Showing papers in "Journal of Sedimentary Research in 1957"

Brazos River bar [Texas]; a study in the significance of grain size parameters

Abstract: A bar on the Brazos River near Calvert, Texas, has been analyzed in order to determine the geologic meaning of certain grain size parameters and to study the behavior of the size fractions with transport. The bar consists of a strongly bimodal mixture of pebble gravel and medium to fine sand; there is a lack of material in the range of 0.5 to 2 mm, because the source does not supply particles of this size. The size distributions of the two modes, which were established in the parent deposits, are nearly invariant over the bar because the present environment of deposition only affects the relative proportions of the two modes, not the grain size properties of the modes themselves. Two proportions are most common; the sediment either contains no gravel or else contains about 60% gravel. Three sediment types with characteristic bedding features occur on the bar in constant stratigraphic order, with the coarsest at the base. Statistical analysis of the data is based on a series of grain size parameters modified from those of Inman (1952) to provide a more detailed coverage of non-normal size curves. Unimodal sediments have nearly normal curves as defined by their skewness and kurtosis. Non-normal kurtosis and skewness values are held to be the identifying characteristics of bimodal sediments even where such modes are not evident in frequency curves. The relative proportions of each mode define a systematic series of changes in numerical properties; mean size, standard deviation and skewness are shown to be linked in a helical trend, which is believed to be applicable to many other sedimentary suites. The equations of the helix may be characteristic of certain environments. Kurtosis values show rhythmic pulsations along the helix and are diagnostic of two-generation sediments.

The nature and origin of Argentine loess

Abstract: Though the loess deposits of Argentina (Pampean Formation) are geologically well known, their granulometric and mineralogical composition has hitherto not been analyzed. The data obtained from a study of more than fifty samples are here summarized. It is shown that Argentine loess is similar in field appearance and texture to the North American and European loess. However, the mineralogical composition is completely different, especially in the coarse fractions where an assemblage of volcanic minerals is predominant. The presence of abundant montmorillonite and glass shards in the fine fraction is a point of resemblance between the Argentine and the American sediments. All this material, doubtless of volcanic-pyroclastic origin, has been transported by winds to the place of deposition

Studies on Bacterial Precipitation of Carbonates in Sea Water

Abstract: Carbonates have been obtained in the form of films at the surface of aquarium cultures containing mud from the bay of Villefranche sur mer (Alpes maritimes, France) and sea water enriched with glucose to hasten the bacterial development. In order to establish the best conditions of formation of this film, I tried to vary the different factors susceptible of variation in nature, i.e. light, temperature, concentration of organic matter, and cultures have been made with sea water concentrated by evaporation (with an extent to salt marshes). Analyses of the sea water during the experiments have been made to try to determine the process of the formation of the carbonates. A brief mineralogical study of the films obtained has been made including microscopical analysis, chemical analysis for Ca and Mg, and some X-ray diagrams.

Beach erosion and concentration of heavy mineral sands

Abstract: The east coast of India, extending from Vasishta Godavari river in the south to Vamsadhara river in the north was surveyed with special reference to the beach configuration and concentration of heavy mineral sands. It was found that storms in the Bay of Bengal and the annual changes in sea level cause beach erosion, while large scale regression of the beach is the result of changes in the oceanographic environment. The concentration of well-sorted heavy mineral sands is effected by such beach erosion and beach regression. This is believed to be due to the sorting action of the powerful waves responsible for the erosion and the transporting action of the along-shore currents.

Adjustment of land derived clays to the marine environment

Abstract: The predominant clay minerals found in the waters of rivers in the area of Chesapeake Bay consist of a well-formed to weathered illite with minor amounts of kaolin and a trace of weathered chlorite. Mixed-layer clays were observed in the estuaries and are related to and difficult to distinguish from differentially hydrated monomineralic clays when these clays are in a weathered condition. A regularly stacked mixed-layer illite-chlorite was observed at one locality in the James Estuary. A chlorite-like and vermiculite clay are forming in estuaries along the Atlantic Coast. Thermal stability of the diagenic chlorite increases with increasing salinity of the environment and to less extent with depth in the sediment. The chloritic material arises principally from the diagenesis of weathered illite in the Atlantic Coastal environment and probably passes through a vermiculite stage. Montmorillonoid, and to less extent illite, are altered to a chloritic material in the Gulf of Mexico and along the Pacific Coast. The first phase planned for the study of the geochemical relation of chloride, sodium, calcium, potassium, and magnesium in the clays of an estuary has been completed. The chemical data lend support to the hypothesis that a chloritic-vermiculitic clay mineral is being constructed by the alteration of weathered illite and montmorillonoid, and the reconstitution of a trace amount of chlorite.

