Natural rock joint roughness quantification through fractal techniques   总被引：8，自引：0，他引：8  

P. H. S. W. Kulatilake  P. Balasingam  Jinyong Park  R. Morgan 《Geotechnical and Geological Engineering》2006,24(5):1181-1202

Accurate quantification of roughness is important in modeling hydro-mechanical behavior of rock joints. A highly refined variogram technique was used to investigate possible existence of anisotropy in natural rock joint roughness. Investigated natural rock joints showed randomly varying roughness anisotropy with the direction. A scale dependant fractal parameter, K _v, seems to play a prominent role than the fractal dimension, D _r1d, with respect to quantification of roughness of natural rock joints. Because the roughness varies randomly, it is impossible to predict the roughness variation of rock joint surfaces from measurements made in only two perpendicular directions on a particular sample. The parameter D _r1d × K _v seems to capture the overall roughness characteristics of natural rock joints well. The one-dimensional modified divider technique was extended to two dimensions to quantify the two-dimensional roughness of rock joints. The developed technique was validated by applying to a generated fractional Brownian surface with fractal dimension equal to 2.5. It was found that the calculated fractal parameters quantify the rock joint roughness well. A new technique is introduced to study the effect of scale on two-dimensional roughness variability and anisotropy. The roughness anisotropy and variability reduced with increasing scale.  相似文献   

The SuperCOSMOS Sky Survey – I. Introduction and description     

N.C. Hambly  H.T. MacGillivray  M.A. Read  S.B. Tritton  E.B. Thomson  B.D. Kelly  D.H. Morgan  R.E. Smith  S.P. Driver  J. Williamson  Q.A. Parker  M.R.S. Hawkins  P.M. Williams  A. Lawrence 《Monthly notices of the Royal Astronomical Society》2001,326(4):1279-1294

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Studies of the prominence-corona transition zone from rocket ultraviolet spectra of the March 1970 eclipse     

C. Y. Yang  R. W. Nicholls  F. J. Morgan 《Solar physics》1975,45(2):351-362

Slitless VUV spectra of the eclipsed Sun were obtained from a rocket experiment for the first time during the 1970 eclipse. The spatially resolved spectra of a quiescent prominence in the wavelength range 900 Å–2200 Å consist of emission lines from ions formed in the temperature range 3.5 × 10⁴k–3.2 × 10⁵k. The spectral intensities have been interpreted in terms of physical parameters which indicate a transition zone of shell-like layers, the inner the cooler and thinner, the outer the hotter and more extended. The transition zone is about 3 km thick for a model thread of 2000 km in diameter.  相似文献   

Features of the interstellar extinction curve     

D. H. Morgan 《Astrophysics and Space Science》1975,34(1):11-17

The extinction curves for spherical particles are subject to the errors of the particle material's refractive index. Their sensitivity to these errors has been investigated and is found to be dependent upon wavelength. For graphite, significant errors are produced in the far ultraviolet part of the extinction curve; for silicates, in the near ultraviolet; while for iron the error is relatively small. The wavelength dependence of the 10 μm and 20 μm absorption bands of small silicate spheroids upon their shape and alignment has been studied. It is found that the bands can be displaced by ～1 μm towards longer wavelengths from their positions for corresponding spheres: and that a further, though small, displacement can be superimposed upon this by their subsequent alignment.  相似文献   

An experimental study of the kinetics of lherzolite reactive dissolution with applications to melt channel formation   总被引：4，自引：1，他引：3  

Zachary?Morgan  Yan?LiangEmail author 《Contributions to Mineralogy and Petrology》2005,150(4):369-385

The kinetics of lherzolite dissolution in an alkali basalt and a basaltic andesite was examined experimentally at 1,300°C and 1 GPa using the dissolution couple method. Dissolution of lherzolite in basaltic liquids produces either the melt-bearing dunite–harzburgite–lherzolite (DHL) sequence or the melt-bearing harzburgite–lherzolite sequence depending on whether the reacting melt is or close to olivine saturation (alkali basalt) or olivine + orthopyroxene saturation (basaltic andesite). The dunite in the DHL sequence is pyroxene-free and the harzburgites in both sequences are clinopyroxene-free. The melt fraction and olivine grain size in the dunite are larger than those in the harzburgite. The olivine grain size in the dunite and harzburgite in the DHL sequence also increases as a function experimental run time. Across the sharp dunite–harzburgite and harzburgite–lherzolite interfaces, systematic compositional variations are observed in the reacting melt, interstitial melt, olivine, and to a lesser extent, pyroxenes as functions of distance and time. The systematic variations in lithology, grain size, mineral chemistry, and melt compositions are broadly similar to those observed in the mantle sections of ophiolites. The processes of lherzolite dissolution in basaltic liquids involve dissolution, precipitation, reprecipitation, and diffusive transport in the interstitial melts and surrounding minerals. Preferential dissolution of olivine and clinopyroxene and precipitation of orthopyroxene in the basaltic andesite produces the melt-bearing harzburgite–lherzolite sequence. Preferential dissolution of clinopyroxene and orthopyroxene and precipitation of olivine results in the melt-bearing DHL sequence. Preferential mineral dissolution can also affect the composition of the through-going melt in a dunite channel or harzburgite matrix. Systematic variations in melt fraction and mineral grain size in the peridotite sequences are likely to play an important role in the development of channelized or diffuse porous melt flow in the mantle.An erratum to this article can be found at  相似文献   

