ALBERT

Notes: The uranium content of twelve rock reference samples, five from the Canada Centre for Mineral and Energy Technology, four from the Czechoslovakian Institute of Mineral Raw Materials and three from the United States Geological Survey was determined by neutron activation followed by delayed-neutron counting. Uranium contents measured ranged from 0.20 to 560 ppm. Three of the Canadian samples have relatively well established uranium contents. Of these we agree well with two of them; our value on the third is ∼13% lower than the recommended value. Comparison of our data on the other samples with other researchers is not yet possible because (i) no determinations are yet reported on several of these samples and (ii) even when several reported values are available, the wide disparity of those values does not allow meaningful comparison.

Notes: Reviews already published on the state of “standard samples” of silicate rocks and minerals, as well as of some samples of other materials that can be used as reference standards for the general analysis of silicate rocks and minerals, have been updated. Usable values of varying degrees of reliability are suggested for major, minor and trace constituents of nearly one hundred different samples. Presentation of the information has been improved with a view to making it more convenient for readers’use.

Notes: Chemical analyses for major and minor constituents are reported for two standard manganese nodule samples available from the U.S. Geological Survey. Description is given of the analytical methods used in the analyses, including gravimetric, titrimetric, and instrumental techniques.

Notes: A demonstration is given that the Gamma Transformation Method (GTM) does not achieve its objective insofar as it gives an estimate of the median and not of the mode (unless they coincide) of a given distribution.Nevertheless, because of the inherent high capability of the method to symmetrize a group of data and of its potential validity and use in other statistical fields, a GTM program which can be used on a programmable pocket or portable calculator is presented.

Notes: The trace elements Ce, Co, Cr, Cs, Dy, Eu, Gd, Hf, La, Nd, Ni, Rb, Sb, Sc, Sm, Ta, Tb, Th, Tm, U, V, Yb and Zr have been determined by instrumental neutron activation analysis and U by delayed neutron counting in the USGS standard rock samples STM-1, RGM-1, QLO-1, SDC-1, BHVO-1, SCo-1, SGR-1 and MAG-1. The results are compared with those found in the literature.

Notes: A suldge ash reference sample has been prepared. It has been analyzed by twenty-one independent laboratories. Information is presented on the number of analysts reporting each element, and the various instrumental methods used. Results are reported for twenty-six elemental determinations. Recommended elemental composition of the sample is given for twenty-one elements.

Notes: Zinc and lead in the six S.A. NIMROC Standards and in DTS-1 and PCC-1 have been determined accurately by means of atomic absorption spectrometry. A selective ion exchange separation procedure, using AG5OW-X8 cation exchange resin and 0.5 M HCl - 60% acetone as eluent, has been employed to separate zinc and lead from the matrix elements. To increase the sensitivity of lead, a slotted stainless steel tube, which is positioned on top of the air-acetylene burner head, has been used during atomic absorption measurements. The accuracy and precision of the described method is demonstrated by the analysis of synthetic mixtures containing various amounts of zinc and lead as well as major rock-forming elements.

Notes: A method which consists essentially in ranking and then plotting on rectangular coordinates the data of a skewed set of results to the purpose of identifying the modal value of the set, is described. The method is simple, fast (if a plotter is used) and requires no calculations.

Notes: A method is described for the determination of mercury at nanogram levels in geological materials by flameless atomic absorption spectroscopy after metal vapor generation. Mercury is converted to a soluble form by H2SO4-HNO3 attack in a teflon bomb at 180°C for 90 minutes. Metal Hg vapor is obtained by reaction with combined NaBH4-NaOH using the Perkin-Elmer MHS - 10 hydride system and determined at room temperature. Mercury can be easily determined in most silicate materials. The sensitivity of the method depends essentially on the purity of the reagents and contaminations during handling rather than on instrumental capabilities. A detection limit of about 10 ng/g Hg for 0.5 g samples has been achieved with the use of normal “suprapure” reagents. Mercury contents on some USGS, CRPG and ANRT reference samples are reported.

Notes: An account is given of the formulation and preparation of synthetic standards suitable for the routine analysis of minerals, ores and ore concentrates by instrumental neutron activation. Fifteen standards were prepared, each containing from one to seven elements. The standards contain forty-four elements that produce isotopes with half-lives longer than 12 hours. An evaluation of the accuracy and precision of the method of preparation is given.

Notes: Twenty seven geochemical reference samples have been analysed for cadmium using the stable isotope dilution technique. These include four USGS, one NBS, five CRPG, eleven ANRT and six NIMROC samples. Each sample has been analysed at least in duplicate.The four USGS samples have previously been measured in this laboratory by Rosman and De Laeter, but the present results are believed to be more accurate than the earlier data. Our results for the other twenty three samples are much lower than most of the published data. There is also evidence of cadmium inhomogeneities in some of the samples.

Notes: Data on the uranium concentration in 25 rock, soil, and fly ash standards obtained by delayed neutron assay are presented.

Notes: The uranium contents of thirteen rock reference samples from the Centre de Recherches Pétrographiques et Géochimiques, Nancy, France, were determined by delayed-neutron activation analysis. Four others from the same laboratory were found to have uranium concentrations below our limit of detection. Meaningful comparison of our data with other workers is presently not possible (i) because of the paucity of uranium data and (ii) because of the disparity of uranium data on the samples for which uranium data exist.

Notes: The molybdenum and tungsten contents of 40 geochemical reference samples have been determined by a spectrophotometric procedure. The agreement between the present results and published data is generally good.

Notes: Sixteen international and six inter-laboratory geochemical reference samples have been analysed for their selenium content. No previous Sedata are available for thirteen of them. Selenium has been separated from silicate matrix by volatilization and was determined with flameless atomic absorption spectrometry. An outline of the procedure is given. The limit of detection is 10 ng Se per 1 g of sample. Time required for one full analysis is 1.2 to 2.5 hours depending on amount of sample to be volatilized.

Notes: Geostandards are needed to intercalibrate environmental research and routine environmental monitoring programs. Because a principal concern in both types of analyses is the elemental concentrations of discrete phases, values for partial extractions of geostandards are also needed. This and other information are solicited for an intercalibration among laboratories which monitor metals in marine sediments and wastewater sludge.

Notes: Ayant eu à ré-étalonner sur une base euro-péenne des lots de deux minerais de fer et d'un laitier de haut fourneau préalablement étalonnés uniquement par des laboratoires français, il y a 6 à 10 ans, on a pu montrer que:-les moyennes certifiées n'ont pas évoluées,- que les dispersions de mesure se sont réduites,- que l'absorption atomique permet de doser correctement les très basses teneurs en Ca et Mg dans les minerais de fer riches.

Notes: An international iron-formation reference sample is warranted as a basis for geochemical investigations of Precambrian iron-formations. A better knowledge of the geochemistry of iron formations will hopefully elucidate the long standing discussion on the genesis of iron-formations. The reference sample can furthermore be used in studies of deep-sea metalliferous deposits.

Notes: Après avoir décrit la structure du laboratoire d'analyse de l'IRSID à Maizières-lès-Metz, en abordant les éléments dosés par spectrométrie de fluorescence X et l'absorption atomique, les auteurs passent en revue les méthodes chimiques dans le cadre de l'analyse des minerais de fer.Quelques informations sont données sur l'activité au sein de l'ISO/TC 102/SC1 puis le point est fait sur les matériaux de référence certifiés actuellement connus dans le monde.Si le laboratoire comporte comme équipement de base un spectromètre de fluorescence X associéà diverses autres techniques qui devraient peu évoluer dans le futur, il semble qu'à l'avenir une bonne place soit réservée pour les minerais tout comme pour bien d'autres matrices, à la spectrométrie avec torche à plasma inductif.

Notes: Rhizoliths are defined as organosedimentary structures resulting in the preservation of roots of higher plants, or remains thereof, in mineral matter. They are abundant and characteristic features of Quaternary terrestrial carbonates (calcretes and aeolianites) from coastal regions of the western Mediterranean. Field and petrographic observations indicate that five basic types of rhizoliths can be recognized: (1) root moulds, which are tubular voids that outline positions of former, now decayed roots; (2) root casts, which are sediment- and/or cement-filled root moulds; (3) root tubules, which are cemented cylinders around root moulds; (4) rhizocretions s.s., which are pedodiagenetic mineral accumulations (here low magnesian calcite) around living or dead plant roots; and (5) root petrifactions, which are mineral impregnations or mineral replacements of organic matter whereby anatomical features of roots have been preserved partially or totally. Apart from rhizoliths themselves, roots of higher plants are responsible for the formation of numerous and characteristic features of pedogenetically affected terrestrial carbonates. Plant roots are responsible for, or contribute to, the formation of alveolar textures, in situ brecciation (rhizobrecciation) textures, horizontal sheet cracks, vertically elongate glaebules (concretionary soil structures) and micritization (rhizomicritization) within terrestrial carbonates. Rhizoliths, together with the above features, are products of pedodiagenesis. More significantly, rhizoliths and related features are indicators of palaeosols and hence of subaerial vadose environments in ancient (post-Silurian) successions.

