Determination of the strain ellipsoid from measurements on any three sections     

Nicholas J. Milton 《Tectonophysics》1980,64(1-2)

An ellipsoid is defined by, and may be re-constructed from, any three sections through it. In the field, calculation of the strain ellipsoid from general sections (two-dimensional strain ellipses determined from measured strain markers) is complicated by the fact that, due to experimental error and/or strain inhomogeneity, the three ellipses may not come from the same ellipsoid. The ellipses must first be adjusted to make them compatible. A method is suggested by which an adjustment ellipse is determined analytically for each of the three sections. Application of these adjustment ellipses makes the three sections compatible, and the strain ellipsoid may be determined. The principal axes of the ellipsoid are derived from the ellipsoid matrix by eigenvector analysis. Examples are given of practical applications of this method.  相似文献   

“Rare-earth and other trace element contents and the origin of minettes.” A critical comment on a paper by Bachinski and Scott (1979)     

Nicholas M.S. Rock 《Geochimica et cosmochimica acta》1980,44(9):1385-1388

  相似文献   

The changing atmosphere: A review     

G. A. McKay 《Natural Hazards》1991,4(4):353-372

Concern over the effects of human activities on this planet and on it's ecosystems is widespread. Changes wrought within the atmosphere are of particular concern because they have pervasive social, environmental, and economic effects; some potentially serious and very long-term. The problems they pose and the need for remedial measures creates both scientific and policy challenges. This paper bridges the two domains, outlining how the atmosphere is being changed, some of the possible consequences thereof, and actions being taken to address the issue.Emissions to the atmosphere are attacking the stratospheric ozone shield, causing acidification, spreading toxic substances and increasing the greenhouse effect. Of these concerns, the global issue of greenhouse warming will have the greatest overall impact and it the most difficult to address. While some countries have taken important preventative and mitigating measures, action on the greenhouse threat generally has been restrained because of related uncertainties, possible economic upsets and the enormity of the problem. The paper ends by noting recent international initiatives toward development of needed public policies and the roles of the scientist in addressing the issue.  相似文献   

Biochemical Effects on Contaminant Fate and Transport     

Evan K. Nyer  Victoria Kramer  Nicholas Valkenburg 《Ground Water Monitoring & Remediation》1991,11(2):80-82

  相似文献   

The application of a finite difference model of internal tide generation to the NW European Shelf     

Dr. Toby Sherwin  Nicholas Taylor 《Ocean Dynamics》1989,42(3-6):151-167

  相似文献   

Rupture geometry from high-precision relative hypocentre locations of microearthquake clusters   总被引：2，自引：0，他引：2  

Nicholas Deichmann  Mariano Garcia-Fernandez 《Geophysical Journal International》1992,110(3):501-517

  相似文献   

The influence of microform bed roughness elements on flow and sediment transport in gravel bed rivers: Comment on a paper by marwan A. Hassan and ian reid     

Nicholas J. Clifford  Keith S. Richards  Andre Robert 《地球表面变化过程与地形》1992,17(5):529-534

Data from Turkey Brook are used to demonstrate that the interaction between gravel bedforms, flow resistance and bedload transport is a dynamic one, both between and within hydrographs. and that creation of a significant component of form drag through construction of microforms (pebble clusters) may precede the eventual break-up of the bed in a transport event. This process of drag augmentation', which can be seen as a feedback mechanism delaying transport and can be likened to dilation of a soil tested in a direct shear apparatus, itself appears to be dependent on the characteristics of turbulence, and therefore involves feedback at a finer resolution than envisaged by Hassan and Reid (1990).  相似文献   

TOPOGRAPHIC SURVEYING: THE JUBILEE LINE EXTENSION SURVEY     

D. Stevens  W. M. McKay  M. R. May 《The Photogrammetric Record》1992,14(79):85-98

  相似文献   

Internal control of fluid compositions in amphibolite-facies scapolitic calc-silicates,Mary Kathleen,Australia     

Nicholas H. S. Oliver  Victor J. Wall  Ian Cartwright 《Contributions to Mineralogy and Petrology》1992,111(1):94-112

Unaltered metasediments of the Mary Kathleen Fold Belt are composed predominantly of layered amphibolite-facies scapolitic calc-silicate rocks in which minimal infiltration of externally derived fluids occurred during regional metamorphism. There were substantial differences in volatile activities between different layers in the layered sequences, in particular: a _CO2/a _{H 2 O} inferred from reaction progress estimates and analysis of biotite-clinopyroxene-fluid phase relations; a _NaCl/a _{H 2 O} inferred from scapolite compositions; and a _HCl/a _{H 2 O} inferred from biotite compositions. In one outcrop in which a clinopyroxene-producing reaction dominated, differences in approximate X _{CO 2}of up to 0.25 occurred between several samples collected over 50 metres. Variations in a _{H 2 O}/a _HCl of up to one order of magnitude are inferred at 1 to 50 m scales from biotite-Cl contents, and variations in NaCl contents of scapolite from 0.0 to up to 0.6 Cl atoms in the Cl–CO₃–SO₄ site reflect a large variation of a _NaCl in the coexisting fluid at similar scales. Most calcsilicate layers internally buffered fluid compositions in the H₂O–CO₂–NaCl–HCl system. Local occurrences of NaCl-rich scapolite suggest that some layers may have been in equilibrium with halite during early prograde metamorphism. At peak metamorphic temperatures, disolution of halite was complete but layers containing high-NaCl scapolite continued to buffer fluid at high values of a _NaCl. Fluid immiscibility does not appear to have affected the progress of the devolatilization reactions. Although fluid was predominantly internally buffered, moderate quantities of fluid were released by prograde mineral reactions in many layers, up to 30 cm³ fluid per 100 cm³ rock. Numerous episodes of fluid escape were required, probably via microfractures, such that the released fluid did not obviously influence reaction progress in the layers through which it passed. The anomaly of beautifully preserved internal buffering signatures and the requirement for produced fluid locally to pass across layers in a deforming rock sequence suggest that the escaping fluid did not leave any readily observable tracks. This is explained by rapid rates of fracture propogation and fluid migration therein. This internally buffered system contrasts strongly with adjacent calc-silicate rocks that show evidence for infiltration of externally derived fluids at high fluid/rock ratios, and highlights the broad range of fluid behaviour that can be expected in deforming, heterogeneous rock sequences.  相似文献   

Seismic displacements on shear surfaces in cohesive soils     

Theodora E. Tika-Vassilikos  Sarada K. Sarma  Nicholas N. Ambraseys 《地震工程与结构动力学》1993,22(8):709-721

The paper is concerned with the earthquake-induced displacements on pre-existing shear surfaces in cohesive soils. Results from ring shear tests have shown that during fast shearing the strength of such surfaces depends on displacement and rate of shearing. The test results have been used in a numerical analysis to assess the displacement of a rigid block sliding on a plane surface. The results from the analysis show that the earthquake-induced displacements on pre-existing shear surfaces are influenced significantly by the soil behaviour under earthquake loading conditions. The results are consistent with the field performance of pre-existing slides in cohesive soils during earthquakes.  相似文献