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  • 1
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    A 2-D Tomographic Model of the Juan de Fuca Plate from Accretion at Axial Seamount to Subduction at the Cascadia Margin from an Active Source OBS survey (2016)
    Wiley
    Details
    Publication Date: 2016-07-23
    Description: We report results from a wide-angle controlled source seismic experiment across the Juan de Fuca plate designed to investigate the evolution of the plate from accretion at the Juan de Fuca Ridge to subduction at the Cascadia margin. A two-dimensional velocity model of the crust and upper mantle is derived from a joint reflection-refraction travel-time inversion. To interpret our tomography results, we first generate a plausible baseline velocity model, assuming a plate cooling model and realistic oceanic lithologies. We then use an effective medium theory to infer from our tomography results the extent of porosity, alteration, and water content that would be required to explain the departure from the baseline model. In crust of ages 〉1 Ma and away from propagator wakes and regions of faulting due to plate bending, we obtain estimates of upper crustal hydration of 0.5-2.1 wt% and find mostly dry lower crust and upper mantle. In sections of the crust affected by propagator wakes we find upper estimates of upper crustal, lower crustal, and upper mantle hydration of 3.1, 0.8, and 1.8 wt%, respectively. At the Cascadia deformation front, we find that the amount of water stored at uppermost mantle levels in the downgoing JdF plate is very limited (〈0.3 wt%), with most of the water carried into the subduction zone being stored in the oceanic crust.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    A new view of the mid-ocean ridge from the behaviour of ridge-axis discontinuities (1988)
    In:  Nature, Stuttgart, Pergamon, vol. 335, no. 2, pp. 217-225, pp. B05315, (ISSN: 1340-4202)
    Details
    Publication Date: 1988
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Plate tectonics ; GeodesyY ; Volcanology ; transform
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
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    Network of off-axis melt bodies at the East Pacific Rise (2012)
    Springer Nature
    Details
    Publication Date: 2012-03-31
    Description: Network of off-axis melt bodies at the East Pacific Rise Nature Geoscience 5, 279 (2012). doi:10.1038/ngeo1377 Authors: J. P. Canales, H. Carton, S. M. Carbotte, J. C. Mutter, M. R. Nedimović, M. Xu, O. Aghaei, M. Marjanović & K. Newman Magmatic accretion of new oceanic crust at intermediate- to fast-spreading mid-ocean ridges occurs along a narrow axial zone. This zone is characterized by molten sills in the crust that are emplaced within about 3 km of the ridge axis and overlie a zone of elevated temperatures and partial melt. There are disparate indications of off-axis magmatism and lavas erupted in the near-axis region are more compositionally variable than in the axial zone. Here we present three-dimensional seismic reflection images from the fast-spreading East Pacific Rise that reveal a network of sills 4 to 8 km east of the ridge axis. Our crustal model, constrained using seismic velocity and attenuation data, shows that the sills are located outside of the main axial zone of crustal accretion, and above a region containing partial melt. We infer that the sills represent sites of sustained off-axis magmatism. Pockets of melt extend from the off-axis sills to the axial zone and may represent melt migration pathways. These pathways could promote mixing between enriched off-axis melts and normal on-axis melts, contributing to the compositional variability of the near-axis lavas. We suggest that off-axis magmatism occurs preferentially, but not exclusively, where pre-existing fractures inherited from offsets of the spreading axis promote melt transport from the mantle into the crust.
    Print ISSN: 1752-0894
    Electronic ISSN: 1752-0908
    Topics: Geosciences
    Published by Springer Nature
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  • 4
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    Seismic reflection images of a near-axis melt sill within the lower crust at the Juan de Fuca ridge (2009)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2009-07-03
    Description: The oceanic crust extends over two-thirds of the Earth's solid surface, and is generated along mid-ocean ridges from melts derived from the upwelling mantle. The upper and middle crust are constructed by dyking and sea-floor eruptions originating from magma accumulated in mid-crustal lenses at the spreading axis, but the style of accretion of the lower oceanic crust is actively debated. Models based on geological and petrological data from ophiolites propose that the lower oceanic crust is accreted from melt sills intruded at multiple levels between the Moho transition zone (MTZ) and the mid-crustal lens, consistent with geophysical studies that suggest the presence of melt within the lower crust. However, seismic images of molten sills within the lower crust have been elusive. Until now, only seismic reflections from mid-crustal melt lenses and sills within the MTZ have been described, suggesting that melt is efficiently transported through the lower crust. Here we report deep crustal seismic reflections off the southern Juan de Fuca ridge that we interpret as originating from a molten sill at present accreting the lower oceanic crust. The sill sits 5-6 km beneath the sea floor and 850-900 m above the MTZ, and is located 1.4-3.2 km off the spreading axis. Our results provide evidence for the existence of low-permeability barriers to melt migration within the lower section of modern oceanic crust forming at intermediate-to-fast spreading rates, as inferred from ophiolite studies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Canales, J Pablo -- Nedimovic, Mladen R -- Kent, Graham M -- Carbotte, Suzanne M -- Detrick, Robert S -- England -- Nature. 2009 Jul 2;460(7251):89-93. doi: 10.1038/nature08095.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA. jpcanales@whoi.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19571883" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 5
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    Mid-ocean ridges: discontinuities, segments and giant cracks (1991)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1991-08-30
