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Lin YP, Ko JYT, Huang BS, Lin CH, Shih MH. Unveiling attenuation structures in the northern Taiwan volcanic zone. Sci Rep 2024; 14:4716. [PMID: 38413803 PMCID: PMC10899250 DOI: 10.1038/s41598-024-55397-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 02/22/2024] [Indexed: 02/29/2024] Open
Abstract
This cutting-edge study delves into regional magmatism in northern Taiwan through advanced 3-D P- and S-wave frequency-dependent attenuation tomography. Positioned at the dynamic convergence boundary between the Philippine Sea Plate and the Eurasian Plate, Taiwan experiences moderate earthquakes and intriguing volcanic activity, with a focus on the Tatun volcano group. Employing the Formosa seismic array for high-resolution results, our research identifies high-attenuation anomalies (low Q) beneath the northern Taiwan volcanic zone (NTVZ) and offshore submarine volcanoes, indicative of potential hydrothermal activities and magma reservoirs at varying depths. Additionally, we explore low-attenuation anomalies (high Q) in the forearc region of the Ryukyu subduction zone, suggestive of partial saturation linked to serpentinization processes resulting from seawater infiltration or forearc mantle hydration. These findings shed light on the complex geological features and provide essential insights into the crustal properties of northern Taiwan, contributing to a deeper understanding of its magmatic evolution and tectonic processes.
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Affiliation(s)
- Y-P Lin
- Department of Geosciences, National Taiwan University, Taipei, Taiwan
| | - J Y-T Ko
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan.
| | - B-S Huang
- Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
| | - C-H Lin
- Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
| | - M-H Shih
- National Center for Research on Earthquake Engineering, Taipei, Taiwan
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2
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Xiong Q, Dai HK, Zheng JP, Griffin WL, Zheng HD, Wang L, Reilly SYO. Vertical depletion of ophiolitic mantle reflects melt focusing and interaction in sub-spreading-center asthenosphere. Nat Commun 2022; 13:6956. [PMCID: PMC9663536 DOI: 10.1038/s41467-022-34781-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 11/02/2022] [Indexed: 11/16/2022] Open
Abstract
AbstractDecompressional melting of asthenosphere under spreading centers has been accepted to produce oceanic lithospheric mantle with vertical compositional variations, but these gradients are much smaller than those observed from ophiolites, which clearly require additional causes. Here we conduct high-density sampling and whole-rock and mineral analyses of peridotites across a Tibetan ophiolitic mantle section (~2 km thick), which shows a primary upward depletion (~12% difference) and local more-depleted anomalies. Thermodynamic modeling demonstrates that these features cannot be produced by decompressional melting or proportional compression of residual mantle, but can be explained by melt-peridotite reaction with lateral melt/rock ratio variations in an upwelling asthenospheric column, producing stronger depletion in the melt-focusing center and local zones. This column splits symmetrically and flows to become the horizontal uppermost lithospheric mantle, characterized by upward depletion and local anomalies. This model provides insights into melt extraction and uppermost-mantle origin beneath spreading centers with high melt fluxes.
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3
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Rayleigh-Wave Dispersion Analysis and Inversion Based on the Rotation. SENSORS 2022; 22:s22030983. [PMID: 35161729 PMCID: PMC8839137 DOI: 10.3390/s22030983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/20/2022] [Accepted: 01/22/2022] [Indexed: 02/04/2023]
Abstract
Rotational observation is essential for a comprehensive description of the ground motion, and can provide additional wave-field information. With respect to the three typical layered models in shallow engineering geology, under the assumption of linear small deformation, we simulate the 2-dimensional radial, vertical, and rotational components of the wave fields and analyze the different characteristics of Rayleigh wave dispersion recorded for the rotational and translational components. Then, we compare the results of single-component inversion with the results of multi-component joint inversion. It is found that the rotational component has wider spectral bands and more higher modes than the translational components, especially at high frequencies; the rotational component has better anti-interference performance in the noisy data test, and it can improve the inversion accuracy of the shallow shear-wave velocity. The field examples also show the significant advantages of the joint utility of the translational and rotational components, especially when a low-velocity layer exists. Rotational observation shall be beneficial for shallow surface-wave exploration.
