ALBERT

Description / Table of Contents: INTRODUCTION The awareness that mankind is able to influence and modify not only the local but also the global climate has led to a strongly growing interest in climate research. Strengthened research activities, which also made use of improved and novel experimental techniques, have yielded a wealth of information on climatic patterns in the past. At the same time, climate modelling has made much progress. While some questions have been answered, new problems have been recognized. One question related to anthropogenio climatic change is about the nature and causes of natural variations, against the background of which man-made changes must be viewed. The contributions to this volume all deal with the variabilitY of climate. Some papers are reviews of the knowledge to a current topic, others have more the character of an original contribution. The obseryational studies cover the range from year-to-year variations up to glacial-interglacial contrast, thereby going from instrumental data to results from proxy records...

Description / Table of Contents: PREFACE The search for tin dates back to the earliest days of civilization. For about 40 years, world tin mining has oscillated at a level of 150,000-250,000 t Sn/year, with a mine output in 1989 of 210,000 t Sn (MCS 1990). This figure corresponds to a current annual value of about US$1.5 billion and places tin ninth on the metal market behind iron, gold, uranium, copper, zinc, silver, platinum and nickel. Tin deposits belong to the granite-related ore deposit spectrum which includes many metals vital to current and future technologies such as Cu, W, Mo, U, Nb, Ta, Ag, Au, Sb, Bi, As, Pb, Zn, REE, Be, Ga and Li. The granitic rocks associated with tin and tin-tungsten deposits have long been identified as a special group of granites, the so-called tin granites. These rocks provide a unique opportunity to study the magmatic and hydrothermal history of tin ore formation. Tin granites are more easily identifiable as parent rocks for tin (and tungsten) mineralization than is the case for other mineralized granitic rocks such as molybdenum and copper porphyries. The magmatic molybdenum and copper distribution patterns are more complex (control by sulfide solubilities), and commonly obliterated by fluid interaction. The relatively simple situation of tin granites provides therefore an invaluable opportunity to study some metallogenic aspects of magmatic-hydrothermal ore deposits in general. The present study attempts to develop a general metallogenic model for tin in identifying the essential or relevant processes in tin ore formation. The methodological principle is based, on an interplay between a background of some basic petrogenetic concepts and a number of specific local and regional data on tin deposits and tin provinces, with particular reference to those areas with which the author is most familiar with (Bolivia, SE Asia, Europe). This inductive approach condenses the many apparently specific complexities encountered in individual ore deposits to a few major processes of general importance. The inherent reductionism may have a personal bias which is probably inevitable in any simple and broad-scale picture ("Apr6s tout, la raison est bien I'esclave des passions"; Feyerabend 1979:210). The critical problem of the relevance of those factors chosen for our model can be judged by its degree of consistency and predictive capability for new and analogous cases...

Description / Table of Contents: PREFACE This volume comprises the main lectures delivered at the Fourth International Summer School in the Mountains on "Mathematical and Numerical Techniques in Physical Geodesy", held from August 25 to September 5, 1986 in Admont, Austria. The School was organized by the Institute of Theoretical Geodesy of the Technical University Graz, Austria under the auspices of the International Association of Geodesy. All five continents were represented by 70 participants from over 20 countries. The purpose of the Summer School was to provide an introduction to advanced techniques which represent the mathematical vehicle for the treatment of modern geodetic problems, to familiarize participants with the present state of the art of global and local gravity field determination methods, ranging from orbit theory, the key satellite techniques, to inertial and standard terrestrial methods, and to discuss future scientific developments. The arrangement of this volume matches the sequence of lectures given at the School. The theoretical PART A represents the mathematical framework of modern physical geodesy, the application PART B deals with the key satellite and surface techniques, providing the detailed structure of the earth's