Pennsylvanian sandstones of the Eastern Interior Coal Basin

Abstract: The Pennsylvanian sandstones of the Eastern Interior Coal Basin were studied petrographically and stratigraphically to get a better understanding of source areas, sediment transport patterns, and conditions of sedimentation. The petrographic study was extended to adjoining basins, the Appalachian, Michigan, and northern Mid-Continent, to obtain a regional picture of mineral composition. Stratigraphic patterns are described in terms of general character, lateral persistence, thickness, and contrasts between channel and sheet sandstones. The sheet sandstones are commonly thinner, finer grained, more argillaceous, and more widely persistent than channel sandstones. In the petrographic study, modal mineralogy, quartz variety, and rough size analyses were made of 176 samples and heavy minerals were estimated from 35 samples. The sandstones fall into three petrographic types that correlate with stratigraphic position: orthoquartzites in the basal zone (Caseyville Group), types intermediate between orthoquartzites and subgraywackes in the next higher zone (lower Tradewater Group) and subgraywackes in all higher groups. Although there are minor differences in composition bet een geographic provinces, the major aspect is one of homogeneity over the entire area of the northcentral and northeastern states. Current intensity, the primary factor in sedimentation conditions, varied greatly both locally and regionally, but the range of variability was more or less homogeneous throughout the stratigraphic section and in all of the geographic provinces. Conflicting evidence on marine or nonmarine origin of the sandstones is harmonized, to infer deposition in a combination of a variety of shallow water marine, deltaic, and coastal plain environments. Source areas and patterns of movement of detritus to sedimentary basins were largely inherited from early Pennsylvanian time. After Caseyville time, detritus from the east and northeast moved over the entire basin of deposition, vastly diluting material derived from the north and northwest. Continued mild erosion of source areas throughout Pennsyl anian time led to gradual but incomplete removal of a sedimentary cover and to the exposure of limited areas of igneous and metamorphic rocks.

A Fabric and Petrologic Study of the Pleasantview Sandstone

Abstract: The Pleasantview sandstone is a typical Pennsylvanian cyclothem sandstone in western Illinois exhibiting both channel and non-channel phases. In order to describe the sandstone and to interpret the sediment transport direction and the environmental conditions existing at the time of deposition, an investigation was made of the texture, composition, depositional structure, cross-bedding, and dimensional fabric. Results of this study indicate that the sandstone is a subgraywacke which was deposited in a north and northwest direction. It is concluded that the process which cut the Pleasantview channel was to a large degree independent of the processes which later filled the channel with sediment. No conclusive evidence could be found for the exact nature of the processes operating at the time of channel cutting and filling. However, it is suggested that the environmental conditions of the Pleasantview most closely resemble those conditions existing at present in the Dutch Wadden Sea.

Dolomite Growth in Coralline Algae

Abstract: Thin-section study of dolomitized limestone of Eocene age from the subsurface of Eniwetok reveals the localization of dolomite crystals within segments of articulate coralline algae. Corals and large Foraminifera are little affected. The writer suggests, in view of recent work by others on the crystal chemistry and occurrence of high-magnesian calcite, that the dolomitized algae are the end product of the crystallographic ordering of the Ca-Mg solid solution that made up the original high-magnesian algal calcite. This ordering is thought to take place on scattered dolomite nuclei inherent in the original algal precipitate, these nuclei being the result of local concentrations of Mg ions within the algal calcite.

CLassification of Limestones and Dolomites on Basis of Ca/Mg Ratio

Abstract: Because of shortcomings of the existing classifications of dolomites and limestones, a new classification on the basis of Ca/Mg ratios is proposed, with some divisions dictated by the ratios which are determined by the mode of formation.

