Morphometric analysis and tectonic interpretation of digital terrain data: a case study     

Gyozo Jordan 《地球表面变化过程与地形》2003,28(8):807-822

Tectonic movement along faults is often re?ected by characteristic geomorphological features such as linear valleys, ridgelines and slope‐breaks, steep slopes of uniform aspect, regional anisotropy and tilt of terrain. Analysis of digital elevation models, by means of numerical geomorphology, provides a means of recognizing fractures and characterizing the tectonics of an area in a quantitative way. The objective of this study is to investigate the use of numerical geomorphometric methods for tectonic geomorphology through a case study. The methodology is based on general geomorphometry. In this study, the basic geometric attributes (elevation, slope, aspect and curvatures) are complemented with the automatic extraction of ridge and valley lines and surface speci?c points. Evans' univariate and bivariate methodology of general geomorphometry is extended with texture (spatial) analysis methods, such as trend, autocorrelation, spectral, and network analysis. Terrain modelling is implemented with the integrated use of: (1) numerical differential geometry; (2) digital drainage network analysis; (3) digital image processing; and (4) statistical and geostatistical analysis. Application of digital drainage network analysis is emphasized. A simple shear model with principal displacement zone with an NE–SW orientation can account for most of the the morphotectonic features found in the basin by geological and digital tectonic geomorphology analyses. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Apophyllite (001) surface alteration in aqueous solutions studied by HAFM     

Kirill Aldushin  Guntram Jordan  Werner Rammensee  Hans-Werner Becker 《Geochimica et cosmochimica acta》2004,68(2):217-226

Depending on pH and temperature, two different types of surface reactions occur on the apophyllite (001) surface in aqueous HCl-solutions at temperatures from 20 to 130 °C. At low pH, laterally spreading hillocks cover the surface. The hillocks are softer than the pristine surface, chemical analysis shows a depletion in Ca + K, and the spreading velocity of hillocks depends on pH. This indicates a change in chemical bond strength, non-stoichiometric dissolution and a mechanism involving protons. External disturbances such as the AFM scanning tip cause the upper surface layers to peel off revealing that the active sites of hillock formation are between the silicate layers of apophyllite. The observed process can therefore be described by a penetrative ion-replacement reaction which proceeds well below the surface monolayer. By this ion-replacement, the silicate layers eventually become destabilised. The observed reaction, therefore, is equivalent to an incongruent dissolution process. Despite structural similarities, this process is only superficially similar to the ion-exchange occurring in clay minerals or zeolites. In these minerals, the structural backbone is not destabilized. At a more neutral pH and high temperatures, step retreat and etch pit formation can be observed on the apophyllite (001) surface thus indicating a more congruent dissolution mechanism.  相似文献   

Noble gas loss may indicate groundwater flow across flow barriers in southern Nevada     

James M. Thomas  Bryant G. Hudson  Martin Stute  Jordan F. Clark 《Environmental Geology》2003,43(5):568-579

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Investigating the transition between the 1967 Mudurnu Valley and 1999 Izmit earthquakes along the North Anatolian fault with static stress changes   总被引：1，自引：0，他引：1  

Jordan R. Muller  Atilla Aydin  Frantz Maerten 《Geophysical Journal International》2003,154(2):471-482

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Phylogeny, diet, and habitat of an extinct ground sloth from Cuchillo Curá, Neuquén Province, southwest Argentina     

Michael Hofreiter  Julio L. Betancourt  Alicia Pelliza Sbriller  Vera Markgraf  H. Gregory McDonald 《Quaternary Research》2003,59(3):364-378

Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidium sp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá ground sloth browsed on many of the same herb, grass, and shrub genera common at the site today, and that its habitat was treeless Patagonian scrub-steppe. We envision a day when molecular analyses are used routinely to supplement morphological identifications and possibly to provide a time-lapse view of molecular diversification.  相似文献   

Night-to-night changes in the characteristics of gravity waves at stratospheric and lower-mesospheric heights     

A. J. McDonald  L. Thomas  D. P. Wareing 《Annales Geophysicae》1998,16(2):229-237

Observations made with the co-located Rayleigh lidar and MST radar systems at Aberystwyth (52.4°N, 4.1°W) in Wales and radiosondes from Valentia (51.9°N, 10.2°W) in Eire are used to investigate the changes in the vertical propagation of gravity waves during periods of 4 days in June 1995 and February 1993. In each month, the lidar observations show that the wave activity in the upper stratosphere and lower mesosphere changes between two pairs of days. The radar and radiosonde measurements indicate that mountain waves make no contribution to the changes in intensity. Instead, the changes seem to arise largely from the presence or absence of long-period waves with vertical wavelengths near 8 and 10 km in June and February, respectively. The influence of such waves on the vertical wavenumber spectra is examined and related to the evidence for convective instabilities provided by the temperature profiles.  相似文献   

