Large-scale Structural Features Research Articles

Statistical characteristics of large scale structure

We generalize and extend the statistical description of formation and evolution of Large Scale matter distribution in the Universe proposed in our previous papers. We investigate the impact of transverse motions – expansion and/or compression – on properties of the Large Scale Structure elements – walls, pancakes, filaments and clouds – and, generalizing the Press-Schechter formalism, derive their mass functions. Using the Zel'dovich theory of gravitational instability we show that these mass functions are approximately the same and the mass of each type of elements is found to be concentrated near the corresponding mean mass. At high redshifts, both the mass function and the mean mass of formed elements depend upon the small scale part of the initial power spectrum and, in particular, upon the mass of dominant fraction of dark matter (DM) particles. Using these results we obtain independent estimates of probable redshifts of the reionization and reheating periods of the Universe. We show that the transverse motions do not significantly change the redshift evolution of the observed mass function and the mean linear number density of low mass pancakes related to absorption lines in the spectra of the farthest quasars. Application of this approach to the observed Lyman–α forest allows one to directly estimate the shape of initial power spectrum on small scales.

X-ray galaxy clusters in the large-scale structure

In this contribution we investigate the connection between clusters of galaxies and their large-scale environment, with an emphasis on clusters which are well characterized by their X-ray emission. We show that this connection is so tight that clusters can be used as perfect tracers of the large-scale matter distribution and thus for cosmological tests. The correlation of the X-ray traced cluster mass and the optical luminosity of the galaxy content of clusters shows that the dark matter and galaxy distribution are tightly connected, but we also observe a scatter which is so far not well understood. We further explore the correlation of the galaxy population mix with the geometry of the large-scale structure features. On larger scales we also find correlations of the properties of galaxy clusters with the density of their large-scale structure environment. To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Ocean Interpolation by Four-Dimensional Weighted Least Squares—Application to the Waters around Australasia

A new four-dimensional ocean interpolation system based on locally weighted least squares fitting is presented. A loess filter is used to interpolate irregularly spaced data onto a uniform grid. This involves projecting the data onto quadratic functions of latitude and longitude while simultaneously fitting annual and semiannual harmonics by weighted least squares. The smoothness scale of the mapping method adapts to match the data density, thus producing gridded estimates with maximum resolution. The filter has a vertical dimension, such that the data on adjacent levels are included in the computation. This greatly reduces the effects of discontinuities in data distributions between adjacent levels, since the estimates at each level are no longer independent. The loess scheme has been further modified so that the weighting of data points is adjusted to allow for the influence of both bathymetry and land barriers. This allows the bathymetry to influence the mapped fields in a natural way, reduces leakage of structure between deep and shallow regions and produces far more realistic coastal gradients. The flexibility of the loess approach has allowed further adjustments to compensate for irregularities in spatial and temporal sampling. The mapping is shown to be statistically consistent with an objective measure of the a priori noise of the dataset. Departures of the mapped fields from independent surface temperature climatologies and mean vertical sections derived from withheld expendable bathythermograph (XBT) data are within error limits. The method is applied to the major seas around Australia, New Zealand, Papua New Guinea, and Indonesia (508S‐108N, 1008E;‐1808) to form a high-resolution seasonal climatology of temperature, salinity, oxygen, nitrate, phosphate, and silicate, referred to as the CSIRO (Commonwealth Scientific and Industrial Research Organisation) Atlas of Regional Seas (CARS). Stringent quality control procedures have been applied to a comprehensive dataset assembled from all known sources. The resulting maps successfully resolve both the large-scale structure and narrow coastal features and illustrate how the bathymetry influences the property distributions.