A fabric and petrologic study of the Pleasantview sandstone [Illinois]

Abstract: The Pleasantview sandstone is a typical Pennsylvanian cyclothem sandstone in western Illinois exhibiting both channel and non-channel phases. In order to describe the sandstone and to interpret the sediment transport direction and the environmental conditions existing at the time of deposition, an investigation was made of the texture, composition, depositional structure, cross-bedding, and dimensional fabric. Results of this study indicate that the sandstone is a subgraywacke which was deposited in a north and northwest direction. It is concluded that the process which cut the Pleasantview channel was to a large degree independent of the processes which later filled the channel with sediment. No conclusive evidence could be found for the exact nature of the processes operating at the time of channel cutting and filling. However, it is suggested that the environmental conditions of the Pleasantview most closely resemble those conditions existing at present in the Dutch Wadden Sea.

A Bahamian Faecal-Pellet Sediment

Abstract: The sediment in the extreme northern portion of the lagoon of the island of Bimini, B.W.I., consists principally of elongate tapered pellets. These distinctive pellets were identified as excrement from Batillaria minima, a marine gastropod abundant in the area of pellet accumulation. Since this gastropod is ecologically restricted, the occurrence of such pellets in situ in the fossil record would be of paleoecological significance.

Heavy mineral studies in tills of Ontario and adjacent areas

Abstract: Investigations of heavy minerals in tills peripheral to the Canadian Shield indicate the following characteristics: the Grenville tills contain more garnets, tremolite-actinolite, and hypersthene than the Superior tills, which are richer in chlorite-serpentine, clinopyroxenes, and epidotes. Epidotes dominate in some Superior tills northwest of Lake Superior. Hornblende is very abundant in all tills, but particularly along the Grenville-Superior boundary north of Lake Huron. The Huron lobe tills contain more heavy minerals than the Erie tills. The heavy mineral content in the Huron tills of southwestern Ontario derive principally from the Superior province, with some admixture from the west end of the Grenville, while typical Grenville minerals dominate in the Erie tills. Comparison of heavy mineral content between successive tills and recessional moraines reveal a shifting of ice flow in both lobal areas during Wisconsin time. First each lobe entered its lake depression from north-northeast. Later the major flows drifted apart, the Huron lobe assuming a more north-south, and the Ontario-Erie lobe, a northeast-southwesterly direction. The space between them became occupied by minor but tributary ice-flows.

Size Analysis of Sand by a Sedimentation Technique

Abstract: The particle size distributions of sand-size material can be determined either directly by microscopic measurement, or indirectly by sieving or by sedimentation techniques. Routine size analyses by microscopic measurements are impractical because they are too time consuming, although other properties such as grain shape or roundness can be determined when making size analyses by this method. Sieve analyses, because of their convenience and resulting fractionation, have been most extensively used to determine the size frequency distribution of sands. however, since most sediments are deposited in fluid media, sedimentation size analyses are often desirable because they most nearly approach the hydrodynamic conditions of deposition. This paper discusses a sedimentation technique employe for the analysis of sand-size material, and demonstrates, by means of experiments with glass spheres, that single grain terminal settling velocities can be used as suitable approximations for fall rates of grain groups. The settling velocities for groups of grains are 10 to 15 percent faster than those for single grains of the same diameter. Comparative results of size analyses of the same sample indicate that sedimentation diameters generally were coarser than sieve diameters but finer than microscopically measured diameters.

Structural Petrology of the Pico Anticline, Los Angeles County, California

Abstract: A petrofabric field and laboratory study was made of the rocks of the Pico Anticline, Los Angeles County, California, to investigate the correlation between microstructures and large scale structures and to determine the possibility of predicting large scale structures from microstructures Methods of petrofabric analysis, such as the determination of dimensional and crystallographic orientation of quartz grains, showed preferred orientations; but no well-defined relationships were noted between micro- and megastructures. The anisotropies observed in the orientation data are attributed to depositional rather than to deformational fabrics. The study of microfractures, however, provided a means of relating the microscopically observed features to the large structure. Statistically, the microfractures are strongly oriented, and the preferred orientation in any sample can be used to determine the strike and plunge of the anticline within usable angular limits.

