Download or read book Role of the Overriding Plate in the Subduction Process written by Zhihao Chen and published by . This book was released on 2015 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subduction zones are thought to be the main driver of plate tectonics and mantle convection. Since the development of the theory of plate tectonics, subduction zones have been investigated and discussed, but in many ways they are still an enigma. Geodynamic modelling (analogue or numerical) can be an effective tool to gain insight into the temporal evolution of subduction zones as it provides quantitative and conceptual insights into the interactions between the plates, the slab and the mantle. Moreover, modelling results can then be compared to their natural prototypes providing crucial insight into regional processes.In my PhD project I use four-dimensional laboratory-based (analogue) geodynamic models to investigate the kinematics and dynamics of subduction, with a particular emphasis on the deformation in the overriding plate. I then compare and constrain my results with natural observations from subduction zones. My thesis has been divided into two parts. The first part focuses on the patterns of overriding plate deformation during progressive subduction when some parameters of the overriding plate are varied. In the first work (Chapter 4), the strength of the overriding plate (i.e., viscosity ratio between the overriding plate and the sub-lithospheric upper mantle, and the overriding plate thickness) is varied to quantify the energy dissipation of overriding plate deformation. The results show that only a small portion of the slab negative buoyancy force and its potential energy are used to deform the overriding plate, and the force required to deform the overriding plate is comparable in magnitude with the ridge push force. Furthermore, the results also show that the bending dissipation at the subduction zone hinge remains relatively low (during steady state subduction), irrespectively of including/excluding an overriding plate in the models. In the second work (Chapter 5), far-field boundary conditions of the overriding plate and subducting plate are varied. The results indicate that such a variation has an influence on the slab geometry and subduction kinematics. The models imply that in natural (narrow) subduction zones, assuming a homogeneous overriding plate, the formation of a backarc basin (e.g., Tyrrhenian Sea, Aegean Sea, Scotia Sea) is generally expected to occur at a comparable location with respect to the trench, irrespective of the boundary condition. In addition, my models indicate that the style of forearc deformation (shortening or extension) is affected by the mobility of the overriding plate through controlling the force normal to the subduction zone interface (trench suction). Finally, the results of the model with both plates fixed at their trailing edges are applied to the Calabria subduction zone. This model explains the latest Middle Miocene to present backarc and forearc extension at the Calabria subduction zone as a direct consequence of subduction of the narrow Calabrian slab and the immobility of both the subducting African plate and overriding Eurasian plate.The second part of this thesis focuses on the role of subduction-induced mantle flow in driving deformation of the overriding plate, including (horizontal) trench-normal backarc deformation (Chapter 6) and topography of the overriding plate (Chapter 7). In Chapter 6, a stereoscopic Particle Image Velocimetry (sPIV) technique was used to map simultaneously the horizontal overriding plate deformation and the 3D subduction-induced mantle flow underneath and around the overriding plate. The results show that the strain field of the overriding plate is characterized by localization of an area of maximum extension within its interior (at 300-500 km from the trench). The position of this maximum extension corresponds to that of the maximum trench-normal horizontal velocity gradient measured in the mantle at a scaled depth of 15-25 km below the base of the overriding plate. The results robustly support the hypothesis that in narrow subduction zones backarc extension in the overriding plate is mainly a consequence of the trench-normal horizontal gradients of basal drag force at the base of overriding plate. Such gradients result from a differential in the mantle flow velocity field induced by slab rollback. In Chapter 7, I also used the sPIV technique to investigate the vertical displacement of the overriding plate in a self-consistent subduction model with free boundary conditions. It is suggested that the trench suction force normal to the subduction zone interface, in combination with the shear force at the interface, has an overall influence on the topography of the overriding plate, through bending the overriding plate downward at the trench. Furthermore, the overriding plate is characterized by a transient topographic subsidence located in the forearc, at ~2-5 cm (scaling to 100-250 km) from the trench, with a magnitude of 0.65-1.35 mm (scaling to 3.25-6.75 km). These transient features are most pronounced during the early, transient, free slab sinking phase and predominantly results from the variation of the vertical component of the trench suction along the subduction zone interface, which is induced by the gradual slab steepening during this early phase. The downward mantle flow in the nose of the mantle wedge plays a minor role in the forearc subsidence.
