ALBERT

Description / Table of Contents: Introduction / Pages 1-32 --- Interpretation using nomograms / Pages 33-47 --- Linear parameters / Pages 49-114 --- Non-linear parameters / Pages 115-173 --- Maximum likelihood and maximum entropy / Pages 175-193 --- Analytic inversion / Pages 195-211 --- Advanced inversion methods / Pages 213-227 --- Error analysis / Pages 229-243 --- Parallel computation in modelling and inversion / Pages 245-255

Description / Table of Contents: INTRODUCTION The International Summer School of Theoretical Geodesy on Satellite Altimetry in Geodesy and Oceanography was held in Trieste (Italy) from May 25 to June 6, igg2. It was organized by Prof. R. Rummel of the Delft University of Technology and by Prof. F. Sansò of the Politecnico di Milano and was attended by 63 participants and 7 lecturers from 17 countries. The School was hosted by the International Centre of Theoretical Physics of Trieste. Satellite altimetry provides a lot of data that require more and more sophisticated models in order to be interpreted and exploited. One of the main problems related to the practical treatment of the data can be summarized as follows: oceanographers would like to ask geodesists to compute precise orbits and a precise geoid in order to put into evidence the Sea Surface Topography that can be interpreted as an oceanographic signal related to currents and to several physical parameters; on the other hand, geodesists would like to ask oceanographers to a-priori determine the Sea Surface Topography, in order to be able to extract from the altimeter data the geoid and the orbit errors to be used in the gravity field modelling. The solution to this dilemma can only be found in a cooperative frame. An integrated model to be used for a single-step treatment of altimetry is probably far to be defined, so at present geodesists and oceanographers must cooperate to obtain step-wise and iterative modelling of the gravity field and of the oceanographic phenomena. This is precisely the reason why the school on Satellite Altimetry was organized on an interdisciplinary basis...

Description / Table of Contents: PREFACE This book represents the first attempt in three decades to marshall out available information on the regional geology of Africa for advanced undergraduates and beginning graduate students. Geologic education in African universities is severely hampered by the lack of a textbook on African regional geology. This situation is greatly exacerbated by the inability of most African universities to purchase reference books and maintain journal subscriptions. Besides, geologic information about Africa is so widely dispersed that a balanced and comprehensive course content on Africa is beyond the routine preparation of lecture notes by university teachers. Since geology is a universal subject and Africa is one of the largest landmasses on Earth with one of the longest continuous records of Earth history, there is no doubt that geologic education in other parts of the world will benefit from a comprehensive presentation of African geologic case histories. The scope of this text also addresses the need of the professional geologist, who may require some general or background information about an unfamiliar African geologic region or age interval. Africa occupies a central position in the world's mineral raw materials trade. Because of its enormous extent and great geologic age, the diversity and size of Africa's mineral endowment is unparalleled. Africa is the leading source of gold, diamond, uranium, and dominates the world's supply of strategic minerals such as chromium, manganese, cobalt, and platinum. Consequently, African nations from Algeria to Zimbabwe depend solely on mineral exports for economic survival. The geologic factors which govern economic mineral deposits are stressed in this text. The geological history of Africa spans 3.8 billion years, a record that is unique both in duration and continuity. Few other parts of our planet match the plethora of geologic phenomena and processes that are displayed in the African continent. From the various stages of crustal evolution decipherable from the Archean of southern Africa, through the plate tectonics scenarios in the ubiquitous Late Proterozoic-Early Paleozoic Pan-African mobile belts and in the Hercynian and Alpine orogenies of northwest Africa, to the East African Rift Valley, Africa is replete with excellent examples and problems for a course on regional tectonics. Teachers of igneous and metamorphic petrology can hardly ignore Africa's anorogenic magmatism (e.g.. layered ultramafic intrusives such as the Great Dyke and the Bushveld Complex; the Tete gabbro-anorthosite pluton; alkaline complexes; basaltic volcanism), or tantalizing highgrade metamorphic terranes such as the Limpopo belt, the Namaqua mobile belt, and the Mozambique belt. From the extensive Precambrian supracrustal sequences throughout the continent with enormous thicknesses of sedimentary rocks that have hardly been deformed or metamorphosed, to the stratigraphic evolution of Africa's present-day passive continental margin, there is a complete spectrum of facies models upon which to base a course on basin analysis and stratigraphy. To maintain its integrity a course on historical geology anywhere in the world must address the theory of Continental Drift beyond invoking past continuities between West Africa and South America. Past connections between West Africa and eastern North America must equally be explored, so also connections between northeast Africa and Arabia, and the paleogeography of southern Gondwana where Africa occupied centre stage. The Precambrian fossil record, the transitions from reptiles to the earliest mammals and dinosaurs, and the evolution of Man are among Africa's unique contributions to the history of life and the story of organic evolution. Although it lies today in the tropics Africa was the theatre of the Earth's most-spectacular glaciations. Even after the scene of continental glaciation had shifted to the northern continents only lately during the Pleistocene, Africa still witnessed spectacular climatic fluctuations during the Quaternary. Certainly students of archeology and paleoanthropology cannot overlook the Quaternary paleoenvironmental record of the Olduvai Gorge in Tanzania, the Lake Turkana basin in Kenya, the Nile valley, the Sahara, and southern Africa. But since African examples have already been cited in standard geologic textbook, I have often been asked why it has become necessary to revive the idea of a full-length textbook on African geology, 30 years after this idea was abandoned by the geologic community. My simple answer, as already stated, is that the wealth of available geologic information about Africa is so enormous and fascinating, but so diffuse, that an attempt must be made to assemble and pass on this knowledge.

