Thermal Structure Of Mid Ocean Ridges Lucky Strike Mid Atlantic Ridge And Magma Chambers
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Thermal Structure Of Mid Ocean Ridges Lucky Strike Mid Atlantic Ridge And Magma Chambers
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Author : Doga Dusunur
language : en
Publisher:
Release Date : 2008
Thermal Structure Of Mid Ocean Ridges Lucky Strike Mid Atlantic Ridge And Magma Chambers written by Doga Dusunur and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
Modeling the thermal state of the oceanic crust is an important task to understand the construction of oceanic crust which covers two thirds of the surface of our planet. The interplays among magma delivery to the axis and cooling of the oceanic lithosphere as a function of both space and time are key factors to understand the creation of the oceanic crust, which is primarily determined by the overall thermal structure of mid-ocean ridges. Classical thermal models do not predict steady state axial magma chambers (AMCs) along mid-ocean ridges at spreading rates less than 30 mm/year. The identification and seismic imaging of an axial magma chamber underlying the Lucky Strike central volcano and hydrothermal field at the Mid-Atlantic Ridge provides a unique opportunity to study the thermal structure of slow spreading ridges. Here we present coupled microseismic data and thermal modeling to provide insight on the nature of ephemeral magma chambers at slow-spreading ridges, to constrain the timescales associated with changes in melt supply and the parameters that can create them, and to shed light on the different mechanisms that can result on the cooling and disappearance of these structures. Both the coupled microseismic and thermal modeling results, and the time-constraints derived from the geological constraints put forward, suggest that focused melt supply to the segment center is required regularly, and that this supply is maintained over extended periods of time, that can lead to a durable magma chamber. This thesis, while focusing on the processes occurring at the Lucky Strike, provide a more general template to both understand and study other slow-spreading ridge segments, and to gain insight on how the oceanic crust is formed along them.
Mid Ocean Ridges Processes
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Author : Violaine Combier
language : en
Publisher:
Release Date : 2007
Mid Ocean Ridges Processes written by Violaine Combier and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
At fast spreading ridges such as the East Pacific Rise, the nature and geometry of the magma chamber are relatively well constrained, due in part to the fact that melt has been quasi ubiquitously identified in the crust beneath the ridge axis with seismic methods experiments since the end of the 1970s. In contrast, at slow-spreading ridges such as the Mid-Atlantic Ridge, the nature of the magma chamber is less well understood, because until recently, seismic methods revealed little evidence of melt in the crut. During the SISMOMAR scientific cruise in 2005, a seismic reflector interpreted as the roof of a maga chamber was discovered beneath the Lucky Strike Volcano at the Mid-Atlantic Ridge, providing new contraints on accretion processes at slow-spreading ridges. The first part of this thesis concerns the overlapping spreading center (OSC) at 9°N on the East-Pacifc Rise. Accretion at fast-spreading ridges is often treated as bi-dimensional, with no variation along the ridge axis. At OSCs, which are non-transform discontinuities of the ridge axis found at fast-spreaing ridges, volcanic and tectonic processes are tri-dimensional (3D). The study of OSCs provides new insights into the coupling between the melt supply and the tectonics of the brittle lithosphere. I will present my study of the relationships between seafloor volcanic and tectonic structures and the geometry of melt concentrations in the crust at the 9°N OSC. My study is based mainly on a new interpretation of 3D reflection seismic data acquired during the 1997 ARAD cruise. I produced a high-resolution bathymtric map derived from the seismics and a map of the melt lens reflectors in depth. The main results inlude firstly, the identification of decoupled stresses between the brittle upper crust and the lower cust, with the melt lens acting as an effective decoupling zone; and secondly, the determination of factors controlling the geometry of the melt lens: the location of the melt source beneath the melt lens, the ambient stress-field at melt lens depth which is the regional stress-field controlled by plate separation, and the brittle upper crust local stress-field. A second part of the thesis concerns the 3D processing and interpretation of the seismic reflection data acquired at the Lucky Strike Volcano during the SISMOMAR cruise. The newly processed data constrain the depth and geometry of the reflector corresponding to the roof of the magma chamber. Faults are also imaged at depth, including the axial valley bounding faults and faults on the volcano itself. The spatial relationships between the magma chamber roof and the faults suggest a vigorous cooling of the magma chamber through hydrothermal circulation.
