Preferred Orientation and Velocity Anisotropy in Marine Clay-Bearing Calcareous Sediments

1993 ◽  
pp. 149-161 ◽  
Author(s):  
David K. O’Brien ◽  
Murli H. Manghnani ◽  
Jane S. Tribble ◽  
H.-R. Wenk
Keyword(s):  
Preferred Orientation ◽  
Marine Clay ◽  
Velocity Anisotropy

Anisotropy of experimentally compressed kaolinite-illite-quartz mixtures

Geophysics ◽  
2009 ◽  
Vol 74 (1) ◽  
pp. D13-D23 ◽  
Author(s):  
Marco Voltolini ◽  
Hans-Rudolf Wenk ◽  
Nazmul Haque Mondol ◽  
Knut Bjørlykke ◽  
Jens Jahren
Keyword(s):  
Single Crystal ◽  
Elastic Properties ◽  
Compaction Pressure ◽  
Clay Content ◽  
Orientation Distribution ◽  
Rietveld Analysis ◽  
Preferred Orientation ◽  
P Wave ◽  
Velocity Anisotropy ◽  
Pole Figures

The anisotropy of physical properties is a well-known characteristic of many clay-bearing rocks. This anisotropy has important implications for elastic properties of rocks and must be considered in seismic modeling. Preferred orientation of clay minerals is an important factor causing anisotropy in clay-bearing rocks such as shales and mudstones that are the main cap rocks of oil reservoirs. The preferred orientation of clays depends mostly on the amount of clays and the degree of compaction. To study the effect of these parameters, we prepared several samples compressing (at two effective vertical stresses) a mixture of clays (illite and kaolinite) and quartz (silt) with different clay/quartz ratios. The preferred orientation of the phases was quantified with Rietveld analysis on synchrotron hard X-ray images. Pole figures for kaolinite and illite display a preferred orientationof clay platelets perpendicular to the compaction direction, increasing in strength with clay content and compaction pressure. Quartz particles have a random orientation distribution. Aggregate elastic properties can be estimated by averaging the single-crystal properties over the orientation distribution obtained from the diffraction data analysis. Calculated P-wave velocity anisotropy ranges from 0% (pure quartz sample) to 44% (pure clay sample, highly compacted), but calculated velocities are much higher than measured velocities. This is attributed to uncertainties about single-crystal elastic properties and oriented micropores and limited grain contacts that are not accounted for in the model. In this work, we present an effective method to obtain quantitative data, helping to evaluate the role of clay percentage and compaction pressure on the anisotropy of elastic properties of clay-bearing rocks.

scholarly journals Lattice-Preferred Orientation and Seismic Anisotropy of Minerals in Retrograded Eclogites from Xitieshan, Northwestern China, and Implications for Seismic Reflectance of Rocks in the Subduction Zone

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 380
Author(s):  
Jaeseok Lee ◽  
Haemyeong Jung
Keyword(s):  
Subduction Zones ◽  
Seismic Anisotropy ◽  
Seismic Velocity ◽  
Northwest China ◽  
Preferred Orientation ◽  
P Wave ◽  
Contact Boundary ◽  
Seismic Properties ◽  
Velocity Anisotropy ◽  
Lattice Preferred Orientation

Various rock phases, including those in subducting slabs, impact seismic anisotropy in subduction zones. The seismic velocity and anisotropy of rocks are strongly affected by the lattice-preferred orientation (LPO) of minerals; this was measured in retrograded eclogites from Xitieshan, northwest China, to understand the seismic velocity, anisotropy, and seismic reflectance of the upper part of the subducting slab. For omphacite, an S-type LPO was observed in three samples. For amphibole, the <001> axes were aligned subparallel to the lineation, and the (010) poles were aligned subnormal to foliation. The LPOs of amphibole and omphacite were similar in most samples. The misorientation angle between amphibole and neighboring omphacite was small, and a lack of intracrystalline deformation features was observed in the amphibole. This indicates that the LPO of amphibole was formed by the topotactic growth of amphibole during retrogression of eclogites. The P-wave anisotropy of amphibole in retrograded eclogites was large (approximately 3.7–7.3%). The seismic properties of retrograded eclogites and amphibole were similar, indicating that the seismic properties of retrograded eclogites are strongly affected by the amphibole LPO. The contact boundary between serpentinized peridotites and retrograded eclogites showed a high reflection coefficient, indicating that a reflected seismic wave can be easily detected at this boundary.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

