New Insights Into Accretion And Cooling Of Lower Ocean Crust At Ultraslow And Fast Spreading Mid Ocean Ridges
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New Insights Into Accretion And Cooling Of Lower Ocean Crust At Ultraslow And Fast Spreading Mid Ocean Ridges
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Author : Christopher James Doorn
language : en
Publisher:
Release Date : 2022
New Insights Into Accretion And Cooling Of Lower Ocean Crust At Ultraslow And Fast Spreading Mid Ocean Ridges written by Christopher James Doorn and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with Earth (Planet) categories.
Mid-ocean ridges are the primary divergent tectonic margins and generate the ocean crust, which covers ~60% of Earth’s surface. The gabbroic lower ocean crust hosts lithologic and structural diversity varying with spreading rate and magma supply. This dissertation examines lower crustal accretion at ultraslow- and fast-spreading ridges to better constrain crustal accretion and cooling across spreading rates. Trace element compositions of zircon from Atlantis Bank (Southwest Indian Ridge) characterize the final stages of magmatism and the thermal architecture in the lower crust produced along an ultraslow-spreading ridge. U-Pb zircon dates of evolved gabbroic rocks from the fast-spread lower crust at Pito Deep (East Pacific Rise) reveal significant off-axis magmatism, implying locally robust magmatism and relatively slow cooling of this nascent ocean crust. Textural characteristics of gabbroic rocks from Pito Deep highlight the lateral complexity of the fast-spread lower crust, and record increasing degrees of magmatic strain with depth. Synthesizing textural data, U-Pb geochronology, mineral chemistry, and magnetic data from Pito Deep supports a pulsed gabbro glacier flow process for generating the lower ocean crust at magmatically robust fast-spreading ridges.
Cooling And Accretion Of The Lower Oceanic Crust At Fast Spreading Mid Ocean Ridges
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Author : Kathrin Faak
language : en
Publisher:
Release Date : 2013
Cooling And Accretion Of The Lower Oceanic Crust At Fast Spreading Mid Ocean Ridges written by Kathrin Faak and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Cooling categories.
Crustal Accretion And Evolution At Slow And Ultra Slow Spreading Mid Ocean Ridges
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Author :
language : en
Publisher:
Release Date : 2001
Crustal Accretion And Evolution At Slow And Ultra Slow Spreading Mid Ocean Ridges written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with categories.
Funding was provided by the National Science Foundation through Contract No. OCE-9300450 and by the Joint Oceanographic Institutions through Subcontract No. JSC1-00.
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.
Duration Rates And Patterns Of Crustal Growth At Slow Spreading Mid Ocean Ridges
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Author : Craig B. Grimes
language : en
Publisher: ProQuest
Release Date : 2008
Duration Rates And Patterns Of Crustal Growth At Slow Spreading Mid Ocean Ridges written by Craig B. Grimes and has been published by ProQuest this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Earth (Planet) categories.
This dissertation addresses temporal and spatial characteristics of magmatic and tectonic accretion processes occurring at mid-ocean ridges during formation of new ocean lithosphere. The accretion histories of plutonic crust recovered by deep drilling of footwalls to large-displacement normal faults at three locations on the MAR are emphasized. Pb/U zircon dating of evolved gabbros and oceanic plagiogranites show that magmatic accretion typically occurs over 100-200 kyr. Magmatic accretion occurs by emplacement of many short-lived intrusive pulses that are focused at different depths within the crust and mantle. During formation of the Atlantis Massif core complex (30° N, MAR), spreading may have been partitioned up to 100% on the North American plate for at least 200 kyr, implying crustal accretion was highly asymmetric. Cooling rates of 1000-2000° C/m.y. over 900-200° C are documented at Atlantis Massif and two locations from 14-16°N, MAR, consistent with rapid denudation of the footwall sections to the seafloor following emplacement. Spreading rates combined with the time interval over which cooling to
Treatise On Geophysics
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Author :
language : en
Publisher: Elsevier
Release Date : 2015-04-17
Treatise On Geophysics written by and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-04-17 with Science categories.
Treatise on Geophysics, Second Edition, is a comprehensive and in-depth study of the physics of the Earth beyond what any geophysics text has provided previously. Thoroughly revised and updated, it provides fundamental and state-of-the-art discussion of all aspects of geophysics. A highlight of the second edition is a new volume on Near Surface Geophysics that discusses the role of geophysics in the exploitation and conservation of natural resources and the assessment of degradation of natural systems by pollution. Additional features include new material in the Planets and Moon, Mantle Dynamics, Core Dynamics, Crustal and Lithosphere Dynamics, Evolution of the Earth, and Geodesy volumes. New material is also presented on the uses of Earth gravity measurements. This title is essential for professionals, researchers, professors, and advanced undergraduate and graduate students in the fields of Geophysics and Earth system science. Comprehensive and detailed coverage of all aspects of geophysics Fundamental and state-of-the-art discussions of all research topics Integration of topics into a coherent whole
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.
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.
Magma Rock And Magma Mush Interactions As Fundamental Processes Of Magmatic Differentiation
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Author : Anastassia Borisova
language : en
Publisher: Frontiers Media SA
Release Date : 2024-08-08
Magma Rock And Magma Mush Interactions As Fundamental Processes Of Magmatic Differentiation written by Anastassia Borisova and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-08-08 with Science categories.
During transport, a percolating melt or magma may contact rock or a magmatic mush, resulting in inevitable interactions that may be described as magma/melt-rock or magma/melt-mush interactions. Examples of these types of interactions include mantle metasomatism, mineral-melt reaction in the mantle, mineral dissolution in magma, crustal wallrock partial melting, and thermal remobilization of preexisting mushy magma (rejuvenation of mush) by intruding high specific enthalpy magma. This spectrum of processes plays a major role in the composition, thickness, and age of the mantle lithosphere and its associated crust. These interactions also impact the asthenosphere because melts that form in the deepest parts of the mantle may ascend and interact with shallower mantle during transport.
Mid Ocean Ridges
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Author : Christopher R. German
language : en
Publisher: American Geophysical Union
Release Date : 2004-01-09
Mid Ocean Ridges written by Christopher R. German 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 2004-01-09 with Science categories.
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 148. Mid-ocean ridges play an important role in the plate-tectonic cycle of our planet. Extending some 50–60,000 km across the ocean-floor, the global mid-ocean ridge system is the site of creation of the oceanic crust and lithosphere that covers more than two thirds of the Earth's exterior. Approximately 75% of Earth's total heat flux occurs through oceanic crust, much of it at mid-ocean ridges through complex processes associated with magma solidification, heat transfer, and cooling of young oceanic lithosphere. While the majority of this heat loss occurs through conduction, approximately one third of the total heat loss at mid-ocean ridges is influenced by a convective process: hydrothermal circulation.