gravity field. PART A: One of the main goals in physical geodesy, global and local gravity field determination, is pursued by extensively applying functional analytic methods. Recently special attention is being given to the base function and norm choice problem, and to the establishment of a sound link between density distributions inside the earth as the source and observed or estimated gravity field quantities as the effect. The lectures by C.C. Tscherning focus on this topic. Space and time dependent problems of discrete and continuous type are encountered in modern geodesy nowadays and dealt with in the lectures by F. Sans6. Estimation theory either in its stochastic or statistic formulation plays a key role in the processing of processes like the earth's gravity field. The consistent processing of large structured data sets calls for equally structured numerical algorithms. Spectral analysis with its powerful fast Fourier transform has become a common tool for the treatment of such problems. An introduction to spectral methods, supplemented by numerous examples, is provided by B. Hofmann-Wellenhof and H. Moritz. PART B: The theory of orbit dynamics, tailored to the near circular orbits of most geodetic satellites, is fundamental to modern geodetic satellite techniques and discussed in the lectures by O.L. Colombo. Particular emphasis is put on the interplay between orbit perturbations and the earth's disturbing gravity field and its mapping by satellite techniques like satellite altimetry, satellite-tosatellite tracking and satellite gradiometry. Satellite gradiometry, which is discussed in the lectures by R. Rummel in detail, with regard to the geometric structure of the gravitational field, the observability of the gradients, and the mathematical model underlying the gravity field recovery problem, promises to provide particularly detailed information about the gravity field of our planet. The global structure of the earth's gravity field is described in terms of earth gravity field models which are derived from both satellite and surface data. The many delicate, mathematically as well as numerically challenging problems, related to the consistent processing of very large space distributed data sets, and proposed solutions are presented in the lecture by R.H. Rapp. For many years various attempts have been made to explain the shorter wavelength part of the earth's anomalous gravity field by isostatic phenomena. Recently several high resolution topographicisostatic earth models have been computed based on global digital terrain data using different techniques fo~ the estimation of the parameters of the chosen isostatic model. A declared goal is the maximum smoothing of the observed gravity field by removing the contribution of the topography and its isostatic compensation. This topic is discussed in the lectures by H. SUnkel. Inertial methods are steadily gaining importance, power and application. This is not only due to hardware improvements in terms of precision and reliability, but also due to recent advances in the mathematical and numerical modelling of the system's performance. An investigation of the error characteristics of inertial survey systems and their interaction with the anomalous gravity field, studied in the framework of dynamic system analysis, is the topic of the lectures by K.-P. Schwarz and the key issue for further improvements and possible integrations with other positioning systems. Geodetic data have both geometric and physical ingredients of various nature. Standard geodetic processing procedures aim at a separation of geometry from physics. Integrated geodesy, in contrast, has been designed as a very sophisticated melting pot which handles practically all available geodetic data in a consistent and optimal way.lt handles surface and satellite data with either geometrically or gravity field dominated content, and geophysical data in terms of density and seismic informatlon just as well and represents as such the great synthesis of mathematical modelling in connexion with geodetic data processing techniques; these advanced ideas are presented in the lectures by G. Hein. This volume presents highlights of modern geodetic activity and takes the reader to the frontiers of current research. It is not a textbook on a closed and limited subject, but rather a reference book for graduates and scientists working in the vast and beautiful, demanding but rewarding field of earth science in general and physical geodesy in particular. The editor expresses his appreciation to all authors of this volume for their advice and help in formulating and designing the scientific program of the Summer School, for providing typewritten lecture notes, and for their excellent cooperation.