Fluvial gravel fabric

Abstract: The importance of gravel fabric lies in its potential aid in determination of source area and genesis of a sedimentary deposit. Gravel fabric in fluvial sediments has received scant attention in the past because its determination is overly time consuming, and because of lack of agreement among workers on the relation between the fabric pattern and the direction of stream flow. A new method is suggested for fabric determination on unconsolidated deposits which is faster than the old procedure, and can be done in the field. Another refinement includes selecting the pebbles to be plotted on the basis of shape (disc- and rod-shape). Such selection results in a clearer fabric pattern with fewer pebble measurements. Two streams were studied to obtain the orientation of the disc- and rod-shaped pebbles with respect to the direction of stream flow. It was found that discoid pebbles shingle, with their short axes dipping downstream at a steep angle. The long axes of rod-shaped pebbles have a limited tendency to describe a plane (as outlined by the maxima in the fabric diagrams) which dips in an upcurrent direction. In a further attempt to reduce the time involved and still obtain the sediment transport direction, apparent dip studies were undertaken on partly consolidated ancient fluvial gravel deposits. Utilizing the results from the two stream studies, readings of the dip of the apparent long axes of pebbles were made on intersecting vertical faces of flat lying gravel, to reconstruct the upcurrent dipping plane for the sedimentation unit involved, and thereby determine the direction of sediment transport. Through comparison with other means of flow direction determination, an affirmative check on the apparent dip readings was possible.

Secondary Gypsum of the Sulphur Series, Sicily, and the So-called Integration

Abstract: The Upper Miocene Sulphur Series of Sicily comprises four main formations, which are, in ascending order, the diatomitic Tripoli Formation, the evaporitic Basal Limestone, the Gypsum Formation, and finally the Trubi Formation, an ancient Globigerina ooze Other less continuous units are also present Peculiar sedimentational conditions are described in detail in a larger Italian paper In the Gypsum formation primary anhydrite and primary gypsum are varved rocks with inverse graded bedding of the laminae, due to chemical deposition Secondary gypsum derives from anhydrite by paradiagenetic transformation and shows two different petrologic types In the "sulphiferous facies" of the Gypsum Formation selenitic secondary gypsum is developed, with large size crystals and a peculiar fabric of almost free growth In the "saliferous facies" alabastrine secondary gypsum shows structures caused by hindered growth under considerable load A sequence of stages in the anhydrite-gypsum transformation seem to be the following: (1) building of limpid selenite crystals; (2) ruptural deformation of their peripheral zones, giving rise to super-individual polarisation; (3) production of intergranular fine-size gypsum aggregate of mylonitic character Ruptural deformation is originated by volume increase of the solid phase during the transformation Residual anhydrite inclusions are present in the first two stages, absent in the last one The above sequence is just the reverse of that described in the studies on American and German salt domes Goldman (1952) gives the name "integration" to a process of progressive adjustment of randomly oriented fine-size gypsum pieces to superindividuals with less dispersed optical orientation and finally to limpid selenite crystals This process is very different from the well-known "Sammelkristallisation" and does not seem to be feasible in view of the physico-chemical forces known thus far The little disturbed Upper Miocene Gypsum Formation is likely to give a clearer picture than the severely disturbed Paleozoic salt domes

Sediments of three bays of Baja California [Mexico]; Sebastian Viscaino, San Cristobal and Todos Santos

Abstract: Study of more than 1350 sediment samples from three bays facing the Pacific coast of Baja California shows that the sediments are closely related to oceanographic conditions. At Sebastian Viscaino Bay the sediments are coarsest and of highest calcium carbonate content in a strait that is swept by tidal currents. Adjoining bands of progressively finer sediment result from lower velocities of the water at both ends of the strait. At one end of San Cristobal Bay the sediments are coarse and of high calcium carbonate content owing probably to local upwelling of water. The rest of the bay is an area of slow deposition of detrital sediments and thus it contains the authigenic minerals glauconite and phosphorite. The third bay, Todos Santos, is largely closed off from the open sea by protect ng islands; accordingly, its sediments show a decrease in grain size from shore to deep water. Sediments of the same grain size in the different bays do not necessarily have the same percentage of calcium carbonate or of organic matter because of the different environmental controls. Such present-day background knowledge is useful in interpreting ancient sediments with respect to depositional environments.