Notes: The calcretes of the Kalahari are amongst the thickest in the world representing pedogenic episodes in a semi-arid climate during Pliocene to Recent times. The descriptive morphological terminology of Netterberg is used to describe the calcrete types and a differentiation into simple and composite profiles is made. A pedogenic/diagenetic scheme has been constructed using all available data. Early calcite cementation is induced by two mechanisms. Slow evaporation and/or CO2 loss causes the precipitation of low-Mg calcite, whereas rapid evaporation and/or CO2 loss precipitates predominantly high-Mg calcite, in thermodynamic disequilibrium with the low Mg/Ca ratio vadose water, and minor aragonite (which transforms rapidly to low-Mg calcite). High-Mg calcite is also precipitated from high Mg/Ca ratio vadose waters in calcretes developed on Mg-rich host lithologies and by capillary rise from shallow groundwaters in saline depressions. Calcite precipitation may be passive (cement), displacive or replacive, in the latter released silica migrating down-profile to precipitate length-slow chalcedony, clinoptilolite (saline conditions), length-fast chalcedony and megaquartz (non-saline conditions). Displacive introduction of calcite takes place from highly supersaturated solutions due to rapid evaporation (with CO2 loss) of vadose waters. During low-Mg calcite precipitation (in a ‘closed’ system) the Mg concentration of the resulting solution increases. This, combined with Mg released during high-Mg to low-Mg calcite transformation, induces precipitation of authigenic palygorskite, sepiolite and minor dolomite. Vadose dolomite is often present whilst some dolomite may be precipitated at the mixing-zone of vadose and phreatic waters. The proposed model applies to the Kalahari calcretes, although it may perhaps be extrapolated to other areas. Further detailed studies, involving analyses of pore water chemistry, soil microclimate, and trace element and isotopic analyses of individual cements are necessary.

Notes: The Famennian-Tournaisian conglomerates and sandstones of the Ksiaz Formation are interpreted as marine resedimented deposits. Matrix- and clast-supported conglomerate beds are equally common, and two textural sequences (motifs) have been recognized: (I) matrix-rich conglomerate → pebbly sandstone → sandstone, and (II) clast-supported conglomerate → sandstone. Variation in clast type partly controls motif type, and therefore, to some extent, matrix percentage in the conglomerates generally. Grading is extremely common in both clast- and matrix-supported conglomerates: inverse (19%), inverse-to-normal (14%) and normal (26%). The studied succession, itself part of a 4 km thick, fan delta, basin-fill sequence, is organized into large (110–150 m) and small-scale (5–30 m) sequences, both of which show (1) upward coarsening and thickening, (2) upward trend of sandstones and pebbly sandstone → matrix-rich conglomerates → clast-supported conglomerates and (3) a less clear upward tendency of massive and normally graded beds → inversely graded beds. Variation in matrix percentage in beds is therefore also partly controlled by fan processes, during the progradation of fan bodies and lobes. It is predicted that individual resedimented conglomerate beds or motifs show general downfan trends in thickness, texture and structure opposite to those evident in the vertical sequences.

Notes: Fossil soils occur in the Reading Beds of Alum Bay. All soils have hydromorphic characteristics, caused by either groundwater or stagnating pluvial water; some have illuviation of clay. The combination of bioturbation (striated burrows) and iron segregation may indicate that the Reading Beds in Alum Bay are of fluviomarine origin. The soils were formed in a warm climate with a marked dry season. They indicate a landscape with minor variations in surface level. The Reading Beds have clay mineral assemblages that are partly inherited and partly changed by soil formation. Some soil horizons might be used for stratigraphic correlation.

Notes: The upper part of the Lower Cambrian succession in northeast Kangaroo Island comprises three interbedded facies associations. The fine-grained association is composed of siltstone, mudstone and minor sandstone. It contains flat lamination and abundant ripple cross-lamination which shows bipolar palaeocurrents, and occurs in combinations of flaser bedding, lenticular bedding and wavy lamination. Although body fossils are relatively rare, trilobite traces and desiccation cracks are common, and the association is interpreted as a predominantly subtidal to intertidal deposit. The conglomerate facies association contains horizontally bedded cobble to boulder conglomerate, with subordinate trough cross-stratified coarse sandstone to granule/pebble conglomerate. Fabrics and structures in the coarse conglomerates are consistent with alluvial transport (stream and debris flow), but not beach deposition. The conglomerate association is attributed to tectonic uplift and erosion of a Precambrian-Lower Cambrian succession developed adjacent to the present north coast of Kangaroo Island. Southward progradation of an alluvial fan complex occurred across east-west oriented tidal flats on which limited wave activity reworked sand and fine gravel, but not coarser material. The sandstone facies association mainly comprises trough cross-stratified and plane-laminated sandstone, the latter with current lineation predominantly sub-parallel to the east-west shoreline. Trough cross-stratification is ascribed to onshore waves and longshore currents, and current lineation to predominantly shore-parallel tidal currents, augmented by longshore drift and storm surge. Tectonic movements gave rise to cycles of transgression and regression as tidal and alluvial processes dominated alternately.

Notes: In his recent paper on surge mark formation and morphology, Bull (1978) has provided considerable new and interesting information on these peculiar features. Of particular note is his observation that the laminae within surge marks are continuous and not dissected as would be expected if the surge marks were erosional rills: the previously proposed mechanism of formation (High & Picard, 1968; Picard & High, 1973). Consequently, it becomes necessary to formulate an alternative explanation for surge mark origin, and Bull (1978, p. 885) offers the suggestion that: ‘Surge marks may be the result of selective depositional/erosional processes together with external deformation pressures.’

Notes: Theoretical work, laboratory studies, and field observations indicate that the oscillatory boundary layers generated by the tidal wave differ fundamentally in dynamics and kinematic structure from the unidirectional boundary layers of rivers. Unique to the former are mass-transport currents attributable to: (1) the wave motion itself, and (2) bed curvature in the presence of the oscillatory flow. The implication of this difference for bed-material transport is that the larger flow-transverse bedforms of shallow-water environments are divisible hydraulically between two major classes: (A) those related to tidal conditions, under which the fluid reverses in direction of flow with each reversal of the tide, permitting the initiation and maintenance of bed features by the spatially reversing, curvature-related mass transport, and (B) those related strictly to rivers and river-like flows, in which the fluid motion is unidirectional, and therefore the only mechanisms available for bedform initiation and maintenance are those creating a finite spatial lag between the transport rate and the bed waviness. Forms of Class B are best called dunes and bars, and only those attributable to Class A should be termed sand waves. The latter, restricted to oscillatory boundary layers of tidal origin, apparently correspond to the very much smaller; but also commonly symmetrical, ripple marks produced in wind-wave oscillatory boundary layers.

Notes: Relatively pure lacustrine carbonates referred to as marl are being deposited in Littlefield Lake, central Michigan, a hard-water lake with little terrigenous clastic influx. Thick accumulations of marl form both progradational marl benches along lake margins, and islands or lakemounts in the lake centre. Marl benches develop flat platforms up to 20 m wide in very shallow water and steeply inclined slopes, up to 30°, extending into deep water. The flat landward platform is frequently covered by algal pisoliths while the upper portion of the lakeward-sloping bottom is overgrown by Chara which in the summertime becomes thickly encrusted with low-magnesian calcite. Marl islands are flat-topped features that formed over relict highs on Pleistocene drift which underlies the lake basin. These are fringed by marl benches identical to those found along lake margins. Marl benches are composed of four units: two thin facies deposited on the shallow-water bench platform and two thicker faces deposited on the bench slope developed in moderate water depths. These in turn overlie a fifth facies deposited in deep water. A coarsening-upward sequence is developed in these sediments as a result of both mechanical sorting, and primary production of carbonate sand and gravel in shallow water. In addition to facies sequences and size grading, trends upsection of increasing carbonate content and decreasing insoluble content may serve to identify temperate-region lacustrine carbonate deposits in the rock record.

Notes: The pattern of empirical distributions, in particular size distributions, is often best brought out by drawing a log-histogram. The Gaussian or ‘normal’ distribution furnishes a description of the empirical distribution if the log-histogram approximates to a parabola. In many cases, however, the log-histogram is far from parabolic but may be closely approximated by a hyperbola. It is therefore natural to consider those theoretical probability distributions for which the graph of the log-probability (density) function is a hyperbola. The theory and applicability of such hyperbolic distributions have been the subject of a number of recent investigations and it is the purpose of the present paper to summarize these developments, with regard to the interest they may have to sedimentologists. A precise description of the hyperbolic distributions is given and their wide applicability is indicated. Methods for fitting these distributions to data are discussed and a number of sedimentological examples are presented. Furthermore, the question of finding dynamical explanations for the occurrence of the hyperbolic shape is considered from various points of view.

Notes: The flows above ripples of glass beads and ripple models have been visualized in an oscillatory water tunnel. Some ripples were observed to form without flow separation. Two types of vortices, the standing vortices without flow separation and the separation vortices have been observed, and their similarity is discussed.

Notes: Books review in this article: Sedimentary Environments and Facies, Ed. by H. G. ReadingA Color Illustrated Guide to Carbonate Rock Constituents, Textures, Cements, and Porosities, by Peter A. Scholle.A Color Illustrated Guide to Constituents, Textures, Cements, and Porosities of Sandstones and Associated Rocks by Peter A. Scholle.Cathodoluminescenceof Quartz and Its Application to Sandstone Petrology. Contributions to Sedimentology, No. 8, by U. Zinkernagel.

