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The Upper Red Formation (URF) comprises over 1–5 km of late Miocene siliciclastic sediments in the Central Iran Basin. The formation is dominated by volcaniclastic conglomerates and arenites. The prevailing arid conditions during most of the basin's history resulted in deposition of predominantly organic-poor, red sediments with gypsum and zeolites. This investigation concentrates on the mineralogy and geochemistry of the URF in the southern and northern margins of the basin where the formation was buried to depths of 2.4 and 6.6 km, respectively. Fine fraction mineral separates from the southern margin consist of nearly pure smectite and zeolites at a depth of 400 m and smectite with minor quartz and calcite at 1800 m. Shallow samples (1350 m) from the northern section are rich in smectite, illite/smectite with some discrete illite and chlorite. This assemblage is progressively replaced by discrete illite and chlorite with increasing burial depth so that only these two minerals are found at depths greater than 4300 m. The initial alteration process involved replacement of glass and volcanic lithics by smectite and zeolites in both margins of the basin. Increased depth of burial in the northern margin resulted in the progressive isochemical alteration of smectite to discrete illite and chlorite. Diagenesis of clay assemblages occurred essentially in a closed system. Solute products of glass hydrolysis reactions were retained in highly alkaline, saline ground waters from which zeolites, carbonates and oxides precipitated as cements. It is unlikely that these sediments were ever significantly leached by meteoric waters or by organic acids generated during burial diagenesis. Copyright © 2010 John Wiley & Sons, Ltd.

Soil profiles developed in different climates and physical settings are highly variable in structure, in mineralogy, in the local biosphere and in the compositions of the soil gas and water phases. Discussion of metals in ‘the weathering environment’ needs to acknowledge and address this diversity.The thermochemical methods developed by Pourbaix (1949) and Garrels and Christ (1965) remain useful predictors of metal speciation and solubility but the approach is valid only for processes involving carbonates, sulphides, hydroxides and similar minerals in soils and sediments. Almost no primary silicates are thermodynamically stable: they spontaneously decompose to non-equilibrium solid products with metal release determined by kinetics.Hydrolysis constants for aquo-complexes are useful indicators of metal speciation, mobility and availability. Recent work on soluble soil organic matter confirms that the active ligands are overwhelmingly oxygen based: phenols, carboxylic acids, alcohols. Many of these molecules compete very effectively with aquo-complexes to form strong metal chelates and appear to be responsible for substantial Al and Fe mobilization within and translocation down soil profiles.It is important to note also that strong clay mineral/organic matter associations (clay-organic complex) will fix metals as a consequence of the same chelation reactions (in this case removing them from solution - retardation).

The physico-chemical properties of iron oxyhydroxide plaques formed on the roots of Phragmites australis under field and laboratory conditions were determined using electron microscopy and energy dispersive spectrometry (EDS) analysis. Plaques were present as an amorphous coating on roots with an uneven distribution. They were shown to be composed of iron in both the field and laboratory, and phosphorus was found to be adsorbed onto the surface of plaques formed in the laboratory. The uptake of copper and manganese in the presence and absence of plaque was investigated under two different pH regimes. Concentrations of Cu were lower in the shoots of P. australis in the presence of plaque (565 mg kg−1) than when it was absent (1400 mg kg−1), under growth conditions of higher pH (6.0). The adsorption of Cu and Mn onto the plaque surface was not the mechanism by which plaque reduced the uptake of other metals. Alternatively, the plaque may simply act as a physical barrier. Under conditions of lower pH (3.5) the activity of hydrogen ions at the root surface interfered with the movement of metals into the root and masked any potential effect of iron plaque.

Although the quantities of sediment exported to the sea by large rivers are relatively well known, information on mineralogical and geochemical characteristics is less readily available. Quantity and composition are strongly influenced by tectonic environment and also by both present and past climate. An analysis of diagenetic processes in fine-grained clastic sediments suggests that bed-parallel changes in the intensity of diagenetic modification (reflected in phenomena such as cemenstone horizons) and marked changes in authigenic mineral assemblages (sulphides, carbonates, silicates) could be explained by changes in sediment supply rate driven by climatic fluctuations. It is less easy to explain fluctuations in detrital sediment composition: diagenetic reorganization would appear to be the most common cause of marked local compositional contrast in mudstones.