Existence of Cubic ZrO2 at 300°C on Bulk Zirconium

1969 ◽  
Vol 27 ◽  
pp. 166-167
Author(s):  
R.A. Ploc
Keyword(s):  
Metal Oxide ◽  
Metal Substrate ◽  
Preferred Orientation ◽  
Monoclinic Zirconia ◽  
Epitaxial Relationship

The manner in which ZrO2 forms on zirconium at 300°C in air has been discussed in the first reference. In short, monoclinic zirconia nucleates and grows with a preferred orientation relative to the metal substrate. The mode of growth is not well understood since an epitaxial relationship which gives minimum misfit between the zirconium ions in the metal/oxide combination is not realized. The reason may be associated with a thin cubic or tetragonal layer of ZrO2 between the inner oxygen saturated metal and the outer monoclinic zirconia.

Preferred orientation of rolling-induced ε martensite in an Fe-Mn-Si alloy

2003 ◽  
Vol 112 ◽  
pp. 365-368 ◽  
Author(s):  
K. K. Jee ◽  
W. Y. Jang ◽  
Y. H. Chung
Keyword(s):  
Preferred Orientation ◽  
Ε Martensite

Prediction, Testing, and Analysis of a 50 m Long Pile in Soft Marine Clay

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Bengt Fellenius
Keyword(s):  
Peak Load ◽  
Pile Head ◽  
Marine Clay ◽  
Loading Test ◽  
Head Displacement ◽  
Floating Pile ◽  
Peak Loads ◽  
Static Loading Test ◽  
Beta Coefficient ◽  
Load Movement

On April 4, 2018, 209 days after driving, a static loading test was performed on a 50 m long, strain-gage instrumented, square 275-mm diameter, precast, shaft-bearing (“floating”) pile in Göteborg, Sweden. The soil profile consisted of a 90 m thick, soft, postglacial, marine clay. The groundwater table was at about 1.0 m depth. The undrained shear strength was about 20 kPa at 10 m depth and increased linearly to about 80 kPa at 55m depth. The load-distribution at the peak load correlated to an average effective stress beta-coefficient of 0.19 along the pile or, alternatively, a unit shaft shear resistance of 15 kPa at 10 m depth increasing to about 65 kPa at 50 m depth, indicating an α-coefficient of about 0.80. Prior to the test, geotechnical engineers around the world were invited to predict the load-movement curve to be established in the test—22 predictions from 10 countries were received. The predictions of pile stiffness, and pile head displacement showed considerable scatter, however. Predicted peak loads ranged from 65% to 200% of the actual 1,800-kN peak-load, and 35% to 300% of the load at 22-mm movement.

Measurement of growth rates for single crystals and pressed tablets of CuSO4.5 H2O on a rotating disc

1989 ◽  
Vol 54 (11) ◽  
pp. 2951-2961 ◽  
Author(s):  
Miloslav Karel ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Growth Rates ◽  
Diffusion Coefficients ◽  
Preferred Orientation ◽  
Rotating Disc ◽  
Dissolution Rates ◽  
Rates Of Growth ◽  
Good Agreement

Measured growth and dissolution rates of single crystals and tablets were used to calculate the overall linear rates of growth and dissolution of CuSO4.5 H2O crystals. The growth rate for the tablet is by 20% higher than that calculated for the single crystal. It has been concluded that this difference is due to a preferred orientation of crystal faces on the tablet surface. Calculated diffusion coefficients and thicknesses of the diffusion and hydrodynamic layers in the vicinity of the growing or dissolving crystal are in good agreement with published values.

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