Notes: Turbidite muds in cores from the outer Scotian continental margin, off eastern Canada, contain abundant thin silt laminae. Graded laminated units are recognized in parts of this sequence. These represent single depositional events, and show a regular decrease in modal grain size and thickness of the silt laminae through the unit. A similar fining trend is shown by both silt and mud layers over hundreds of kilometres downslope. Textural analysis of individual laminae allows the construction of a dynamically consistent physical model for transport and sorting in muddy turbidity currents. Hydraulic sorting aggregates finer material to the top and tail regions of a large turbidity flow which then overspills its channel banks. Downslope lateral sorting occurs with preferential deposition of coarser silt grains and larger mud flocs. Depositional sorting by increased shear in the boundary layer separates clay flocs from silt grains and results in a regular mud/silt lamination. Estimates can be made of the physical parameters of the turbidity flows involved. They are a minimum of several hundreds of metres thick, have low concentrations (of the order of 10−3 or 2500 mg 1−1), and move downslope at velocities of 10-20 cm s−1. A 5 mm thick, coarse silt lamina takes about 10 h to deposit, and the subsequent mud layer ‘blankets’ very rapidly over this. A complete unit is deposited in 2-6 days which is the time it takes for the turbidity flow to pass a particular point. These thick, dilute, low-velocity flows are significantly different from the ‘classical’ turbidity current. However, there is mounting evidence in support of the new concept from laboratory observations and direct field measurements.

Notes: Geochemical and petrographic data suggest early submarine cementation of hardgrounds from the Lincolnshire Limestone Formation, Middle Jurassic, England. The three hardgrounds, from Cowthick, Castle Bytham and Leadenham quarries, developed in tidal-inlet, on-barrier and lagoonal sub-environments of a carbonate barrier-island complex. At Cowthick early composite (acicular-bladed) radial-fibrous cements, which pre-date aragonite dissolution, completely fill intergranular pore-space at the hardground surface; away from it isopachous fringing cements decrease in thickness. Microprobe analyses demonstrate zoning within the fringes with magnesium concentrations (〉 2 wt % MgCO3) higher than those in allochems or later, ferroan cement (≅0.5 wt % MgCO3, 1.7 wt % FeCO3). At Castle Bytham early granular isopachous cements, which post-date aragonite dissolution, occur within 5 cm of the surface. At Leadenham early lithification is superficial and represented by ferruginous crusts and micritic internal sediment. Late blocky cement fills residual pore-space in all three examples. Carbon and oxygen isotopic composition of whole-rock samples taken at intervals away from each hardground surface demonstrate the increasing proportion of late 18O depleted cements (δ18O – 8 to – 10). Early cements must have a marine isotopic composition; different δ18O values from each hardground reflect the intensity of early lithification and exclusion of late cements at the hardened surface. There is no isotopic evidence for subaerial cement precipitation during possible emergence at Castle Bytham. Oyster samples (with δ18O, – 2.9 and δ13C, 2.4) give estimated palaeotemperatures of 22–25°C. Early cements from Cowthick are enriched in 18O and 13C (δ18O = 0 δ13C ≅ 3‰) compared to the oyster values. In conjunction with trace element data this is interpreted as evidence for high-magnesium calcite precursor cements which underwent replacement in a system with a low water: rock ratio. The intensity of early lithification is related to depositional environment: maximum circulation of sea-water producing the most lithified hardground (Cowthick). This is directly analogous to the formation of Recent hardgrounds.

Notes: The degree of preferred orientation of clay minerals in a series of fifteen fine-grained sediments has been precisely measured by transmitted X-ray goniometry. This varies systematically with quartz content. By contrast it is apparently unrelated to fissility since the one fissile sample (a ‘paper shale’) occurs at the mid-point of the sample series ranked in order of degree of preferred orientation. In this series fissility corresponds with the presence of fine-scale lamination. Estimates of compaction strain using the theory of March (1932) and assuming random initial clay orientation are consistent with the view that these samples started life with porosities similar to those of present-day muddy sediments. On this basis it is concluded that preferred orientation in clay-rich sediments results almost entirely from compaction strain. The degree to which this can be attained is limited by the presence of nonplaty particles (such as quartz grains) which prevent planar fabric development in their immediate vicinity.

Notes: Calcrete profiles (caliche) have been recognized in the Eyam Limestone from the Lower Carboniferous in the area around Monyash, Derbyshire. They occur at the top of the flank facies surrounding carbonate-mud buildups (‘knoll reefs’). Four units make up the complete profile. These are from base to top: (1) grain-supported sediment with rhizocretions, (2) matrix-supported sediment with alveolar texture, (3) pelleted calcrete, (4) laminar calcrete. Commonly one or more units are missing from the profile. Calcretes indicate subaerial exposure. The carbonate buildups of the Eyam Limestone were completely exposed soon after deposition, requiring a fall in sea-level probably in excess of 10 m. This discovery demands a review of previous regional palaeoenvironmental studies.

Notes: Recent caliche, including nodules, pisolites, crusts, internal sediment, speleothem deposits, and spherulites, has formed within the dolomitic Cretaceous Edwards Formation of central Texas. As weathering altered the host strata, rhombic crystals of calcite were precipitated concomitantly with dissolution of the dolomite, thereby forming nodules. The highly altered dolomite (i.e. pulverulite) was then removed and spar, internal sediment, and travertine accumulated in the internodular voids. Nodular masses of calcite and dolomite are the most prominent constituent of the caliche. Some of the nodules have a well developed concentric structure as well as other characteristics similar to hypersaline pisolites. Features which appear to be useful in distinguishing caliche from hypersaline pisolites are: regional geological setting, association with other caliche and palaeosoil deposits, types of fossils present, and the presence of rhombic calcite and/or bladed sparry calcite with triangular shaped cross-section. A brick-like calcite texture and relict aragonite rays characterize hypersaline pisolites. Incipient neomorphism of the nodules and pisolites has resulted in the development of a radial pattern of spar within these structures. Geopetal deposits of internal sediment, including terra rossa soil, inhibited spar growth in the upward direction; consequently, spar is much better developed on the undersides of pisolites. Crusts and travertine flowstone (speleothem) deposits are intimately associated with the nodular masses and internal sediment. The brecciated thin crusts and travertine flowstone are end products of the same processes. The crusts formed during times of periodic desiccation of the growing surface while the flowstone formed when water was relatively abundant. Spherulitic bodies within the caliche, commonly 1–2 mm in diameter, display a radial texture and yet are composed of single crystals of calcite. The structures are the product of neomorphosed Microcodium or Microcodium-like globular bodies.

Notes: In the argillaceous sequence of Kimmeridge Clay a carbonate rich bed is composed of ferroan dolomite cement with varying amounts of excess CaCO3, and Fe2+ substitution in the Mg2+ sites. The isotopic and chemical compositions change symmetrically about the centre of the band proving that it grew by vertical accretion during diagenesis. Textural and isotopic evidence shows that growth centred on a horizon rich in primary carbonate which became dolomitized and assimilated during production of diagenetic carbonate. This accounts for the lateral extent of the concretion. Early central diagenetic carbonate was produced from organic matter by bacterial fermentation (δ13C =+0.59‰) and later marginal carbonate by abiotic breakdown, (δ13C tending towards — 2.73‰). δ18O values range from — 1.56 to — 4.46‰ because the dolomite precipitated during progressive burial. As burial increased, magnesium, whose dominant source was trapped seawater, became depleted while the relative availability of Fe2+, whose source was dominantly reduced detrital oxides, increased. Dolomitization and the source of diagenetic components for dolomite formation are discussed. Diffusion and pore fluid migration transported ions to the site of precipitation. Early cementation of the band served to influence pore fluid migration, but thereafter pore fluid migration controlled carbonate precipitation.

Notes: Sedimentary chert breccias are the product of two stages of silicification: one which produced ‘fragments’, the other, during which the ‘matrix’ crystallized. Fragments and matrix of twenty-five breccias from the Senonian Mishash Formation in Southern Israel were separated and analysed for δ18O in quartz. The matrix is significantly depleted in 18O in comparison with fragments (δ18O of fragments ranges between +29.4 and +34.7‰, for matrix the range is +21.1–32.6‰). Boron has been mapped in the same rocks using the 10B(n, α)7Li reaction and α-track etching. Fragments are significantly enriched in boron in comparison to the matrix. The correspondence between boron maps and rock texture is perfect.These results when combined with Steinitz's (1977) report of evaporites and evaporite ghosts in the same rocks are interpreted as indicating two different environments of chert diagenesis: a first, normal marine to hypersaline stage during which the microquartz in fragments crystallized, and a second stage of matrix chertification which in most cases occurred when fresh water was interacting with the crystallizing sediment. These conclusions are corroborated by isotopic analysis of carbonates which coexist with the cherts, as well as stratigraphical and palaeontological analysis.