Download or read book Physical Geology written by Steven Earle and published by . This book was released on 2016-08-12 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a discount Black and white version. Some images may be unclear, please see BCCampus website for the digital version.This book was born out of a 2014 meeting of earth science educators representing most of the universities and colleges in British Columbia, and nurtured by a widely shared frustration that many students are not thriving in courses because textbooks have become too expensive for them to buy. But the real inspiration comes from a fascination for the spectacular geology of western Canada and the many decades that the author spent exploring this region along with colleagues, students, family, and friends. My goal has been to provide an accessible and comprehensive guide to the important topics of geology, richly illustrated with examples from western Canada. Although this text is intended to complement a typical first-year course in physical geology, its contents could be applied to numerous other related courses.
Download or read book Subduction Zone Magmatism written by Yashiyuki Tatsumi and published by Wiley. This book was released on 1995-06-15 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subduction zones are major sites of volcanism on the Earth. As one crustal plate sinks or is pushed beneath another, hot magma is produced and the resultant magma flux is fundamental to both the thermal evolution and chemical differentiation of the mantle and the Earth itself. To understand these evolutionary processes, we need to understand the physical and chemical consequences of all aspects of the subduction process. In this book, the authors present a simple, current and comprehensive model that explains the dominant geological processes at work in subduction zones. Structuring the book around the model, the authors describe the physical characteristics and geochemical dynamics of subduction zones, arc magma generation, and the dynamics and flow in the mantle. Students and researchers alike will find this book of immense value in understanding this most complex of subjects.
Download or read book Arc Continent Collision written by Dennis Brown and published by Springer Science & Business Media. This book was released on 2011-06-29 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arc-continent collision has been one of the important tectonic processes in the formation of mountain belts throughout geological time, and it continues to be so today along tectonically active plate boundaries such as those in the SW Pacific or the Caribbean. Arc-continent collision is thought to have been one of the most important process involved in the growth of the continental crust over geological time, and may also play an important role in its recycling back into the mantle via subduction. Understanding the geological processes that take place during arc-continent collision is therefore of importance for our understanding of how collisional orogens evolve and how the continental crust grows or is destroyed. Furthermore, zones of arc-continent collision are producers of much of the worlds primary economic wealth in the form of minerals, so understanding the processes that take place during these tectonic events is of importance in modeling how this mineral wealth is formed and preserved. This book brings together seventeen papers that are dedicated to the investigation of the tectonic processes that take place during arc-continent collision. It is divided into four sections that deal firstly with the main players involved in any arc-continent collision; the continental margin, the subduction zone, and finally the volcanic arc and its mineral deposits. The second section presents eight examples of arc-continent collisions that range from being currently active through to Palaeoproterozoic in age. The third section contains two papers, one that deals with the obduction of large-slab ophiolites and a second that presents a wide range of physical models of arc-continent collision. The fourth section brings everything that comes before together into a discussion of the processes of arc-continent collision.
Download or read book Plate Tectonics A Very Short Introduction written by Peter Molnar and published by Oxford University Press, USA. This book was released on 2015 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: La 4e de couv. indique : "The concept of plate tectonics is relatively new - it was only in the 1960s that the idea that continents drifted with respect to one another came to be accepted. Plate tectonics now forms one of geology's basic principles and explains much of the large-scale structure and phenomena we see on Earth today. In this Very Short Introduction Peter Molnar explores the impact that plate tectonics has had on our understanding of Earth : how the ocean floor forms, widens, and disappears ; why earthquakes and volcanoes are found in distinct zones ; and how the great mountain ranges of the world were built. As the Himalaya continues to grow, the Atlantic widens, and new ocean floor is forming, the mechanisms of plate tectonics continue to alter the surface of our planet."
Download or read book Encyclopedia of Marine Geosciences written by Jan Harff and published by Springer. This book was released on 2021-01-14 with total page 1000 pages. Available in PDF, EPUB and Kindle. Book excerpt: Globally growing demand of energy and mineral resources, reliable future projection of climate processes and the protection of coasts to mitigate the threats of disasters and hazards require a comprehensive understanding of the structure, ongoing processes and genesis of the marine geosphere. Beyond the “classical” research fields in marine geology in current time more general concepts have been evolved integrating marine geophysics, hydrography, marine biology, climatology and ecology. As an umbrella the term “marine geosciences” has been broadly accepted for this new complex field of research and the solutions of practical tasks in the marine realm. The “Encyclopedia of Marine Geosciences” comprises the current knowledge in marine geosciences whereby not only basic but also applied and technical sciences are covered. Through this concept a broad scale of users in the field of marine sciences and techniques is addressed from students and scholars in academia to engineers and decision makers in industry and politics.