Description / Table of Contents: INTRODUCTION While the complex mechanical properties of rocks and soils are studied for quite a while, it is only in the last decades that sound established mathematical models were developed based on accurate experimental data. Some rheological properties of geomaterials as for instance creep, were studied for a long time but the experimental data reported were incomplete and, as a consequence, the models developed have missed either the generality necessary for the solving of engineering problems or some of the major specific mechanical properties possessed by these materials as for instance dilatancy and/or compressibility , long term damage etc. Generally, these very particular empirical models were made for a specific test only and therefore are not appropriate for solving problems involving general loading histories. Let us remind that due to the presence of a great number of cracks and/or pores existing in roks and soils, the mechanical behaviour of geomaterials is quite distinct from that of other materials as for instance metals or plastics. That is why rock and soil rheology has some specific aspects. It must also be mentioned that the solving of various problems of rock and soil mechanics posed by modern technology was not possible by using time-independent models, thus the study and development of rehological models become absolutely necessary. In the last decade or so, very accurate experimantal data became available as a result of the development of experimental techniques and of the growing interest for this field of research in the scientific community. These data, in turn, have made possible the development of genuine models for geomaterials, mainly rheological models, able to describe such properties as creep, dilatancy and/or compressibility during creep, long term damage and failure occurring after various time intervals, slip surface formation etc. Today it is clear that no accurate constitutive equation for rocks can be formulated unless the dilatancy phenomena and the time effects are not included. Another idea is the need of a better description of the concepts of damage and failure of rocks, again using in someway the concepts of irreversible dilatancy or another related notion. In soil rheology it is clear that the scale effect may be taken into consideration in order to obtain a corect information from the routine tests. Also in writing the constitutive equations for soils it is neccessary to take into account the microscopic or local phenomena, because there is a great variety of types of saturated or nonsaturated soils, granular or cohesionless soil etc. The aim of the Euromech Colloquium 196 devoted to Rock and Soil Rheology and therefore that of the present volume too, is to review some of the main results obtained in the last years in this field of research and also to formulate some of the major not yet solved problems which are now under consideration. Exchange of opinions and scientific discussions are quite helpful mainly in those areas where some approaches are controversial and the progress made is quite fast. That is especially true for the rheology of geomaterials, domain of great interest for mining and petroleum engineers, engineering geology, seismology, geophlsics, civil engineering, nuclear and industrial waste storage, geothermal energy storage, caverns for sports, culture, telecommunications, storage of goods and foodstuffs (cold, hot and refrigerated storages), underground oil and natural gas reservoirs etc. Some of the last obtained results are mentioned in the present volume...

