Seismic models of a mixed carbonate‐siliciclastic shelf margin: Permian upper San Andres Formation, Last Chance Canyon, New Mexico

Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1744-1748 ◽  
Author(s):  
J. A. M. Kenter ◽  
G. L. Bracco Gartner ◽  
W. Schlager
Keyword(s):  
New Mexico ◽  
Cross Section ◽  
Cross Sections ◽  
Phase Changes ◽  
Genetic Sequence ◽  
Sequence Boundaries ◽  
Seismic Models ◽  
Seismic Reflections ◽  
San Andres ◽  
Mixed Carbonate

Seismic models based on randomly distributed samples from the Permian upper San Andres Formation (Last Chance Canyon, New Mexico) verify that the most prominent seismic reflections are related to stratal geometry. However, at least some reflections arise from lateral facies transitions that are commonly associated with highly prograding mixed carbonate‐siliciclastic sediments. Understanding seismic reflections and reflection terminations in sedimentary rocks requires simulation of at least 2‐D cross‐sections of the impedance distribution. To investigate the cause of reflections in strongly prograding mixed carbonate‐siliciclastic shelf margins, acoustic velocity and bulk density were measured on more than 60 plugs that spatially cover one higher order genetic sequence. The resulting impedance values were gridded and contoured, and the genetic sequence was repeated to create a cross‐section. Averaging impedance values for each lithofacies zone generated a second impedance cross‐section. Seismic models of both impedance cross‐sections revealed the following observations: (1) reflections associated with the sequence boundaries are subject to amplitude and polarity phase changes and (2) at least one reflection within the high‐order sequences is related to subhorizontal facies changes and is associated with two pseudounconformities. The contoured impedance model is suggested to closer resemble the true impedance function in outcrop and shows subtle vertical shifts and significantly higher impedance contrasts.

GRADING SYSTEM FOR SEISMIC REFLECTIONS AND CORRELATIONS

Geophysics ◽  
1947 ◽  
Vol 12 (4) ◽  
pp. 590-617 ◽  
Author(s):  
Phil P. Gaby
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Practical Method ◽  
Base Line ◽  
Subsurface Structure ◽  
Conflicting Information ◽  
Conflicting Evidence ◽  
Pertinent Information ◽  
Seismic Reflections

The modern reflection seismograph places progressively more emphasis on continuous profiling. The use of the continuous profile method automatically makes possible the computation of dip and the plotting of dip cross sections. Fundamentally the accuracy of a dip computed on such a continuous‐profile symmetrical record is of the same order as the accuracy of a “correlation” between adjacent records because the dip consists of a continuous‐profile correlation over the same length of subsurface base line as that obtained by “correlation” of adjacent, continuous profiles. Dip computation is the fundamental procedure in areas of discontinuous correlation. Further, the use of dip and of correlation provides two essentially independent approaches to the determination of subsurface structure. The combination of the two is used to provide more uniformly accurate results than can be had through the use of either one alone. We require a practical method for sorting and grading the accuracy of dip indications and of correlation, which system should be based on substantially the same fundamentals in each case and should be as free as possible from the vagaries of personal judgment. A system is outlined which is adapted to both purposes. In evaluating dip attitudes, the grade indicates: (a) The certainty with which the event may be identified as a true reflection, and (b) The accuracy of the indicated dip. Similarly, in evaluating correlation, the grade indicates: (a) The certainty with which the events being correlated are known to be correlatives, and (b) The accuracy of the indicated correlation drop. These grades, placed on the cross section, serve as a guide in sorting out any conflicting information at the time the interpretation (and map) is being made. The use of such grades allows the concentration of all pertinent information in one place where any conflicting evidence can be weighed in terms of relative merit.

Parameters controlling sonic velocities in a mixed carbonate‐siliciclastics Permian shelf‐margin (upper San Andres formation, Last Chance Canyon, New Mexico)

Geophysics ◽  
1997 ◽  
Vol 62 (2) ◽  
pp. 505-520 ◽  
Author(s):  
Jeroen A. M. Kenter ◽  
F. F. Podladchikov ◽  
Marc Reinders ◽  
Sjierk J. Van der Gaast ◽  
Bruce W. Fouke ◽  
...  
Keyword(s):  
New Mexico ◽  
Velocity Ratio ◽  
Acoustic Properties ◽  
Carbonate Content ◽  
Sonic Velocity ◽  
Carbonate Minerals ◽  
Data Set ◽  
San Andres ◽  
Mixed Carbonate ◽  
Mineralogic Composition