Download or read book Subduction Dynamics written by Gabriele Morra and published by John Wiley & Sons. This book was released on 2015-09-23 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subduction dynamics has been actively studied through seismology, mineral physics, and laboratory and numerical experiments. Understanding the dynamics of the subducting slab is critical to a better understanding of the primary societally relevant natural hazards emerging from our planetary interior, the megathrust earthquakes and consequent tsunamis. Subduction Dynamics is the result of a meeting that was held between August 19 and 22, 2012 on Jeju island, South Korea, where about fifty researchers from East Asia, North America and Europe met. Chapters treat diverse topics ranging from the response of the ionosphere to earthquake and tsunamis, to the origin of mid-continental volcanism thousands kilometers distant from the subduction zone, from the mysterious deep earthquakes triggered in the interior of the descending slabs, to the detailed pattern of accretionary wedges in convergent zones, from the induced mantle flow in the deep mantle, to the nature of the paradigms of earthquake occurrence, showing that all of them ultimately are due to the subduction process. Volume highlights include: Multidisciplinary research involving geology, mineral physics, geophysics and geodynamics Extremely large-scale numerical models with sliate-of-the art high performance computing facilities Overview of exceptional three-dimensional dynamic representation of the evolution of the Earth interiors and of the earthquake and subsequent tsunami dynamics Global risk assessment strategies in predicting natural disasters This volume is a valuable contribution in earth and environmental sciences that will assist with understanding the mechanisms behind plate tectonics and predicting and mitigating future natural hazards like earthquakes, volcanoes and tsunamis.
Download or read book Interactions Between a Flat Slab and Overriding Plate written by Xiaowen Liu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subduction zones are active plate margins that have an important role in mantle and lithosphere processes. Subduction is driven by the negative buoyancy of the downgoing oceanic plate, resulting in a steep descent angle at most subduction zones. However, in approximately 10% of modern subduction zones, shallow to flat-slab subduction occurs. In these regions, the oceanic plate unbends to become subhorizontal, underplating the continental plate for several hundred kilometers inboard of the plate margin at depths of 45-150 km. Development of a flat slab is generally characterized by migration and termination of arc magmatism, reduced continental surface heat flow, and thick-skinned deformation in the continental interior. The mechanisms that lead to flat-slab subduction include anomalous buoyancy of the oceanic plate, high trenchward velocity of the continental plate, and increased suction force in the mantle wedge. Recent studies have made significant progress in mapping flat slabs and understanding how a flat slab develops. However, there are many fundamental problems that are still not well understood, such as why the depth of the flat slab varies between different regions, and how flat slabs affect the thermal structure and deformation of the continental upper plate. This thesis uses 2D thermal-mechanical models to investigate flat-slab dynamics and the interactions between a flat slab and the overlying continent. Models focus on regions of flat-slab subduction in western North and South America, where slab flattening is driven by a combination of trenchward continental motion and subduction of a buoyant aseismic oceanic ridge. The models show that flat-slab depth is primarily determined by the initial thickness of the overriding plate, such that the slab is deeper below an initially thick (cool) continent. The depth is also controlled by the strength of the continental mantle lithosphere, whereby a weak (hydrated) lithosphere is able to be displaced by the flat slab. Through reasonable variations in these parameters, the depth of the flat slab varies by more than 100 km, in good agreement with observed depths. The models also indicate that the observed low surface heat flow in flat-slab regions does not solely result from conductive cooling by the cold slab. The continental lithosphere cools over 10's of millions of years through conductive heat transfer after flat-slab emplacement. The timescale of cooling is mainly controlled by flat-slab depth, with an earlier onset of cooling and a greater amount of cooling for a shallower slab. The magnitude of cooling is also enhanced by longer slab emplacement times, faster convergence rate, and an older oceanic plate. The presence of a flat slab can also trigger thick-skinned deformation of the continent 100's of km from the plate margin. Deformation is the result of both high compressional stresses through end-loading at the distal plate margin and the presence of pre-existing weak structures in the continent. Deformation is modulated by dynamic topography associated with the flat slab, where dynamic uplift inhibits deformation. The model results are in good agreement with geological and geophysical observations from flat-slab regions. This thesis provides new insights into the flat-slab regions in both North and South America and deepens our understanding of flat-slab subduction dynamics and the origin of thermal anomalies and thick-skinned deformation of the Laramide Orogeny in North America and the Sierras Pampeanas in South America.