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4
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Williams EF, Fernández-Ruiz MR, Magalhaes R, Vanthillo R, Zhan Z, González-Herráez M, Martins HF. Distributed sensing of microseisms and teleseisms with submarine dark fibers. Nat Commun 2019; 10:5778. [PMID: 31852889 PMCID: PMC6920360 DOI: 10.1038/s41467-019-13262-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 10/21/2019] [Indexed: 11/09/2022] Open
Abstract
Sparse seismic instrumentation in the oceans limits our understanding of deep Earth dynamics and submarine earthquakes. Distributed acoustic sensing (DAS), an emerging technology that converts optical fiber to seismic sensors, allows us to leverage pre-existing submarine telecommunication cables for seismic monitoring. Here we report observations of microseism, local surface gravity waves, and a teleseismic earthquake along a 4192-sensor ocean-bottom DAS array offshore Belgium. We observe in-situ how opposing groups of ocean surface gravity waves generate double-frequency seismic Scholte waves, as described by the Longuet-Higgins theory of microseism generation. We also extract P- and S-wave phases from the 2018-08-19 [Formula: see text] Fiji deep earthquake in the 0.01-1 Hz frequency band, though waveform fidelity is low at high frequencies. These results suggest significant potential of DAS in next-generation submarine seismic networks.
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Affiliation(s)
- Ethan F Williams
- Seismological Laboratory, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125-2100, USA.
| | - María R Fernández-Ruiz
- Department of Electronics, University of Alcalá, Polytechnic School, 28805, Alcalá de Henares, Spain
| | - Regina Magalhaes
- Department of Electronics, University of Alcalá, Polytechnic School, 28805, Alcalá de Henares, Spain
| | | | - Zhongwen Zhan
- Seismological Laboratory, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125-2100, USA
| | - Miguel González-Herráez
- Department of Electronics, University of Alcalá, Polytechnic School, 28805, Alcalá de Henares, Spain
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5
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Kono Y, Kenney-Benson C, Hummer D, Ohfuji H, Park C, Shen G, Wang Y, Kavner A, Manning CE. Ultralow viscosity of carbonate melts at high pressures. Nat Commun 2014; 5:5091. [PMID: 25311627 DOI: 10.1038/ncomms6091] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 08/28/2014] [Indexed: 11/09/2022] Open
Abstract
Knowledge of the occurrence and mobility of carbonate-rich melts in the Earth's mantle is important for understanding the deep carbon cycle and related geochemical and geophysical processes. However, our understanding of the mobility of carbonate-rich melts remains poor. Here we report viscosities of carbonate melts up to 6.2 GPa using a newly developed technique of ultrafast synchrotron X-ray imaging. These carbonate melts display ultralow viscosities, much lower than previously thought, in the range of 0.006-0.010 Pa s, which are ~2 to 3 orders of magnitude lower than those of basaltic melts in the upper mantle. As a result, the mobility of carbonate melts (defined as the ratio of melt-solid density contrast to melt viscosity) is ~2 to 3 orders of magnitude higher than that of basaltic melts. Such high mobility has significant influence on several magmatic processes, such as fast melt migration and effective melt extraction beneath mid-ocean ridges.