    Description: Geological observations reveal that mid-ocean ridges are segmented by numerous rigid and nonrigid discontinuities. A hierarchy of segmentation, ranging from large, long-lived segments to others that are small, migratory, and transient, determines the pattern and timing of creation of new ocean floor. To the extent that spreading segments behave like giant cracks in a plate, the crack propagation force at segment tips increases with segment length, which may explain why long segments tend to lengthen and prevail over shorter neighboring segments. Partial melting caused by decompression of the upper mantle due to plate separation and changes in the direction of spreading result in the spawning of new short segments so that a balance of long and short segments is maintained.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Macdonald, K C -- Scheirer, D S -- Carbotte, S M -- New York, N.Y. -- Science. 1991 Aug 30;253(5023):986-94.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17775341" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 6
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    Seismic Images of Active Magma Systems Beneath the East Pacific Rise Between 17{degrees}05' and 17{degrees}35'S (1995)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1995-04-21
    Description: Seismic reflection data from the East Pacific Rise between 17 degrees 05' and 17 degrees 35'S image a magma lens that varies regularly in depth and width as ridge morphology changes, confirming the notion that axial morphology can be used to infer ridge magmatic state. However, at 17 degrees 26'S, where the ridge is locally shallow and broad, the magma lens is markedly shallower and wider than predicted from regional trends. In this area, submersible dives reveal recent volcanic eruptions. These observations indicate that it is where the width and depth of the magma chamber differ from regional trends, indicating an enhanced magmatic budget, that is diagnostic of current magmatism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mutter, J C -- Carbotte, S M -- Su, W -- Xu, L -- Buhl, P -- Detrick, R S -- Kent, G M -- Orcutt, J A -- Harding, A J -- New York, N.Y. -- Science. 1995 Apr 21;268(5209):391-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17746545" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 7
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    Anatomy of an active submarine volcano (2014)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publication Date: 2014-07-31
    Description: Most of the magma erupted at mid-ocean ridges is stored in a mid-crustal melt lens that lies at the boundary between sheeted dikes and gabbros. Nevertheless, images of the magma pathways linking this melt lens to the overlying eruption site have remained elusive. Here, we have used seismic methods to image the thickest magma reservoir observed beneath any spreading center to date, which is principally attributed to the juxtaposition of the Juan de Fuca Ridge with the Cobb hotspot (northwestern USA). Our results reveal a complex melt body, which is ~14 km long, 3 km wide, and up to 1 km thick, beneath the summit caldera. The estimated volume of the reservoir is 18–30 km 3 , more than two orders of magnitude greater than the erupted magma volumes of either the A.D. 1998 or 2011 eruption. Our images show a network of sub-horizontal to shallow-dipping (〈30°) features that we interpret as pathways facilitating melt transport from the magma reservoir to the eruption sites.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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  • 8
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    (Table 2) Age determination from different sediment cores of the Juan de Fuca Ridge (2017)
    PANGAEA
    In:  Supplement to: Costa, K M; McManus, Jerry F; Boulahanis, B; Carbotte, S M; Winckler, Gisela; Huybers, Peter; Langmuir, Charles H (2016): Sedimentation, stratigraphy and physical properties of sediment on the Juan de Fuca Ridge. Marine Geology, 380, 163-173, https://doi.org/10.1016/j.margeo.2016.08.003
    Details
    Publication Date: 2024-03-02
    Description: Sedimentation near mid-ocean ridges may differ from pelagic sedimentation due to the influence of the ridges' rough topography on sediment deposition and transport. This study explores whether the near-ridge environment responds to glacial-interglacial changes in climate and oceanography. New benthic d18O, radiocarbon, multi-sensor track, and physical property (sedimentation rates, density, magnetic susceptibility) data for seven cores on the Juan de Fuca Ridge provide multiple records covering the past 700,000 years of oceanographic history of the Northeast Pacific Ocean. Systematic variations in sediment density and coarse fraction correspond to glacial-interglacial cycles identified in benthic d18O, and these observations may provide a framework for mapping the d18O chronostratigraphy via sediment density to other locations on the Juan de Fuca Ridge and beyond. Sedimentation rates generally range from 0.5 to 3 cm/kyr, with background pelagic sedimentation rates close to 1 cm/kyr. Variability in sedimentation rates close to the ridge likely reflects remobilization of sediment caused by the high relief of the ridge bathymetry. Sedimentation patterns primarily reflect divergence of sedimentation rates with distance from the ridge axis and glacial-interglacial variation in sedimentation that may reflect carbonate preservation cycles as well as preferential remobilization of fine material.
    Keywords: Age, 14C calibrated; Age, dated; Age, dated material; Age, dated standard deviation; AT26-19; AT26-19-05PC; AT26-19-09PC; AT26-19-12PC; AT26-19-38PC; Atlantis (1997); Calendar age; Calendar age, standard deviation; DEPTH, sediment/rock; Event label; Juan de Fuca Ridge, North Pacific Ocean; Latitude of event; Longitude of event; PC; Piston corer; Sample ID; see further details
    Type: Dataset
    Format: text/tab-separated-values, 24 data points
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    DATA PANGAEA
  • 9
    Electronic Resource
    Electronic Resource
    The influence of ridge migration on the magmatic segmentation of mid-ocean ridges (2004)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 429 (2004), S. 743-746 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Earth's mid-ocean ridges display systematic changes in depth and shape, which subdivide the ridges into discrete spreading segments bounded by transform faults and smaller non-transform offsets of the axis. These morphological changes have been attributed to spatial variations in the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature02652
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    A new view of the mid-ocean ridge from the behaviour of ridge-axis discontinuities (1988)
    [s.l.] : Nature Publishing Group
    Nature 335 (1988), S. 217-225 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] High-resolution images covering large areas of the seafloor reveal numerous discontinuities along the mid-ocean ridge. These discontinuities occur at a range of scales (10–1,000 km) and define a fundamental segmentation of seafloor spreading centres. Some are transient; others persist for ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/335217a0
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