Download or read book Deep Carbon written by Beth N. Orcutt and published by Cambridge University Press. This book was released on 2019-10-17 with total page 687 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive guide to carbon inside Earth - its quantities, movements, forms, origins, changes over time and impact on planetary processes. This title is also available as Open Access on Cambridge Core.
Download or read book Encyclopedia of Solid Earth Geophysics written by D.E. James and published by Springer Science & Business Media. This book was released on 1989-11-30 with total page 1299 pages. Available in PDF, EPUB and Kindle. Book excerpt: Consisting of more than 150 articles written by leading experts, this authoritative reference encompasses the entire field of solid-earth geophysics. It describes in detail the state of current knowledge, including advanced instrumentation and techniques, and focuses on important areas of exploration geophysics. It also offers clear and complete coverage of seismology, geodesy, gravimetry, magnetotellurics and related areas in the adjacent disciplines of physics, geology, oceanography and space science.
Download or read book Regional Geology and Tectonics Principles of Geologic Analysis written by David G. Roberts and published by Elsevier. This book was released on 2012-03-16 with total page 908 pages. Available in PDF, EPUB and Kindle. Book excerpt: Expert petroleum geologists David Roberts and Albert Bally bring you Regional Geology and Tectonics: Principles of Geologic Analysis, volume one in a three-volume series covering Phanerozoic regional geology and tectonics. It has been written to provide you with a detailed overview of geologic rift systems, passive margins, and cratonic basins, it features the basic principles necessary to grasping the conceptual approaches to hydrocarbon exploration in a broad range of geological settings globally. - Named a 2013 Outstanding Academic Title by the American Library Association's Choice publication - A "how-to" regional geology primer that provides a detailed overview of tectonics, rift systems, passive margins, and cratonic basins - The principles of regional geological analysis and the main geological and geophysical tools are discussed in detail. - The tectonics of the world are captured and identified in detail through a series of unique geographic maps, allowing quick access to exact tectonic locations. - Serves as the ideal introductory overview and complementary reference to the core concepts of regional geology and tectonics offered in volumes two and three in the series.
Download or read book The Andes written by Onno Oncken and published by Springer Science & Business Media. This book was released on 2006-11-22 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the first comprehensive overview of a complete subduction orogen, the Andes. To date the results provide the densest and most highly resolved geophysical image of an active subduction orogen.
Download or read book Subduction written by Alexander I. Shemenda and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is devoted to the quantitative physical modeling of subduction and subduction-related processes. It presents a coherent description of the modeling method (including similarity criteria, and a novel applied experimental technique), results from model experiments, theoretical analysis of results on the basis of continuum mechanics, and their geodynamic interpretation. Subduction is modeled in general as well as applied to particular regions using both 2-D and 3-D approaches, with both slab-push and slab-pull driving forces. The modeling covers all stages from subduction initiation to `death', different regimes of subduction producing back arc extension and compression, blocking of subduction and jumps of subduction zone, arc-continent collision and continental subduction. This work is for geologists and geophysicists interested in geodynamics of the convergent plate boundaries and in mechanics of the lithosphere.
Download or read book Subduction Zones Part II written by Larry J. Ruff and published by Birkhäuser. This book was released on 2012-12-06 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Subduction zones consume oceanic lithosphere and are an indispensible part of plate tectonics. Unlike the oceanic lithosphere production system which can be linked as a nearly continuous, albeit sinuous, strand around the earth, subduction zones are a rather dissociated group and are found in several isolated corners of the world. While plate tectonics can predict that subduction zones are required along certain plate boundaries, it does not stipulate how subduction zones initiate and develop. The preservation of newly created oceanic lithosphere and the propensity for spreading centers to fragment continents leaves a wealth of geological informa tion on the initiation and evolution of spreading. On the other hand, the subject of subduction initiation has little observational basis. To find such observations, we need to look at some muddled tectonic regimes. The Macquarie Ridge complex presents a natural laboratory for studies of subduction initiation. 2. Tectonics of the Macquarie Ridge Complex The Macquarie Ridge complex is a complicated physiographic feature that trends approximately north-south between South Island, New Zealand and the Pacific-Antarctica spreading center. This feature consists of a sequence of troughs and ridges, with Macquarie Island as the only exposed expression. The seismically active Macquarie Ridge complex (hereafter: MRC) is crudely continuous with the Tonga-Kermadec-New Zealand seismic activity. The basic physiographic features and seismicity of the MRC are shown in Figure I. The earthquake epicenters generally cluster about the bathymetric expression of the MRC.