Mid Ocean Ridges
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Author : Johnson Robin Cann
language : en
Publisher: Cambridge University Press
Release Date : 1999-07-22
Mid Ocean Ridges written by Johnson Robin Cann and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999-07-22 with Science categories.
Covers the most important problems that arise at mid-ocean ridges; for researchers working in the earth sciences.
Faulting And Magmatism At Mid Ocean Ridges
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Author : W. Roger Buck
language : en
Publisher: American Geophysical Union
Release Date : 1998-02-04
Faulting And Magmatism At Mid Ocean Ridges written by W. Roger Buck and has been published by American Geophysical Union this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998-02-04 with Science categories.
This book can benefit the nonspecialist who wants to keep up with work on magmatism and tectonics, as well as researchers working on mid-ocean ridges."--BOOK JACKET.
Diversity Of Hydrothermal Systems On Slow Spreading Ocean Ridges
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Author : Peter A. Rona
language : en
Publisher: John Wiley & Sons
Release Date : 2013-05-02
Diversity Of Hydrothermal Systems On Slow Spreading Ocean Ridges written by Peter A. Rona and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-05-02 with Science categories.
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 188. Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridges presents a multidisciplinary overview of the remarkable emerging diversity of hydrothermal systems on slow spreading ocean ridges in the Atlantic, Indian, and Arctic oceans. When hydrothermal systems were first found on the East Pacific Rise and other Pacific Ocean ridges beginning in the late 1970s, the community consensus held that the magma delivery rate of intermediate to fast spreading was necessary to support black smoker-type high-temperature systems and associated chemosynthetic ecosystems and polymetallic sulfide deposits. Contrary to that consensus, hydrothermal systems not only occur on slow spreading ocean ridges but, as reported in this volume, are generally larger, exhibit different chemosynthetic ecosystems, produce larger mineral deposits, and occur in a much greater diversity of geologic settings than those systems in the Pacific. The full diversity of hydrothermal systems on slow spreading ocean ridges, reflected in the contributions to this volume, is only now emerging and opens an exciting new frontier for ocean ridge exploration, including Processes of heat and chemical transfer from the Earth's mantle and crust via slow spreading ocean ridges to the oceans The major role of detachment faulting linking crust and mantle in hydrothermal circulation Chemical reaction products of mantle involvement including serpentinization, natural hydrogen, abiotic methane, and hydrocarbon synthesis Generation of large polymetallic sulfide deposits hosted in ocean crust and mantle Chemosynthetic vent communities hosted in the diverse settings The readership for this volume will include schools, universities, government laboratories, and scientific societies in developed and developing nations, including over 150 nations that have ratified the United Nations Convention on the Law of the Sea.
Mid Ocean Ridges
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Author : Roger Searle
language : en
Publisher: Cambridge University Press
Release Date : 2013-09-19
Mid Ocean Ridges written by Roger Searle and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-09-19 with Science categories.
The world's mid-ocean ridges form a single, connected global ridge system that is part of every ocean, and is the longest mountain range in the world. Geologically active, mid-ocean ridges are key sites of tectonic movement, intimately involved in seafloor spreading. This coursebook presents a multidisciplinary approach to the science of mid-ocean ridges – essential for a complete understanding of global tectonics and geodynamics. Designed for graduate and advanced undergraduate students, it will also provide a valuable reference for professionals in relevant fields. Background chapters provide a historical introduction and an overview of research techniques, with succeeding chapters covering the structure of the lithosphere and crust, and volcanic, tectonic and hydrothermal processes. A summary and synthesis chapter recaps essential points to consolidate new learning. Accessible to students and professionals working in marine geology, plate tectonics, geophysics, geodynamics, volcanism and oceanography, this is the ideal introduction to a key global phenomenon.
Ridge Events
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Author :
language : en
Publisher:
Release Date : 1990
Ridge Events written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Mid-ocean ridges categories.
Towards A Petrologically Constrained Thermal Model Of Mid Ocean Ridges
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Author : Jameson Lee Scott
language : en
Publisher:
Release Date : 2017
Towards A Petrologically Constrained Thermal Model Of Mid Ocean Ridges written by Jameson Lee Scott and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Geology categories.
