minerals. The B zone is not considered in this study. Samples of drill core were collected from sections crossing the A1 and A2 zones and analyzed for total Si, Al, Fe, Mg, Ca, Na, K, Ti, Mn, P, and S by X-ray fluorescence, and for aqua-regia-extractable Cu, Zn, Ni, Pb, Fe, and Mn by atomic absorption. Although the distribution of individual element concentrations is clearly related to bedrock type, rocks proximal to mineralization have higher SiO₂, Fe₂O₃, Cu, Zn, Fe, and S contents, and lower Al₂O₃ and K₂O contents, than rocks more distal from mineralization. MgO content shows an irregular distribution and may also increase toward mineralization. CaO and Na₂O contents are very low in all pyroclastic rocks.In order to take into account the effect of bedrock type, linear regression analysis was performed on the data to estimate the normal concentration of individual elements using SiO₂ contents as the predicted variable. Spatial distributions of residual values of element concentrations indicate that rocks close to mineralization have higher residual Fe₂O₃, Cu, Zn, Pb, and Fe contents, and lower residual Al₂O₃ and K₂O contents, compared to rocks more remote from mineralization. These distribution patterns are clearer than in the case of the single-element data but variations between element responses still exist in some instances. In an attempt to overcome the variation in patterns revealed by some element distributions, discriminant analysis was undertaken to see whether mineralized areas could be distinguished on the basis of an element association. Discriminant functions were calculated for data from areas adjacent to mineralization, and from areas remote from mineralization. Areal distribution of discriminant scores outlined an anomalous area extending up to 200 m beyond the mineralization. Petrographic studies of selected samples correlated high SiO₂ and low Al₂O₃ content with silicification in the most altered rocks adjacent to mineralization. High Fe₂O₃, MgO, and extractable Fe concentrations were found to occur in chlorite- and carbonate-rich zones. Samples rich in S, Cu, Zn, and b, and to a lesser extent Fe, were characterized by the presence of sulfides. High concentrations of Al₂O₃ and K₂O relative to that of SiO₂ are typical of sericitization. On this basis, the results demonstrate that anomalously high or low concentrations of element associations, revealed by discriminant analysis, occur in large coherent zones exceeding the size of the deposit. The procedure is potentially useful as an exploration guide for epigenetic disseminated and vein-type base-metal styles of mineralization as well as the syngenetic massive sulfide type of deposits that have been extensively studied in the past.  相似文献   

Nighttime temperature field in a valley     

T. G. Kyle  W. E. Clements 《Meteorology and Atmospheric Physics》1985,34(2):131-139

Summary An analysis of the nighttime near-surface temperature field at 27 stations in a deep mountain valley has been carried out for 5 nights during which drainage winds developed. It was found that a simple exponential function of time and the pressure level of each station accurately represents the temperature evolution during the night. Of particular interest is the fact that above a particular pressure elevation the temperature increases during the night.

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Nächtliches Temperaturfeld in einem Tal

Zusammenfassung Es wurde eine Analyse des nächdichen oberflächennahen Temperaturfeldes an 27 Stationen in einem tiefen Gebirgstal für funf Nächte, in denen Bergwind auftrat, durchgeführt. Es stellte sich heraus, da\ die Temperaturentwicklung während der Nacht exakt durch eine einfache Exponentialfunktion der Zeit und des Druckniveaus jeder Station beschrieben wird. Von besonderem Interesse ist die Tatsache, da\ die Temperatur während der Nacht über einem bestimmten Druckniveau ansteigt.

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With 3 Figures  相似文献