ALBERT

Beschreibung / Inhaltsverzeichnis: This volume of Reviews in Mineralogy attempts to synthesize our present understanding of certain aspects of the mineralogy and chemistry of the rock-forming carbonates. Hopefully, it reflects the presently more active areas of research. This review follows, by ten years, a major assessment of (sedimentary) carbonate minerals by Lippmann (1973). There is only minor overlap of subject material, and I hope that this difference reflects fairly how this field has developed. In some respects carbonates are unique, for they are one of the few mineral groups providing an abundant record of biological, physical, and chemical processes throughout much of geologic time. Because of their relative importance in sedimentary rocks, lowtemperature examples are given more emphasis here. Moreover, the obvious correlation with energy resources has been a significant factor contributing to the current resurgence of interest in this area. However, the broader interest in carbonates is also a reflection of their widespread occurrence in vastly different geologic environments, including metamorphic and igneous settings, as well as an appreciation of their role in both atmospheric and oceanic chemistry, both past and present. In this volume, some of the papers are general (i.e., those addressing crystal chemistry and phase relations), and they provide overviews of a fundamental nature and are of interest to many. Others are more specialized in coverage and generally reflect the different approaches used in carbonate geochemistry. The final chapter introduces transmission electron microscopy, a relatively new and powerful technique for mineralogical research that has great potential in carbonate research. Owing to the short time interval between the completion of manuscripts and publication, much of the newer material in this volume is still "fresh." The various reviewers, all gratefully acknowledged, were expeditious in their efforts. A hurried schedule, however, allows for unnoticed errors to persist; these should be brought to my attention.

Beschreibung / Inhaltsverzeichnis: Geochemistry is a science that is based on an understanding of chemical processes in the earth. One of the principal tools available to the chemist for understanding systems at equilibrium is thermodynamics. The awareness and application of thermodynamic techniques has increased at a very fast pace in geosciences; in fact, one may be so bold as to say that thermodynamics in geology has reached the "mature" stage, although much future thermodynamic research is certainly needed. However, the natural processes in the earth are often sluggish enough that a particular system may not reach equilibrium. This observation is being supported constantly by new experimental and field data available to the geochemist e.g. the non-applicability of the phase rule in some assemblages, the compositional inhomogeneities of mineral grains, the partial reaction rims surrounding original minerals, the lack of isotopic equilibration or the absence of minerals (e.g. dolomite), which should be present according to thermodynamics. The need to apply kinetics has produced a large number of papers dealing with kinetics in geochemistry. As an initial response to this growing field, a conference on geochemical transport and kinetics was conducted at Airlie House, VA, in 1973, sponsored by the Carnegie Institution of Washington. The papers there dealt with several kinetic topics including diffusion, exsolution, metasomatism and metamorphic layering. Since 1973 the number of kinetic papers has continued to increase greatly. Therefore, the time is ripe for a Short Course in Kinetics, which brings together the fundamentals needed to explain field observations using kinetic data. It is hoped that this book may serve, not only as a reference for researchers dealing with the rates of geochemical processes, but also as a text in courses on geochemical kinetics. One of us has found this need of a text in teaching a graduate course on geochemical kinetics at Harvard and at Penn State during the past several years. Finally, it is our hope that the book may itself further even more research into the rates of geochemical processes and into the quantification of geochemical observations. The book is organized with a rough temperature gradient in mind, i.e. low temperature kinetics at the beginning and igneous kinetics at the end (no prejudices are intended with this scheme!). However, the topics in each chapter are general enough that they can be applied often to any geochemical domain: sedimentary, metamorphic or igneous. The theory of kinetics operates at two complementary levels: the phenomenological and the atomistic. The former relies on macroscopic variables (e.g. temperature or concentrations) to describe the rates of reactions or the rates of transport; the latter relates the rates to the basic forces operating between the particular atomic or molecular species of any system. This book deals with both descriptions of the kinetics of geochemical processes. Chapter one sets the framework for the phenomenological theory of reaction rates. If any geochemical reaction is to be described quantitatively, the rate law must be experimentally obtained in a kinetically sound manner and the reaction mechanism must be understood. This applies to heterogeneous fluid-rock reactions such as those occurring during metamorphism, hydrothermal alteration or weathering as well as to homogeneous reactions. Chapter 2 extends the theory to the global kinetics of geochemical cycles. This enables the kinetic concepts of stability and feedback to be applied to the cycling of elements in the many reservoirs of the earth. Chapter 3 applies the phenomenological treatment of chapter 1 to diagenesis and weathering. The rate of dissolution of minerals as well as the chemical evolution of pore waters are discussed. The atomistic basis of rates of reaction, transition state theory, is introduced in Chapter 4. Transition state theory can be applied to relate the rate constants of geochemical reactions to the atomic processes taking place. This includes not only homogeneous reactions but also reactions that occur at the surface of minerals. Chapter 5 discusses the theory of irreversible thermodynamics and its application to petrology. The use of the second law of thermodynamics along with the expressions for the rate of entropy production in a system have been used successfully since 1935 to describe kinetic phenomena. The chapter applies the concepts to the growth of minerals during metamorphism as well as to the formation of differentiated layers (banding) in petrology. Chapter 6 describes the phenomenological theory of diffusion both in aqueous solutions and in minerals. In particular, the multicomponent nature of diffusion and its consequence in natural systems is elaborated. Chapter 7 provides the atomistic basis for the rates of reactions in minerals. Understanding of the rates of diffusion, conduction, order-disorder reactions or exsolution in minerals depends on proper description of the defects in the various mineral structures. Chapter 8 provides the kinetic theory of crystal nucleation and growth. While many of the concepts in the chapter can be applied to aqueous systems, the emphasis is on igneous processes occurring during crystallization of a melt. To fully understand both the mineral composition as well as the texture of igneous rocks, the processes whereby new crystals form and grow must be quantified by using kinetic theory. Due to space and time limitations (kinetics!) some topics have not been covered in detail. In particular, the mathematical solution of diffusion or conduction equations is discussed very well by Crank in his book, Mathematics of Diffusion, and so is not covered to a great extent here. The treatment of fluid flow (e.g. convection) is also not covered in the text.