The significance of sedim entary indicators of palaeoclimate to future palaeoclimatic research will depend on more rigorous calibration of the climatic controls on the formation of those indicators.

Laterally persistent carbonate cementation, in the form of concretions or cemented horizons, is common within shallow marine sandstones reservoirs. Understanding the distribution of such cemented zones is of immense value, as within the subsurface they may lead to reservoir compartmentalisation and associated production problems. However, the exact sedimentological and stratigraphic relationships of these cemented horizons are generally lacking as the majority of studies have been undertaken on borehole material or outcrops of limited lateral extent. In this paper the field relationships between cementation and stratigraphy from the exceptionally well-exposed Upper Cretaceous sediments in Book Cliffs, Utah-Colorado are documented. We show that laterally persistent cemented horizons consistently occur beneath major marine flooding surfaces and propose that the initial precipitation of these cemented horizons took place at periods of markedly reduced sediment accumulation rates associated with these flooding events.

Morecambe field is centered on Block 110/2, 26 mi (42 km) off the northwestern coast of England. The gas-bearing structure occurs in Triassic sandstones with the top of the reservoir at an average depth of 3,000 ft (915 m), about 6,500 ft (2 km) less than maximum burial. Production is constrained by the presence of coarse-textured (crystals often >20 micrometers) platy illite. Thin-section and scanning electron microscopy have shown this phase to have a well developed, pore-bridging boxwork texture and indicates a depth zonation in which platy illite occurs below a productive illite-free interval and above a zone of fibrous illite. The top of the platy illite zone forms a mappable datum but cannot be predicted from present structure. Illite also is present throughout t e reservoir as grain-tangential rims and as a replacement of unstable framework grains, matrix clays, and neoformed kaolinite cement. Analytical transmission electron microscopy, used to define the chemistry of the illites, has shown that all morphological types (grain tangential, replacement, platy, and fibrous) have compositions close to phengitic muscovite. A calculated maximum paleotemperature of 270 degrees F (132 degrees C) indicates that phengite can form as a lower temperature mineral than hitherto has been recognized. Excluding replacement illite, which has no specific association with respect to the sandstone pore system, minor increases in Al/Si and K/Mg + Fe ratios (0.69 to 0.72 and 1.86 to 2.26, respectively) correspond to the morphological change from tangential/fibrous to platy. This suggests that platy illite represents the closest approach to ideal muscovite. Geochemistry indicates that either K-feldspar dissolution or brines could have provided K for illitization. The latter reaction (smectite + KCl changes to illite) would result in pore-water acidification and is unlikely to have occurred unless accompanied by acid-consuming reactions such as carbonate dissolution or iron reduction. The presence of a mappable illite datum in Morecambe supports a neoformational origin for platy illite and suggests that Gulf Coast data are not directly applicable to this field. This consideration should not be overlooked in development of exploration strategies for other comparable reservoir targets.

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.

Textural, mineralogical and chemical data are presented for glauconites and illites from the Lower Cretaceous Glauconitic Sand Formation, Alberta, Canada. Single crystal analyses by scanning transmission electron microscopy (STEM) indicate that both glauconite (29 analyses) and illite (44 analyses) correspond very closely to ideal dioctahedral structures. Al dominates the octahedral sheet in illite. Very extensive A1 for FeIII substitution was also found in some of the glauconites, much more than previously recorded. The dioctahedral mica structure is clearly very stable and flexible with respect to A1 for FeIII substitution. Iron-poor glauconites were found associated with pyrite. We believe that glauconites tend to lose iron progressively during burial diagenesis, especially where pore water iron activities are low (high HS− activity and low Eh). It seems probable that A1 for Si tetrahedral substitution also takes place during diagenesis with consequent loss of swelling properties. This is the same trend which is responsible for conversion of smectite to illite. Glauconite forms only where sediments reside for lengthy periods at the interface between oxidizing and reducing environments, where Fe3+ is transiently available in solution. Related marine and terrestrial nontronites also form only in similar ‘interface’ environments.

