Intra-continental Rift Volcanism: Petrological, Paleomagnetic and Rock Magnetic Data Bearing on Lava Vent Plumbing and Eruption Dynamics at Lemptègy Volcano and Cerro Colorado PDF Download
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Author: Joao Pedro Noguiera Lages Publisher: 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.
Author: Joao Pedro Noguiera Lages Publisher: 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.
Author: M.H. Ort Publisher: Geological Society of London ISBN: 1862396299 Category : Science Languages : en Pages : 283
Book Description
This volume provides a synopsis of current research on volcanic processes, as gained through the use of palaeomagnetic and rock magnetic techniques. Thermoremanent magnetization information provides a powerful means of deciphering thermal processes in volcanic deposits, including estimating the emplacement temperature of pyroclastic deposits, which allows us to understand better the rates of cooling during eruption and transport. Anisotropy of magnetic susceptibility and anisotropy of remanence are used primarily to investigate rock fabrics and to quantify flow dynamics in dykes, lava flows, and pyroclastic deposits, as well as identify vent locations. Rock-magnetic characteristics allow correlation of volcanic deposits, but also provide means to date volcanic deposits and to understand better their cooling history. Because lava flows are typically good recorders of past magnetic fields, data from them allow understanding of changes in geomagnetic field directions and intensity, providing clues on the origin of Earth’s magnetic field.
Author: K. Németh Publisher: 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.
Author: Evgeniy V. Kulakov Publisher: ISBN: Category : Geophysics Languages : en Pages : 264
Book Description
Rocks of the North American Midcontinent rift (MCR) exposed in the Lake Superior area provide an excellent opportunity to use paleomagnetism as a means of studying the characteristics of geomagnetic field in Proterozoic and the history of the rift itself. The detailed paleomagnetic and paleointensity studies of different rock units associated with the MCR, including the 1108 Ma alkaline Coldwell Complex (Ontario, Canada), presumably 1107-1108 Ma basaltic flows of the Geordie Lake (Ontario, Canada) and Silver Mountain (Upper Michigan, USA), ~1095 Ma lava flows of the Portage Lake Volcanics (PLV) (Keweenaw Peninsula, Michigan), and ~1088 Ma lava flows of the Lake Shore Traps (LST) (Keweenaw Peninsula, Michigan) are presented. Paleomagnetic study of the Coldwell Complex indicates that the apparent asymmetry of geomagnetic reversal, recorded by many Keweenawan rocks is an artifact due to missing paleomagnetic record of an equator-ward plate motion in most MCR sequences. The result supports the validity of the geocentric axial dipole assumption for the ~1.1 Ga. Extrusive sequences exposed on the Keweenaw Peninsula revealed lower paleosecular variation than that recorded by 0-5 Ma lava flows, indicating that the Proterozoic field was more stable. Samples from the ~1088 Ma Lake Shore Traps yielded consistent paleofield values with a mean value of 26.3 ± 4.7 μ T, which corresponds to a virtual dipole moment of 5.9 ± 1.1 × 1022 Am2. The mean and range of paleofield values are similar to those of the recent Earth's magnetic field and incompatible with a "Proterozoic dipole low.". These results are consistent with a stable compositionally-driven geodynamo operating by the end of Mesoproterozoic. New high-quality paleomagnetic poles calculated for the ~1108 Ma Coldwell Complex and coeval extrusive rocks, and ~ 1094 Ma PLV indicate that North America was moving directly equator-ward with an approximately 20-25 cm/year rate between 1108 and 1094 Ma. However, the paleomagnetic data indicates a significant slowdown in motion between 1094 and 1088 Ma. This change in the plate tectonics regime coincides with a cessation of the MCR magmatism, which may indicate the beginning of renewed compression from the Grenville Front caused by continent-continent collision during the assemblage of the supercontinent Rodinia. New paleomagnetic data from the LST flows further confirm the idea of a primary nature of the MCR curvature in the Lake Superior area.
Author: Henry R. Frankel Publisher: Cambridge University Press ISBN: 9780521875059 Category : Science Languages : en Pages : 0
Book Description
Resolution of the sixty year debate over continental drift, culminating in the triumph of plate tectonics, changed the very fabric of Earth Science. This four-volume treatise on the continental drift controversy is the first complete history of the origin, debate and gradual acceptance of this revolutionary theory. Based on extensive interviews, archival papers and original works, Frankel weaves together the lives and work of the scientists involved, producing an accessible narrative for scientists and non-scientists alike. This second volume provides the first extensive account of the growing paleomagnetic case for continental drift in the 1950s and the development of Apparent Polar Wander Paths that showed how the continents had changed their positions relative to one another - more or less as Wegener had proposed. Paleomagnetism offered the first physical measure that continental drift had occurred and helped determine the changing latitudes of the continents through geologic time. Other volumes in this set: Volume 1: Wegener and the Early Debate Volume 3: Introduction of Seafloor Spreading Volume 4: Evolution into Plate Tectonics 4 Volume Set
Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Recent advances in environmental magnetism offer the opportunity to link the magnetic signature of marine and continental rocks to the paleoenvironmental and paleoclimatic settings that controlled their formation or deposition, as well as to post-depositional events, such as diagenesis, that can alter their primary signature. This Research Topic assembles studies that used state of the art rock magnetic techniques to unravel the causes and effects of catastrophic geological events, including tsunami, meteorite impacts, Archean oxygenation event, geomagnetic reversals, and global climate changes linked to large volcanic eruptions.
Author: Karoly Nemeth Publisher: BoD – Books on Demand ISBN: 9535126229 Category : Science Languages : en Pages : 426
Book Description
Updates in Volcanology - From Volcano Modeling to Volcano Geology is a new book that is based on book chapters offered by various authors to provide a snapshot of current trends in volcanological researches. Following a short Introduction, the book consists of three sections, namely, ''Understanding the Volcano System from Petrology, Geophysics to Large Scale Experiments,'' ''Volcanic Eruptions and Their Impact to the Environment,' and ''Volcanism in the Geological Record.'' These sections collect a total of 13 book chapters demonstrating clearly the research activity in volcanology from geophysical aspects of volcanic systems to their geological framework. Each chapter provides a comprehensive summary of their subject's current research directions. This book hence can equally be useful for students and researchers.
Author: Joao Pedro Noguiera Lages
Author: Joao Pedro Noguiera Lages
Author: M.H. Ort
Author: Sindy D. Lauricella
Author: K. Németh
Author: Evgeniy V. Kulakov
Author: Duane E. Champion
Author: Henry R. Frankel
Author: 
Author: Claus Siebe
Author: Karoly Nemeth