Desiccation tolerance ofEurypanopeus depressus (smith) (Decapoda: Xanthidae) and the exploitation of microhabitat     

Jonathan Grant  Jack McDonald 《Estuaries and Coasts》1979,2(3):172-177

Investigations into zonation of estuarine invertebrates often indicate that animals living higher in the intertidal region have greater tolerance to effects of aerial exposure. Desiccation tolerances ofEurypanopeus depressus, a xanthid mud crab, were measured in the laboratory for both intertidal and subtidal populations to determine whether intertidal distribution is the result of either increased physiological resistance to drying or other factors. Initially, both populations had a similar percentage of body weight due to water, and at time of death both had lost a similar percentage of water. Desiccation tolerance increased exponentially with size. In laboratory experiments,E. depressus appears very susceptible to desiccation stress with loss of tactile response occurring at 30% depletion of body water. This crab may be able to avoid desiccation and survive in the intertidal zone by remaining in the shelter and moisture of oyster shells and mud at low tide. However,E. depressus may not be limited strictly by physical factors of its environment. Biotic factors such as behavior leading to predator avoidance are possibly more important components in limiting distribution.  相似文献   

Hydrogen and oxygen isotope ratios in the waters of the Ngawha hydrothermal area,North Auckland     

D. C. McDonald 《Bulletin of Volcanology》1966,29(1):691-707

The ratios of D/H and O¹⁸/O¹⁶ in natural waters from streams, boreholes, soda springs, hot pools, ponds and larger bodies of water in the Ngawha hydrothermal area were determined. The results are considered in relation to the isotopic changes known to occur in water subjected to evaporation. Where applicable chemical and other work was also considered. It is assumed that stream water isotope composition is the mean value for the isotopic composition of meteoric waters. Measurements on waters taken from boreholes drilled to 65 feet and 350 feet and from the other water sources mentioned, indicate that they were of meteoric origin as judged by stream isotope composition. The waters from the soda springs appeared to be isotopically the same as the stream water, a finding consistent with the absence of evaporative surface. These borehole waters were similar but slightly different in O¹⁸ due probably to exchange between rock and water. Heavy isotope enrichment of the ponds and larger bodies of water appeared to be due to non-equilibrium evaporation at ambient temperature. The hot pools in the Ngawha springs area proper were enriched in the heavier isotopes probably due to non-equilibrium evaporation at the usual hot pool temperature of about 40°C and also to exchange of O¹⁸ between water and rock. The water from a further borehole drilled to approximately 2,000 feet appeared also to be of meteoric origin but was changed in O¹⁸ content to an extent consistent with the assumption that oxygen isotope exchange with rock had taken place at approximately 230°C. The results are used to illustrate possibilities for the use of oxygen and hydrogen isotope measurements in hydrothermal investigations.  相似文献   

The Colorado river: Instability and basin management,William L. Graf,association of american geographers, 1985. isbn 0-89291-186-7     

Adrian McDonald 《地球表面变化过程与地形》1986,11(4):468-468

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Correlation of He II lyman alpha with He I 10830 Å, and with chromospheric and EUV coronal emission     

W. T. Thompson  W. M. Neupert  S. D. Jordan  H. Jones  R. J. Thomas  B. Schmieder 《Solar physics》1993,147(1):29-46

This paper describes the results of comparing SERTS-3 images obtained in the transition region line of Heii 304 with chromospheric Hei 10830 absorption, with strong coronal lines of Mgix 368 , Fexv 284 and 417 , and Fexvi 335 and 31 , with H, with Caii 8542 , and with magnetograms in Fei 8688H. All of the images are illustrated, and the image reconstruction techniques used are described and evaluated. The high correlation of the Heii 304 and Hei 10830 images, originally found by Harvey and Sheeley (1977), is confirmed and is put on a quantitative basis. We find that the supergranulation network has greater contrast, and that filaments appear darker, in 10830 than in 304 . In active regions, the 304 line follows more closely the behavior of H and Caii 8542 than the 10830 line.  相似文献