Beschreibung / Inhaltsverzeichnis: A field guide to the wild flowers of western Canada and the adjoining Great Plains states of the United States, including illustrations of nearly 400 species.

Beschreibung / Inhaltsverzeichnis: The probability density function of the gouge depths into the sediment is represented by a simple negative exponential over four decades of gouge frequency. The exceedance probability function is, therefore, e to the -lambda d, where d is the gouge depth in meters and lambda is a constant. The value of lambda shows a general decrease with increasing water depth, from 9/m in shallow water to less than 3/m in water 30 to 35 m deep. The deepest gouge observed was 3.6 m, from a sample of 20,354 gouges that have depths greater than or equal to 0.2 m. The dominant gouge orientations are usually unimodal and reasonably clustered, with the most frequent alignments roughly parallel to the general trend to the coastline. The value of N(bar) sub 1, the mean number of gouges (deeper than 0.2 m) per kilometer measured normal to the trend of the gouges, varies from 0.2 for protected lagoons to 80 in water between 20 and 38 m deep in unprotected offshore regions. The distribution of the spacings between gouges as measured along a sampling track is a negative exponential. The form of the frequency distribution of N sub 1 varies with water depth and is exponential for lagoons and shallow offshore areas, previously skewed for 10 to 20 m depths off the barrier islands, and near-normal for deeper water. As a Poisson distribution gives a reasonable fit to the N sub 1 distributions for all water depths, it is suggested that gouging can be taken as approximating a Poisson process in both space and time. The distributions of the largest values per kilometer of gouge depths, gouge widths, and the heights of the lateral embankment of sediments plowed from the gouges are also investigated.