The Cluster Mass Function inCOBE‐ and Cluster‐normalized Cold Dark Matter Simulations

We introduce a set of four new publicly available N-body simulations, the most recent additions to the ever expanding Texas P3M Database. Our models probe the less studied parameter space region of moderate volume (100 h-1 Mpc box) combined with fine mass resolution (∝1012 M☉, roughly comparable to an L* galaxy; 1403 particles with Mparticle = 1011Ω0 h-1 M☉), making these simulations especially suitable for study of major large-scale structure features, such as voids and walls, and for comparison with the largest three-dimensional redshift surveys currently available (CfA2, SSRS2, IRAS PSCz). We match the above quartet with a set of smaller (40 h-1 Mpc), higher resolution simulations (Mparticle = 1010Ω0 h-1 M☉), to verify the reliability of the derived dark matter halo mass function at the small mass end. Our cosmological models (LCDM, TOCDM, OCDM, TCDM) are all COBE-normalized and, when possible (LCDM and TOCDM), also cluster-normalized, based on the X-ray cluster M-T relation. The COBE- and cluster-normalized LCDM model reiterates the attractiveness of this currently favored model, which does not require the introduction of tilt in order to snugly fit the ever narrowing constraints imposed by observational estimates of other cosmological parameters.

ABSTRACT: The Interaction Between Basin-Scale Extensional Folding and Sedimentation in a Supradetachment Basin

Hanging-wall deformation in extensional settings has the potential to create complex syntectonic sedimentary packages. These sediments record interplay between sedimentation and synextensional folding, as recorded in Grasshopper rift basin, SW Montana. As a result of this interaction, Grasshopper basin, has a complex, threedimensional stratigraphic and structural geometry. Large, basin-scale extensional folds developed in this north-trending Paleogene supradetachment basin during extensional deformation. A major N-trending anticline, 10 km long and 1.8 km in structural relief, occupies the western half of the basin. Approximately perpendicular to the anticline, a major syncline 8 km long and roughly 0.5 km in structural relief plunges 88 toward an antiform in the underlying listric detachment fault. Sedimentologically, we interpret the basin as a sediment starved lacustrine system dominated by southward axial infilling and lesser, yet significant, transverse sediment influx. The basin contains about 4 km of Tertiary basin fill. Stratigraphic and sedimentological analyses reveal that several basin-scale lacustrine transgressions, facilitated by slip on the eastern border-fault and increased accommodation space due to folding, laterally shifted depositional environments. Interruptions in the southward progradation of the fluvial-deltaic facies are marked by the north-northeast retreat of conglomerates and sandstones on the north limb of the transverse syncline. In the mid to late stages of basin deformation, current data suggests that the longitudinal anticline evolved. To help visualize the large-scale stratigraphic and structural features of this basin, we integrated seismic data and structural, stratigraphic, and sedimentological field data into three-dimensional structural models (2D/3DMove from Midland Valley Exploration) of the basin.

Large-scale purification and structural features of Paracoccus denitrificans (ATCC 35512) no reductase

Large-scale purification and structural features of Paracoccus denitrificans (ATCC 35512) no reductase

Global variations in the heliosphere, and their geophysical manifestations

This paper addresses the evolutionary patterns of global events on the Sun and in the heliosphere as well as their relation to large-scale disturbances of the Earth's magnetosphere and atmosphere. Large-scale and global events on the Sun and times at which the solar periodicity regimes change have not yet received an adequate physical explanation. Using data on the most recent cycles of solar activity it has been established that large-scale changes in background fields are often accompained by coronal mass ejections and intrinsic variations in galactic cosmic rays, and correlate with dynamical features of large-scale structures of background magnetic field of the Sun. Based on comprehensive helio-geophysical data an analysis is made of the global events on the Sun and in the heliosphere, and they are compared with solar and geomagnetic activity variations, dynamical features of background structures of magnetic field, and with cosmic ray intensity variations. A first approximation is used to construct a phenomenological scenario of development of global events on the Sun and in the heliosphere, their relation to the dynamics of large-scale structures of background field, significant enhancements of solar and geomagnetic activity.

Evaluation of the Upper-Tropospheric Moisture Climatology in a General Circulation Model Using TOVS Radiance Observations

Abstract TOVS satellite observations are used to evaluate the upper-tropospheric (400–200 mb) moisture distribution simulated by the GLA GCM in a 10-yr (1979–1988) integration produced for the Atmospheric Model Inter-comparison Project, in which several models participated worldwide. The simulated moisture fields show remarkable success in duplicating the large-scale structure and seasonal features in the observations, but they show insufficient contrast between very dry and very moist regions. The simulation generally does well in northern summer (June–July–August) but worse in northern winter. This is consistent with deficiencies in the annual cycle of moist convection so that convective rain stays too close to the equator in northern winter. The related misplacement of convective activity associated with the Asian monsoon produces discrepancies in the moisture over much of the Eastern Hemisphere. The simulation also shows a too weak moisture response to interannual fluctuations in the sea surface tempe...

