Clay-sized Material Research Articles

Effect of Texture on the Distribution of Oil in the Athabasca Oil Sands, Alberta, Canada

ABSTRACT The Athabasca oil sands consist of uncemented quartzose sand, silt, and clay, impregnated by extremely viscous oil. Seventy-six per cent of the variation in the oil content of these sediments is related to the median diameter and to the percentage of clay-size material (less than 2 microns). Analysis of variance of the two independent variables shows that the percentage of clay-size material is more effective than the median diameter in determining the amount of oil that the sediment can hold. Most samples of Athabasca oil sand containing more than ten per cent of oil by weight have median diameters within the range of those of sandstone reservoir rocks from which oil has been produced in commercial quantities.

Cross section of a floodplain in a moist region of moderate relief [Pennsylvania

The cross section of a small floodplain [Beaverdam Run, Cambria County, Pennsylvania] in the Appalachian Plateau was shown in excavations and borings for a dam. Deposits of vertical accretion, lateral accretion, lag deposits, channel fill, and colluvium fill the valley of an aggrading stream. Colluvium comprises almost 1/5 of the total valley fill and contains isolated lenses of vertical accretion. The colluvium built out from the valley side as the stream shifted laterally across the floodplain. Vertical and lateral accretion deposits may be sharply differentiated where exposed in a trench; the lateral accretion is composed of 70-75% sand size material and the vertical accretion of 35-60% clay size material.

Study of the distribution of some geochemical data

An examination of geochemical data is made by statistical methods. Values are plotted on logarithmic probability paper. In most cases results suggest that more than one distribution may be present. Examples and proposed interpretations are given for data for mineralization in rock and soil, for biogeochemical values, for Fe in soil, and clay size material in soil. It is suggested that such tests may be useful in exploration and in evaluation of some of the large amounts of collected geochemical data.

The occurrence of zinc in soil

This paper describes procedures for determining the form in which zinc is held in soil. The procedures involve removal of the iron oxide and determination of the associated zinc, a similar treatment of the clay size material to determine, indirectly, the lattice-held zinc, and an ammonium chloride extraction to determine the base-exchanged zinc. Values for the distribution of zinc in some Tennessee soil composites are given.

Studies of the Clay Fraction of Southwestern Iowa Loess

AbstractThis paper presents data on clay-size material in the loess of southwestern Iowa. Most of the loess samples studied are Wisconsin in age. Regional distribution of clay-size material in the loess is discussed, and data are given on the modes of occurrence of clay in the loess. The following test methods were used to study the clay fractions of selected loess samples: Mechanical analysis, differential thermal analysis, cation-exchange determinations, refractive index determinations, and x-ray diffraction techniques. These tests indicate a uniformity in clay-mineral composition, with montmorillonite and illite group minerals predominating. Clay contents from mechanical analysis are correlated with various properties of the loess; in most cases the properties appear to be linear functions of the clay content. The plastic limit is discussed in detail.

Mathematical Analysis of a Layer Extraction Method for Separating Clay-Size Material from Soils

AbstractThis paper presents a layer extraction method for obtaining a representative sample of clay-size material from a soil suspension. This method is especially advantageous in preparing a sample of relatively large size, and the procedure is simpler than that of the decantation method, a comparable method of extraction.In the layer method, the position and the thickness of the layer to be extracted from a soil suspension can be varied and one or more extractions can be made. The effect of these variables on the size composition and the quantity of the extracted material is analyzed mathematically. Based upon such an analysis, the proper position and thickness of the layer and the desirable number of extractions can be determined to suit the requirements of a particular test.

THREE CRITICAL ENVIRONMENTS OF DEPOSITION, AND CRITERIA FOR RECOGNITION OF ROCKS DEPOSITED IN EACH OF THEM

In any body of standing water subject to wave action, three depositional environments can be distinguished. They are here named the unda, the clino, and the fondo environments. In each, conditions are distinctive, but within each relatively uniform. The physical agencies operative in each of them, together with the kind and rate of sedimentation and rate of subsidence, control sedimentary facies and produce distinctive features of composition and bedding which are criteria for determining the depositional environments. Wave base, the greatest depth to which the bottom is stirred by waves during storms, is a critical factor. Above it, on the undaform, the sediments are relatively coarse, generally fossiliferous, rippled and cross-bedded, and show a peculiar “wavy” type of relatively thin bedding. The clinoform is the sloping surface extending from wave base down to the generally flat floor of the water body, here called the fondoform. In the clino environment— i.e., that on the clinoform—mud is dominant. Fossils, except for microforms in the later sediments, tend to be scarce. The bedding shows a distinctive alternation of thin and remarkably even layers of silt- and clay-sized material. Flute markings, probably produced during storms by density currents, and various indications of slumping and flowage of and in the sediments are common. The fondo environment is characterized by fine material with even, uniform, and generally rather massive bedding, but uniform, thin-bedded alternations of silt and shale without flute markings may develop close to the base of the adjoining clinoform. Changes in sea level shift these environments and produce characteristic sequences of strata. One inferred effect of a drop in see, level is the deposition, all along the outer edge of the undaform, of a belt of sands—here called undaform-edge sands—capable of becoming reservoirs for oil and gas. Such sand zones are likely to be misinterpreted as “shoreline trends.” Rocks deposited in the unda environment are relatively coarse, being most commonly sandstone, coarse siltstone, fragmental limestone, or oolite. The bedding is distinct and commonly has a characteristic waviness. Ripple marks, cross-bedding, flow-and-plunge structure, and lenticularity are characteristic. Criteria for clino rocks are: texture fine enough for the material to have been carried in suspension, bedding relatively thin and remarkably even, and the presence of flow markings and flutings and of evidences of gravity sliding. Criteria for fondo rocks are: fine grain, lack of secondary sorting, generally massive bedding, and a composition generally derived from clays and oozes.