Beschreibung / Inhaltsverzeichnis: Small-scale laboratory experiments were conducted on model bridge piers in the CRREL test basin. The experiments were performed by pushing model ice sheets against structures and monitoring the ice forces during the ice/structure interaction. The parameters, varied during the test program, were the geometry of the bridge piers and the velocity, thickness, and flexural strength of the ice. The results are presented in the form of ice forces on sloping and vertical structures with different geometries. During ice action on sloping structures, a phenomenon of transition of failure mode from bending to crushing was observed as the ice velocity was steadily increased.

Beschreibung / Inhaltsverzeichnis: An evaluation of an impulse radar system for detecting cavities under concrete pavement is discussed, and field results are presented. It was found that a dual antenna mode of surveying was ideal for void detection. In this mode one antenna operated in a transceive mode and a second, offset from the first, operated in a receive-only mode. This arrangement allowed a refraction-type profile survey to be performed, which enabled subpavement voids to be easily detected. Field trails were held at Plattsburgh Air Force Base, where 28 cavities were detected and mapped. Drilling of holes verified that a cavity existed and allowed cavity depth to be measured. The cavities varied from 1.5 in. to 23 in, depth and were up to 20 ft. long.

Beschreibung / Inhaltsverzeichnis: This paper documents the development and verification of two finite difference models that solve the general two-dimensional form of the heat conduction equation, using the alternative-direction implicit method. Both can handle convective, constant flux, specified temperature and semi-infinite boundaries. The conducting medium may be composed of many materials. The first program, ADI, solves for the case where no change of state occurs. ADIPC solves for case where a freeze/thaw change of phase may occur, using the apparent heat capacity method. Both models are verified by comparison to analytical results.

Beschreibung / Inhaltsverzeichnis: A new experimental method for measuring the soil-water diffusivity of frozen soil under isothermal conditions is introduced. The theoretical justification of the method is presented and the feasibility of the method is demonstrated by experiments conducted using marine-deposited clay. The measured values of the soil-water diffusivity are found comparable to reported experimental data.

Beschreibung / Inhaltsverzeichnis: Investigations of ground radar performance over thawed and seasonally frozen silts, and sands and gravels containing artificial and natural reflectors were carried out in Alaska. The radar emitted 5-10 ns pulses, the center frequency of which was approximately 150 MHz. The artificial reflectors were metal sheets and discs and the natural reflectors were the groundwater table and interfaces between frozen and thawed material. The water table was profiled at three sites where the subsurface material was coarse-grained alluvium. Dielectric constants of 16 to 18 were measured for the thawed silts, 6 to 7 for the frozen silts and 3 to 9 for the sands and gravels. Signal penetration in the thawed high moisture content silts may be achieved only by use of a lower frequency radar, whereas in the sands and gravels greater depths may be detected with more sophisticated signal processing.

Beschreibung / Inhaltsverzeichnis: The problems associated with measuring stresses in ice are reviewed. Theory and laboratory test results are then presented for a stiff cylindrical sensor made of steel that is designed to measure ice stresses in a biaxial stress field. Loading tests on freshwater and saline ice blocks containing the biaxial ice stress sensor indicate that the sensor has a resolution of 20 kPa and an accuracy of better than 15% under a variety of uniaxial and biaxial loading conditions. Principal stress directions can also be determined within 5 degrees. The biaxial ice stress sensor is not significantly affected by variations in the ice elastic modulus, ice creep or differential thermal expansion between the ice and gauge. The sensor also has a low temperature sensitivity (5 kPa/deg C).

Beschreibung / Inhaltsverzeichnis: Ice accreted on high-speed rotors operating in supercooled fog can be thrown off by centrifugal force, creating severe unbalance and dangerous projectiles. A simple force balance analysis indicates that the strength of accreted ice and its adhesive strength can be obtained by measuring the thickness of the accretion, the location of the separation, the rotor speed, and the density. Such an analysis was applied to field and laboratory observations of self-shedding events. The results agree reasonably well with other observations.

