bluuebunny/crossref_metadata_2025_split huggingface dataset:
CLAY MINERAL POST‐SEDIMENTARY RANKS IN TERRIGENOUS ROCKS
Authors: KARPOVA G. V. 
Published: June 2006

SUMMARYKaolinite, dioctahedral 1M and 2M1 hydromicas, trioctahedral Ib and IIb chlorites, montmorillonite and mixed‐layer phases from the terrigenous Carboniferous rocks of the Bolshoy Donbas at the southwestern border of the Russian Platform are described. Clay minerals form definite assemblages connected with the facies character and mineral composition of the rocks and with the intensity of post‐sedimentary alteration. This post‐sedimentary evolution of the terrigenous rocks is characterized by regional ranks of clay polytypes and clay isomorphous varieties, viz.:
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The persistence of mineral assemblages in definite PT intervals leads to the possibility of their use for characterizing post‐sedimentary alteration stages.
NOUVELLE MÉTHODE DE DÉTERMINATION DE LA SPHÉRICITÉ DES SÉDIMENTS MEUBLES
Authors: WEYDERT PIERRE 
Published: June 2006

SUMMARY A new method to determine the sphericity of mobile sediments In this paper we show a new method to determine the sphericity of sand particles with sedimentary analysis. We use two different sieves: the one with open squares: the side is a and the diagonal d=a√2 the other with circular openings: the diameter is D. Experimentation shows that elements crossed the open‐square sieves in diagonal positions. When we reported the cumulative curves into arithmetic or semi‐logarithmic graphs, we used the value d and not the side square a.A sediment C, which is composed of not very angular or subspherical par‐ ticles, is represented by two cumulativecurves on the same graph. If a sediment A is very angular, the two curves are disconcerted. The sediment B is subspherical, the difference between the two curves is maximum. We call this difference δ which is equal to d–D. For C this difference is Δ, which is always inferior to δ. The absolute sphericity index Sa is the ratio AId in yo. When the particles are very angular, sphericity values are 0—like A and when they are sphericals the index is 1—like B. This index is determined with graphic solutions. The values obtained are compa‐ rable with those of visual charts.
FAULT‐GRADED BEDS INTERPRETED AS SEISMITES
Authors: SEILACHER ADOLF 
Published: June 2006

SUMMARYFault grading is expressed by a regular structural sequence of (from top) liquified zone, rubble zone and step‐faulted zone, with gradational contacts between these zones and the bottom, but with a sharp boundary at the top. It is interpreted as an effect of strong earthquakes on gradationally compacted muds in quiet water basins. Fault‐graded beds are geopetal and paleoslope criteria. If interpreted as seismites they may also be used as paleo‐seismograms.
A QUANTITATIVE MODEL OF CLIMBING RIPPLES AND THEIR CROSS‐LAMINATED DEPOSITS
Authors: ALLEN J. R. L. 
Published: June 2006

SUMMARYThe angle of climb of ripples in cross‐laminated deposits is governed by the simple relation:in which ζ is the angle of climb, M is the rate of sediment deposition normal to the rippled bed, H is the ripple height, and jb is the bedload sediment transport rate. After introducing sediment transport functions, this relation is developed using the assumptions of gradually varied flow to predict the spatial patterns of cross‐lamination types in deposits due to pure non‐uniform flow, pure unsteady flow, and simultaneous non‐uniform and unsteady flow. Most of the predicted patterns can be matched from the geological record, and the analysis affords a hitherto missing insight into the environmental significance of climbing‐ripple cross‐lamination. The analysis also results in a rigorous definition of the kinds of environmental interpretation that may legitimately be made from examples of this structure.
TREATMENT OF SPHERICITY AND ROUNDNESS DATA OF QUARTZ GRAINS OF CLASTIC SEDIMENTS
Authors: SAHU BASANTA K. , PATRO B. C. 
Published: June 2006