Features of the solar wind large-scale structure in the different periods of solar activity based on the variations of cosmic rays

The relations between the energy spectrum exponent γ of cosmic ray isotropic intensity variations ( δD(R) D (R) ∝ R −γ ) and the parameter α which characterizes the diffusion coefficient's χ dependence on the cosmic ray particle's rigidity R ( χ∝ R α ) has shown ( α ∝ γ). The large-scale structural changes of the magnetic inhomogeneities of solar wind in the different periods of solar activity is the general mechanism of 11-year variations of cosmic rays above energy 1–2 GeV. The energy spectrum exponent γ of cosmic ray isotropic intensity variations can be considered as a important tool for the investigation of the temporal and spatial changes of the large-scale fluctuations in the interplanetary magnetic field strength.

Deep structure of the Anglo–Brabant massif revealed by seismic profiling

AbstractDeep seismic reflection profiles over the Anglo–Brabant massif in the southern North Sea reveal reflection patterns throughout the crust that are distinctive and which differ significantly from those observed beneath adjacent areas with Mesozoic basins. Comparisons with reflection profiles from other platform areas suggest that the reflection patterns indicate large-scale structural features associated with compressional tectonics. If so, they may represent thrust structures associated with continental accretion of preferred Caledonian age.

Small- and large-scale global shape features in macromolecular backbones

A methodology to analyze and characterize small- and large-scale shape and structural features in a macromolecule is presented. The procedure involves the construction of a continuum of spherical shape maps. This continuum is built by analyzing the overcrossing pattern of a molecular space curve from every direction in 3-space as seen by a viewer with a reduced vision field. The method derives global shape descriptors (shape maps) that characterize the backbone as a whole (large-scale structure), but also allows one to focus the analysis on details of the backbone's small-scale structure. A continuous function is proposed as a simplified descriptor derived from the shape maps. This function discriminates reasonably well among elements of secondary structure and supersecondary structural motifs in proteins. The procedure is applied to α-helices, β-sheets, and models of α-helical packing.

The Effect of Plate Movements in the Northern Region of South America on Tectonics and Sedimentation in the Eastern Llanos Basin

The geological configuration of the Eastern Llanos pericratonic mega-basin has been directly affected by the overall tectonic regime experienced in the Northern part of South America. Interaction between the Pacific (Cocos), South American and Caribbean Plates generated a regional compressional dextral rotational force expressed as a regional North-South striking structural trend in the southern part of the basin and an east-west striking trend in portion nearest the Caribbean Plate Boundary. Nearly 90% of the strike-slip faults in this northern area show right lateral displacement. The majority of the structures in the East Llanos basin are related to the Late Miocene uplift of the Eastern Andes. Nevertheless we can subdivide the structures into two major groups: pre-Miocene and post-Miocene. By being able to recognize pre-Miocene Cretaceous age structures, much altered by later movements, we can envision remigration of hydrocarbons out of early traps into those created more recently. Plate tectonic events in the north of South America have produced a general regional structure strike directional through time. Sedimentary-tectonic relationships depend upon regional phenomena which, if interpreted correctly, help to sub-divide the mega-basin into genetically related parts. By understanding the mechanism that creates large scale structural features, the geologist is thus providedmore » with an important tool that can aid him in exploring the Eastern Llanos basin.« less

Seismicity distribution from temporary earthquake recording networks in Kenya

The seismic activity associated with the Cenozoic rift valley in Kenya generally consists of seismic events of magnitudes M L < 3, whilst that associated with the western branch of the East African Rift System includes many higher magnitude ( M s > 4) events, indicating a difference in the manner of energy release between the eastern and western branches. This paper combines the results from recent temporary seismic networks within Kenya and analyses the coverage of small-scale seismicity to date. The seismicity distribution derived from temporary local networks is primarily associated with the Kenya Rift and the east-west-trending Nyanza trough on the western flank of the Kenya dome. There is a scattered distribution to the east of the Rift, apparently originating in regions suffering recent volcanism and possibly associated with a shallowing of the lithosphere-asthenosphere boundary. The principal concentrations of activity are in the Nyanza trough, the Suguta valley and its continuation to the north into southern Lake Turkana, and in the Lake Bogoria region where the activity appears to be linked to the large-scale structural features of the rift. Generally, the activity can be correlated with geothermal and volcanic regions and the large-scale structural features of the main rift. The Lake Bogoria area has a higher frequency of events than other areas of the rift and has a lower b value, indicating an area of higher stress concentration. In order to determine the local fault kinematics to constrain models of the rifting process, accurate determination of the focal mechanisms of the larger events is required. This can only be achieved by deploying a larger-scale network on a more permanent basis.