Description / Table of Contents: PREFACE The suggestion to compile and publish this volume dealing with some geoscientific problems of the Central Andes came up during a conference on "Mobility of Active Continental Margins" held in Berlin, February 1986. At this international conference, organized by the Berlin Research Group "Mobility of Active Continental Margins", colleagues from Europe, Southern and Northern America reported on their current investigations in the Central Andes. The Central Andes claim a special position in the 7000 km long Andean mountain range. In Northern Chile, Southern Bolivia and Northwest Argentina the Central Andes show their largest width with more than 650 km and along a Geotraverse between the Pacific coast and the Chaco all typical Andean morphotectonic units are well developed. Here, the pre-Andean evolution is documented by outcropping of Paleozoic and pre-Cambrian rocks. The characteristic phenomena of the Andean cycle can be studied along the entire geotraverse. The migration of the tectonic and magmatic activity starting in Jurassic and being active t i l l Quaternary is clearly evidenced. Besides the Himalaya, the Central Andes show with 70-80 km and -400 mgal the largest crustal thickness known in mountain ranges. These and many other interesting and exciting geoscientific features encouraged a group of geoscientists from both West-Berlin universities (Freie UniversitAt and Technische UniversitAt) to focus their studies along a geotraverse through the Central Andes. The realization of these studies would not have been possible without the active assistance and close cooperation of our colleagues from the geoscientific institutions in Salta (Argentina), La Paz and Santa Cruz (Bolivia) and Antofagasta and Santiago (Chile). Concerning the German participation, this joint and interdisciplinary project is financially supported since 1982 as Reserach Group" Mobility of Active Continental Margins" by the German Research Society and by the West-Berlin universities as well. A number of colleagues from universities in West Germany take part in this project, too. The papers presented here deal with the period from Late Precambrian up to the youngest phenomena in Quaternary. The contributions cover the whole spectrum of geoscientific research, geology, paleontology, petrology, geochemistry, geophysics and geomorphology. In conclusion, the data published here may help to improve the picture of Andean structure and evolution. The detailed investigations carried out in the past years show, that the first simple plate tectonic models proposed in the beginning of the seventies have to improved and modified. Furthermore, the results can be seen as contribution to the international Lithospheric Project and as a useful data base for the construction of a Central Andean Transect...

Description / Table of Contents: The present study will provide an introduction into the biomechanics of trees and will give a critical survey of the phylogeny and the constructional principles of the tree habit. Since the trunk is considered the basic and crucial element of a tree, the analysis is largely restricted to a functional comparison of the stem anatomy of the various tree forms. It is based on the concept of constructional morphology, thus considering simultaneously the functional aspect and the ontogenetical and phylogenetical development of the various trunk types. The main questions to be answered in this study are; Why do trees exist? - Which are the constructional principles of tree trunks and when and in which group of plants do they appear? - How important are internal (phylogenetic) and external (functional, constructional) constraints? - What are the specific properties of the different constructional principles and does a correlation between trunk design and growth habit exist? - Is there a tendency in phylogeny to a better performance? The study does not (and cannot) intend to provide a detailed biophysical analysis of individual cases because experimental data on the mechanical properties of the structural elements of the different kinds of trees are still lacking. Instead, it will he the task to evaluate in a comprehensive and qualitative or semi-quantitative manner the available data of the morphology, anatomy and phylogeny of fossil and recent trees by using concepts of biomechanics and constructional morphology. Thus a somewhat holistic approach is used, which is becoming increasingly more acceptable today.

Description / Table of Contents: This book is the collection of the Lecture Notes of an International Summer School of Theoretical Geodesy held in Assisi (Italy) from May 23 to June 3 -1988.

Description / Table of Contents: PREFACE Turbidity currents have been comprehensively studied in the past although much remains unknown about both their flow characteristics and resultant sedimentary deposits. Much of this uncertainty arises from the catastrophic nature of their formation which makes them difficult to study in the environment, and has resulted in the majority of studies being experimental or theoretical. Experiments have shown that reversals in the flow of density currents can be associated with the generation of internal solitary waves. This is in contrast to the belief held by many workers that the reversal of a turbidity current simply generates an identical flow travelling in the opposite direction. This book arose from the need for a detailed experimental study to examine the effects and to consider the consequences of density current reversals from a variety of obstructions to their flow. The first part of this book comprises a detailed review of literature covering the fluid dynamics and sedimentology relevant to the experimental study (chapter one). Chapter two presents the results from the comprehensive experimental programme which are discussed and compared with appropiate theoretical hypotheses. This permits the synthesis of a model for the general features of flows that result from the incidence of density currents upon obstructions to the flow. The application of this model to both modern and ancient turbidite systems is then discussed in chapter three. This book is suitable for earth scientists with an interest in the dynamics of turbidity currents. In addition, workers from other fields such as applied maths, meteorology and engineering who have an interest in density currents and bores in practical situations may find it useful...