SUMMARYSphericity and roundness data of quartz grains (of varying size) of sieve fractions are empirically shown to be non‐normally distributed. It is also demonstrated that log10 [ψ/(1−ψ)] and −log10(P) transformations, respectively, normalize the sphericity and roundness data, where ψ denotes the two‐dimensional sphericity and P the roundness of the grains in a plane. Laboratory experiments on sampling quartz grains from a sieve fraction show that the cone‐and‐quartering method is preferable as it yields similar results to those of the more time‐consuming random sampling procedure. Results of laboratory measurement errors on two‐dimensional sphericity and roundness data are also presented. The frequency of sphericity and roundness data are noted on number basis.For all parametric statistical studies of sphericity and roundness the sample statistics should, therefore, be calculated according to the above normalizing log functions. Suitable grade scales of sphericity and roundness data are proposed here basing on these log functions and the total range and the minimum range of the variates (sphericity and roundness).
THE IDENTIFICATION OF ANCIENT BEACH SANDS BY THE COMBINATION OF SIZE ANALYSIS AND ELECTRON MICROSCOPY
Authors: HODGSON A. V. , SCOTT W. B. 
Published: June 2006

SUMMARYThe combined use of size analysis and electron microscopy has indicated the presence of beach sands within the Lower Carboniferous Fell Sandstone of southeast Scotland and northern England.Environmental interpretations are based on a comparison of the statistical parameters summarizing the size distributions of the Fell Sandstone specimens with similar data from modern sediments. The spread of standard‐deviation values (sorting coefficients) indicates the presence of littoral, alluvial, and possibly offshore marine environments within the Fell Sandstone. These environments are further defined by plotting standard deviation against skewness on a scatter diagram.Electron micrographs (E.M.G.'s) of the quartz grain surface textures of selected Fell Sandstone specimens corroborate the interpretations based on the size analysis.E.M.G.'s of the Fell Sandstone beach specimens show all the diagnostic surface features developed on modern quartz beach sand grains.
PHYSIOGRAPHIC FEATURES AND STRATIFICATION TYPES OF COARSE‐GRAINED POINTBARS: MODERN AND ANCIENT EXAMPLES1
Authors: McGOWEN J. H. , GARNER L. E. 
Published: June 2006

SUMMARYPrimary sedimentary structures in modern point bar deposits of the Amite River in Louisiana and the Colorado River in Texas are analogous to features observed in Eocene Simsboro and Pleistocene Colorado River deposits of the Texas Gulf Coastal Plain.Short‐duration peak flow, channel pattern, average stream gradient of about 2–3 ft./mile, and bank stabilization by dense vegetation are major parameters controlling the depositional pattern of coarse sand and pebble gravel of the Amite and Colorado rivers. Stratification is directly related to specific depositional features and consists of: large‐scale trough‐fill cross‐stratification in the scour pool; trough‐fill cross‐stratification and foreset cross‐stratification in the lower point bar; parallel laminae, large foreset cross‐stratification, and trough‐fill cross‐stratification in the chute bar; parallel inclined laminae, climbing ripple laminae, and mud drapes in the chute fill; and parallel inclined laminae, mud drape, and foreset cross‐stratification in overbank, flood‐plain deposits.Fundamental differences between point bars of bed‐load streams (low suspended load/bed load ratio) and mixed‐load streams (high suspended load/bed load ratio) are that upper point bar sediments with small trough sets and parallel inclined laminae occur only in fine‐grained (mixed load) fluvial deposits, and large scale foresets of chute bars are common to coarse‐grained (bed load) fluvial deposits but are not found in fine‐grained fluvial deposits. Upward fining sequences, characteristic of fine‐grained fluvial deposits, are uncommon in sediments deposited by bed‐load streams such as the Amite and Colorado rivers.The Simsboro Sandstone consists mainly of scour pool, lower point bar, and chute bar sediments. Chute fill and flood‐plain deposits are preserved only in the highest stratigraphic sequence. Pleistocene Colorado River deposits display the same sequence of stratification types as the Simsboro but are composed of coarser material.
EXPERIMENTS ON THE ANGLES OF REPOSE OF GRANULAR MATERIALS1
Authors: CARRIGY MAURICE A. 
Published: June 2006