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Affiliation(s)
- Yoshio Kono
- HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, 9700 South Cass Avenue, Argonne, Illinois 60439, USA
| | - Curtis Kenney-Benson
- HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, 9700 South Cass Avenue, Argonne, Illinois 60439, USA
| | - Daniel Hummer
- Department of Earth, Planetary and Space Sciences, University of California Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, California 90095, USA
| | - Hiroaki Ohfuji
- Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577, Japan
| | - Changyong Park
- HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, 9700 South Cass Avenue, Argonne, Illinois 60439, USA
| | - Guoyin Shen
- HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, 9700 South Cass Avenue, Argonne, Illinois 60439, USA
| | - Yanbin Wang
- GeoSoilEnviroCARS, Center for Advanced Radiation Sources, The University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA
| | - Abby Kavner
- Department of Earth, Planetary and Space Sciences, University of California Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, California 90095, USA
| | - Craig E Manning
- Department of Earth, Planetary and Space Sciences, University of California Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, California 90095, USA
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6
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Liu C, Hua Q, Pei Y, Yang T, Xia S, Xue M, Le BM, Huo D, Liu F, Huang H. Passive-source ocean bottom seismograph (OBS) array experiment in South China Sea and data quality analyses. CHINESE SCIENCE BULLETIN-CHINESE 2014. [DOI: 10.1007/s11434-014-0369-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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7
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Key K, Constable S, Liu L, Pommier A. Electrical image of passive mantle upwelling beneath the northern East Pacific Rise. Nature 2013; 495:499-502. [PMID: 23538832 DOI: 10.1038/nature11932] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 01/23/2013] [Indexed: 11/09/2022]
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8
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Rohrbach A, Schmidt MW. Redox freezing and melting in the Earth's deep mantle resulting from carbon-iron redox coupling. Nature 2011; 472:209-12. [PMID: 21441908 DOI: 10.1038/nature09899] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 01/31/2011] [Indexed: 11/09/2022]
Abstract
Very low seismic velocity anomalies in the Earth's mantle may reflect small amounts of melt present in the peridotite matrix, and the onset of melting in the Earth's upper mantle is likely to be triggered by the presence of small amounts of carbonate. Such carbonates stem from subducted oceanic lithosphere in part buried to depths below the 660-kilometre discontinuity and remixed into the mantle. Here we demonstrate that carbonate-induced melting may occur in deeply subducted lithosphere at near-adiabatic temperatures in the Earth's transition zone and lower mantle. We show experimentally that these carbonatite melts are unstable when infiltrating ambient mantle and are reduced to immobile diamond when recycled at depths greater than ∼250 kilometres, where mantle redox conditions are determined by the presence of an (Fe,Ni) metal phase. This 'redox freezing' process leads to diamond-enriched mantle domains in which the Fe(0), resulting from Fe(2+) disproportionation in perovskites and garnet, is consumed but the Fe(3+) preserved. When such carbon-enriched mantle heterogeneities become part of the upwelling mantle, diamond will inevitably react with the Fe(3+) leading to true carbonatite redox melting at ∼660 and ∼250 kilometres depth to form deep-seated melts in the Earth's mantle.
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Affiliation(s)
- Arno Rohrbach
- Institut für Geochemie und Petrologie, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland.
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9
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Contrasting crustal production and rapid mantle transitions beneath back-arc ridges. Nature 2011; 469:198-202. [PMID: 21228874 DOI: 10.1038/nature09690] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 11/18/2010] [Indexed: 11/09/2022]
Abstract
The opening of back-arc basins behind subduction zones progresses from initial rifting near the volcanic arc to seafloor spreading. During this process, the spreading ridge and the volcanic arc separate and lavas erupted at the ridge are predicted to evolve away from being heavily subduction influenced (with high volatile contents derived from the subducting plate). Current models predict gradational, rather than abrupt, changes in the crust formed along the ridge as the inferred broad melting region beneath it migrates away from heavily subduction-influenced mantle. In contrast, here we show that across-strike and along-strike changes in crustal properties at the Eastern Lau spreading centre are large and abrupt, implying correspondingly large discontinuities in the nature of the mantle supplying melt to the ridge axes. With incremental separation of the ridge axis from the volcanic front of as little as 5 km, seafloor morphology changes from shallower complex volcanic landforms to deeper flat sea floor dominated by linear abyssal hills, upper crustal seismic velocities abruptly increase by over 20%, and gravity anomalies and isostasy indicate crustal thinning of more than 1.9 km. We infer that the abrupt changes in crustal properties reflect rapid evolution of the mantle entrained by the ridge, such that stable, broad triangular upwelling regions, as inferred for mid-ocean ridges, cannot form near the mantle wedge corner. Instead, the observations imply a dynamic process in which the ridge upwelling zone preferentially captures water-rich low-viscosity mantle when it is near the arc. As the ridge moves away from the arc, a tipping point is reached at which that material is rapidly released from the upwelling zone, resulting in rapid changes in the character of the crust formed at the ridge.
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10
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11
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Katz RF, Spiegelman M, Holtzman B. The dynamics of melt and shear localization in partially molten aggregates. Nature 2006; 442:676-9. [PMID: 16900197 DOI: 10.1038/nature05039] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2006] [Accepted: 06/30/2006] [Indexed: 11/09/2022]
Abstract
The volcanoes that lie along the Earth's tectonic boundaries are fed by melt generated in the mantle. How this melt is extracted and focused to the volcanoes, however, remains an unresolved question. Here we present new theoretical results with implications for melt focusing beneath mid-ocean ridges. By modelling laboratory experiments, we test a formulation for magma dynamics and provide an explanation for localized bands of high-porosity and concentrated shear deformation observed in experiments. These bands emerge and persist at 15 degrees-25 degrees to the plane of shear. Past theoretical work on this system predicted the emergence of melt bands but at an angle inconsistent with experiments. Our results suggest that the observed band angle results from a balance of porosity-weakening and strain-rate-weakening deformation mechanisms. Lower band angles are predicted for greater strain-rate weakening. From these lower band angles, we estimate the orientation of melt bands beneath mid-ocean ridges and show that they may enhance magma focusing toward the ridge axis.