Description / Table of Contents: INTRODUCTION The study is essentially empirical, since it portrays and appraises two different water management systems, and relates them to one another. Yet the analysis has also been made with definite research aims in mind. Its focus has been narrowed down to the environmental assessment of urban water management systems in arid and semi-arid regions, especially with an eye to deal with information problems in the Developing World. The study addresses a set of very critical issues of global concern, and, thus, delineates a crucial topic for international research. The fact that a wide range of critical issues usually complicates and aggravates the given problem setting provides the comparative analysis with a special practical incentive to explore the opportunities for joint strategies and comprehensive solutions. However, the complexities involved between water management and the environment and the relative lack of a joint theory in that field pose certain difficulties to such an undertaking. In order to fully appreciate the underlying purpose of the study and the scope of its implications, the various facets of the problem setting and the essential ingredients of the general line of approach have first to be unravelled and expounded at some length. Above all, it needs to be shown how these facets combine to produce the complex, burning issues which in turn seem to, both in theory and practice, require correspondingly intricate, strategic approaches for their solutions...

Description / Table of Contents: PREFACE Seismic imaging is the process through which seismograms recorded on the Earth's surface are mapped into representations of its interior properties. Imaging methods are nowadays applied to a broad range of seismic observations: from nearsurface environmental studies, to oil and gas exploration, even to long-period earthquake seismology. The characteristic length scales of the features imaged by these techniques range over many orders of magnitude. Yet there is a common body of physical theory and mathematical techniques which underlies all these methods. The focus of this book is the imaging of reflection seismic data from controlled sources. At the frequencies typical of such experiments, the Earth is, to a first approximation, a vertically stratified medium. These stratifications have resulted from the slow, constant deposition of sediments, sands, ash, and so on. Due to compaction, erosion, change of sea level, and many other factors, the geologic, and hence elastic, character of these layers varies with depth and age. One has only to look at an exposed sedimentary cross section to be impressed by the fact that these changes can occur over such short distances that the properties themselves are effectively discontinuous relative to the seismic wavelength. These layers can vary in thickness from less than a meter to many hundreds of meters. As a result, when the Earth's surface is excited with some source of seismic energy and the response recorded on seismometers, we will see a complicated zoo of elastic wave types: reflections from the discontinuities in material properties, multiple reflections within the layers, guided waves, interface waves which propagate along the boundary between two different layers, surface waves which are exponentially attenuated with depth, waves which are refracted by continuous changes in material properties, and others. The character of these seismic waves allows seismologists to make inferences about the nature of the subsurface geology. Because of tectonic and other dynamic forces at work in the Earth, this first-order view of the subsurface geology as a layer cake must often be modified to take into account bent and fractured strata. Extreme deformations can occur in processes such as mountain building. Under the influence of great heat and stress, some rocks exhibit a taffy-like consistency and can be bent into exotic shapes without breaking, while others become severely fractured. In marine environments, less dense salt can be overlain by more dense sediments; as the salt rises under its own buoyancy, it pushes the overburden out of the way, severely deforming originally flat layers. Further, even on the relatively localized scale of exploration seismology, there may be significant lateral variations in material properties. For example, if we look at the sediments carried downstream by a river, it isclear that lighter particles will be carried further, while bigger ones will be deposited first; flows near the center of the channel will be faster than the flow on the verge. This gives rise to significant variation is the density and porosity of a given sedimentary formation as a function of just how the sediments were deposited. Taking all these effects into account, seismic waves propagating in the Earth will be refracted, reflected and diffracted. In order to be able to image the Earth, to see through the complicated distorting lens that its heterogeneous subsurface presents to us, in other words, to be able to solve the inverse scattering problem, we need to be able to undo all of these