Author: Dario PedrazziPublisher:
ISBN:
Category :
Languages : en
Pages : 153
Book Description
Hydromagmatic Monogenetic Volcanism in Continental and Oceanic Island Environments
Author: Dario PedrazziHydrmagmatic Monogenetic Volcanism in Continental and Oceanic Island Environments
Author: Dario PedrazziPublisher:
ISBN:
Category :
Languages : en
Pages : 293
Book Description
Monogenetic volcanism is characterized by a large diversity of eruptive styles, morphologies and deposits. Monogenetic landforms are the result of a complex merging of internal (magma composition, vesiculation) and external (geological setting, fracturation, hydrogeology, substrate stratigraphy, etc) parameters that govern the physics of the eruptions. Changes in these parameters may cause variations in the eruption style several times during the course of such short-lived volcanoes. Monogenetic volcanoes may form in any type of geological environment with scoria cones being the most common volcano type and hydrovolcanic tuff rings, tuff cones, and maars as the second in abundance. These small-volume volcanoes are generally the result of short-lived eruptions but the activity in a monogenetic volcanic field might exceed the total life of composite volcanoes. The attention of this work was focused on the relation between monogenetic volcanic landforms and the external variables that influenced the dynamics of the eruptions (i.e. magmatism vs phreatomagmatism) through a multidisciplinary perspective, in marine and continental geological settings under which monogenetic volcanism may develop. Different case studies representative of this type of activity and of these different environments have been considered. The first one corresponds to the La Crosa De Sant Dalmai volcano (Garrotxa Volcanic Field, southern sector of the Catalan Volcanic Zone), a roughly circular asymmetrical maar-diatreme volcano, which is one of the most characteristic volcanic edifices of this continental monogenetic volcanic field and the largest Quaternary volcanic crater on the Iberian Peninsula. This edifice is an example of monogenetic landform, mostly composed of phreatomagmatic deposits with subordinate Strombolian phases, constructed on a mixed basement made of hard Paleozoic granites and schists rocks and soft Plio-Quaternary deposits. Here, I reconstructed the hydrogeological conditions of the substrate and the implication for the eruptive dynamics. As a second case study, I carried out detailed stratigraphic and sedimentological studies of the succession of El Golfo tuff cone (Lanzarote, Canary Islands). The main objective of the work was to describe in detail the structure and association of facies of this edifice and use this information to infer changes in eruption style and depositional processes. Another type of eruption was studied in the same archipelago at El Hierro, an island essentially characterized by basaltic volcanism with both Strombolian and Hawaiian activity. Here I reported the stratigraphic, lithological, sedimentological and petrographic characteristics of a felsic hydrovolcanic episode in order to discuss, transport/depositional mechanisms, dynamics, relative age and implications for hazard assessment on the island. Finally, the same type of methodology was applied at Deception Island (Southern Shetland Archipelago, Antarctica), determining the lithological and sedimentological characteristics, and clasts distribution (isopach and isopleth maps) of the eruption of 1970. This information was, then, used to determine depositional processes, eruption style and physical parameters (i.e. plume height, erupted volume, VEI) of the eruption in order to compare this episode with the previous 1967 episode, and to deduce their implications to conduct hazard assessment at the island. Each work represents a diverse aspect of hydrovolcanism and the results obtained helped to better understand the eruptive behavior of this type of volcanoes, which is a fundamental task in order to understand the possible future hazards associated with this type of volcanism. The results obtained can be applied to monogenetic volcanic fields worldwide and are, therefore, useful to reconstruct the evolution of a certain volcanic fields, through the study of single monogenetic volcanoes, and to evaluate the possible volcanic hazards, as similar eruptions represent a serious threat, which is often underestimated. A more systematic study is, thus, needed in order to understand the role of shallow-level conditions in the formation of specific volcano types in such complex volcanic fields.