Beschreibung / Inhaltsverzeichnis: Ice action on two cylindrical and conical structures, located side by side, was investigated in a small-scale experimental study to determine the interference on the ice forces generated during ice-structure interaction. The proximity of the two structures changes the mode of ice failure, the magnitude and direction of ice forces on the individual structure, and the dominant frequency of ice force variations. Interference effects were determined by comparing the experimental results of tests at different structure spacings.

Beschreibung / Inhaltsverzeichnis: Secondary recovery of oil at Prudhoe Bay, Alaska, will involve transporting large quantities of seawater in elevated pipelines across tundra for injection into oil-bearing rock strata. The possibility of a pipeline rupture raises questions concerning the effects of seawater on tundra vegetation and soils. To evaluate the relative sensitivities of different plant communities to seawater, eight sites representing the range of vegetation types along the pipeline route were treated with single, saturating applications of seawater during the summer of 1980. Within a month of the treatment 30 of 37 taxa of shrubs and forbs in the experimental plots developed clear symptoms of stress, while none of the 14 graminoid taxa showed apparent adverse affects. Live vascular plant cover was thus reduced by 89 and 91% in the two dry sites and by 54, 74 and 83% in the three moist sites, respectively. Live(green) bryophyte cover was markedly reduced in the moist experimental sites in 1981. Bryophytes in all but one of the wet-site experimental plots were apparently unaffected by the seawater treatment. Two species of foliose lichens treated with seawater showed marked deterioration in 1981. All other lichen taxa were apparently unaffected by the seawater treatment. The absorption and retention of salts by the soil is inversely related to the soil moisture regime. In the wet sites, conductivities approached prespill levels within about 30 days. In such sites, spills at the experimental volumes are quickly diluted and the salts flushed from the soil. In the dry sites, on the other hand, salts are retained in the soil, apparently concentrating at or near the seasonal thaw line.

Beschreibung / Inhaltsverzeichnis: A thermodynamic model has been developed that for the first time describes the entire creep process, including primary, secondary, and tertiary creep, and failure for both constant stress (CSR) tests (σ= const.) and constant strain rate (CSR) tests (ϵ = const.), in the form of a unified constitutive equation and unified failure criteria. Deformation and failure areconsidered as a single thermoactivated process in which the dominant role belongs to the change of entropy. Failure occurs when the entropy change is zero. At that moment the strain rates in CS tests reach the minima and stress in CSR tests reaches the maximum (peak) values. Families of creep (ϵ vs τ) and stress-strain (σ vs ϵ) curves, obtained from uni-axial compression CS and CSR tests of frozen soil, respectively (both presented in dimensionless coordinates), are plotted as straight lines and are superposed, confirming the unity of the deformation and failure process and the validity of the model. A method is developed for determining the parameters of the model, so that creep deformation and the stress-strain relationship of ductile materials such as soils can be predicted based upon information obtained from either type of test.

Beschreibung / Inhaltsverzeichnis: Diatom species composition and relative abundances were determined for ice cores obtained from Weddell Sea pack ice during the October-November 1981 Weddell Polynya Expedition (WEPOLEX). Ice thickness and salinity indicate that the ice was less than one year old. The predominant ice type (70%) was frazil, which has the capacity to mechanically incorporate biological material through nucleation and scavenging. Diatoms were found throughout the length of the cores. Species showed down-core fluctuations in abundance that appeared to be correlated with changes in ice type. Pennate forms were more abundant than centrics, the average ratio being 16:1. Diatom frustules with intact organic material were more abundant (5 billion cells/liter). Differences in species abundances are attributed initially to incorporation of algal cells from a temporally changing water column and subsequently to diatom reproduction within the ice. Scanning electron micrographs illustrating the morphologic characteristics of the predominant species are included.