wave propagation effects. In a nutshell, that is the goal of imaging: to transform a suite of seismograms recorded at the surface of the Earth into a depth section, i.e., a spatial image of some property of the Earth (usually wave speed or impedance). There are two main types of spatial variations of the Earth's properties. There are the smooth changes (smooth meaning possessing spatial wavelengths which are long compared to seismic wavelengths) associated with processes such as compaction. These gradual variations cause ray paths to be gently turned or refracted. On the other hand, there are the sharp changes (short spatial wavelength), mostly in the vertical direction, which we associate with changes in lithology and, to a lesser extent, fracturing. These short wavelength features give rise to the reflections and diffractions we see on seismic sections. If the Earth were only smoothly varying, with no discontinuities, then we would not see any events at all in exploration seismology because the distances between the sources and receivers are not often large enough for rays to turn upward and be recorded. This means that to first order, reflection seismology is sensitive primarily to the short spatial wavelength features in the velocity model. We usually assume that we know the smoothly varying part of the velocity model (somehow) and use an imaging algorithm to find the discontinuities. The earliest forms of imaging involved moving, literally migrating, events around seismic time sections by manual or mechanical means. Later, these manual migration methods were replaced by computer-oriented methods which took into account, to varying degrees, the physics of wave propagation and scattering. It is now apparent that all accurate imaging methods can be viewed essentially as linearized inversions of the wave equation, whether in terms of Fourier integral operators or direct gradient-based optimization of a waveform misfit function. The implicit caveat hanging on the word "essentially" in the last sentence is this: people in the exploration community who practice migration are usually not able to obtain or preserve the true amplitudes of the data. As a result, attempts to interpret subtle changes in reflector strength, as opposed to reflector position, usually run afoul of one or more approximations made in the sequence of processing steps that makes up a migration (trace equalization, gaining, deconvolution, etc.) On the other hand, if we had true amplitude data, that is, if the samples recorded on the seismogram really were proportional to the velocity of the piece of Earth to which the geophone were attached, then we could make quantitative statements about how spatial variations in reflector strength are related to changes in geological properties. The distinction here is the distinction between imaging reflectors, on the one hand, and doing a true inverse problem for the subsurface properties on the other. Until quite recently the exploration community was exclusively concerned with the former, and today the word "migration" almost always refers to the imaging problem. The more sophisticated view of imaging as an inverse problem is gradually making its way into the production software of oil and gas exploration companies, since careful treatment of amplitudes is often crucial in making decisions on subtle lithologic plays (amplitude versus offset or AVO) and in resolving the chaotic wave propagation effects of complex structures. When studying migration methods, the student is faced with a bewildering assortment of algorithms, based upon diverse physical approximations. What sort of velocity model can be used: constant wave speed v? v(x), v(x, z), v(x, y, z)? Gentle dips? Steep dips? Shall we attempt to use turning or refracted rays? Take into account mode converted arrivals? 2D (two dimensions)? 3D? Prestack? Poststack? If poststack, how does one effect one-way wave propagation, given that stacking attenuates multiple reflections? What domain shall we use? Time-space? Time-wave number? Frequency-space? Frequency-wave number? Do we want to image the entire dataset or just some part of it? Are we just trying to refine a crude velocity model or are we attempting to resolve an important feature with high resolution? It is possible to imagine imaging algorithms that would work under the most demanding of these assumptions, but they would be highly inefficient when one of the simpler physical models pertains. And since all of these situations arise at one time or another, it is necessary to look at a variety of migration algorithms in daily use. Given the hundreds of papers that have been published in the past 15 years, to do a reasonably comprehensive job of presenting all the different imaging algorithms would require a book many times the length of this one. This was not my goal in any case. I have tried to emphasize the fundamental physical and mathematical ideas of imaging rather than the details of particular applications. I hope that rather than appearing as a disparate bag of tricks, seismic imaging will be seen as a coherent body of knowledge, much as optics is...