Notes: An attempt was made to distinguish aspects of the shape of rock particles, and to discover by analysis and empirical considerations the most appropriate parameters for describing these aspects. The shape of a rock particle can be expressed in terms of three independent properties: form (overall shape), roundness (large-scale smoothness) and surface texture. These form a three-tiered hierarchy of observational scale, and of response to geological processes. Form can be represented by only two independent measures from the three orthogonal axes normally measured. Of the four pairs of independent measures commonly used for bivariate plots, the two sphericity/shape factor pairs appear to be more efficient discriminators than simple axial ratios. Of the two, the most desirable pair is the maximum projection sphericity and oblate-prolate index for both measures show an arithmetic normal distribution for the range investigated. A measure of form that is independent of the three orthogonal axes, and measures derived from them, is the angularity measure of Lees. Roundness has measures of three types, those estimating average roundness of corners, those based on the sharpest corner, and a measure of convexity in the particle outline. Although each type measures a different aspect, they are not independent of each other. Only roundness from corners is considered in detail. As neither average nor sharpest corner measures are inherently more objective or more quantitative, purpose should determine which is more appropriate. Of the visual comparison charts for average roundness, Krumbein's appears best. The Modified Wentworth roundness is the most satisfactory for estimating roundness from the sharpest corner. The Cailleux Roundness index should not be used because it includes aspects of roundness and form. Shape is a difficult parameter to use for solving sedimentological problems. Even the best of the commonly used procedures are limited by observational subjectivity and a low discriminating power. Unambiguous interpretation of particle shape in terms of source material and processes will always be made difficult by the large number of natural variables and their interactions. For ancient sediments satisfactory results can be expected only from carefully planned studies or rather unusual geological situations.

Notes: Abundant wave ripples with wavelengths of up to 0.3 m, top-surface granule lags and tabular sand-stone beds suggest that the interbedded sandstones and siltstones of the Skaergårdnes Formation are shallow marine deposits. A simple orthogonal relationship between crestal trends of wave ripples and trough axes/cross-bed dip directions indicates that bottom currents and surface waves were closely related, suggesting that wind-drift currents were responsible for deposition. Interbedding of the tabular sandstones with siltstone is more probably due to the patchy nature of sand cover on the sea floor than to episodic sand derivation from the coast. The top-surface granule lags indicate local, temporary excess of sand removal over supply, and were probably formed by both wave-winnowing and non-depositional megaripple migration. The well developed lags in this and similar ancient sediments suggest that winnowing, leading to bed armouring and sediment bypassing may be an important shallow marine process.

Notes: Diagenetic transformation of clay minerals, zeolites and silica minerals in Cretaceous and Tertiary argillaceous rocks from deeply drilled wells in Japan were studied. Transformations of these minerals during diagenesis were as follows: in clay minerals, montmorillonite → montmorillonite-illite mixed-layer mineral → illite; in zeolites, volcanic glass → clinoptilolite → heulandite and/or analcite → laumontite and/or albite; in silica minerals, amorphous silica → low-cristobalite → low-quartz. Maximum overburden pressures and geothermal temperatures corresponding to these transformations in each well studied were calculated. For clay minerals, a pressure of approximately 900 kg cm−2 and a temperature of about 100°C are necessary for the transformation from montmorillonite to mixed-layer mineral and 920 kg cm−2 and 140°C for mixed-layer mineral to illite. Transformation from kaolinite to other minerals requires much higher pressures and temperatures than from montmorillonite to mixed-layer mineral. For zeolites, 330 kg cm−2 and 60°C are required for the transformation from volcanic glass to clinoptilolite, 860 kg cm−2 and 120°C for clinoptilolite to heulandite and/or analcite, and 930 kg cm−2 and 140°C for heulandite and/or analcite to laumontite and/or albite. For silica minerals, 250 kg cm−2 and 50°C are necessary for the transformation from amorphous silica to low-cristobalite and 660 kg cm−2 and 70°C for low-cristobalite to low-quartz. Based on these diagenetic mineral transformations, seven mineral zones are recognized in argillaceous sediments. On the other hand, from the porosity studies of argillaceous sediments in Japan, the process of diagenesis is classified into the following three stages. The early compaction stage is marked by shallow burial and viscous rocks with more than 30% porosity. The late compaction stage is characterized by intermediate burial and plastic rocks with 30-10% porosities. The transformation stage is marked by deep burial and elastic rocks with less than 10% porosity.

Notes: Some important papers have apparently gone unnoticed by most sedimentologists, as shown by their absence from bibliographies of recent texts. These papers concern sample size, permissible number of splits, sieving time, and sieve-vs-settling tube comparisons. These papers were published where sedimentologists would not ordinarily see them, but should be required reading for students.

Notes: A numerical model is presented that solves the partial differential equations describing the motion of salt water and fresh water separated by a sharp interface. The areal equations are based on the Dupuit approximation and are obtained from partial integration over the vertical dimension. Finite-difference techniques are applied and the utility of several solution schemes is tested. The most efficient and accurate solution scheme uses block line-successive over-relaxation. Examples are given to: (1) test the model, (2) evaluate the Dupuit approximation, and (3) demonstrate the application to a field situation. The results show that the model is in good agreement with an analytical solution, but under severe conditions the Dupuit approximation may be inappropriate. The model is applied to a field area near Kahului, Maui, Hawaii and results extend the analysis of the problem beyond previous efforts.

Notes: Ground-water discharge was found to be the primary cause of flood peaks generated at two small wetland controlled basins in eastern Massachusetts. Within the wetlands, ground water rose rapidly following precipitation and in near synchronization with stream levels indicating a close coupling between ground water and the stream. Stream hydrographs were separated into baseflow and surface runoff by a dynamic technique which matches the hydrograph of an index well with the stream hydrograph to determine the moment of maximum ground-water discharge. Hydrograph analysis showed that for both wetlands ground water was the major component of all flood peaks and accounted for approximately 93% of the total annual discharge.

Notes: There are many geological situations where moving ground water transfers a significant amount of heat. Yet, while convective heat transfer is a common phenomenon, it is very difficult to treat analytically. In this paper we present a simple model of convective heat transfer in porous materials and a numerical method of solving the model. The model is then applied to three diverse field situations: (1) a thermal anomaly on the Hartville uplift in eastern Wyoming; (2) a fault-controlled hydrothermal system near Monroe, Utah; and (3) the Luanshya copper mine in the Republic of Zambia. In each case heat transfer by moving ground water is shown to explain the observed thermal anomalies satisfactorily. Our results indicate that in certain situations the effect of ground-water flow needs to be considered in making local and regional assessments of heat-flow data. Furthermore, temperature measurements can be very useful in estimating aquifer recharge, particularly when thermal conductivity and structural information are available.

Notes: A major potential failure mode of thermoplastic well casing is collapse. The casing may be subjected to a collapsing pressure during grouting operations, backfilling, well development or simply from lateral soil pressure. Since the strength of thermoplastic materials significantly decreases at elevated temperatures, it is important to know how casing collapse resistance varies with temperature.A series of experiments have been performed to determine the collapse resistance of poly (vinyl chloride) (PVC) and acrilonitrile-butadiene-styrene (ABS) well casing over a wide range of temperature. Results indicate that collapse resistance is inversely proportional to a function of the outside diameter-to-wall thickness ratio as indicated in the ASTM F480 standard and that collapse resistance decreases by approximately ½ psi per degree Fahrenheit increase in temperature above room temperature.

Notes: Monitoring the chemistry of ground water near in-situ uranium leach mines is complicated by chemical variations unrelated to the mining operation that result from (1) spatial differences in the aquifer environment, and hence, in the water chemistry, (2) inconsistent or inadequate sampling procedures, and (3) errors in chemical analyses. Differences in the chemistry of water from place to place in the aquifer should be identified in pre-mining baseline studies and must be taken into account during monitoring of the leaching operation, because natural waters of chemistry different from that established at a particular well during the baseline sampling period may be drawn into the monitoring well by pumping. The most important factor in developing proper sampling techniques is the configuration of the well and pumping equipment; if the pump intake is set near the point where water enters the well, and if the pumping rate is kept low to reduce turbulent mixing of waters in the well, it is not necessary to pump a full well-bore volume before collecting a sample. Errors in chemical data can be eliminated by proper storage and handling of the samples and by careful checking of the analyses for chemical balance and eliminating the analyses that do not balance properly. Interpretation of the chemical data should be made only after assuring that these monitoring problems have been taken into account.

Notes: Abstract. Microcomputers can be a major tool for the hydrologist. Small and portable, microcomputers can be useful for the acquisition and modeling of an aquifer while on site. This would result in very low cost for computer usage and fast processing time. Their low cost makes the availability almost universal. Tests were run on the TRS-80 system using the Prickett finite difference model and the Theis equation. The results indicate that with the exception of memory storage no problems should arise. With newer generations of microcomputers core memory storage will no longer be a problem.

Notes: Polynomial approximations have been developed for the infinite series embodied in the Theis equation. These have the following advantages when programmed for use on computers or hand calculators: (1) they are easy to program; (2) they are computationally efficient; and (3) they eliminate round-off errors.

Notes: The Fort Payne Formation of Early Mississippian (Osagean) age crops out over extensive areas of central Tennessee, south-central Kentucky, and northern Alabama. Specific formation lithologies are known to have been modified locally through weathering into an artesian aquifer along the Eastern Highland Rim of central Tennessee. The shallow aquifer can be divided into two parts; uppermost is a highly permeable chert gravel zone that is in hydraulic communication with a lower zone of interconnected solution cavities within bedrock. The gravel, at depths as great as 24.4 m (80 ft), fines upward into the clay-sized chert of the upper confining bed. The lower confining bed is the Chattanooga Shale of Late Devonian to Early Mississippian age.Field and petrographic studies of the Fort Payne Formation indicate that the aquifer has developed near the base of the unit. The chert gravel portion of the aquifer has developed from silicified dolowackestones of the Beaver Creek Limestone Member and from interbedded Fort Payne dolostones. The lower portion of the aquifer occurs within preferentially weathered, silicified and non-silicified dolosiltstone.