SUMMARYA simple apparatus for measuring the angles of repose of masses of granular material in various media, based on the rotating‐drum principle, is described. Two angles of repose are measured by this method. The critical angle of repose (ac), is defined as the angle through which a mass of granular material can be rotated before it fails by avalanching, and the angle of rest (aR), is defined as the inclination of the slope after avalanching has ceased.Measurements of the angles of repose of several materials in air and under water with the “rotatable‐drum apparatus” indicate that for materials with similar surface characteristics the angles of repose increase with departure of the grains from a spherical form. For masses of spherical particles the angles of repose increase with increasing intergranular friction caused by changes in the surface characteristics of the spheres. For mixtures of spheres and cubes the angles of repose are proportional to the volumes of the end members present. For natural quartz sands the critical angle of repose (ac), is always greater in air than under water, but the angle of rest (aR), is the same in both media. Measurement of the inclinations of slip faces of subaerial dunes and subaqueous deltas indicates that these faces stand at, or less than, the angle of rest (aR), of the sand from which they are built.It is concluded that shape and surface characteristics of the particles have the greatest effect on the angles of repose.
PHREATIC VERSUS VADOSE METEORIC DIAGENESIS OF LIMESTONES: EVIDENCE FROM A FOSSIL WATER TABLE
Authors: LAND LYNTON S. 
Published: June 2006

SUMMARYThe Middle Pleistocene Belmont Formation of Bermuda consists in part of beach‐dune biocalcarenites which underwent intense contemporaneous cementation and diagenesis. The beach deposits were contemporaneously cemented by fibrous isophacous cement to form beachrock, whereas previously deposited eolianites further inland underwent intense meteoric phreatic diagenesis, resulting in coarse‐grained cementation and stabilization of most of the metastable components of the rock. Above the Belmont water table, vadose diagenesis was relatively ineffective in cementing and altering the biocalcarenites. Phreatic meteoric diagenesis is interpreted to be a very rapid process, relative to vadose meteoric diagenesis, and to result in a much coarser‐grained sparite.
MIXED‐LAYER BIOTITE‐CHLORITE FORMED IN THE COURSE OF LOCAL EPIGENESIS IN THE WEATHERING CRUST OF A BIOTITE GNEISS
Authors: EROSHCHEV‐SHAK V. A. 
Published: June 2006

SUMMARYIn the course of deep weathering of a biotite gneiss, biotite is transformed into mixed‐layer biotite‐vermiculite hydrobiotite. Later biotite‐vermiculite is transformed into biotite‐chlorite under the action of hydrothermal solutions at the stage of epigenesis.
DENSITY AND OPTICAL DATA OF LOW‐TEMPERATURE FELDSPARS AND MICA
Authors: KATZ M. YA. , MURAVYOV V. I. 
Published: June 2006

SUMMARYPrecision measurements of the densities and the optical constants of authigenic low‐temperature orthoclases, albites, muscovites and quartz, and comparisons with those of their high‐temperature counterparts of identical or similar composition proved that the authigenic orthoclase and muscovite have significantly lower densities than the high‐temperature modifications.For quartz and albite density differences are not established.The optical constants of the low‐temperature minerals (except for quartz) likewise possess specific properties, manifested in the orientation of the optical indicatrix and the values of the angle 2V.
MINERAL STUDIES IN THE GRAVITATION‐GRADIENT FIELD, I. THE METHOD
Authors: KATZ M. YA. 
Published: June 2006

SUMMARYThis paper describes a new equipment for investigating the density properties of minerals and rocks. A description is given of the principle and operation of a gravitation gradient tube, of density standards and of a device for the precise density determination and separation of minerals. The possibility of using the method described for geological and mineralogical studies is discussed.
A COARSE‐GRAINED POCKET BEACH COMPLEX, TANAFJORD (NORWAY)
Authors: HOBDAY D. K. , BANKS N. L. 
Published: June 2006

ABSTRACTThe bulk of the material comprising the pocket beach at the mouth of the Manndraperelv, Tanafjord, northern Norway, is supplied by the river. The stream bed consists of poorly sorted coarse sediments which show a crude upstream imbrication. Dampening of wave activity near the mouth of the stream by the outflow of water has caused relatively fine‐grained material to accumulate on spits. Size‐shape sorting by waves concentrates the finest pebbles on landward moving swash bars.Away from the stream mouth beach deposits become finer grained landward, and are zoned in a manner similar to that described by BLUCK (1967). If similar deposits were preserved in the geological record they might be confused with coarse‐grained fluviatile sequences. Study of the textures of the Manndraperelv deposits establishes criteria for distinguishing between these two possibilities.
GEOCHEMICAL HISTORY OF THE CRYSTALLINE BASEMENT AND THE SEDIMENTARY COVER OF THE RUSSIAN AND NORTH AMERICAN PLATFORMS
Authors: RONOV A. B. , MIGDISOV A. A. 
Published: June 2006