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Affiliation(s)
- Richard F Katz
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, USA.
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12
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Baba K, Chave AD, Evans RL, Hirth G, Mackie RL. Mantle dynamics beneath the East Pacific Rise at 17°S: Insights from the Mantle Electromagnetic and Tomography (MELT) experiment. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2004jb003598] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Kiyoshi Baba
- Institute for Research on Earth Evolution; Japan Agency for Marine-Earth Science and Technology; Yokosuka Kanagawa Japan
| | - Alan D. Chave
- Woods Hole Oceanographic Institution; Woods Hole Massachusetts USA
| | - Rob L. Evans
- Woods Hole Oceanographic Institution; Woods Hole Massachusetts USA
| | - Greg Hirth
- Woods Hole Oceanographic Institution; Woods Hole Massachusetts USA
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13
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Yang Y, Forsyth DW. Rayleigh wave phase velocities, small-scale convection, and azimuthal anisotropy beneath southern California. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jb004180] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Evans RL, Hirth G, Baba K, Forsyth D, Chave A, Mackie R. Geophysical evidence from the MELT area for compositional controls on oceanic plates. Nature 2005; 437:249-52. [PMID: 16148932 DOI: 10.1038/nature04014] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Accepted: 06/29/2005] [Indexed: 11/09/2022]
Abstract
Magnetotelluric and seismic data, collected during the MELT experiment at the southern East Pacific Rise, constrain the distribution of melt beneath this mid-ocean-ridge spreading centre and also the evolution of the oceanic lithosphere during its early cooling history. Here we focus on structures imaged at distances approximately 100 to 350 km east of the ridge crest, corresponding to seafloor ages of approximately 1.3 to 4.5 million years (Myr), where the seismic and electrical conductivity structure is nearly constant and independent of age. Beginning at a depth of about 60 km, we image a large increase in electrical conductivity and a change from isotropic to transversely anisotropic electrical structure, with higher conductivity in the direction of fast propagation for seismic waves. Conductive cooling models predict structure that increases in depth with age, extending to about 30 km at 4.5 Myr ago. We infer, however, that the structure of young oceanic plates is instead controlled by a decrease in water content above a depth of 60 km induced by the melting process beneath the spreading centre.
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Affiliation(s)
- Rob L Evans
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
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15
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Forsyth DW, Li A. Array analysis of two-dimensional variations in surface wave phase velocity and azimuthal anisotropy in the presence of multipathing interference. SEISMIC EARTH: ARRAY ANALYSIS OF BROADBAND SEISMOGRAMS 2005. [DOI: 10.1029/157gm06] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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16
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Hillier JK, Watts AB. “Plate-like” subsidence of the East Pacific Rise-South Pacific superswell system. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004jb003041] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- J. K. Hillier
- Department of Earth Sciences; University of Oxford; Oxford UK
| | - A. B. Watts
- Department of Earth Sciences; University of Oxford; Oxford UK
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17
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Carbotte SM, Small C, Donnelly K. The influence of ridge migration on the magmatic segmentation of mid-ocean ridges. Nature 2004; 429:743-6. [PMID: 15201906 DOI: 10.1038/nature02652] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Accepted: 05/13/2004] [Indexed: 11/09/2022]
Abstract
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 supply of magma from the mantle, although the origin of the variations is poorly understood. Here we show that magmatic segmentation of ridges with fast and intermediate spreading rates is directly related to the migration velocity of the spreading axis over the mantle. For over 9,500 km of mid-ocean ridge examined, leading ridge segments in the 'hotspot' reference frame coincide with the shallow magmatically robust segments across 86 per cent of all transform faults and 73 per cent of all second-order discontinuities. We attribute this relationship to asymmetric mantle upwelling and melt production due to ridge migration, with focusing of melt towards ridge segments across discontinuities. The model is consistent with variations in crustal structure across discontinuities of the East Pacific Rise, and may explain variations in depth of melting and the distribution of enriched lavas.