Notes: The assumptions inherent in the theoretical analysis of constant drawdown overflow tests are difficult to achieve in practice. This paper shows that, even if there is a restriction in the flow which causes some delay in the achievement of the constant drawdown condition, the theoretical discharge curve is followed once the constant drawdown condition is reached. Recovery tests following overflow are also examined and it is shown that the discharge used in the calculation should be the discharge at the instant that the test is stopped. Further, it is demonstrated that if well and formation losses occur, the aquifer response is distinctly different from that of the theoretical analysis.A brief description is given of an alternative method of analysis using a numerical model. A preliminary study of a field test yields promising results.

Notes: The low organic concentration and high specific surface area that characterize ground-water recharge environments allow biofilms to predominate microbial kinetics. Consideration of the kinetics of substrate utilization and growth of biofilms indicates that microbiological activity occurs very near the injection well. The aggregate substrate expressed, for example, as chemical oxygen demand, can be considered the primary substrate; the biofilm's growth is supported through the utilization of the aggregate primary substrate. Individual trace organic compounds, none of which could support biofilm growth alone, are utilized as secondary substrates. Although biodegradable, secondary substrates that have slow utilization kinetics will pass through the biologically active zone undegraded. Field data from the ground-water recharge project in Palo Alto, California, illustrate that naphthalene and heptaldehyde are biodegraded, while other compounds, such as chloroform and chlorobenzene, pass through the biologically active zone without biodegradation.

Notes: Ground-water chemical quality in alluvial valleys can be stratified, which can cause well-water quality to vary with pumping time, especially after a pump shutdown of several hours. These changes in chemical quality could have public health implications for automatically controlled high-capacity municipal water wells that pump directly into the distribution mains.For a large number of municipal wells, the shapes of the curves for the change-in-specific electrical conductivity and the NO3-N content of well water during the first 96 minutes of constant rate pumping are reported after a 24-hour shutdown as compared with “steady-state” quality. The variables recovery-transmissivity, well specific capacity, type of well construction, and equivalent specific yield of aquifer computed from driller's logs of the bore holes were considered in the analysis.The results showed that well-water quality vs. time curves vary in shape and are related mainly to the well depth and the depth to the perforations. The “steady-state” specific electrical conductivity and NO3-N values were significantly correlated to each other and inversely to recovery-transmissivity and equivalent specific yield. The specific capacity of wells was related to the recovery-transmissivity and to type of well construction.

Notes: Step-testing of wells penetrating a jointed, fractured, sometimes cavernous limestone-dolomite artesian aquifer showed characteristic patterns of extreme variation in specific capacity at different discharge rates. The application of principles developed by Jacob for well-loss determinations, and subsequent modifications by others, did not yield meaningful results. It was found that a log-log relationship between discharge and drawdown, through a large number of steps, could be used to evaluate the degree of nonlinear head losses in and near the well bore and make possible the extrapolation of drawdowns at higher discharge rates. This technique also has been used to estimate transmissivity which, in at least one instance, was confirmed by the subsequent evaluation of observation-well data by both straight-line and type-curve methods. The easy use and rapid initial evaluation of test data afforded by this method gave rise to the name “Cheat Sheet.”

Notes: An investigation of waste-migration patterns from a septic system indicates that complex patterns result from minor variations in regolith adsorptive capacity and texture, local hydrology, and possibly soil microbiology. The existence of multichemical, bifurcating plumes suggest that monitor wells arranged up and downgradient and capable of multilevel sampling are essential to adequately delineate contaminant migration in ground water. The data also indicate that sampling for a single constituent could yield misleading information about the nature and distribution of other ground-water contaminants. The ability for chemical removal by the regolith is in direct response to minor variations in silt- and clay-sized particle content and corresponds to Langmuir adsorption isotherms. Silt- and clay-sized particles are dominantly organic in origin. Minor iron and aluminum hydroxyoxides and clays are present.Substrate samples, when collected at regular intervals and analyzed for adsorbed constituents and textural variability, provide an integrated picture of the distribution of waste chemicals through time. Such samples also provide insight into the mechanics of plume configuration and flow characteristics within the regolith. The study shows that regolith adsorption data are essential to the determination of life expectancy of the regolith as a contaminant treatment system.

Notes: A comparison of the concentrations of nitrate in three public supply borehole sources which abstract water from the Chalk in a relatively local area, led to a more detailed study of the possible causes of high nitrate values at one of the sources and the geological and recharge characteristics of all three.The local catchment area of the high nitrate source is actively fertilized, both by sludge spreading and the application of artificial fertilizers. The catchment areas of the other two ground-water sources are not subject to the same intensive agricultural activity. It is suggested the differences in water quality between the three supplies are related to the variations in land use and the local hydrogeology.The study makes it clear that due to local influences each source may have a unique hydrogeochemical character irrespective of being located in the same regional geological catchment area.More detailed investigations on the origins of the nitrate in the abstracted ground waters are planned as a follow-up to this initial study.

Notes: Tracers are used widely to determine the direction and velocity of ground-water movement. Failures of tracer tests are most commonly a result of incorrect choice of tracers, insufficient concentrations of tracers, and a lack of an understanding of the hydrogeologic system being tested. Some of the most useful general tracers are bromide chloride, rhodamine WT, and various fluorocarbons. For certain purposes, dyed clubmoss and baker's yeast have proved valuable. Many radionuclides including 3H, 82Br, and 198Au are almost ideal for numerous purposes, but radiation hazards associated with their use together with local, State, and Federal regulations have discouraged widespread field applications in recent years within the United States.

Notes: Varve-like parallel laminated and homogeneous muds on natural levees of submarine channels result from the spill-over of the dilute upper parts of channelized turbidity currents. On the levees of the Northwest Atlantic Mid-Ocean Channel, Labrador Sea, laminated turbidite muds show a systematic upward thickness variation of the granular silt laminae and the clay laminae. In many depositional units the former decrease logarithmically upwards in thickness while the latter increase logarithmically. The origin of parallel lamination in current-deposited, fine-grained sediments is interpreted in terms of the ‘burst-and-sweep model’ for the viscous sublayer of turbulent flows. Individual silt laminae of laminated turbidite muds form due to shear sorting during burst-and-sweep events which have a winnowing effect on the clay fraction. In contrast to sand-transporting flows the viscous sublayer of silt- and clay-carrying dilute turbidity currents cannot be permanently in a turbulent state. The presence of clay laminae suggests that the boundary layer relaminarizes periodically. It is speculated that this is caused by pressure waves with negative pressure gradients favouring the suppression of bursts and sweeps. The observed vertical thickness variations suggest that the periods of laminar boundary-layer flow increase in duration as turbulence of the main current decays. The upward thickness decrease of the silt laminae is explained in terms of decreasing supply rates to the boundary layer from the main flow. A multiple bursting-cycle mechanism is favored over a single bursting cycle mechanism for the formation of individual silt laminae by shear sorting.

Notes: Sandyhaven Pill is a ‘drowned valley’ type of estuary. Thus the deposits differ from most other described estuarine deposits which are of ‘tidally influenced river’ type. The surface sediments may be divided broadly into wave-dominated deposits (22% of area), tide-dominated deposits (65%), deposits related to marginal cliff collapse (12%) and river-dominated deposits (1%). Further subdivision shows that the subenvironments are nested in a progression up the estuary with trends to finer sediment size, reduced sorting and increased biogenic activity. The latter relates to a marine to estuarine faunal change and a strong relationship between the distributions of biota and depositional subenvironments. Over a 29 day period, reduction in wave height was reflected in wave-dominated areas by shoreward movement of some subenvironment boundaries and by improved definition of symmetrical ripples. The tidal cycle had only a limited effect on the tide-dominated sediments. The most reliable indicators of estuary trend are channels and asymmetrical ripples; but coring shows that ripples and other minor structures are rarely preserved. Heavy mineral analysis indicates that most of the estuarine sand came from offshore. Gradual sediment build-up will result in a regressive sequence. If this were preserved under a later transgression, the resultant deposit would be an elongate sediment body bounded laterally by a coarse marginal facies. The sediment sequence would be inward and upward fining with diachronous facies boundaries sloping upwards towards the offshore end and towards the axis of the body.

Notes: The calcite fossils of the Derbyhaven Beds, Isle of Man, have δ13C values (+ 1·8 PDB) similar to modern, shallow-water marine skeletons, but the δ18O values (−6·1 PDB) are much lighter than modern skeletons. The light oxygen values indicate either re-equilibration with isotopically light water before cementation started, or Carboniferous sea water with δ18O of −6‰. Aragonite dissolution was followed by precipitation of zoned calcite cement. In this cement, up to six intracrystalline zones, recognized in stained thin sections, show isotopic variation. Carbon varies from + 3-8 to + 1-2‰. and oxygen from − 2-6 to − 12-4‰. with decreasing age of the cement. This trend is attributed to increasing temperature and to isotopic evolution of the pore waters during burial. The zoned calcite is sequentially followed by dolomite and kaolinite cements which continue the trend towards light isotopic values. This trend is continued with younger, fault-controlled dolomite, and is terminated by vein-filling calcite and dolomite. The younger calcite, interpreted as a near-surface precipitate from meteoric waters, is unrelated to the older sequence of carbonates and has distinctly different carbon isotope ratios: δ13C − 6-8‰.