ABSTRACTA vast amount of analytical material (more than 8,000 analyses) on the chemical composition of the main rock types occurring in the crystalline shields and sedimentary covers of the Russian and North American platforms has been compared, taking into account the abundance of these rocks. The comparison covers structures as a whole and separately—their sections representing very large stratigraphical complexes (A. Pt1_2, Pt3. Pz. Mz‐Cz). Based on generalization of these data, the more important development stages in the composition of the shields and platforms were traced for the last 3.5 billion years and the more general tendencies in their geochemical history were outlined. An almost complete uniformity of the “granite” shell's average composition, a striking similarity of the average composition of the sedimentary cover and similar ways of its development have been proved for different continents. At the same time a discrepancy was established in the average compositions of the rocks of the shields and derivative platform sediments, which by their composition are nearer to basic than to acid rocks. This fact obviously indicates a wider spread of the basic rocks during the earlier stages of the development of the Earth's crust. The more general tendencies in the evolution of the rock composition of shield and platform sediments have been retraced. They outlined a causal relationship, with the development of granitization processes of the primary, more basic material, with the passing of denudation products through numerous cycles of weathering and sedimentation and with the biosphere growth and life development which determined the change of the atmospheric and oceanic compositions as well as the oxidation‐reduction conditions on the surface of the Earth and in the formation of sedimentary series.
THE DEPOSITIONAL ENVIRONMENT OF MARINE EVAPORITES: A CASE FOR SHALLOW, CLASTIC ACCUMULATION
Authors: HARDIE LAWRENCE A. , EUGSTER HANS P. 
Published: June 2006

ABSTRACTThe Upper Miocene Solfifera Series of Sicily contains very coarse, massive selenite; parallel laminated gypsum; wavy, stromatolitic laminated gypsum; planar‐ and ripple cross‐laminated gypsum‐skeletal calcite sandstones; flat‐pebble and fining‐upward gypsum conglomerates; and nodular gypsum. The assemblage of sedimentary features indicates deposition—much of it detrital—in a shallow lagoon‐littoral flat complex.Using modern tidal flats as a guide, we interpret the laminations to form when onshore storms flood the shore‐line area with sediment‐charged seawater. Algal mats bind the newly deposited gypsiferous layer. Flat‐pebble conglomerates are formed when storm waves rip up mudcracked, algally‐bound laminated sediment. The gypsum nodules are similar to the anhydrite nodules of the modern Persian Gulf sabkhas. They form within sub‐aerially exposed skeletal sand just above the groundwater table. The gypsum sandstones accumulated periodically in very shallow shoals formed by wind‐driven currents. Large selenite crystals grew in increments during deposition, as indicated by flat‐topped pockets of gypsum sand between selenite crystals, selenite crystals draped by algal laminations, and intraformational conglomerates of selenite fragments.We believe this model of very shallow strand‐line lagoonal accumulation, partly detrital and partly diagenetic, may apply to the early stages of many ancient marine evaporite deposits.
FLUME STUDY OF RIPPLE PROPAGATION BEHIND MOUNDS ON FLAT SAND BEDS
Authors: SOUTHARD JOHN B. , DINGLER JOHN R. 
Published: June 2006

ABSTRACTPropagation of sediment ripples behind mounds of sediment in uniform flows of water over flat beds of fine sand was studied in a recirculating open channel. If the flow is strong enough, scour downstream of the mound, due to flow separation and impingement of strong eddies on the bed, generates a ripple, which itself grows large enough to cause downstream scour and production of a second ripple; the result is a widening train of ripples. Propagation vs. non‐propagation, as a function of mound height and bed shear stress, is interpreted in terms of the tentative hypothesis that ripple development is governed by the relationship between minimum height of bed irregularity necessary to generate ripples on an otherwise flat bed and the maximum height of bed irregularity that can be built up by flow over an originally flat bed. Minimum mound height for propagation of ripples was found to be non‐zero even when there was some sediment movement on the surrounding flat bed, but there was no sign of spontaneous development of ripples on the flat bed under these conditions; this suggests that there is a range of bed shear stresses for which a flat bed in uniform flow is metastable rather than unstable.
FLOOD DEPOSITS OF THE SAND‐BED EPHEMERAL STREAMS OF CENTRAL AUSTRALIA
Authors: WILLIAMS GEORGE E. 
Published: June 2006