Description / Table of Contents: INTRODUCTION Over the past 18 years the author and several colleagues have developed a mathematical model designed to predict the propagation characteristics of acoustic waves in marine sediments. The model is based on the classical work of Maurice Biot who developed a comprehensive theory for the mechanics of porous, deformable media in a series of papers spanning the time period from 1941 to 1973. Since our objective was to develop a practical working model that could be used as a guide in planning and interpreting experimental work, we began with the simplest possible form of the model and added various complexities only as they were needed to explain new variations in the data that were obtained. Thus the number of material parameters that had to be measured or assumed at any stage in the development of the model was kept to a minimum. Since the first version of the model was introduced in 1970, we have published over twenty technical papers covering various stages of its development and many papers have been published by colleagues who have utilized our work in various ways. This monograph is an attempt to summarize the development and use of the model to date. Acoustic waves in ocean sediments may be considered as a limiting case in the more general category of mechanical waves that can propagate in fluid-saturated porous media. The general problem of wave motion in this kind of material has been studied extensively over the past thirty years by engineers, geophysicists and acousticians for a variety of reasons. In some cases, interest is focused on low-frequency waves of rather large amplitude, such as those that arise near the source of an earthquake or near a building housing heavy, vibrating machinery. At other times, the main interest is in waves of low frequency and amplitude that have traversed long distances through the sediment. In still another category, high-frequency waves that are able to resolve thin layering and other fine structural details are of interest in studying near-bottom sediments. Thus the full spread of frequency and amplitude has been studied for geological materials ranging from soft, unconsolidated sediments to rock. Because of the almost limitless combinations of different types of sediment, stratification and structure, accurate mathematical description of the wave field produced by a particular source can be constructed only if accurate descriptions of the acoustic properties of individual components can be specified. These properties depend on the geological history of the sediment deposit, on the frequency content of the wave field and on a number of other factors that depend on the environment in situ. A survey of the literature suggests that there are a number of parameters that play principal roles in controlling the dynamic response of saturated sediments...

Description / Table of Contents: PREFACE Sedimentation as a Three-Component System describes the most common styles of deposition in marine environments as they relate to sediment composition. Three components, organic matter, carbonate, and siliciclastic sediment, may settle concurrently, but at different rates, intermixing on the sea floor to form a particular sediment composition. A change in the flux of one component is capable of relatively diluting or concentrating the other two components, which can be expressed in the characteristic ratio of organic carbon to carbonate in the resulting sediment. The basic concept of this book is to address organic carbon-carbonate associations in terms of depositional inputs and time spans. In addition, the three-component system describes organic carbon changes related to major facies transitions. Examples include models of the genesis of carbonaceous sediments, with their various laminated to bioturbated lithotypes, and numerical organic carbon prediction. I hope that this book will encourage stimulating discussions and promote a new approach to quantitative stratigraphy...

Description / Table of Contents: INTRODUCTION In the context of evolutionary studies, it is the privilege of paleontologists to trace the actual course of evolutionary change over time spans that are adequate for such a slow process. At the same time it is their crux that they can not always hope to do this with the resolution necessary to reveal the causal relationships involved. The Tübingen Sonderforschungsbereich 53, "Palökologie", was primarily geared to study the interrelationships between organisms and environments in the fossil record. As is pointed out in this volume, such an approach will necessarily emphasize the static aspect of this relationship, all the more since this is what we need for the practical purposes of facies recognition. This was clone during a time interval of thirteen years at the level of individual species and taxonomic groups ("Konstruktions-Morphologie"), of characteristic facies complexes ("Fossil-Lagerstätten") and of assemblages ("Fossil- VergeseIlschaftungen") with the aim to recognize general patterns that persist in spite of the historical and evolutionary changes in the biosphere. But as our project came closer to its end, the possible causal relationships between physical and evolutionary changes became more tangible. This trend is expressed by symposia devoted to the biological effects of long term tectonic changes (KULLMANN & SCHÖNENBERG, eds., 1983) and of short term physical events (EINSELE & SEILACHER, eds., 1982). But in retrospect it appears that the time scales of the environmental changes chosen were either too large or too small to reveal the mechanisms of evolutionary response. The present volume is the outcome of a symposium of the projects B 20 ("Bankungsrhythmen in sedimentologischer, ökologischer und diagenetischer Sicht", directed by U. BAYER), D 40 ("Analoge Gehäuse-Aberrationen bei Ammonoideen", directed by J. WIEDMANN) and D 60 ("Substratwechsel im marinen Benthos", directed by A. SEILACHER) in September, 1983. tt addresses environmental changes at time scales large enough to produce more than a local ecological response and short enough to observe evolutionary and/or migratory changes at the species and genus levels. It also focusses on basins which by various degrees of isolation provided suitable sites for "evolutionary experiments", such as lakes and marginal epicontinental basins. In a way, this book is a successor of the previous one on "Cyclic and event stratification" (EINSELE & SEILACHER, eds., 1982). Small scale cycles and events are the 'primitives' of a sedimentary sequence, the lowermost scale from which it can be deciphered. However, medium and long term physical cycles commonly impress sedimentological and lithological trends on the stratigraphic column which are accompanied by faunal replacements and cycles. But since sedimentation is controlled both by physical and biological processes, which are intercorrelated in complicated ways, we also need to decode the stratigraphic text. In this effort, paleontological and sedimentological interpretation must go hand in hand. On the 'megascale' of global sea-level changes faunal and species evolution is triggered by opening and closing of migration pathways, sometimes providing us with malor biostratigraphic boundaries. As it turns out, however, integrated research and the choice of suitable scales do not free us from problems of resolution. Thus our inability to distinguish local speciation from ecophenotypic modification and from immigration in the fossil record excludes definite evolutionary answers even in well studied cases. Nevertheless we hope that this approach opens a fruitful discussion, in which stratigraphy, systematic paleontology and paleoecology will be reconciled in a concerted effort to eventually understand the evolutionary mechanisms of our biosphere.