Comparison of percentage and ratio data in facies mapping

Abstract: In facies map practice percentage maps and ratio maps are sometimes considered as strongly alternative ways of expressing certain facies patterns The fixed relation between percentages and ratios for a common set of data implies that the maps are supplementary instead of competitive It is shown in this paper that the conventional arc sine transformation of percentage data yields numbers identical with an arc tan transformation of the corresponding ratios, and that a single facies map of the transformed variables simultaneously presents some of the implications of both types of individual map The transformation also facilitates further statistical analysis of the map data, especially in connection with analysis of variance

A New Method for Obtaining Significant Average Directional Measurements in Cross-Stratification Studies

Abstract: A new method is described that can be used conveniently in the field to determine the number of measurements of cross-strata dip directions necessary to obtain a significant average direction for an area. The method commonly used in the past has involved a great deal of graphical computation in the field. The suggested method is based on the fact that the number of measurements needed is approximately proportional to their variation. The estimated standard deviation of the first 50 measurements is determined, and, by simple linear regression equation, the number of measurements needed is computed. This regression equation has a standard error of plus or minus 18 measurements. If 36 measurements are taken in addition to the number indicated by the equation, the geologist can be about 9 percent confident he has enough measurements to compute an average dip direction that will be comparable to that which would be obtained with the standard cumulative vector direction curve method. With the suggested method confidence intervals for the average directions can be obtained easily. A brief discussion of the application of Stein's two-stage sampling method to cross-stratification studies is also given. Stein's method is applicable to the case where an average direction must be within previously specified confidence limits.

Lithology, with Particular Reference to Cementation, of Upper Carboniferous Sandstones in Northern Derbyshire, England

Abstract: The mineralogy and texture of the coarser clastic sediments exposed in a 940 feet long core at Smeekley in northern Derbyshire indicate that they are orthoquartzites with subordinate subgreywackes. The most abundant cement is quartz which was precipitated contemporaneously from the dominantly acidic waters at the site of deposition. Calcite, the second most common cement, was a primary precipitate in some cases but, together with kaolinite, has been partially redistributed later. Small, discrete pockets of primary chalcedonic silica and sericitic mica (?illite) also occur. At irregular intervals, the prevalent acid depositional conditions were locally modified probably by decomposing organic matter, to give conditions suitable for the precipitation of the calcite and siderite. Subsequ nt limonitisation of the siderite is the only mineralogical change which has been effected since the deposition of the sediments.

Observations on Limestones

Abstract: This paper discusses the origin of pyrite and ankeritic dolomite in certain Pennsylvanian limestones from Iowa, as well as evidence for the clastic nature of the limestones. It is concluded that: Pyrite can form in bottom sediment within a few centimeters of the depositional interface in spite of a flourishing benthonic fauna; Ankeritic dolomite may form in the same environment as, and contemporaneous with, pyrite; All the limestones studied show evidence of clastic origin, including abrasion of the fine-grained calcite matrix.

Authigenic Montmorillonoid Cement in Andesitic Sandstones of Central California

Abstract: Distinctively blue upper Tertiary sandstones, composed almost entirely of andesitic detritus derived from upper Tertiary andesite breccias of the northern Sierra Nevada, are widespread in central California. These volcanic arenites are well sorted and loosely cemented by a thin coating of authigenic clay mineral encasing each detrital grain. The clay has grown in laths or fibers oriented perpendicular to the surfaces of the clastic grains. The blue color is due to the effect of this translucent coating on light reflected from the dominant dark-colored grains beneath it. Optical, X-ray, differential thermal, and chemical data indicate that the mineral is a montmorillonoid intermediate between beidellite and nontronite, a composition not commonly recorded in published analyses. The clay mineral crystallized from pore solutions permeating the sandstone, the material probably being mostly derived by solution of the groundmass of the andesite rock fragments, which make up half or more of the sandstone.

Effects of Sphericity, Roundness, and Velocity on Traction Transportation of Sand Grains

Abstract: Detrital quartz grains were introduced into a tube under conditions of differing average fluid velocity in order to note quantitatively as well as qualitatively the importance of particle attributes affecting rate of transportation. Difference in rate of transport due to sphericity, roundness, and size were measured and compared by use of arithmetic mean and standard deviation. Results indicate that rate of transportation is influenced by the local turbulence created by individual grains. However, rate of transport of small grains, where local turbulence is minor, is more dependent upon the ability of the particle to roll. The effect of sphericity on rate of transport is complex and is dependent upon rate of fluid flow and degree of sphericity.