Download or read book Earth and Life Processes Discovered from Subseafloor Environments written by and published by Elsevier. This book was released on 2014-12-03 with total page 829 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Integrated Ocean Drilling Program (IODP: 2000-2013) has provided crucial records of past and present processes and interactions within and between the biosphere, cryosphere, atmosphere, hydrosphere and geosphere. Research in IODP encompasses a wide range of fundamental and applied issues that affect society, such as global climate change, biodiversity, the origin of life, natural hazards involving the study of earthquakes processes, and the internal structure and dynamics of our planet. This compilation of major findings from the 2003-2013/14 phase of IODP, focusing on scientific results rather than description of data acquisition and early inferences, provides invaluable information. Anyone wondering what scientific drilling can achieve will gain quick understanding of the range of questions that are uniquely addressed with this methodology and the ways these data dovetail with other regional information. The excitement of breakthrough findings that occasionally accompanies a drilling project will be evident. IODP obtained unique records from the global ocean basins during the 2003-2013 program phase. This book highlights findings in three theme areas: Subseafloor life and the marine biosphere; Earth's changing environments; and Dynamics of the solid Earth. Each core or borehole log provides a window revealing insights that no other data achieve. - Presents syntheses of key results from the Integrated Ocean Drilling Program - Encompasses a wide range of issues that affect society - Describes the Integrated Ocean Drilling Program and its expeditions
Download or read book Geomorphology of Central America written by Jean Pierre Bergoeing and published by Elsevier. This book was released on 2015-05-18 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geomorphology of Central America is authored by a scientist with more than 30 years of regional assessment research experience in Central American countries, arming scientists with a classic research method—a method most effective when applied to specific geographic regions globally. The scientific techniques used for assessing regional studies of an area reflect a level of expertise that has become more difficult to come by over the past three decades and underscores the importance of regional assessments of geomorphological features. Complemented with beautifully crafted and exacting maps that capture the region's unique landscapes, Geomorphology of Central America introduces a global vision of the geomorphology and volcanic field of Central America from Guatemala to Panama, making it the first single source of geomorphological content for the region. - Features the latest research on the seismic behavior of the Central America region, including volcanic activity, landslides, rivers, forest areas, and topographic environments. - More than 100 figures, illustrations, and photographs underscore key concepts and aid in retention. - Authored by a geomorphologist with more than 30 years of research experience in the field with a focus on Central America.
Download or read book Slab Behavior Overriding Plate Deformation and Topography at Subduction Zones and the India Eurasia Collision Zone written by and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: On earth, two types of convergent plate boundaries exist, namely subduction zones and collision zones. Subduction zones are the main driver of plate tectonics through sinking of negatively buoyant oceanic lithospheric slabs in the mantle and the subduction-induced large-scale mantle flow. Collision zones form when two positively buoyant continental plates meet and collide, following a phase of subduction. Both subduction zones and collision zones cause frequent and tremendous geological activities, which cause overriding plate deformation and form large-scale topography. However, the processes of subduction and collision and the mechanisms driving the associated overriding plate deformation and topography still remain unclear. Since subduction and collision operate at large spatial and temporal scales, a useful and effective way to investigate the processes of subduction and collision is by using analog or numerical modeling. Therefore, in this PhD project, I implement four-dimensional subduction and collision experiments to investigate different subduction/collision styles and mechanisms for deforming the overriding plate and forming topography during subduction/collision. This project comprises two equally weighted parts: (1) The first part investigates the two end-member styles of subduction, namely slab rollback and slab rollover, and their effect on overriding plate deformation and topography, because little research has been conducted on the rollover subduction style, and it remains unclear how and why these different subduction styles emerge. Therefore, Chapters 2 and 3 focus on subduction styles and how the two contrasting subduction styles affect mantle flow, overriding plate deformation and topography in subduction zones. This part of the thesis demonstrates how plate length can control the subduction style, and how the subduction style affects the overriding plate differently.