Description / Table of Contents: PREFACE It was only during the last few years, that the geological effects of storms and hurricanes in shallow-marine environments have been better appreciated. Not only were storm deposits recognized to dominate many shelf sequences, they also proved to be valuable tools in facies and paleogeographical analysis. Additionally, storm layers form important hydrocarbon reservoirs. Storm-generated sequences are now reasonably mell documented in terms of their facies associations in the stratigraphic record. Much less is known, however, about the effects and the depositional processes of modern storms, and about the styles of storm sedimentation on basinwide scales. Accordingly, the goal of this study is two-fold: 1. it presents two case studies of modern carbonate and terrigenous clastics storm sedimentatioq. The models derived from these actualistic examples can be used to interprete possible ancient analogues. 2. it presents a comprehensive analysis of an ancient storm depositional system (Muschelkalk) on a basin-wide scale. The underlying approach of this study is a process-oriented analysis of sedimentary sequences, an approach that ~as summarized by Matthews (1974, 1984) as "dynamic stratigraphy". The integration of actualistic models with a "dynamic" stratigraphic analysis helps to understand the dynamics of storm depositional systems; these models have a potential to be applied to other basins and to predict the facies organisation and the facies evolution in such systems...

Description / Table of Contents: PREFACE It is to-day generally recognized by environmental scientists that the particular behaviour of trace metals in the environment is determined by their specific physico-chemical forms rather than by their total concentration. With the introduction, several years ago, of atomic absorption spectrometry at many laboratories involved in environmental studies, a technique for simple, rapid and cheap determination of total metal concentrations in environmental samples became available. As a consequence, there is a plethora of scientific papers and reports where metal concentrations in the environment are only reported as total concentrations. It appears that the simplicity of making accurate determinations of total metal contents in water, sediment and biological samples has somewhat masked the need for improved knowledge about the various forms of metals occurring in the environment as well as the bioavailahility of these forms. In other words, the need for metal speciation in studies of metals in the environment does not seem to have become obvious to most environmental scientists until relatively recently. As a matter of fact, it was only in the middle of the 1970s that the first systematic attempts were made to obtain information about the various metal species occurring in environmental samples. During the last ten years, however, a revolutionary change of attitude towards the importance of metal speciation has occurred and considerable research effort has been devoted by environmental scientists to measuring the concentrations of biologically important trace metals in surface waters. There is currently an increasing effort to couple the development of chemical analytical techniques to process-related biological problems. Concurrently, a new focus is being imposed on ecological impact studies, that of determining which active trace metal species merit the most intensive research from the standpoint of environmental perturbation. Current efforts are directed towards the development of chemical speciation schemes which can be related directly to measures of bioavailability...

Description / Table of Contents: INTRODUCTION "The geological history, as expressed by the stratigraphic column, is basically composed of cycles of sedimentation, stratification and magmatism which correlate with relative changes in sea level determined in turn by different types of crustal movements. The classical sequence of stages "transgression - inundation - differentiation - regression - emergence" is believed to reflect the deformation phases of a geotectonic cycle" (Wezel,1988: p.37). The concept of geotectonic cycle is fundamental in geology because it links tectonics with sedimentary processes. According to Wezel (1988) the geotectonic cycle is an expression of cyclic variations in the behavior of the crust; more precisely,it is a geodynamic response to the Earth's variations in the rate of rotation (Mörner,19869 Whyte,1977~ Carey,1976).Based on a global analysis of geotectonic data, synchronous episodes of intense global swelling, governed by cyclically ordered diastrophic processes, were identified (Wezel,1985;1988). The process leading to these swells was termed krikogenesis (Wezel, 1988).It basically consists of not steady, localized, migratory vertical movements linked to mantle diapirism and concentrated in single zones.The overlying crust adjusts itself to mantle motions induced by krikogenesis, with the formation of transient troughs and swells ('touche-de-piano' tectonics).This mechanism was individuated in several areas (Wezel,1988). The history of the Earth is described by six episodes that repeat in the same way in the course of geological time.Their duration progressively decreases:the first cycle has a duration of about 200 million years, the following,younger cycles lasted 150, 115, 65, A5 and 20 m.y. ...