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Affiliation(s)
- S M Carbotte
- Lamont-Doherty Earth Observatory, 61 Rte 9W, Palisades, New York 10964, USA.
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18
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Weeraratne DS, Forsyth DW, Fischer KM, Nyblade AA. Evidence for an upper mantle plume beneath the Tanzanian craton from Rayleigh wave tomography. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb002273] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | - Donald W. Forsyth
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
| | - Karen M. Fischer
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
| | - Andrew A. Nyblade
- Department of Geosciences; Pennsylvania State University; University Park Pennsylvania USA
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19
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Dunn RA, Forsyth DW. Imaging the transition between the region of mantle melt generation and the crustal magma chamber beneath the southern East Pacific Rise with short-period Love waves. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb002217] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Robert A. Dunn
- Department of Geological and Geophysics, SOEST; University of Hawaii at Manoa; Honolulu Hawaii USA
| | - Donald W. Forsyth
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
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20
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Hammond WC, Toomey DR. Seismic velocity anisotropy and heterogeneity beneath the Mantle Electromagnetic and Tomography Experiment (MELT) region of the East Pacific Rise from analysis ofPandSbody waves. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2002jb001789] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- William C. Hammond
- Department of Geological Sciences; University of Oregon; Eugene Oregon USA
| | - Douglas R. Toomey
- Department of Geological Sciences; University of Oregon; Eugene Oregon USA
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21
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Kelemen PB, Rilling JL, Parmentier EM, Mehl L, Hacker BR. Thermal structure due to solid-state flow in the mantle wedge beneath arcs. INSIDE THE SUBDUCTION FACTORY 2003. [DOI: 10.1029/138gm13] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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22
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Conder JA, Forsyth DW, Parmentier EM. Asthenospheric flow and asymmetry of the East Pacific Rise, MELT area. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jb000807] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- James A. Conder
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
| | - Donald W. Forsyth
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
| | - E. M. Parmentier
- Department of Geological Sciences; Brown University; Providence Rhode Island USA
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23
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Zou H, Zindler A, Niu Y. Constraints on melt movement beneath the East Pacific Rise from 230Th-238U disequilibrium. Science 2002; 295:107-10. [PMID: 11778043 DOI: 10.1126/science.1064295] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report 230Th-238U disequilibrium data on mid-ocean ridge basalts recovered 5 to 40 kilometers off the ridge axis near 9 degrees 30'N of the East Pacific Rise. These data indicate near-symmetrical eruptions of normal mid-ocean ridge basalts (NMORBs) and incompatible element-enriched mid-ocean ridge basalts (EMORBs) as far as 20 kilometers off axis. Our results suggest large-scale subsurface lateral transport of NMORB melt at 19 to 21 centimeters per year and also provide constraints on the petrogenesis of EMORBs of off-axis origin.
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Affiliation(s)
- Haibo Zou
- Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095, USA.
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24
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Smith GP, Wiens DA, Fischer KM, Dorman LM, Webb SC, Hildebrand JA. A complex pattern of mantle flow in the Lau backarc. Science 2001; 292:713-6. [PMID: 11326095 DOI: 10.1126/science.1058763] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Shear-wave splitting analysis of local events recorded on land and on the ocean floor in the Tonga arc and Lau backarc indicate a complex pattern of azimuthal anisotropy that cannot be explained by mantle flow coupled to the downgoing plate. These observations suggest that the direction of mantle flow rotates from convergence-parallel in the Fiji plateau to north-south beneath the Lau basin and arc-parallel beneath the Tonga arc. These results correlate with helium isotopes that map mantle flow of the Samoan plume into the Lau basin through an opening tear in the Pacific plate.