We have measured the acoustic properties and mineralogic composition of 48 rock specimens from mixed carbonate‐siliciclastic outcrops of the Permian upper San Andres formation in Last Chance Canyon, New Mexico. The goals were: (1) identify and model the parameters controlling the sonic velocities; (2) assess the influence of postburial diagenesis on the acoustic velocities. The variation in sonic velocity in the 0 to 25% porosity range is primarily controlled by porosity, and secondly by the ratio of carbonate‐siliciclastic material. Linear multivariate fitting resulted in a velocity‐porosity‐carbonate content transform that accurately predicts sonic velocity at different effective stresses. The slope of the velocity‐porosity transform steepens with increasing carbonate content, which may be explained by the higher velocity of carbonate minerals. Another reason may be the property of carbonate minerals to form more perfect intercrystalline boundaries that improve the transmission properties of acoustic waves and are less sensitive to changes in effective stress. The velocity ratio [Formula: see text] is an excellent tool to discriminate between predominantly calcitic lithologies (ratio between 1.8 and 1.95) and predominantly dolomitic and quartz‐rich lithologies (ratio between 1.65 and 1.8). Gardner's experimental curve overestimates, and the velocity‐porosity transforms by Wyllie and Raymer underestimate, the observed sonic velocities, probably because they do not account for variations in texture, carbonate mineralogy, and pore geometry. Petrographic observations show that postburial diagenesis is minor and does not seem to significanfly affect porosity. Therefore, the outcrop data set can be regarded as a proxy for the subsurface analog. These findings underline the significantly more complex acoustic behavior in mixed carbonate‐siliciclastic sedimentary rocks than in pure siliciclastics where mineralogic composition explains most of the observed relationships between porosity and sonic velocity.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

A technique for preparing semiconductor cross sections for both TEM and SEM analysis

1989 ◽  
Vol 47 ◽  
pp. 712-713
Author(s):  
Stanley J. Klepeis ◽  
J.P. Benedict ◽  
R.M Anderson
Keyword(s):  
Sample Preparation ◽  
Cross Section ◽  
Cross Sections ◽  
Sem Analysis ◽  
Preparation Technique ◽  
Ion Milling ◽  
Tem Analysis ◽  
Polished Cross Section ◽  
Area Of Interest ◽  
Polished Side

The ability to prepare a cross-section of a specific semiconductor structure for both SEM and TEM analysis is vital in characterizing the smaller, more complex devices that are now being designed and manufactured. In the past, a unique sample was prepared for either SEM or TEM analysis of a structure. In choosing to do SEM, valuable and unique information was lost to TEM analysis. An alternative, the SEM examination of thinned TEM samples, was frequently made difficult by topographical artifacts introduced by mechanical polishing and lengthy ion-milling. Thus, the need to produce a TEM sample from a unique,cross-sectioned SEM sample has produced this sample preparation technique.The technique is divided into an SEM and a TEM sample preparation phase. The first four steps in the SEM phase: bulk reduction, cleaning, gluing and trimming produces a reinforced sample with the area of interest in the center of the sample. This sample is then mounted on a special SEM stud. The stud is inserted into an L-shaped holder and this holder is attached to the Klepeis polisher (see figs. 1 and 2). An SEM cross-section of the sample is then prepared by mechanically polishing the sample to the area of interest using the Klepeis polisher. The polished cross-section is cleaned and the SEM stud with the attached sample, is removed from the L-shaped holder. The stud is then inserted into the ion-miller and the sample is briefly milled (less than 2 minutes) on the polished side. The sample on the stud may then be carbon coated and placed in the SEM for analysis.

Experimental Studies Of Multilayer Glass Structures On Compression, Compression With Bending And Simple Bending

2019 ◽  
pp. 22-30
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Applied Load ◽  
Experimental Studies ◽  
Strength Properties ◽  
Research Topic ◽  
Normative Values ◽  
Laminated Glass ◽  
The Cross ◽  
Experimental Values

The work of multilayer glass structures for central and eccentric compression and bending are considered. The substantiation of the chosen research topic is made. The description and features of laminated glass for the structures investigated, their characteristics are presented. The analysis of the results obtained when testing for compression, compression with bending, simple bending of models of columns, beams, samples of laminated glass was made. Overview of the types and nature of destruction of the models are presented, diagrams of material operation are constructed, average values of the resistance of the cross-sections of samples are obtained, the table of destructive loads is generated. The need for development of a set of rules and guidelines for the design of glass structures, including laminated glass, for bearing elements, as well as standards for testing, rules for assessing the strength, stiffness, crack resistance and methods for determining the strength of control samples is emphasized. It is established that the strength properties of glass depend on the type of applied load and vary widely, and significantly lower than the corresponding normative values of the strength of heat-strengthened glass. The effect of the connecting polymeric material and manufacturing technology of laminated glass on the strength of the structure is also shown. The experimental values of the elastic modulus are different in different directions of the cross section and in the direction perpendicular to the glass layers are two times less than along the glass layers.

Sign in / Sign up

Export Citation Format

Share Document