Plate spreading at mid-ocean ridges (MOR) is responsible for the creation of most of the crust on earth. The ridge system is very complex and many questions remain unresolved. Among these are the controls on the architecture of magma plumbing systems beneath mid-ocean ridges of different spreading rates and in proximity to transform faults. Previous studies have called into question the hypothesis that a decrease in magma flux and increase in conductive cooling along transforms faults promotes higher pressures of partial crystallization, and that this also explains the higher partial pressures of crystallization inferred for magmas erupted along slow spreading ridges compared to magmas erupted along faster spreading ridges. To test these hypothesis, I undertook a detailed analysis of pressures of partial crystallization (PPC) for magmas erupted along the slow spreading Reykjanes Ridge (RR), indeterminate spreading Juan de Fuca Ridge (JdF), 3 transforms along the fast to intermediate spreading East Pacific Rise (Blanco, Clipperton, and Siqueiros), and 5 transforms along the slow spreading Mid Atlantic Ridge (Oceanographer, Famous Transform A & B, Kane, and 15°20’N). PPC were calculated from the compositions of glasses (quenched liquids) lying along the P (and T) dependent olivine, plagioclase, and augite cotectic using the method described by Kelley and Barton (2008). Published analyses of MOR basalt glasses sampled from the ridges and transforms were used as input data. Samples with anomalous chemical compositions and samples that yielded pressures associated with unrealistically large uncertainties were filtered out of the database. The calculated pressures for the remaining 459 samples for the RR, 564 samples for the JdF, and 1056 samples for the transforms were used to calculate the depths of partial crystallization and to identify the likely location of magma chambers. The RR results indicate that the pressure of partial crystallization decreases from 102 ± 37 MPa at the Charlie Gibbs Fracture Zone to 12 ± 14 MPa at 56°N, then increases to 357 ± 68 MPa as Iceland is approached. Five magma lenses were identified at depths of 3.6 ± 1.15 km, 0.2 ± .48 km, 2.2 ± 1km, 6.7 ± 1km, and 5.1 ± 0.8km. The magma lens at 2.2 ± 1 km agrees very well with seismically imaged sill at 2.5 km. The JDF results indicate that the pressure of partial crystallization decreases from 207 ± 90 MPa near the Blanco fracture zone to 107 ± 54 MPa along the Cleft segment of the ridge to the north. Calculated pressures remain approximately constant at 87± 73 MPa along ridge segments to the north of Cleft. One magma lens was identified at depths of 2.90± 0.9 km which is in good agreement with a nearby seismically imaged magma lens at 2.5 km depth. The pressures of partial crystallization for the transforms ranged from 0 to 520 MPa with most samples returning pressures of less than 300 MPa. Pressures of
Hydrothermal Activity And Near Axis Structure At Mid Ocean Spreading Centers
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Author : Kathleen Crane
language : en
Publisher:
Release Date : 1977
Hydrothermal Activity And Near Axis Structure At Mid Ocean Spreading Centers written by Kathleen Crane and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Sea-floor spreading categories.
Magma To Microbe
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Author : Robert P. Lowell
language : en
Publisher: John Wiley & Sons
Release Date : 2013-04-30
Magma To Microbe written by Robert P. Lowell and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-04-30 with Science categories.
Magma to Microbe Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 178. Hydrothermal systems at oceanic spreading centers reflect the complex interactions among transport, cooling and crystallization of magma, fluid circulation in the crust, tectonic processes, water-rock interaction, and the utilization of hydrothermal fluids as a metabolic energy source by microbial and macro-biological ecosystems. The development of mathematical and numerical models that address these complex linkages is a fundamental part the RIDGE 2000 program that attempts to quantify and model the transfer of heat and chemicals from “mantle to microbes” at oceanic ridges. This volume presents the first “state of the art” picture of model development in this context. The most outstanding feature of this volume is its emphasis on mathematical and numerical modeling of a broad array of hydrothermal processes associated with oceanic spreading centers. By examining the state of model development in one volume, both cross-fertilization of ideas and integration across the disparate disciplines that study seafloor hydrothermal systems is facilitated. Students and scientists with an interest in oceanic spreading centers in general and more specifically in ridge hydrothermal processes will find this volume to be an up-to-date and indispensable resource.