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Affiliation(s)
- G P Smith
- Department of Earth and Planetary Sciences, Washington University in St. Louis, 1 Brookings Drive, CB1169, St. Louis, MO 63130, USA
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25
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Hall CE, Fischer KM, Parmentier EM, Blackman DK. The influence of plate motions on three-dimensional back arc mantle flow and shear wave splitting. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jb900297] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Fouch MJ, Fischer KM, Parmentier EM, Wysession ME, Clarke TJ. Shear wave splitting, continental keels, and patterns of mantle flow. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999jb900372] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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28
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Combined dynamic and geochemical evidence for convergent melt flow beneath the East Pacific Rise. Nature 1999. [DOI: 10.1038/46260] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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29
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White SM, Macdonald KC, Scheirer DS, Cormier MH. Distribution of isolated volcanoes on the flanks of the East Pacific Rise, 15.3°S-20°S. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jb02791] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Scheirer DS, Forsyth DW, Cormier MH, Macdonald KC. Shipboard geophysical indications of asymmetry and melt production beneath the east pacific rise near the MELT experiment. Science 1998; 280:1221-4. [PMID: 9596566 DOI: 10.1126/science.280.5367.1221] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Near the Mantle Electromagnetic and Tomography (MELT) Experiment, seamounts form and off-axis lava flows occur in a zone that extends farther to the west of the East Pacific Rise than to the east, indicating a broad, asymmetric region of melt production. More seamounts, slower subsidence, and less dense mantle on the western flank suggest transport of hotter mantle toward the axis from the west. Variations in axial ridge shape, axial magma chamber continuity, off-axis volcanism, and apparent mantle density indicate that upwelling is probably faster and more melt is produced beneath 17 degrees15'S than beneath 15 degrees55'S. Recent volcanism occurs above mantle with the lowest seismic velocities.
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Affiliation(s)
- DS Scheirer
- D. S. Scheirer and D. W. Forsyth, Department of Geological Sciences, Box 1846, Brown University, Providence, RI 02912, USA. M.-H. Cormier, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA. K. C. Macdonald, Department of
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Webb SC, Forsyth DW. Structure of the upper mantle under the EPR from waveform inversion of regional events. Science 1998; 280:1227-9. [PMID: 9596568 DOI: 10.1126/science.280.5367.1227] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Waveform inversions of seismograms recorded at the Mantle Electromagnetic and Tomography (MELT) Experiment ocean bottom seismometer array from regional events with paths following the East Pacific Rise (EPR) require that low shear velocities (<3.7 km/s) extend to depths of more than 100 km below the rise axis. Velocities increase with average crustal age along ray paths. The reconciliation of Love and Rayleigh wave data requires that shear flow has aligned melt pockets or olivine crystals, creating an anisotropic uppermost mantle.
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Affiliation(s)
- SC Webb
- S. C. Webb, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA. D. W. Forsyth, Department of Geological Science, Brown University, Providence, RI 02912, USA
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Wolfe CJ, Solomon SC. Shear-wave splitting and implications for mantle flow beneath the MELT region of the east pacific rise. Science 1998; 280:1230-2. [PMID: 9596569 DOI: 10.1126/science.280.5367.1230] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Shear-wave splitting across the fast-spreading East Pacific Rise has been measured from records of SKS and SKKS phases on the ocean-bottom seismometers of the Mantle Electromagnetic and Tomography (MELT) Experiment. The direction of fast shear-wave polarization is aligned parallel to the spreading direction. Delay times between fast and slow shear waves are asymmetric across the rise, and off-axis values on the Pacific Plate are twice those on the Nazca Plate. Splitting on the Pacific Plate may reflect anisotropy associated with spreading-induced flow above a depth of about 100 km, as well as a deeper contribution from warm asthenospheric return flow from the Pacific Superswell region.
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Affiliation(s)
- CJ Wolfe
- C. J. Wolfe, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. S. C. Solomon, Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
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Shen Y, Sheehan AF, Dueker KG, Gilbert H. Mantle discontinuity structure beneath the southern east pacific rise from P-to-S converted phases. Science 1998; 280:1232-5. [PMID: 9596570 DOI: 10.1126/science.280.5367.1232] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Receiver functions derived from teleseismic body waves recorded by ocean-bottom seismometers on the southern East Pacific Rise reveal shear waves converted from compressional waves at the mantle discontinuities near 410- and 660-kilometer depth. The thickness of the mantle transition zone between the two discontinuities is normal relative to the global average and indicates that upwelling beneath the southern East Pacific Rise is not associated with an excess temperature in the mantle transition zone.
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Affiliation(s)
- Y Shen
- Y. Shen, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. A. F. Sheehan, K. G. Dueker, H. Gilbert, Cooperative Institute for Research in Environmental Sciences (CIRES), University of
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