Criteria Used for Distinguishing Lacustrine and Fluvial Sediments in Tertiary Beds of Uinta Basin, Utah

Abstract: Lacustrine and fluvial Tertiary sediments of the Uinta Basin, Utah differ markedly in many primary respects, and display features which may be diagnostic of the principal environment in which they were formed. The fluvial and lacustrine sandstones are similar in mass properties, differing primarily in that lacustrine sands are more uniform in appearance than fluvial sands. The lacustrine shales are denser, harder, better bedded, more continuous, somewhat thicker, and contain considerably more of the carbonates, limestone and dolomite, than the fluvial shales. Many limestone and dolomite types (coquinoid, coquinal, algal, and calcarenites, and more common varieties of bedded limestone and dolomite) are found in the lacustrine sediments, but only thin "fluvial" limestone beds are present in the Tertiary rocks of the Uinta Basin. Final conclusions, applicable to a large number of separate continental deposits, are not drawn because studies of this type are still very much in the "gathering stage."

Observations on limestone [Iowa]

Abstract: This paper discusses the origin of pyrite and ankeritic dolomite in certain Pennsylvanian limestones from Iowa, as well as evidence for the clastic nature of the limestones. It is concluded that:

Suggested use of bed-thickness measurements in stratigraphic descriptions

Abstract: The description of stratification in sedimentary rocks in terms of the mean thickness and standard deviation of beds is suggested. The procedure is outlined and illustrated with an example from the Atoka Formation of Arkansas.

Trends of Sedimentation in Giridih Basin, Bihar, India

Abstract: A detailed lithologic and petrographic study of the sedimentaries of the Giridih Basin was under taken. The chief rock types belonging to the Lower Gondwana subdivision (Upper Carboniferous) are represented by two stages, Talchir and Karharbari. The Talchir Stage consists of a boulder bed, needle shales, with alternating lenses of silty sandstones, and coarse grits. The boulder bed is unfossiliferous as are the silty sandstones and the coarse grits, but the needle shales frequently contain inclusions of carbonaceous material. The Karharbari Stage starts with a conglomerate at the base and consists chiefly of alternating grey arkoses, micaceous shales, carbonaceous shales, and coal seams. The arkoses are cross bedded, the cross bedding being of the type that is usually characteristic of shallow water current. All lines of evidence suggest that the Talchirs are in part glacial and in part glaciofluvial and that the lake basin became shallower at the close of the Talchir period. The Karharbari sediments were interpreted as having been deposited in shallow water and based on cross bedding and heavy mineral constitution were thought to have been derived from a proximate western source.

Combined Preferential Staining and Cellulose Peel Technique

Abstract: Minerals in exposed thin-sections, diamond-sawed slabs, and detrital minerals partially embedded in mounting media can be preferentially stained with various dyes, and cellulose peels can be obtained from these materials to show both fabric and discrete mineral species. These have the advantage of providing inexpensive "copies" which can be utilized in projection, microscopic examination, and in some instances in preparation of photographic illustrations. They can be readily filed for ready reference in a small storage space, are practically indestructible in routine work, and last indefinitely.

Authigenic Biotite in Spheroidal Reduction Spots, Pierce Canyon Redbeds, Texas and New Mexico

Abstract: Spheroidal reduction spots with dark gray bulls-eye centers have been found in the Pierce Canyon Redbeds of Texas and New Mexico. The dark gray center is a concentration of authigenic biotite disseminated between the fibrous crystals of gypsum cement.

Differentiation of marine and sub-aerial sedimentary environments by volume percentage of heavy minerals, Mustang Island, Texas

Abstract: The marine and sub-aerial sedimentary environments across Mustang Island, Texas, can be differentiated by the volume percentage of heavy minerals in the sediments. The barrier island sediments average .45% heavy minerals and the gulf sediments average .04% heavy minerals. The berm, averaging .34% heavy minerals, is the transition zone between the environments. Analyses of the amount of heavy minerals may be valuable in characterizing the environment of deposition of ancient sediments.