ABSTRACTThis study investigates the deposits of sand‐bed ephemeral streams within an area of 250,000 km2 in the western Lake Eyre basin, central Australia, being initiated after the record floods of February–March 1967.Large‐scale ripples were the most common bed forms preserved in the majority of channels, covering 30–40% of the depositional area. Other bed forms included longitudinal, transverse and linguoid bars (20%), upper‐regime plane beds (<5%), small‐scale ripples (25–30%), and flute marks (<1%). Major bed forms could be related to flood stage: plane beds (upper regime), large‐scale ripples, and longitudinal bars usually were generated by high‐stage flow, and transverse and linguoid bars by waning and low‐stage flow.Trough cross‐stratification was produced by migrating small‐scale and large‐scale ripples, large‐scale sets comprising about 60% of the deposits. Tabular cross‐stratification (25% of deposits) resulted from the downstream and lateral growth of channel bars. Flat‐bedding with parting lineation (<5%) was dominant only along the middle reach of the Finke, the major stream in the western Lake Eyre basin. Disturbed bedding was almost totally absent. Bed forms, in order of increasing overall mean grain size (?) of deposits, are plane beds (upper regime), small‐scale ripples, transverse and linguoid bars, and large‐scale ripples. Sorting (σI) and skewness (SkI) are dependent on mean grain size (Mz).Lower‐regime flow prevailed for the majority of streams, upper‐regime flow being dominant only in the middle reach of the Finke. Using estimated Froude numbers and Darcy‐Weisbach resistance coefficients, the greatest mean velocities of flow have been calculated at about 0.8–3.7 m/sec.
ANTIDUNE CROSS‐STRATIFICATION IN A TURBIDITE SEQUENCE, CLORIDORME FORMATION, GASPÉ, QUEBEC
Authors: SKIPPER KEITH 
Published: June 2006

ABSTRACTSingle‐set cross‐stratification, considered to have been produced by the upstream migration of antidunes, is present in the basal division of certain thick turbidite beds.The basal divisions of these turbidites consist of very coarse to medium sand with a smooth or fluted base and sinusoid top. Internal laminae are inclined upstream at a shallow angle (less than 15°), opposing the local paleocurrent direction shown by flutes and ripple‐drift cross‐lamination.The sinusoid (antidune) bed forms and their associated internal cross‐strata were preserved by the rapid fall‐out of sediment from suspension normal to the bed.A paleohydraulic analysis suggests that during the final stages of antidune growth and migration, the currents moved at approx. 1 m/sec over very low slopes (much less than 1°).
DIFFERENT SOURCES CONTRIBUTING TO A BEACH SAND, SOUTHEASTERN BORNHOLM (DENMARK)
Authors: And HANS FÜCHTBAUER , ELROD JOHN M. 
Published: June 2006

ABSTRACTAn abnormal relationship between quartz roundness and grain size, and unusual K‐feldspar accumulation in the medium sand fraction, quartz grains with overgrowths, and a differentiated heavy‐mineral community made it possible to calculate quantitatively the contributions of four sources to a modern beach sand in southeastern Bornholm. The quartz grains with overgrowths were particularly sensitive to transport and clearly showed an increase in roundness away from their origin, the Balka Quartzite. This rock, due to its high resistance, contributed only about 1% to the beach sands.
CONTROL OF SLOPE ON DEPOSITION FROM SMALL‐SCALE TURBIDITY CURRENTS: EXPERIMENTAL RESULTS AND POSSIBLE GEOLOGICAL SIGNIFICANCE
Authors: LOVELL J. P. B. 
Published: June 2006

ABSTRACTThe experiments involved pouring aqueous starting suspensions of pumice sand and kaolinite silt into a submerged trough. The steepness of the bottom slope of the trough was varied from run to run. Heights of sand and silt were recorded at 10‐cm intervals away from source. The results: (1) support earlier suggestions that the ratio of sandstone to shale is a sensitive indicator of proximality in ancient turbidites, but do not support clearly the suggestion that the rate of decrease in that ratio away from source may indicate steepness of bottom slope; (2) suggest that the rate of decrease in sandstone thickness away from source in ancient turbidites may be inversely proportional to steepness of bottom slope.The possible application of the results to the geological record is discussed.