Beschreibung / Inhaltsverzeichnis: An expression relating aerosol growth to cold environmental conditions was developed. This was accomplished by solving the diffusion equation with the method of Laplace transformation. The series solution was expressed in terms of the dimensionless parameters K (ratio of vapor density over droplet surface to droplet density), ω (ratio of environmental vapor density at time zero to vapor density over droplet surface), and dimensionless time τ (ratio of product of diffusion coefficient D and time t to square of initial radius of condensation nucleus). To take into account the variation of the vapor density over the surface of an acidic condensation nucleus due to the continuous dilution of the droplet, the solution was obtained by assuming various levels of constant vapor concentration. The final expression [R/R sub o - 1 = 2.4917 x 10 to the minus 18th power) exp(0.0737 θ) (P sub RHS/25) x (100-P sub RHS) τ to the 0.9890 powder] can be used to compute the value of R once the values of initial radius R sub o, relative humidity P sub RH, percent of relative humidity at the droplet surface P sub RHS, and environmental temperature θ are given.

Beschreibung / Inhaltsverzeichnis: Ice problems developed in the Sault Ste. Marie, Michigan, portion of the St. Marys River because of winter navigation. Passing ships and natural influences moved ice from Soo Harbor into Little Rapids Cut in sufficient quantities to jam, cause high water in the harbor, and prevent further ship passage. After physical model and engineering studies, two ice booms with a total span of 1375 ft (419 m) with a 250-ft (76-m) navigation opening between were installed at the head of Little Rapids Cut in 1975. A modest field study program on the booms was conducted for the ensuring four winters to determine ice and boom interaction and the effects of ship passages on the system. Forces on some anchors were recorded and supplemental data were taken by local personnel. Several reports have been written about the booms' early operations. This paper presents four-year summary of the main effects of the booms on ice and ship interaction and vice versa. Throughout the four winter seasons, the small quantities of ice lost over and between the booms were manageable. Ships usually passed through the boom without influencing the boom force levels, but at time they brought about large changes. One boom needed strengthening, and artificial islands were added for upstream ice stability. Coast Guard icebreakers were also a necessary part of winter navigation in this area.

Beschreibung / Inhaltsverzeichnis: This report describes the equipment and procedures that were used for acquiring, preparing and testing samples of multi-year sea ice. Techniques and procedures are discussed for testing ice samples in compression and tension at constant strain rates and constant loads, as well as in a conventional triaxial cell. A detailed account is given of the application and measurement of forces and dispiacements on the ice test specimens under these different loading conditions.

Beschreibung / Inhaltsverzeichnis: Experiments were conducted in CRREL's refrigerated flume facility to examine the two-dimensional force distribution of a floating, fragmented ice cover restrained by a boom in a simulated river channel. To determine the force distribution, a vertically walled channel, instrumented for measuring normal and tangential forces, and an instrumented restraining boom were installed in a 40.0- by 1.3-m flume. Two sizes of polyethylene blocks and two similar sizes of fresh-water ice blocks were tested using water velocities ranging from 10 to 30 cm/s. The forces measured at the instrumented boom leveled off with increasing cover length. The contribution of the increasing shear forces developed along theshorelines to this leveling off in the data was clearly evident. The shear coefficients of the polyethylene blocks averaged 0.43, and the freshwater ice averaged 0.044. The normal force measured along the instrumented shoreline could not be related simply by a K coefficient to the longitudinal force; another expression was required, with a term being a function of the cover thickness and independent of the undercover shear stress or cover length. By adding this term, good agreement was then found between the measured and predicted values of the boom forces and the shoreline normal and shear forces

Beschreibung / Inhaltsverzeichnis: Observations of shore ice pile-up and ride-up along the Alaska Beaufort Sea coast in 1983 and 1984 are presented. New information on historical accounts of onshore ice movement, uncovered since publication of Part I in this series, is reported. An account is given of ice overtopping a concrete caisson exploration island in the Canadian Beaufort Sea.