Notes: Rare earth element (REE) distributions and 87Sr/86Sr ratios were determined for nodule crusts and associated surface sediments collected in the southeastern Pacific Ocean between South America and the Tuamotu archipelago. The shale-normalized patterns of the REE from the surface sediments show pronounced negative anomalies in Ce which indicate a marine origin. One 87Sr/86Sr ratio also has a value characteristic for seawater strontium. REE patterns from the nodule crusts, when normalized to shales, seawater or associated surface sediment, show that a marine origin can also be proposed for the oxy-hydroxides. Only the Ce shows a systematic scatter, which could be the result of fluctuations in the oxidation-reduction conditions during nodule growth. The marine origin for REE is corroborated by the 87Sr/86Sr ratios which average 0 · 70905 ± 0 · 00019 (2σ), a value close to the seawater 87Sr/86Sr ratio of 0·70910 ± 0 · 00035. If the major metals of the polymetallic nodules have the same origin as these trace elements, then a direct precipitation from seawater can be postulated for the crusts studied here.

Notes: The Lower Sandfjord Formation is a 1.5 km thick late Precambrian sandstone. It is a remarkably homogeneous unit consisting largely (98%) of cross-bedded, texturally and mineralogically mature, coarse or medium sandstone, and is interpreted as a shallow marine deposit. This interpretation is based on the maturity, the exclusively tabular bed geometry, occasional sets of herring-bone cross-bedding and most importantly, the abundance of sheet-like pebble layers only 1–5 grain diameters thick and sometimes overlain by thin siltstone drapes. Various different types of compound cross-bedding, all of which show evidence of reversing currents, are interpreted as sub-tidal sandwaves. These sets range in thickness from 0.5 to 14 m, and in conjunction with the overall abundance of cross-bedding probably indicate strong tidal currents. A tide-dominated current regime is also considered essential to explain the derivation of such large quantities of sand from the contemporary coasts. It is suggested that sand transport offshore took place during the erosional transgression of abandoned delta lobes. However, the predominance of a single, easterly, mode in the palaeocurrent patterns suggests that the tidal currents were reinforced by some other current system. The predominantly unimodal palaeocurrent patterns and the coarse, sand-rich nature of the succession, taken together with the thickness do not superficially seem likely characteristics for a shallow marine sequence. Nevertheless this study appears to demonstrate that such deposits were formed on tidal shelves in at least late Precambrian time.

Notes: The rain-induced resuspension of bottom sediment in shallow water is measured in a simple laboratory experiment, and found to increase significantly with increasing drop size and rain intensity, and decreasing water depth.

Notes: Thick turbidites accumulated along the northern margin of the Iapetus Ocean in Britain from mid-Ordovician to late Silurian times. Recent plate tectonic reconstructions hold that, during subduction, packets of these sediments, together with the underlying pelagic facies and thin portions of the uppermost ocean crust, were stripped from the descending plate and accreted to the inner trench wall on the Laurentian (North American) continental margin. The resulting accretionary prism is represented today by the Ordovician and Silurian rocks of the Southern Uplands of Scotland and the Longford-Down massif of Ireland. In these areas major reverse faults separate tracts of steeply dipping greywackes and mudstones with minor amounts of cherts and basalts. These tracts are up to several kilometres wide; their constituent beds face predominantly to the northwest, away from the site of the ancient ocean, while becoming progressively younger in each major fault slice towards the Iapetus suture in the southeast. From the stratigraphic sequences in these fault slices the sedimentary history of a portion of the Iapetus Ocean, and the British sector of its northern margin, can be reconstructed. In the Southern Uplands the earliest turbidites (mid- and late-Ordovician) are preserved in the northernmost fault slices. Regional facies trends, and vertical facies analysis, suggest that they accumulated in a trench dominated by a series of relatively small lower trench slope-derived fans. Pelagic sediments of the same age are found in the fault slices to the south, suggesting that the Ordovician turbidites were confined to the trench. During the lower and middle Llandovery, volcaniclastic trench turbidites were separated from quartz-rich ocean-floor turbidites (represented in the southern fault slices) by an elongate rise, on which pelagic deposits accumulated. This is interpreted as the outer trench high. In late Llandovery times the rise was overwhelmed, and thick laterally derived quartzose turbidites blanketed both the trench and the ocean floor. Sedimentation was strongly influenced by the evolution of the accretionary prism. By Llandovery times a trench slope break had emerged, supplying sediment both south to the trench and north to an upper slope basin in the Midland Valley of Scotland. In this basin early Silurian turbidites were followed by shallow-water and terrestrial sediments. Most of the sediment was derived from the emergent trench slope break: the volcanic arc and the Grampian orogenic belt to the north provided little or no detritus. Throughout the Ordovician and Silurian, sediment in the trench and on the ocean floor was derived from the volcanic arc, from the lower trench slope/trench slope break, from a degrading plutonic/metamorphic terrain (the Grampian Orogen), and locally by a minor amount of submarine sliding from carbonate-capped volcanic seamounts. Progressive elevation of the trench slope break in Silurian (and perhaps late Ordovician) times indicates that sediment from the arc-orogen hinterland must have bypassed the upper slope in the unexposed section of the margin to the northeast of the Southern Uplands, and travelled into the area axially along the trench floor.

Notes: This paper gives a modification of Burger's method of approximation for the moments of grain-size data. It is shown that formal integration can be carried out in conjunction with Burger's phi-normal interpolation scheme. This approach obviates Burger's recourse to a discrete numerical integration procedure because exact integration yields a computationally more efficient approximation formula for the moments.

Notes: The relation between the crystallography of artificially abraded quartz sand grains and aeolian surface textures has been studied using an X-ray precession camera and the scanning electron microscope (SEM). Crushed Brazilian quartz was sieved to between 250 and 350 μm, eroded in a paddle wheel device which simulated aeolian action at 8 m s−1 for 3 h, and photographed with the SEM. A typical grain was selected and over 1100 photographs were combined to create a 3 × 3 m photomosaic; because of the large size, it was possible to observe and measure the angular and linear relations between the various features. After the c axis direction in the grain was determined by precession X-ray analysis, the most important aeolian features were related to the crystallography of quartz. The upturned plates or cleavage plates probably represent traces parallel to r(10Ī1) and z(01Ī1) cleavages in quartz. Blocky areas appear to be an expression of a cleavage parallel to m(10Ī0). In addition, plate spacing on thirty-five experimental, modern, and ancient quartz sand grains is fairly constant. Assuming that abrasion in most sedimentary environments acts in the same manner with respect to quartz crystallography, much of the fine silt and clay in sediments and sedimentary rocks may be the result of cleavage following abrasion parallel to the r and z cleavage planes, while the less common blocky particles are probably the result of cleavage parallel to the m planes.

Notes: Eighteen stratigraphic sections, 200 m thick on average, were logged in basin plain deposits of the Marnoso-arenacea Formation (Miocene, northern Apennines) over an area of 123 × 27 km. Turbidites form 80–90% of the facies association, hemipelagites the remainder. Thin and thick-bedded turbidites are separated by an approximate statistical boundary at 40 cm; most prominent beds (〉 1 m thick) are qualified as megaturbidites. With reference to the main supply-dispersal system (NW to SE), the basin plain can be axially subdivided into proximal, intermediate and distal segments by means of the following parameters: bulk sand content, sand/shale ratio in turbidites, mean thickness of individual layers and component beds, and frequency of thick layers. Almost 40% of thick-bedded turbidites can be traced over the whole study area. These basin-wide deposits form the bulk of the basin fill. Geometrical reconstruction shows that some sandstone beds taper downcurrent from the proximal plain or the adjacent fan area while others thin upcurrent suggesting sand by pass of the fan. Mudstone beds in general thicken towards the end and the margins of the plain indicating that turbidite mud, besides bypassing the fan as a rule, was affected by ponding in the plain. Thin-bedded turbidites have a low sand/shale ratio or are completely muddy representing either tails of sandier turbidites of the outer fan (lobe and fringe deposits) or sheets extending to a great part of or to the whole plain. Sandstone lobes advanced from fans into the plain for 40–50 km gradually thinning and shaling out over a transitional zone of 10–20 km. Their internal geometry shows simple and complex growth patterns: end members are defined as progradational and aggradational. Estimates of original length, width and volume of individual turbidites strongly suggest that flows were usually confined and deflected by basin slopes regardless of source location. Basinal deposits are thus characterized by great thickness and volume, abundance of mud and fine sand, extremely low lateral gradients of thickness and grain size (but rapid wedging near the sides). The basin plain developed as a part of an elongated, oversupplied basin with a ‘highly efficient’, probably delta-fed, dispersal system.

Notes: Thin sections and scanning electron microscopy of quartz sand grains from till show clearly that a number of grains have been modified in place. The irregular grains result from the action of circulating alkaline groundwater, episodically concentrated by evaporation on fracture surfaces within grains and on concave surfaces produced by fracture during glacial transport. Evaporation increases the pH of the pore water and localizes its effect in small pores with a high capillary potential. Subsequent dilution by rainwater or snow meltwater flushes the system so that evaporation can repeat the process again. Solution rounding in terrigenous sediments has a number of ramifications for any interpretation based on textural maturity of the sediment.