Description / Table of Contents: PREFACE Some of the major ecological and social problems of the present and future are the production, treatment, and disposal of anthropogenic wastes. Iaais is equally true for sparsely and densely populated industrial areas, including large countries in which sites for waste disposal would seem to be readily available. Especially nonradioactive hazardous wastes with their long-term toxicity need to be isolated from the biosphere just as effectively as radioactive substances. The long-term safety required of waste disposal sites can only be assured under specific geological and mineralogical conditions in certain parts of the lithosphere (underground repositories). The subjects related to the production, avoidance, treatment, and disposal of anthropogenic wastes cover a range of knowledge encompassing the natural sciences, engineering, medicine, and law. This work presents some fundamental situations and problems conceming the disposal of toxic hazardous wastes which have been dealt with in several research projects. The individual chapters are related scientifically. Long-term, effective solutions to our waste problems can only be found when interrelationships and possible future developments are considered. Only the current status of this rapidly developing field can be discussed here. The individual chapters contain scientifically founded data and observations. Other aspects for which there are still controversial opinions and arguments are also discussed, which should stimulate further thought. Further developments and scientific advances can only be achieved by constantly challenging previous theories, and not through static observation and narrow-mindedness. The most extensive quantification possible of the problems related to disposal of hazardous wastes is an essential aim of our work. This not only involves calculating the volume of waste and available repository space, but also compiling data on the long-term effects and the safe, long-term isolation of anthropogenic wastes from the biosphere. A simple description of conditions and processes without using concrete data, which is still widespread, is rejected since it frequently leads to pure speculation. The scientific fundamentals and results presented in this work are of general validity for many questions concerning waste disposal. One example is the amount of waste produced annually in Germany, in which toxic, hazardous wastes play a major role. FoIlowing this train of thought, available data are used to show how limited the possibilities are for the long-term safe underground deposition of hazardous wastes with respect to the current quantities of waste. Of utmost importance is information on the 10ng-term effects of toxic wastes, as well as criteria which have to be considered with respect to the long-term safe deposition of hazardous waste. The natural chemical cycles and material transport in the various zones of the earth are the focus of interest here. They are the scientific basis for assessing every repository for anthropogenic wastes in geological systems. Therefore the significance of material transport and geochemical cycles is emphasized regarding all questions concerning the long-term safety of repositories on the earth's surface and in the lithosphere. Thus, our concept for the scientific evaluation of the long-term safety of underground repositories in geological systems differs from all other models presently under discussion in Germany. In this work, marine evaporites are discussed with respect to the underground deposition of hazardous wastes and the long-term safety of underground repositories in salt rocks. The isolation of hazardous materials from the biosphere can above all be influenced by fluid phases. Fluid phases can mobilize and transport hazardous materials through rocks in the biosphere. This is true, without exception, for all magmatic, sedimentary, and metamorphic rocks, and for marine evaporites, too! In Germany evaporites have commonly been considered to be completely impermeable with respect to fluid phases (solutions and gases). This erroneous view stems from a complete lack of knowledge or misestimation of the dynamic evolution of the composition of evaporite bodies. Unfortunately, this is still true today for parts of some state agencies which deal with repositories. However, all observations of evaporite bodies made over the last more than 100 years have clearly shown that under certain conditions fluid and gaseous components are mobile in evaporites as well. Solutions in marine evaporites have been the object of personal interest and scientific research of A.G. Herrmann for 40 years. The occurrence and formation of salt solutions in the various salt mining districts of Germany are presently being restudied and reevaluated on an extended scientific basis (e.g., v. BORSTEL 1992). A presentation of the current knowledge on salt solutions is beyond the scope of this publication. However, in the interest of continuing research a research project proposed by A.G. Herrmann (1987b) will be introduced here. The direct quantitative analysis of the chemical composition (quatemary and quinary systems) of small fluid inclusions in rocks of the salt deposits of Hessen and Niedersachsen are the primary focus of this project. Information important to fundamental research on the formation and alteration of salt rocks and on the long-term safety of underground repositories should be gained from these studies (e.g., HERRMANN & v. BORSTEL 1991). In addition to salt solutions, gases are also fluid components which occur in practically all marine evaporite deposits. Hence, both salt solutions and gases must be carefully considered when planning underground repositories in an evaporite body and evaluating their long-term safety. This publication contains an up-to-date overview of the gas occurrences in the marine evaporites of Central Europe. Despite previous studies, there is still a considerable deficit in scientific information regarding the distribution and formation of gases in the evaporites occurring in Germany. A detailed research program on the geochemical relationships involving the formation of evaporites and gases will draw attention to this situation. One aspect must be emphasized in the planning and construction of repositories for anthropogenic wastes: their long-term safety. This publication deals precisely with this subject, and in Part III of this work we will present the concept that we have developed. This concept is based on the fact that evaporite bodies are subject to a dynamic evolution and that the chemical and mineralogical composition provides important information on the effect of fluid phases on salt rocks. Previous works contain the testing of methods and presented initial results using the Gorleben salt dome as an example. However, we are just at the beginning of our research project on the long-term safety of underground repositories (e.g., HERRMANN & KNIPPING 1989, HERRMANN 1992). The information contained in this publication is based on years of experience in evaporite research and underground repositories for anthropogenic wastes. Examples are presented which can be applied to similar situations and problems in other countries. Waste disposal is not just a national problem, it has long become an international one for all types of anthropogenic wastes...