Within compacting mudstone sequences several depth zones can be recognised in which distinctive diagenetic reactions take place. Most striking are those involving carbonate precipitation or replacement. The major carbon source is organic matter which is degraded by various microbiological and inorganic reactions to bicarbonate as one product. Other reactions involving silicates and sesquioxides introduce cations to the porewater system and carbonates are precipitated. Their chemical and isotopic composition can be linked with temperature and depth of formation. Analysis of some of the literature of sandstone diagenesis suggests that carbonate cements in sandstones often originate in mudstones, and that precipitation may take place far from the site of solute generation. Vast volumes of porewater excluded from mudstones during compaction are channelled into and travel great distances within sand units. Early diagenetic reactions drastically modify the permeability of both potential source and reservoir rocks. The component of horizontal flow is greatly increased and this must affect later migration of liquid hydrocarbons.

A set of pure iron-rich minerals characteristic of common fine-grained sedimentary rocks has been prepared and their Mossbauer spectra obtained. These include pyrite, carbonates and silicates. Six marine mudrocks were then chosen from a large set for which complete chemical data were available. It proved possible to reproduce mudrock spectra by addition of the pure mineral spectra in proportions indicated by the chemical analyses. Unfortunately, however, overlap of Fe(III) in dioctahedral silicates with Fe(II) in pyrite prevents reliable deconvolution of mudrock spectra to obtain quantitative estimates of component concentrations. Useful information about Fe(II) in other minerals can still be obtained. Mossbauer spectroscopy would appear to have great promise for the study of early reactions in non-marine sediments which are usually low in sulphur. Mineral products are either X-ray amorphous or extremely fine-grained mixtures and very difficult to study by other means.

The N > 5, where N is the number of layers within a diffracting domain. Sections of the K-bentonite were prepared by ion-beam milling and examined in an analytical transmission electron microscope (ATEM). One-dimensional lattice images observed parallel to the a-b plane showed subparallel packets, about 50–100 A thick, each of which consisted of about 10-Â thick unit layers. Somewhat thicker unit layers (as much as 14.5 A) were also seen. The former are presumed to be illite, whereas the latter may be partially collapsed smectite. Selected-area electron diffraction patterns suggested simultaneous diffraction from several packets, each containing at least five layers. Both h0l and 0kl spacings were usually present, indicating that the stacking of the subparallel packets was random. Quantitative analysis by AEM and electron microprobe show the clay to be low in tetrahedral Al but high in octahedral Mg, the latter presumably contributing largely to the interlayer charge responsible for K fixation. The TEM data are broadly reconcilable with the accepted XRD interpretation of a two-component, mixed-layer clay. Alternatively, the TEM images may be interpreted as a single phase having numerous packet boundaries, the latter being responsible for swelling behavior. These two interpretations will not be fully reconciled until greater analytical precision and resolution permit individual packets to be studied. This work suggests that mineral definitions based purely on XRD interpretations may have to be reconsidered as more electron microscope data become available.

An experiment was performed to test the hypothesis of cryogenic trapping of fractionally charged particles, suggested as a possible explanation for the results of LaRue, Fairbank, Hebard, and Phillips at Stanford. A Nb-filament source was built, which could be cooled to 4.2 /sup 0/K and rapidly heated to several hundred /sup 0/K. The source was operated in the terminal of a 700-kV Cockcroft-Walton accelerator and energy spectra of positively charged particles emerging from the filament were measured under a variety of operating conditions. No events above a background of 10/sup -2/ counts/sec were found in the energy regions where one might have expected several hundred particles of charge +(1/3)e or +(2/3)e as the source was heated. A mass range from 10 MeV/c/sup 2/ to 100 GeV/c/sup 2/ was covered in the experiment. Although negative results are rarely unambiguous, our findings exclude one class of hypotheses which might have explained the apparent fractional charges of the Stanford experiments.