Ocean Island Volcanoes: Genesis, Evolution and Impact
Author: Adriano PimentelPublisher: Frontiers Media SA
ISBN: 288963728X
Category :
Languages : en
Pages : 180
Book Description
Ocean island volcanoes constitute some of the most prominent and rapidly-formed features on Earth, and yet they cannot be explained by conventional plate tectonics. Although typically associated with intraplate settings (hotspots), these volcanoes also occur in different geodynamic settings (near mid-ocean ridges). The nature of ocean island magmatism is still the subject of intense debate within the geological community. Traditionally it has been linked to the presence of mantle plumes at depth (e.g. Hawaii), although the interaction with plate tectonics is also recognized to play a significant role (e.g. Azores, Galápagos). Magma compositions may range from basaltic to more differentiated, which consequently is accompanied by striking changes in the eruption style from effusive-dominated to highly explosive volcanism. Understanding how these magmas evolve and how volcanic processes act at ocean island volcanoes are key issues of modern volcanology. Moreover, the growth of ocean island volcanoes from their rise on the seafloor as seamounts, to island emergence and subsequent formation of shield volcanoes (and in some cases large caldera volcanoes) is governed by multiple interrelated changes. It is well known that competing processes model ocean island volcanoes during alternating and/or coeval periods of construction and destruction. The geological evolution of these volcanoes results from the balance among volcanism, intrusions, tectonics, subsidence/uplift, mass wasting, sedimentation, and subaerial and wave erosion. A better knowledge of the interplay between these processes is crucial to obtain a more comprehensive understanding of the evolution of such volcanoes, and to the eventual formulation of a unified model for ocean island evolution. Ocean islands are especially vulnerable to volcanic eruptions and other geological hazards on account of their typical small size, rough topography and isolation, which make risk management and evacuation difficult. Volcanic eruptions, in particular, may have a significant impact on local populations, infrastructures, economy and even on the global climate. It is therefore fundamental to monitor these volcanoes with complementary geophysical, geodetic and geochemical techniques in order to forecast future eruptions and their impacts. However, the assessment of volcanic hazards on ocean islands is challenging due to the large variety of phenomena involved (e.g. lava flows, tephra fallout, pyroclastic density currents, lahars, gas emissions). Different approaches are used to assess volcanic hazards, either based on empirical methods or sophisticated numerical models, focusing on a single phenomenon or the combination of different hazards. This Frontiers Research Topic aims to promote discussion within the scientific community, representing an important step forward in our knowledge of ocean island volcanoes in order to serve as a reference for future research.
Monogenetic Volcanism
Author: K. NémethPublisher: Geological Society of London
ISBN: 178620276X
Category : Science
Languages : en
Pages : 385
Book Description
The nature and origin of the small-scale volcanic systems, generally referred to as 'monogenetic', have enjoyed an elevated level of interest during the past decade. There has been recognition that their ostensibly simple volcano types are a window into the nature of explosive volcanism, landscape evolution and the processes of magma generation in the Earth’s upper mantle. In the past few years, major conferences have offered specialized technical sessions dealing with monogenetic volcanism and there have been thematic conferences, such as the IAVCEI International Maar Conference series, which have provided a focus for discussion of volcanological and geochemical aspects of small-scale basaltic volcanism. Many new aspects of monogenetic volcanism have emerged and have clearly demonstrated that this volcanism can be very complex on a fine scale. This book is a collection of papers arising from two recent Maar Conferences (the fifth in Queretaro Mexico and the sixth in Changchun, China) and serves as a snapshot of current research on monogenetic volcanism.
Large Igneous Provinces
Author: John J. MahoneyPublisher: American Geophysical Union
ISBN: 0875900828
Category : Nature
Languages : en
Pages : 441
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 100. Continental flood basalts, volcanic passive margins, and oceanic plateaus represent the largest known volcanic episodes on our planet, yet they are not easily explained by plate tectonics. Indeed, some are likely to record periods when the outward transfer of material and energy from the Earth's interior operated in a significantly different mode than at present. In recent years, interest in large-scale mafic magmatism has surged as high-precision geochronological, detailed geochemical, and increasingly sophisticated geophysical data have become available for many provinces. However, the sheer amount of recent material, often in the form of detailed collaborative research projects, can overwhelm newcomers to the field and experts alike as the literature continues to grow dramatically. The need for an up-to-date review volume on a sizable subset of the major continental and oceanic flood basalt provinces, termed large igneous provinces, was recognized by the Commission on Large-Volume Basaltic Provinces (International Association of Volcanology and Chemistry of the Earth's Interior), and the co-editors were charged with organizing and implementing such a volume. We hope that this volume will be valuable to researchers and graduate students worldwide, particularly to petrologists, geochemists, geochronologists, geodynamicists, and plate-tectonics specialists; it may also interest planetologists, oceanographers, and atmospheric scientists.
