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Microscopical and chemical examination of intertidal flats of the Wash indicate that phases of iron corresponding to ferric hydroxide and iron monosulphide are involved in the early diagenetic formation of pyrite, the first being an important source of the iron. Sedimentological data are tested against analyses of total iron extractable by hydrochloric acid and concentrated nitric acid, and of the pyritic fraction of this iron; ignition data for residual organic matter are considered. The occurrence of the pyrite as isolated grains and spherules of framboidal texture is recorded, their size ranges given, and iron monosulphide recognised as the precursor of both forms. Ordering in the pyrite framboidal spherules is recorded and internal coalescence confirmed as a feature of primary growth which obscures the ordering. [ABSTRACT FROM AUTHOR]

A simple method to estimate the degree of ‘crystallinity’ of illite has been used for several years in three French laboratories. Many results, which are unpublished, were obtained; three examples are presented in this paper. They show the sensibility of the method, which allows one to appreciate, above all other methods, burial diagenesis, the front of metamorphism, or some regional areas of very weak metamorphism. [ABSTRACT FROM AUTHOR]

The observed size in the thin-section is less than the true train sizes of the clastic rock as the thin-section plane does not necessarily pass through the centre of gravity of the grains. Correction factors based on probability theory give corrected arithmetic moments of the size distribution in the elastic rock from the observed arithmetic moments of the size distribution in the thin-section. The corrected arithmetic moments so obtained are transformed to their equivalent corrected phi moments which are useful to generate the unknown size distribution of the clastic rock by the help of Edgeworth's series. [ABSTRACT FROM AUTHOR]

Indices based on Wentworth phi values of Q1, Md and Q3 are used for textural classification of sediments. Wentworth phi values enable a detailed subdivision. A nomenclature based on the Wentworth phi indices is developed. The indices, and to a smaller degree the names, show sorting and skewness based on integer phi units. The classification scheme gives a continuous scale from gravel to fine clay. The Q1MdQ3-indices can be used for distinction of river, marine and loess deposits. The addition of indices of the 1st and 99th percentile, giving 5-digit indices, augments the Possibilities for a determination of the environment: river deposits can be distinguished from beach and dune sediments and in more detail from shallow marine and coastal deposits. The indices can be handled by data-processing machines. [ABSTRACT FROM AUTHOR]

The crystallinity and mineralogy of both the glauconite and the clay fraction of samples from six contemporary marine environments were investigated by X-ray diffraction. In those areas where glauconite is now forming, the mineralogy and the degree of crystallinity of both the glauconite pellets and the associated clay fraction are similar. In contrast, detrital and relic glauconites are observed to have mineralogies that are different from their clay fractions. No consistent relationship was observed between degree of crystallinity and color of the pellets. Further, only two classes of glauconite as defined by BuRsT (1958) were common: expandable, interlayered clays and two or more clay minerals in a mixed assemblage. Based on the clay fraction-glauconite similarities and other supporting evidence, glauconite on the Scotia Ridge is concluded to be authigenic. Glauconite from Santa Monica Bay, California and from the continental shelf off Morocco appear to be detrital. Glauconite pellets in the shelf sediments off Guinea and the southeastern Atlantic Shelf of the United States are both detrital and authigenic. The poor crystallinity exhibited by the Chatham Rise glauconite is in contrast to the well-crystallized associated clay fraction and indicates that they are not genetically related. However, the origin of this glauconite remains in doubt. [ABSTRACT FROM AUTHOR]