Analytical transmission electron microscopy was applied to some authigenic chlorites occurring as grain coatings in sandstones. Compositional variation proved to be relatively slight: all were magnesian chamosites. The coating chlorites were often intimately mixed with extremely fine-grained (0·01–0·2 µm) hematite but analytical ‘contamination’ was avoided because of the very high resolution of both observation (spot location) and analysis. One example of a water-sensitive (‘swelling chlorite’) coating was also studied. This proved to have a very much more variable composition even within a single section. The coating appeared to include both chloritic and vermiculitic components. The effect of this on structural formulae is discussed and a model proposed in which the ‘talc’ layer may be common to both components.

The concentration profiles of the trace elements, S, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, and Y have been determined across a metasomatic vein in peridotite. The introduced elements Ti, V, Sr, and Y show specific enrichment in particular silicate phases in accordance with the availability of suitable lattice sites. In contrast, the other introduced trace elements (Cu and S) behave more like the redistributed elements, Cr, Ni, Mn, and Co which do not show concentration ‘fronts’ that can be simply related to the silicate minerals. Concentration of pentlandite, chalcopyrite, and Cr-magnetite near the boundary between the enstatite and anthophyllite zones gives rise to maxima in the Ni, Cu, S, and Cr distributions, while in the chlorite zone significant concentrations of Cr and Ni occur in the chlorite itself. Control of the distribution of Ni, Cu, and Cr is ascribed to the oxidation/reduction reactions involved in the formation of pentlandite, chalcopyrite and Cr-magnetite, together with the critical role of Al in limiting chlorite formation during metasomatism.

SUMMARY. Concretionary siderite horizons are quite common in massive clay sequences. One such horizon, from the Westphalian of Yorkshire, has been studied in detail. Two iron-rich carbonate minerals occur together although they cannot be distinguished in thin section on account of very fine grain size. One is much richer in magnesium (pistomesite) than the other (siderite). The latter is relatively rich in manganese and the heavier stable carbon isotope laC whereas the former carbonate is richer in calcium and 1~C. The most important iron source is thought to have been hydrated iron oxides originating in soils. Much of the carbonate carbon started as organic molecules. The siderite appears to have formed earlier than the pistomesite. The stratiform character of these deposits appears to reflect siltier horizons in the mudstones, which presumably channelled pore water migration during compaction. This is probably why such carbonate horizons were formerly believed to be of simple sedimentary rather than diagenetic origin. SII~ERITE occurs very much more widely than is commonly realized. Most clay-rich sequences (which actually make up 7o to 8o % of the sedimentary column) contain dispersed as well as the more obvious concretionary siderite. The sediments studied here, from above and below the Alton Marine Band and Halifax Hard Bed Coal, include from 4 to 18 % iron carbonate (Pearson, 1973). Almost invariably, siderites are found to be extremely fine-grained and intimately mixed with clay, organic matter, and, not infrequently, phosphates. Physical separation of pure material is virtually impossible. In consequence most mineralogists have left these minerals severely alone and there is a noticeable lack of precise information. Most recent data are to be found in Soviet or East European literature (Zaritskiy, I964, for example). There has been a considerable revival of interest in other concretionary carbonate minerals, such as calcite (Saas and Kolodny, 1973) and dolomite (Murata, Friedman, and Cremer, I972). Both papers illustrate that much of the new interest lies in variation of stable carbon isotope ratios and implied fractionations. Such data give unique insight into the role played by microorganisms in diagenesis and are particularly relevant to problems of petroleum genesis. In an attempt to improve the situation with respect to compositional information, one of us developed methods of wet chemical analysis and made a study of covariation of composition with d-spacings (Pearson, I974a, b). An initial investigation of carbon isotope variation was also undertaken and reported (Curtis, Petrowski, and Oertel

The oxidation state and mineralogical distribution of Fe in two different shale sequences have been studied by Mössbauer spectroscopy and chemical methods. Kimmeridge Clay Formation sediments proved to be richer in total Fe than Gulf Coast shales. In such sediments, Fe may be present in clay minerals (Fe(II) in chlorite, Fe(III) in illite and illite/smectite), pyrite, and ferroan carbonates (siderite, dolomite and ankerite). Pyrite accounts for a much greater proportion of the total Fe in the Kimmeridge Clay samples in which it is difficult to reconcile chemical data with Mössbauer data. There is major doublet overlap of Fe(III) in silicates with Fe(II) in pyrite and spectra cannot be satisfactorily deconvoluted. This would appear to be a fundamental limitation for simple applications. In the pyrite-poor Gulf Coast material, however, chemical and spectroscopic evaluations of overall valence state are much more consistent. Confidence in both determinative techniques is generated, and useful information documenting progressive reduction and redistribution of Fe with burial is obtained.