Volcanism
Author: Hans-Ulrich SchminckePublisher: Springer Science & Business Media
ISBN: 9783540436508
Category : Science
Languages : en
Pages : 342
Book Description
Volcanic eruptions are the clear and dramatic expression of dynamic processes in planet Earth. The author, one of the most profound specialists in the field of volcanology, explains in a concise and easy to understand manner the basics and most recent findings in the field. Based on over 300 color figures and the model of plate tectonics, the book offers insight into the generation of magmas and the occurrence and origin of volcanoes. The analysis and description of volcanic structures is followed by process oriented chapters discussing the role of magmatic gases as well as explosive mechanisms and sedimentation of volcanic material. The final chapters deal with the forecast of eruptions and their influence on climate. Students and scientists of a broad range of fields will use this book as an interesting and attractive source of information. Laypeople will find it a highly accessible and graphically beautiful way to acquire a state-of-the-art foundation in this fascinating field. "Volcanism by Hans-Ulrich Schmincke has photos of the best quality I have ever seen in a text on the subject... In addition, the schematic figures in their wide range of styles are clear, colorful, and simplified to emphasize the most important factors while including all significant features... "I have really enjoyed reading and rereading Schmincke’s book. It fills a great gap in texts available for teaching any basic course in volcanology. No other book I know of has the depth and breadth of Volcanism... I have shared Volcanism with my colleagues to their significant benefit, and I am more convinced of its value for a broad range of Earth and planetary scientists. Undoubtedly, I will use Volcanism for my upcoming courses in volcanology. I will never hesitate to recommend it to others. Many geoscientists from very different subdisciplines will benefit from adding the book to their personal libraries. Schmincke has done us all a great service by undertaking the grueling task of writing the book – and it is much better that he alone wrote it." Stanley N. Williams, ASU Tempe, AZ (Physics Today, April 2005) "Schmincke is a German volcanologist with an international reputation, and he has done us all a great favour because he sensibly channelled his fascination with volcanoes into writing this beautifully illustrated book... [he] tackles the entire geological setting of volcanoes within the earth and the processes that form them... And, with more than 400 colour illustrations, including a huge number of really excellent new diagrams, cutaway models and maps, plus a rich glossary and references, this book is accessible to anyone with an interest in the subject." New Scientist (March 2004) "The science of volcanology has made tremendous progress over the past 40 years, primarily because of technological advances and because each tragic eruption has led researchers to recognize the processes behind such serious hazards. Yet scientists are still learning a great deal because of photographs that either capture those processes in action or show us the critical factors left behind in the rock record.Volcanism by Hans-Ulrich Schmincke has photos of the best quality I have ever seen in a text on the subject. I found myself wishing that I had had the photo of Nicaragua’s Masaya volcano, which was the subject of my dissertation, but it was Schmincke who was able to include it in his book. In addition, the schematic figures in their wide range of styles are clear, colorful, and simplified to emphasize the most important factors while including all significant features. The book’s paper is of such high quality that at times I felt I had turned two pages rather than one. I have really enjoyed reading and rereading Schmincke’s book. It fills a great gap in texts available for teaching any basic course in volcanology. No other book I know of has the depth and breadth of Volcanism. I was disappointed that the text did not arrive on my desk until last August, when it was too late for me to choose it for my course in volcanology. I am also disappointed about another fact—the book’s binding is already becoming tattered because of my intense use of it! Schmincke is a volcanologist who, in 1967, first published papers on sedimentary rocks of volcanic origin, the direction traveled by lava flows millions of years ago, and the structures preserved in explosive ignimbrites, or pumice-flow deposits, that reveal important details of their formation. Since then, his studies in Germany’s Laacher