The Antikythera Mechanism: still a mystery of Greek astronomy?     

M G Edmunds FRAS    P Morgan 《Astronomy& Geophysics》2000,41(6):6.10-6.17

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Holocene Climate Variability in Antarctica Based on 11 Ice-Core Isotopic Records   总被引：1，自引：0，他引：1  

Valrie Masson  Franoise Vimeux  Jean Jouzel  Vin Morgan  Marc Delmotte  Philippe Ciais  Claus Hammer  Sigfus Johnsen  Vladimir Ya. Lipenkov  E. Mosley-Thompson  Jean-Robert Petit  Eric J. Steig  Michel Stievenard  Rein Vaikmae 《Quaternary Research》2000,54(3):348

A comparison is made of the Holocene records obtained from water isotope measurements along 11 ice cores from coastal and central sites in east Antarctica (Vostok, Dome B, Plateau Remote, Komsomolskaia, Dome C, Taylor Dome, Dominion Range, D47, KM105, and Law Dome) and west Antarctica (Byrd), with temporal resolution from 20 to 50 yr. The long-term trends possibly reflect local ice sheet elevation fluctuations superimposed on common climatic fluctuations. All the records confirm the widespread Antarctic early Holocene optimum between 11,500 and 9000 yr; in the Ross Sea sector, a secondary optimum is identified between 7000 and 5000 yr, whereas all eastern Antarctic sites show a late optimum between 6000 and 3000 yr. Superimposed on the long time trend, all the records exhibit 9 aperiodic millennial-scale oscillations. Climatic optima show a reduced pacing between warm events (typically 800 yr), whereas cooler periods are associated with less-frequent warm events (pacing >1200 yr).  相似文献   

Lithospheric structure north of Scotland—II. Poisson's ratios and waveform modelling     

Claire Price  Joanna Morgan 《Geophysical Journal International》2000,142(3):737-754

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Direct 40Ar/39Ar dating of Late Ordovician and Silurian brittle faulting in the southwestern Norwegian Caledonides          下载免费PDF全文

Thomas Scheiber  Giulio Viola  Camilla Maya Wilkinson  Morgan Ganerød  Øyvind Skår  Deta Gasser 《地学学报》2016,28(5):374-382

Structural data as well as U–Pb zircon and ⁴⁰Ar/³⁹Ar biotite and muscovite ages were collected from the Rolvsnes granodiorite in western Norway. The granodiorite intruded at c. 466 Ma, cooled quickly and escaped later viscous deformation. Brittle top‐to‐the‐NNW thrust faults (Set I) and WNW–ESE striking dextral strike‐slip faults (Set II) formed in a NNW–SSE transpressional regime. ⁴⁰Ar/³⁹Ar dating of synkinematic mica from both sets reveals a c. 450 Ma (Late Ordovician) age of faulting, which constrains early‐Caledonian brittle deformation. Set I and II faults are overprinted by a set of lower‐grade, variably oriented chlorite‐ and epidote‐coated faults (Set III) constraining WNW–ESE shortening. A lamprophyric dyke oriented compatibly with this stress field intruded at c. 435 Ma (Silurian), indicating that Set III formed at the onset of the Scandian Baltica–Laurentia collision. The preservation of Caledonian brittle structures indicates that the Rolvsnes granodiorite occupied a high tectonic level throughout the Caledonian orogeny.  相似文献   

Reply to Comment on “The Keisarhjelmen detachment records Silurian–Devonian extensional collapse in Northern Svalbard”          下载免费PDF全文

Alvar Braathen  Per Terje Osmundsen  Harmon Maher  Morgan Ganerød 《地学学报》2018,30(4):322-324

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