ON THE UNIVERSAL CHARACTER OF THE LARGE SCALE STRUCTURE OF THE UNIVERSE

We review different theories on the formation of the large scale structure of the Universe. Special emphasis is put on the theory of inertial instability. We show that, for a large class of initial spectra, the resulting two point correlation functions are similar. We also discuss the adhesion theory which uses the Burgers equation, Navier-Stokes equation or coagulation process. We review the Zeldovich theory of gravitational instability and discuss the internal structure of pancakes. Finally, we discuss the role of the velocity potential in determining the global characteristics of large scale structure (distribution of caustics, scale of voids, etc.). In the last section, we list the main unsolved problems and the main successes of the theory of formation of large scale structure.

Magnetic crustal structures in northern Fennoscandia

Cooperation between the Nordic countries has produced a set of geophysical and geological maps in the region north of the 66th parallel in northernmost Europe. The area covers the transition from oceanic crust to the Baltic Shield, a section of the Caledonides, and a part of the Arctic platform. An interpretation of the aeromagnetic and gravity maps reveals several large structural units with distinct boundaries and characteristic anomaly patterns. In combination with data on rock physical properties, some general magnetic crustal features can be outlined: 1. (1) typical occurrence of magnetically banded ocean crust anomalies, 2. (2) the occurrence of magnetically banded patterns in the continental crust connected with metasupracrustal formations separated by culminations of high-density and high-magnetization basement domes and megashear zones (thrusts and transcurrent faults) with large displacements, 3. (3) occurrence of magnetic granitoid batholiths, 4. (4) general low remanence of shield rocks, allowing straightforward interpretation of magnetic total field anomalies, and 5. (5) general low magnetization of Caledonian thrusted units allowing mapping of the depth to their magnetic basement. Merging magnetic, gravity and petrophysical data allows constraints to be applied when modelling crustal structures. Some of the large-scale structural features are illustrated and some examples of profiles through the upper crustal structures are shown.

Methodology of Formation MicroScanner image interpretation in Claymore and Scapa Fields (North Sea)

Abstract The Formation MicroScanner (FMS) * tool is an advanced dipmeter tool capable of producing high-resolution resistivity images of a borehole wall. When integrated with core and open hole logs, FMS images are of great utility in evaluating the thin bedded reservoir sequences of the Claymore and Scapa North Sea oil fields. Sedimentary features as small as 0.5 inches (1.2 cm) can be resolved on FMS images. Such detail is employed in the distinction of massive, parallel laminated, ripple cross-laminated, bioturbated and conglomeratic bedding types. The application of the FMS tool to reservoir description is not limited to bedding type identification. Bed boundaries, as well as small and large scale structural features, can be distinguished, including erosional contacts, slumps, fractures and faults. In the hydrocarbon-bearing zone permeability distribution outwith cored intervals can inferred. This can be confirmed by relating resistivity changes to core measured permeability values. The proposed approach to FMS interpretation involves the integration of all available open hole logs with detailed local geological knowledge and core data. Aspect and image quality of the FMS log are important considerations. By imaging the borehole wall, the aspect of the FMS tool provides a direct method of relating features detected using open hole logs to those observed in cores. Image quality is largely dependent on resistivity contrast in the formation and correlation with cores is imperative to establish confidence limits for extrapolation into uncored intervals.