To most field geologists 9black shales9 are dark, fissile sedimentary rocks which are rich in both carbon and sulphur. The property of fissility probably develops only in sediments deposited from anoxic bottom waters. Carbon and sulphur-rich sediments are formed wherever relatively organic-rich material accumulates at such a rate that intensive diagenetic alteration takes place within the uppermost few metres of the sediment column, but relatively little happens below. Depositional waters must be marine (or at least sulphate-rich) but not necessarily anoxic.

A list of formational free energy data is provided for a range of common rock forming minerals. Free energy changes accompanying their decomposition to realistic stable products are calculated and shown to be in agreement with persistence observations. Weathering mechanisms and environmental controls are discussed.

A range of authigenic sedimentary chlorites from sandstones has been studied by analytical transmission electron microscopy. Selected area (single crystal) electron diffraction patterns are of the Ib (β = 90°) polytype confirming the earlier observations of Hayes (1970).TEM analyses show all samples to be relatively rich in both Al and Fe. In the general formula (Mg,Fe,Al)n [Si8−xAlxO20](OH)16, x varies between 1.5 and 2.6; Fe/(Fe + Mg) between 0.47 and 0.83 and n between 10.80 and 11.54. Octahedral Al is close to 3 in this formulation and Fe2+ predominates over Fe3+. Swelling chlorites have significantly different compositions which are consistent with smectite/chlorite interstratifications.The Ib (β = 90°) polytype appears to be stable under conditions of moderate to deep burial. It replaces berthierine and swelling chlorites formed at lower temperatures. As commonly seen in grain coatings, however, it precipitates from porewater; solutes probably being contributed from several mineral decomposition reactions.

A high voltage, high gradient accelerating column to provide good optics for high current beams has been built and tested by MURA. Design details were chosen to eliminate all possible sparking or corona discharges for reliable high voltage performance. The 12-in. accelerating gap features stainless steel spherical geometry electrodes shaped to produce a converging field. The electrodes are supported by titanium alloy spacers bonded to ceramic rings with a vinyl seal. There are 14 ceramic rings of 14 in. ID, 16 in. OD, and 1-15/32 in. long, giving a column length of 21 in. This column is insulated externally by sulfur hexafluoride gas at three atmospheres absolute pressure confined by a fiber glass pressure shell. The completed column has been tested at 600 kV. Work is being done on ceramic-to-metal seals to eliminate organic materials.

An attempt to combine laboratory and field data on recent sedimentary environments to produce mineral stability diagrams suggests that two distinct situations may be recognized. In depositional water, only ferric compounds can be truly stable. In interstitial water, beneath the sediment-water interface, ferrous compounds (pyrite, pyrrhotite, magnetite, siderite, and chamosite) are stable. Anion activity (sulfide and carbonate) appears to be the most important chemical control. The theoretical findings (Pt. 1 by C. D. Curtis) are consistent with interpretation of petrographic observations on Carboniferous and Jurassic ores of the British Isles (Pt. 2 by D. A. Spears).

(1934). The PRESENCE of TROMP during BLAKE'S REDUCTION of the SCILLY ISLES in 1651. The Mariner's Mirror: Vol. 20, No. 1, pp. 50-66.

Sixty-Mev electrons from a pulsed betatron passed through lead foils of thicknesses 0.001, 0.005, and 0.015 inch placed in a magnetic cloud chamber. Measurements of approximately 1100 large energy losses gave the differential bremsstrahlung cross section as a function of x-ray energy for the high energy portion of the x-ray spectrum. Corrections were applied for instrumental discrimination and for multiple radiation and ionization energy losses in the foils. While the shape of the top 30 percent of the x-ray spectrum agreed with the theory within experimental uncertainty, the magnitude of the cross section was about 7 percent lower than theory.