Notes: Books review in this article: Moraines and Varves. Origin/Genesis/Classification, Ed. by Ch. Schlüchter. A. A. Balkema Growth Conditions of Manganese Nodules, by D. Heye. Surficial Sediments of the English Channel (Map), by the Bureau de Recherches The Global Carbon Cycle. Report No. 13 of the Scientific Committee on Problems of the Environment (SCOPE), Ed. by B. Bolin, E. T. Degens, P. Ketner & S. Kempe. Modelling of Rivers, Ed. by Hsieh Wen Shen Petroleum Geochemistry and Geology, by John M. The Chemistry of Soil Constituents, Ed. D. J. Greenland and M. H. B. Hayes. The Study of Carbonaceous Substances in Geological Formations (‘Contribution A 1'Etude de I'Evolution des substances carbonCes dans les formations g6o- logiques‘), Documents du B.R.G.M. No. 6, By Jean- Paul Ragot. The Ocean Basins and Margins, Vol. 4B: The Western Mediterrmean, Ed. by A. E. M. Nairn, W. H. Kanes & F. G. Stehli. Journal of Structural Geology, Vol. I, No. 1. Inkohlung und Geothermik. Beziehungen zwischen Inkohlung, Illit-Diagenese, Kohlenwasserstoff- Fiihrung und Geothermik. (Coalification and Geothermics. Relationship Between Coalification, Illite Crystallinity, Hydro- carbon Content and Geothermics.) A special issue of the periodical Fortschritte in der Geologie volt Rheinland und Westfalen, Vol. 27, Geologisches Landesamt

Notes: Dolomitization in member 1 of the Dalradian Bonahaven Formation of Islay was sequential. The sediments studied are siliciclastic tidal flat deposits, which originally contained pebbles of ferroan dolomicrite and sandy dolomicrite (type 1 dolomite). Following burial, both dolomicrite and clay-stone pebbles, and possibly other carbonates, were replaced by coarser, fluid-inclusion-bearing, chemically zoned (type 2) dolomite. Ferroan, inclusion-free, intergranular dolomite (type 3) in sandstones may be synchronous with late zones of type 2 dolomite which it closely resembles. Cathodoluminescence and microprobe analyses of type 2 dolomite characterize four ubiquitous growth stages within which there was considerable fluctuation in Fe and Mn content. There was much variation between and within samples in terms of timing of nucleation, absolute speed of growth and relative growth rate of crystals. Type 2 dolomite displays two types of intracrystalline truncation surfaces explicable by dissolution followed by overgrowth, or by replacement by a moving solution film. Type A is characterized by a single later zone cutting across earlier ones along the line of an irregular truncation surface which developed from the edges of the crystals. In type B truncations it is the interior, rather than the edges of crystals which show truncation, the truncations forming smooth closed surfaces which enclose areas filled centripetally with new zones. In general, dolomite has a pronounced tendency to form crystal faces, and thus compromise crystal boundaries, during replacement as well as during cementation. Thus, if nucleation of crystals is restricted to the margins of an area to be replaced, replacive dolomite is capable of completely mimicking a vug-filling texture.

Notes: Fossil surfaces of erosion and non-deposition are common in limestone sequences from the Mesozoic in western Europe and in the Tethys and have been described under the name ‘hardgrounds’. They are of shallow water as well as of oceanic origin. A modern example in the Pacific is described in this paper. The Carnegie Ridge, an east-west trending shallow ridge between South America and the Galapagos Islands, has a central, deeper saddle where erosion has removed most of the sediment cover down to a hard chalk and chert bed (acoustic basement), and has cut intricate channel patterns on the south flank and two deep canyons on the north. The erosion has produced a karst-like relief of steep-walled channels, cliffs, and corroded chalk remnants. The floors of the channels are covered with ferromanganese oxide crusts or crust fragments over which loose sediment is being transported. In the two canyons on the north flank, this sediment consists of foraminiferal sand travelling downslope in the form of barchan dunes. All sediment down to acoustic basement has been stripped from the Carnegie Ridge crest except where it is protected behind basement ridges and pinnacles. Surface features of the eroded chalk are strongly reminiscent of features observed in Mesozoic hardgrounds. Current measurements over several days indicate a net northward movement, slow but possibly adequate to keep the sea floor free of fresh deposits. The rates, however, seem inadequate to explain the formation of the deep channels, and there is no evidence for the southward flow which is implied by the southern channel system. A process of combined carbonate dissolution and removal by the current of fresh sediment and dissolution residues can account for the required erosion in about two million years. Regional unconformities identifiable in seismic reflection profiles and dated in cores are of middle to late Pliocene age, suggesting that the formation of the erosion surface began 2-3 million years ago. Buried Miocene unconformities of local extent show that the present erosion period had minor precursors possibly related to short-lived increases in current action and carbonate dissolution.

Notes: Pellets and ooids are widespread and locally abundant in mature calcrete profiles in the Argus Range, California; near Wickieup, Arizona; and in Kyle Canyon, Nevada. Most concentrations of pellets and ooids either overlie laminar calcrete at various levels in the calcrete profile or fill subhorizontal fractures in the petrocalcic horizon. In all three profiles the petrocalcic horizon has been thickened by the pelletal, chemically deposited fracture fillings. Pellets range from 0.02 to 8.0 mm in diameter and consist principally of micritic calcite and sepiolite. Ooid coatings are chiefly calcite and opal or calcite and sepiolite. The pellets represent small concretions, some of which grew by accretion, either in void space or by displacing adjacent sediment, and the others of which were formed by cementation of pellet-shaped bodies of porous micrite. Ooid coatings with opal or sepiolite may have been deposited as a gel with sufficient strength for surface tension to thin the coatings over angular corners of nuclei so as to increase the roundness and sphericity of the particles. Major problems in calcrete genesis are (1) the cause of subhorizontal fractures and the mechanism for widening a fracture as sediment accumulates in it and (2) what determines the deposition of calcite, sepiolite, and opal as pellets and ooid coatings or as laminar layers.

Notes: Most of the Quaternary sediments of the Mozambique Fan have been derived from Africa-Madagascar and deposited by turbidity currents in Pleistocene time. Currents caused by movement of the Antarctic Bottom Water also played a significant role in reworking and redepositing sediments along the marginal areas of the fan. The inner or upper Mozambique Fan is characterized by a single, leveed valley. Due to the effects of the Coriolis force, the natural levees to the east of the valley (left, looking downstream) are higher and contain more terrigenous sediments than those to the west of the valley. The sea floor to the west of the valley returns regular hyperbolic echoes as seen on 3·5 kHz echograms, whereas to the east of the valley, the sea floor is relatively smooth. The sediments on the valley floor are coarse-grained (with median grain up to 2 mm) and poorly sorted, and occur often as massive turbidites, interbedded with hemipelagic sediments. Away from the valley, both to the east and the west, the terrigenous sediments are relatively fine-grained and have been deposited as overbank turbidite sequences. We estimate the maximum velocities of the channelized turbidity currents in the upper fan to have been 8–32 ms−1. The middle fan has several distributary channels with no levees and has a relatively flat sea floor, characterized by lack of acoustic penetration. Thick, sheet-like, turbidite sand beds, deposited primarily by unchannelized turbidity currents, characterize the middle fan. The middle fan grades, towards the margins, into the outer (lower) fan which is relatively free of channels, has good acoustic penetration and contains hemipelagic and pelagic sediments, and thin, fine-sand turbidite and/or contourite beds. A wide zone of sediment waves, formed from the reworking of the turbidity current-fed sediments by the Antarctic Bottom Water, forms part of the outer fan.

Notes: Campanian (Upper Cretaceous) Chalk exposed in a quarry near Portsmouth is unusual in the occurrence of a contemporaneous anticlinal fold, probably diapiric in origin. Hardgrounds and local slumps developed over the structure, and part of the chalk succession thins considerably over its crest. Erosional channels, sometimes containing bioclastic lag deposits, formed at two levels. Movement on the anticline occurred three times during the part of the Lower Campanian represented in the section; the third phase resulted in extensive fracturing of the crestal region of the fold. Burial of the structure and the onset of normal chalk deposition concluded the Cretaceous phase of its history.

Notes: An early diagenetic non-hydrothermal deposit of Na-alunite [(Na,K)Al3(SO4)2(OH)6] is described from the Miocene Ras Maalab Group at Ras Sudar Sinai. The alunite is nodular and occurs along two horizons parallel to bedding. Displacive growth structures and disrupted bedding within the host rock, together with enterolithic growth structures within the nodules, indicate a period of growth prior to compaction. Linear arrays of fabric elements within the nodules, observed under the microscope, further support early diagenetic growth. The host sequence, believed to be the product of sedimentation within barred coastal lagoons has been subdivided into two lithofacies, one reflecting a subtidal open-lagoonal environment, the other an intertidal restricted-circulation environment. Anaerobic conditions of early diagenesis conducive to generation of H2S and FeS2 preceded an oxidation event produced either by contact with free-circulating oxygenated waters or by emergence. The sulphuric acid generated lowered the pH and clay minerals were converted to alunite.

Notes: Calculations of the critical dimensionless bed stresses that obtain when upper-stage plane beds should revert to ripple and dune bed forms are presented. Strong support is given to the Bagnold ‘universal’ plane-bed instability criterion and to a modified criterion suggested by Allen over a wide range of solids grain size. A reinterpretation of the mechanism of plane bed instability is based upon the extent to which significant grain concentrations in plane bed flows increase apparent fluid viscosity and decrease turbulence production over potential bed defects, thereby preventing ripple or dune propagation and growth.