Application of Remote Geologic Analysis to Gas Exploration in Morgantown Energy Technology Center's Study Area 1, West Virginia: ABSTRACT

Pacific Northwest Laboratory's Remote Geologic Analysis (RGA) system uses a unique, automated pattern-recognition approach to identify potential fracture zones (of any dip from vertical to < 40{degree}) by coplanar analysis of their geomorphic expression in digital models of topography. For its first oil and gas-related field trial, the authors applied the RGA system to the fracture characterization of Morgantown Energy Technology Center's Study Area 1 in the Big Sandy gas field in southwestern West Virginia. They selected this site to blind test their technology because of the characterization data available from well drilling, gas production, and seismic surveys. The Morgantown staff used these data and performed a geologic analysis of the region coincidentally but separately from their fracture analysis to ensure that they did not introduce bias into their interpretations. Their structure and isopach maps show significant trends in the faulting and folding of the producing formations that control production volumes, which correlate well with the principal interpreted fracture sets from their results. Three fracture sets for the Big Creek, West Virginia, 1:24,000 quadrangle parallel major geologic structures that are associated with basement faulting (steep dip, northeast trend) and thrust faulting (60{degree} dip, northwest trend). These structures appear, in combinationmore » with anticlinal folding, to enhance gas production. To date, only the most prominent fracture planes from their analyses have been correlated with the large-scale structural features (basement faulting) in the study area. The next step in this field trial will be to determine if lesser planar features from their analyses correlate with the detailed structural geology and regional geomorphology of the rocks exposed at the surface.« less

The Dupal anomaly as a trace of the upwelling lower mantle

It is now widely accepted that the Earth's mantle is isotopically heterogeneous, but the scale and distribution of this heterogeneity and the structure and evolution of the mantle as a whole are poorly understood. The 'Dupal anomaly'1,2 has an important bearing on this problem because it is the largest isotopic domain yet delineated on the Earth's surface and it is suggested2 to have been formed early in the Earth's history. Here I show that the two Dupal anomaly maxima appear to be closely associated with the two large-scale regions of low seismic velocity in the lower mantle3, which in turn are correlated with the loci of active hotspots. This correlation raises the possibility that large-scale structural features in the lower mantle produce geochemical imprints on the Earth's surface. Thus, the correlation may place severe constraints on the chemical structure of the mantle and the nature of mantle convection.

Solid Mechanics Research for Quantitative Non-Destructive Evaluation

Abstract : Non-destructive evaluation (NDE) procedures play an important role in materials processing, as well as in subsequent material testing, product design, analysis of service life expectancy, manufacturing, and quality control of manufactured products. They are also essential to on line monitoring of the integrity of structural elements and complex systems. Rational accept and reject criteria should be based on NDE tests. Critical safety, efficiency and operational features of large-scale structures depend on adequate NDE capabilities. Acoustic Emission, Dynamic Fracture, Materials and Transducer Characterization, Failure Mechanisms and Processes in Composites using Acoustic Emission, Flaw Characterization by Ultrasonic Scattering Methods, Experimental Research on Ultrasonic Scattering from Flaws, Elastic Wave Interactions with Partially Contacting Surfaces: Application to Fatigue Crack Characterization, Ultrasonic Nondestructive Evaluation, Microstructure, and Fracture Toughness Interrelations, Low Frequency Acoustic Microscopy, Ultrasonic NDE of Composites as Inhomogeneous Media, Non destructive Characterization of Damage in Graphite Epoxy Laminates.

Structural Influences on Facies Distribution in Silurian Medina Group of Northwestern New York: ABSTRACT

The gas-bearing sandstones of the Medina Group in western New York are the basal Whirlpool Sandstone and the Grimsby Sandstone. Toward the west, these are separated by the Cabot Head Shale and the Manitoulin Limestone. Farther east, the Grimsby overlies and interfingers with the Whirlpool. The reservoir is underlain by the Ordovician Queenston Shale and is capped by shales of the Silurian Clinton Group. The depositional sequence of the Medina Group may be summarized as a marine transgression toward the east that yielded the Whirlpool, Cabot Head, and Manitoulin formations, followed by westward progradation of the deltaic Grimsby formation. Aspects of internal stratigraphy noted in subsurface studies may be correlated with anomalies in units much higher in the Silurian section and with disturbances on the Silurian-Devonian unconformity. Repetitive adjustments of large-scale structural features are inferred. These changes mark the transition from the westward-facing depositional front of the Ordovician to development of the isolated basins that dominated the Silurian Period. End_of_Article - Last_Page 1926------------