See, the Canary Islands, the Troodos Ophiolite of Cyprus, and many other regions have forged great fundamental advances. Such contributions have been recognized with his receipt of several international awards and clearly give him a strong base for writing the book. However, as a scientist who has focused on the challenges of monitoring the very diverse activities of volcanoes, I think that the text’s overriding emphasis on the rock record has its cost. The group of scientists who are struggling with their goals to reduce or mitigate the hazards of the eruptions of tomorrow need to learn more about the options of technology, instrumentation, and methodology that are currently available. More than 500 million people live near the more than 1500 known active volcanoes and are constantly facing serious threats of eruptions. An extremely energetic earthquake caused the horrific tsunamis of 2004. However, the tsunamis of 1792, 1815, and 1883, which were caused by the eruptions of Japan’s Unzen volcano and Indonesia’s Tambora and Krakatau volcanoes, each took a similar toll. " ( Stanley N. Williams, PHYSICS TODAY, April 2005)
Intra-continental Rift Volcanism: Petrological, Paleomagnetic and Rock Magnetic Data Bearing on Lava Vent Plumbing and Eruption Dynamics at Lemptègy Volcano and Cerro Colorado
Author: Joao Pedro Noguiera LagesPublisher:
ISBN:
Category : Lemptegy Volcano (France)
Languages : en
Pages : 148
Book Description
Monogenetic basaltic volcanic fields occur in tectonic settings ranging from divergent to convergent. Pleistocene to Holocene volcanic activity transpired along the Limagne graben (France) and the Rio Grande rift (USA) as a result of crustal extension, consequent lithospheric thinning, and mantle upwelling, resulting in abnormal heating of the lithosphere and antectic melting. Both the Chalne des Puys and Cerros de! Rio volcanic field reflect very sim ilar geological environments that created the cinder cones of Puy de Lemptegy and Cerro Colorado. Paleomagnetic data along with structural field mapping stud ies were analyzed to characterize and compare the timing of emplacement of effusive versus extrusive units and the formation and deformation of flow units during cone growth . A total of twenty Currie points and Lowrie- F uller test were obtained to describe the principal magnetic phases that carry both the remanence and anisotropy. Petrographic analyses revealed transitional phases in lava flow composition and changes in vesicu larity and hydrous phases as volcanic activity progressed. Field observations suggested similar eruptive vent dynamics, with structural measurements pointing to a well-defined central vent surrounded by pyroclastic deposits (scoria, bombs, and flows). Successive layered transitions between effusive and eruptive cycles evidenced the change in eruptive behavior over time. The data indicated SD to PSD grain behavior with Fe-Ti oxide phase, likely med-Ti titanomagnetite, as the principal magnetic phase carrying both the remanence and anisotropy. The presence of an iron sulfide (FeS) phase common to both volcanoes possibly revealed a low temperature magmatic source. After processing all data, subvolcanic deformation within the volcanoes' plumbing systems and their external structure. Paleomagnetic data from Cerro Colorado suggests a post-eruption flank deformation of the monogenetic cone through shallow magma accumulation and propagation through a rather complex plumbing system with several ramifications away from the main vent., validating our init ial hypothesis of a rather complex volcanic growth that can most probably be attributed to monogenic volcanoes worldwide.
Compositional variation during monogenetic volcano growth and its implications for magma supply to continental volcanic fields
Author: K. NEMETHDeformation and Flank Instability of Oceanic Island Volcanoes
Author: Derk ElsworthVolcanism Associated with Extension at Consuming Plate Margins
Author: J. L. SmelliePublisher:
ISBN: 9781786200549
Category : Geology, Stratigraphic
Languages : en
Pages :
Book Description
This volume contains a representative cross-section of current research on extension-related arc volcanism in the broadest sense, and is intended to stimulate further discussion and research into the complex tectonics and petrology of covergent plate margins. Papers include: Subduction systems and magmatism; Geochemistry of Lau Basin volcanic rocks: influence of ridge segmentation and arc proximity; Gamilaroi Terrane: A Devonian rifted intra-oceanic island-arc assemblage, NSW, Australia; Neogene volcanoes of Chios, Greece: the relative importance of subduction and back-arc extension; and others.