Notes: Pliocene and Holocene siltstones and silts in outcrops from the Boso Peninsula, Japan and in cores from the East China were studied to determine distinctive characteristics of the turbiditic (Bouma E-Division) and hemipelagic siltstones and silts. Weathering characteristics, colour, grain size, and organic carbon-organic nitrogen ratio, plus clay fabric proved valuable in characterizing each unit. Clay and non-clay mineral content was uniform throughout. Clay fabric differences are pronounced. Random clay flake orientation prevails in the turbiditic interval while the hemipelagic unit has more preferred orientation. The fabric reflects different conditions of sedimentation. The turbiditic clay was deposited more rapidly in the flocculated state while the interturbidite hemipelagic clay may have formed from more slowly sedimented dominantly dispersed clay. Results suggest that clay fabric may be useful in combination with other sedimentary features in the study of mud-turbidite sedimentation.

Notes: Rhythms in fine-grained sediments have not previously been studied because of their complex depositional cycles and diagenetic changes. Examination of nearly 9000 layers in outcrops, polished slab samples, and thin sections has led to recognition of rhythms in the Middle Ordovician Whitesburg, Blockhouse, and Sevier formations of east Tennessee. Rhythms have been described in four orders based on relative magnitude. First order cycles (basin-fill sequences, hundreds of metres thick)are composed of thinning upward debris-flow sequences and thickening upward turbiditic shale sequences. Second order cycles (multiple sedimentation units, tens of centimetres thick) consist of: (1) thinning upward cycles; (2) symmetrical cycles; (3) thickening upward cycles; (4) minor multiple cycles; (5) uniform cycles; and (6) dubious cycles. Third order cycles (single sedimentation unit, tens of millimetres thick) have thinning upward and asymmetrical cycles. Fourth order portrays the grain-size variations within a single layer of the third order. First order rhythms were controlled by tectonism and progradation of a deep-sea fan system. Second and third order rhythms were controlled by depositional processes, bottom topography, and sediment source. Depositional processes, sediment source, and bioturbation were the dominant controlling factors in the fourth order. A deep-sea fan model is proposed for the fine-grained turbidites in which channels and lobes coexist in the lower fan. The lower fan/mid fan boundary is marked by the presence of a channel cycle near the top of a lobe sequence. The basin plain/lower fan boundary is suggested by the appearance of minor lobe cycles over the non-cyclic basin plain sequence.

Notes: The Avon River estuary of Nova Scotia was studied with the intention of analysing the relations between grain-size distributions and hydraulics. The Avon is macrotidal; tidal ranges up to 15·6 m generate tidal currents up to 1·7 m s−1. Maximum current speed increases from the mouth (seaward end) to the head (shoreward end) of the estuary. Mean grain size decreases from the estuary mouth to the head. Thus, there is an inverse relationship between mean grain size and current speed. Consequently, textural parameters do not directly reflect hydraulic conditions. Graphical dissection of cumulative frequency curves into their component grain populations reveals a large coarse population at the estuary mouth that is absent at the head. There are several relationships between hydraulics and cumulative curves. Shields’ criterion predicts that all sediment in the system can be transported so that the large coarse population at the estuary mouth is not a lag. Local maximum shear velocity nearly equals the settling velocity of the grain size at the boundary of the coarse (C) and intermediate (A) grain populations. This has been previously interpreted to signifiy a transition from traction to intermittent suspension transport, and implies that the C population is a function of traction and that the A population is related to intermittent suspension (Middleton, 1976). Each grain population is transported at a different rate; suspended grains travel almost an order of magnitude faster than grains moved by traction according to Einstein's transport formula. Sediment transport paths in the estuary were determined from bedform migration directions and the computed net sediment transport per tidal cycle using Engelund and Hansen's formula. The areal distribution of the transport paths, combined with the differential transport rates of each grain population, produces hydraulic sorting. Hydraulic sorting causes coarse sediment to be excluded from the estuary head and creates the inverse relationship between current speed and mean grain size.

Notes: This study examines the morphology, sedimentology and genesis of the point bars and floodplain of the Beatton River. The formation of point bars occurs in distinct stages. An initial point bar platform composed mainly of coarse sediment is formed adjacent to the convex bank of a migrating meander bend, and is the base on which develops a single scroll bar of fine traction and suspended load. With continued sedimentation, the scroll bar grows, eventually supporting vegetation and becoming a floodplain ridge. Scroll bars form with greatest size and frequency in rapidly migrating bends, and the shape of the meander bend appears to determine both the location of the initial bar deposit, and its direction of growth up or downstream. Approximately one-half of the floodplain sediment is derived from suspended load, and the initiation of a scroll bar appears to be due to excessive deposition of suspended load in a zone of flow separation over a point bar platform. The critical flow condition for the initiation of a scroll bar does not occur with the same recurrence interval on different shaped meander bends, however, the average recurrence interval within the study reach is approximately every 30 years. Sedimentation rates on point bars and on the floodplain indicate two relatively distinct stages of floodplain alluviation. The most rapid is for surfaces less than 50 years old, although sediment accumulation still persists on surfaces up to 250 years in age. Although frequently flooded, surfaces older than this accumulate very little sediment. Despite 2–3 m of overbank deposition, the amplitude of floodplain ridges is maintained by secondary currents which sweep sediment from the swales towards the ridge crests.

Notes: Books review in this article: Framework, Facies and Oil-Trapping Characteristics of the Upper Continental Margin, Ed. by A. H. Bouma, G. T. Moore and J. M. ColemanGeological and Geophysical Investigations of Con- tinental Margins (AAPG Memoir 29), Ed. Joel s. Watkins, Lucien Montadert, and Patricia W. Dickerson.Geochemistry, by A. H. Brownlow.

Notes: Historical records demonstrate that the Lake of Tunis, Tunisia, was an open bay that became separated from the Mediterranean by an accreting barrier spit, forming a lagoon. Closure of the lagoon was caused by increased sedimentation as a consequence of Roman deforestation of the Medjerda River drainage basin to the north and subsequent accelerated longshore transport. The separation of the lagoon from the Mediterranean was completed in the early 1500s. At present, the 48 km2 lagoon averages less than 1 m in depth and reaches eutrophic conditions in the late summer. Consistent with the historical records, the lagoon sedimentary column shows three distinct successive environments of deposition: (1) an arid continental environment; (2) an open marine bay; and (3) the present brackish to hypersaline lagoon. These depositional environments are represented by the lower grey layer, which is less than 0-5 m thick, the middle olive-grey layer, which varies from 1 to 5 m in thickness, and the upper black layer, which is 1 m thick. All of the strata are predominantly silt plus clay, but usually contain at least 10% sand. The lower grey layer consists of pitted quartz sand, with very few abraded, broken molluscan fragments and benthic foraminifera with thick tests. An arid, subaerial depositional environment of latest Pleistocene time best explains these sediment and fossil assemblages. In the middle olive-grey layer, coral, coralline algae, open marine graeses and the dominance of foraminifera over ostracods (expressed as a low percentage of ostracods/ostracods plus foraminifera) attest to a depositional environment of an open marine bay. A sharp increase in the percentage of ostracods/ostracods plus foraminifera and organic carbon from the middle olive-grey layer to the upper black layer signifies a major change in depositional environment. The predominance of ostracods over foraminifera, abundance of gastropods characteristic of eutrophic conditions, high organic carbon content and absence of macro-fossils characteristic of open marine conditions clearly indicate that the upper black layer was deposited in a brackish to hypersaline, eutrophic lagoon which has persisted to the present. Seismic records indicate a karstic bedrock surface underlying the lagoon. The surface is marked by considerable relief, and shows a linear depression which may represent an early sixteenth century ship canal. Heavy metal analyses of total samples in five cores demonstrate that Mn and Fe vary randomly, and are apparently derived from natural sources only. Cd, Cr, Pb, Cu and Zn are typically highest in the uppermost unit, which reflects levels of human contamination since closure of the lagoon.

Notes: The identification of the remains of organisms contributing to carbonate sediments by means of scanning electron-microscopy is limited to particles of the 2–20 μm size class. Mineralogy and the content of Mg, Sr and trace elements alone are usually insufficient to solve the problem of identification, especially in the differentiation between algal and coral aragonite. The organic matrix of calcareous organisms consists of stable biopolymers such as polysaccharides and glycoproteins which are intimately associated with the carbonate skeleton. Analysis of these hydrolysed compounds gives rise to characteristic arrays of monosaccharides which provide independent criteria for producer identification. The calcareous green algae Halimeda, Penicillus and Udotea show high xylose and low fucose levels. Xylose and fucose levels are elevated in the red algae Amphiroa but only fucose is prominent in the brown algae Padina. The corals Oculina, Porites, Millipora and Montastrea are relatively rich in fucose and show little or no xylose. In the bivalves Arca, Codakia and in Argopecten mannose may be characteristic. Analysis of artificial and natural sediments demonstrates that coral and algal aragonite can be distinguished on the basis of the total sugar concentration and respective xylose and fucose levels. The applicability of the technique in comparison to geochemical and mineralogical methods has been demonstrated for surface sediments from varying water depths of Harrington Sound, Bermuda.

Notes: Elutriation from a fluidized bed provides an accurate, economical, direct method of sediment grading by terminal velocity. This is of particular value in studying populations of irregular particles in the range medium sand to granule (e.g. carbonate sands). A column suitable for such material (terminal settling velocity 1-30 cm s−1) is described and sample results from Connemara Lithothamnion beach material are given.