The first three months of operation of the NAL linac after first achieving a 200-MeV beam have been encouraging. The design performance has been achieved at beam intensities of about 20 mA both in the transverse emittance and the momentum spread. Attempts have not been made to go to intensities of 100 mA or greater as yet, and it will be interesting to see how the beam quality is affected by intensity. It is expected that when the linac rf phase and amplitude controls are properly working, the beam quality will be less than the design values. In particular, the momentum spread at the present operating currents is sufficiently small so that a debunching cavity currently is not envisioned. The beam measurements made so far confirm the theoretical results obtained with the PARMILA dynamics program. The particle distributions used in the program are those measured at the entrance to the linac. The large number of components in the systems have lead to concern over the reliability of the linac. The performance over the last three months has dispelled some of this concern. As running periods have increased the failure rate has decreased. Only two major problems stand out at this time. The first is the failure of the spring contacts on the filament leads to the power amplifier tubes. Installation care and the elimination of two of the contact rings which were not water-cooled seem to be providing at least a temporary solution.

An earlier investigation of metasomatic alteration (Curtis and Brown, 1969) is extended to trace element distribution. Most element profiles may be linked simply with diffusive mixing. Between element differentiation is slight, but certain elements are selectively concentrated in particular mineral phases.

An electron gun and an inflection system which satisfy the injection requirements of the MURA 50‐MeV electron accelerator are described. Electrons emitted from a tungsten ribbon filament are accelerated to 100 keV by a converging radial field of cylindrical geometry and deflected parallel to the equilibrium orbit of the accelerator by a 60° electrostatic inflector. The inflector also provides focusing of both the radial and vertical motion of the beam. The gun and inflector are located within the guide field region of the magnets and are adjustable in position as a unit. The emittances of the system are 0.5 π and 1.0 π mrad‐cm for the horizontal and vertical motions, respectively. Although the injector is capable of delivering several hundred millamperes, it is normally operated at much lower currents since fewer than 20 mA are required to reach the space‐charge limit of the accelerator when multiturn injection techniques are employed.

Multiturn injection techniques employed in the MURA 50‐MeV electron accelerator are described, together with an evaluation of their performance. These include shifting of the equilibrium orbit by a time‐varying bump, damping of betatron oscillation amplitudes by an rf voltage, and damping of amplitudes by space‐charge effects. Multiturn injection is achieved by filling the accelerator radial phase space with injected beam. The capture of injected charge approaches 100% when the programmed field bump is used. This high efficiency has been achieved for about 15 turns of total beam from the inflector and for about 40 turns of collimated beam. Injection at the higher beam intensities gives rise to spontaneous longitudinal bunching of the circulating beam for all energies from injection to above transition with the magnitude generally greatest just above transition.

A naturally occurring macroscopic sodium vermiculite from Unst, Shetland is described. It is similar in many respects to synthetic materials recently prepared from phlogopite by potassium replacement. In other respects, however, it is more akin to macroscopic Mg-vermiculites.

SummarySingle-crystal diffraction patterns produced by transmitted radiation, both X-rays and electrons, reveal varying degrees of disorder and long-range order in common phyllosilicates from several different rock types. The transmission electron micrographs and their selected-area diffraction patterns demonstrate the presence of numerous stacking faults parallel to (001) of muscovite and chlorite. Individual stacking faults can be recognized by the diffraction-contrast fringe patterns they cause, and partial dislocations can be seen where such faults terminate inside a crystal. Long-range order of muscovite explains what seemed to be spurious, high ‘background’ levels that are sometimes encountered in the analysis of rock fabrics by transmitted X-rays.

Read (1934b) described the mineralogy and regional setting of spectacularly zoned ultrabasic bodies occurring in Unst, Shetland. Chemical and phase compositional data are presented here for a selection of samples taken from each of the several “monomineralic” zones. The phase sequence and elemental distribution are discussed in some detail since both are complicated. It is shown that virtually all distributional features may be explained on the basis of a diffusion model: transport most probably having occurred via aqueous solutions in pore space. The present configurations represent “frozen” reaction intermediates. Controls upon the nature and extent of reaction are analysed. Certain features may be explained on the basis of “local equilibrium thermodynamics”. These arguments, however, are inadequate. Fairly simple kinetic considerations lead to a much more satisfactory analysis. Some of the problems associated with concepts of element “mobility” are discussed briefly.

Experimental solubility data for gibbsite and kaolinite are reviewed and applied to the pro- blem of gibbsite stability within the natural environment. It is concluded that free alumina compounds formed (only) in lateritic soils will tend to silicify spontaneously in all sedimentary environments. This metasomatic reaction should be accompanied by massive volume expansion: unusual textures are to be anticipated. Petrographic and field descriptions of a number of ancient kaolinitic sediments (some with, some without free alumina) are reviewed. It is concluded that silicification of hydrated aluminum oxides was an important mechanism of kaolinite formation in ancient sediments and that free alumina com- pounds persist only as a result of the unusual volume expansion associated with kaolinite formation.

At present there are two working injection methods; single-turn using a ferrite kicker magnet and multiturn using a pulsed set of 4 dipoles in one straight section. The operating characteristics of these methods are described. The expected implementation of H injection will involve the incorporation of devices for all three methods in one 6-m long straight section. The H-scheme is described and the expected operating characteristics compared to the present methods.

A 200 MHz Radio Frequency Quadrupole (RFQ) Linac is being designed and constructed for the acceleration of H- ions from 30 keV to 750 keV at a current of 30 mA. The RFQ is being developed as a possible replacement for the Fermilab preaccelerator and as an R and D project to investigate RFQ properties for future accelerators. The current status of the project is described.

The Fermilab Linac uses two electrostatic beam deflection systems as beam choppers, a 750-keV system located between the ion source and the input to the Linac and a 200-MeV system at the output of the Linac. This paper discusses the 750-keV chopper experience with both proton and negative ion beams and the ability of these systems to tailor the Linac beam to the diverse requirements of its users; normal accelerator injection, neutron therapy beam, and electron cooling experiments. This flexibility plus a cleaner beam pulse, improved thyratron operation, and mechanical modularity are the results of recent improvements. Additional benefits have been increased reliability and ease of service to the 750-keV chopper.

Acid pore waters generated within organic-rich muds destabilize carbonates and aluminosilicates and take metals, including aluminum, into solution. Sediment compaction forces some of these modified pore waters into sandstones. Once isolated from the principal source of acidity (kerogen maturation), the pH of these solutions must rise as further mineral dissolution occurs. The inevitable consequence is precipitation of kaolinite, even though solutions may still be acid. This explains why kaolinite is commonly the first precipitate to reduce secondary pore space in sandstones and can form even as other minerals are being dissolved away.

The porosity of clastic sediments at deposition varies very approximately between about 45% (sands) and 85% (muds). With burial, consolidation takes place as pore water is progressively eliminated. It would be misleading, however, to attribute alterations in sediment bulk properties to physical processes alone. Very significant mineralogical changes occur and these start soon after burial, especially in mudrocks. Striking heterogeneities such as thin, laterally continuous cemented horizons or discrete concretions are commonly introduced. These shallow burial processes are predominently the result of microbial activity. Thermodynamically unstable mixtures of organic matter and various oxidants [dissolved oxygen, sulphate, nitrate, particulate Fe(III) and Mn(IV)] provide both substrate and energy source for a variety of different microbial ecosystems. Mineralogical consequences include both leaching and the precipitation of carbonate, sulphide, phosphate and silica cements. The type and extent of mineral mo...

Installation of a grooved cathode and addition of a resistive heater around the source body have greatly improved the performance of the magnetron source. Lifetimes of nine months with stable pulsed beams of 50 mA have been achieved. Improvements and operation of the magnetron source at Fermilab will be presented. Recent tests with Lanthanum hexaboride as the cathode will be discussed.