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Sauter D, Manatschal G, Kusznir N, Masquelet C, Werner P, Ulrich M, Bellingham P, Franke D, Autin J. Ignition of the southern Atlantic seafloor spreading machine without hot-mantle booster. Sci Rep 2023; 13:1195. [PMID: 36681722 PMCID: PMC9867738 DOI: 10.1038/s41598-023-28364-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 01/17/2023] [Indexed: 01/22/2023] Open
Abstract
The source of massive magma production at volcanic rifted margins remains strongly disputed since the first observations of thick lava piles in the 1980s. However, volumes of extruded and intruded melt products within rifted continental crust are still not accurately resolved using geophysical methods. Here we investigate the magma budget alongside the South Atlantic margins, at the onset of seafloor spreading, using high-quality seismic reflection profiles to accurately estimate the oceanic crustal thickness. We show that, along ~ 75% of the length of the Early-Cretaceous initial spreading centre, the crustal thickness is similar to regular oceanic thickness with an age > 100 Ma away from hot spots. Thus, most of the southernmost Atlantic Ocean opened without anomalously hot mantle, high magma supply being restricted to the Walvis Ridge area. We suggest that alternative explanations other than a hotter mantle should be favoured to explain the thick magmatic layer of seaward dipping reflectors landward of the initial mid-oceanic ridge.
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Affiliation(s)
- Daniel Sauter
- Institut Terre et Environnement de Strasbourg (ITES), Université de Strasbourg, 5 Rue Descartes, 67084, Strasbourg, France.
| | - Gianreto Manatschal
- Institut Terre et Environnement de Strasbourg (ITES), Université de Strasbourg, 5 Rue Descartes, 67084, Strasbourg, France
| | - Nick Kusznir
- School of Environmental Sciences, Liverpool University, Liverpool, L69 3GP, UK
| | - Charles Masquelet
- Institut des Sciences de la Terre de Paris (ISTeP), Sorbonne Université, 4 Place Jussieu, 75005, Paris, France
| | - Philippe Werner
- Institut Terre et Environnement de Strasbourg (ITES), Université de Strasbourg, 5 Rue Descartes, 67084, Strasbourg, France
| | - Marc Ulrich
- Institut Terre et Environnement de Strasbourg (ITES), Université de Strasbourg, 5 Rue Descartes, 67084, Strasbourg, France
| | | | - Dieter Franke
- Bundesanstalt für Geowissenschaften und Rohstoffe, Geozentrum Hannover, Stilleweg 2, 30655, Hannover, Deutschland
| | - Julia Autin
- Institut Terre et Environnement de Strasbourg (ITES), Université de Strasbourg, 5 Rue Descartes, 67084, Strasbourg, France
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Wang Z, Singh SC. Seismic evidence for uniform crustal accretion along slow-spreading ridges in the equatorial Atlantic Ocean. Nat Commun 2022; 13:7809. [PMID: 36528618 PMCID: PMC9759516 DOI: 10.1038/s41467-022-35459-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022] Open
Abstract
The crustal accretion along mid-ocean ridges is known to be spreading-rate dependent. Along fast-spreading ridges, two-dimensional sheet-like mantle upwelling creates relatively uniform crust. In contrast, the crust formed along slow-spreading ridges shows large along-axis thickness variations with thicker crust at segment centres, which is hypothesised to be due a three-dimensional plume-like mantle upwelling or due to focused melt migration to segment centres. Using wide-angle seismic data acquired from the equatorial Atlantic Ocean, here we show that the crustal thickness is nearly uniform (~5.5 km) across five crustal segments for crust formed at the slow-spreading Mid-Atlantic Ridge with age varying from 8 to 70 Ma. The crustal velocities indicate that this crust is predominantly of magmatic origin. We suggest that this uniform magmatic crustal accretion is due to a two-dimensional sheet-like mantle upwelling facilitated by the long-offset transform faults in the equatorial Atlantic region and the presence of a high concentration of volatiles in the primitive melt in the mantle.
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Affiliation(s)
- Zhikai Wang
- grid.9489.c0000 0001 0675 8101Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 1 rue Jussieu, Paris, 75238 France
| | - Satish C. Singh
- grid.9489.c0000 0001 0675 8101Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 1 rue Jussieu, Paris, 75238 France
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Vaddineni VA, Singh SC, Grevemeyer I, Audhkhasi P, Papenberg C. Evolution of the Crustal and Upper Mantle Seismic Structure From 0-27 Ma in the Equatorial Atlantic Ocean at 2° 43'S. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2021; 126:e2020JB021390. [PMID: 35865731 PMCID: PMC9285972 DOI: 10.1029/2020jb021390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 06/04/2021] [Accepted: 06/08/2021] [Indexed: 06/15/2023]
Abstract
We present seismic tomographic results from a unique seismic refraction and wide-angle survey along a 600 km long flow-line corridor of oceanic lithosphere ranging in age from 0 to 27 Ma in the equatorial Atlantic Ocean at 2° 43'S. The velocities in the crust near the ridge axis rapidly increase in the first 6 Myr and then change gradually with age. The upper crust (Layer 2) thickness varies between 2 and 2.4 km with an average thickness of 2.2 km and the crustal thickness varies from 5.6 to 6 km along the profile with an average crustal thickness of 5.8 km. At some locations, we observe negative velocity anomalies (∼-0.3 km/s) in the lower crust which could be either due to chemical heterogeneity in gabbroic rocks and/or the effects of fault related deformation zones leading to an increase in porosities up to 1.6% depending on the pore/crack geometry. The existence of a low velocity anomaly beneath the ridge axis suggests the presence of partial melt (∼1.3%) in the lower crust. Upper mantle velocities also remain low (∼7.8 km/s) from ridge axis up to 5 Ma, indicating a high temperature regime associated with mantle melting zone underneath. These results suggest that the evolution of the crust and uppermost mantle at this location occur in the first 10 Ma of its formation and then remains unchanged. Most of the structures in the older crust and upper mantle are fossilized structures and could provide information about past processes at ocean spreading centers.
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Affiliation(s)
| | - Satish C. Singh
- Université de ParisInstitut de Physique du Globe de ParisCNRSParisFrance
| | - Ingo Grevemeyer
- GEOMAR Helmholtz Centre of Ocean Research KielRD4‐Marine GeodynamicsKielGermany
| | - Pranav Audhkhasi
- Université de ParisInstitut de Physique du Globe de ParisCNRSParisFrance
| | - Cord Papenberg
- GEOMAR Helmholtz Centre of Ocean Research KielRD4‐Marine GeodynamicsKielGermany
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Marjanović M, Singh SC, Gregory EPM, Grevemeyer I, Growe K, Wang Z, Vaddineni V, Laurencin M, Carton H, Gómez de la Peña L, Filbrandt C. Seismic Crustal Structure and Morphotectonic Features Associated With the Chain Fracture Zone and Their Role in the Evolution of the Equatorial Atlantic Region. JOURNAL OF GEOPHYSICAL RESEARCH. SOLID EARTH 2020; 125:e2020JB020275. [PMID: 33282617 PMCID: PMC7685155 DOI: 10.1029/2020jb020275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/31/2020] [Accepted: 09/01/2020] [Indexed: 06/12/2023]
Abstract
Oceanic transform faults and fracture zones (FZs) represent major bathymetric features that keep the records of past and present strike-slip motion along conservative plate boundaries. Although they play an important role in ridge segmentation and evolution of the lithosphere, their structural characteristics, and their variation in space and time, are poorly understood. To address some of the unknowns, we conducted interdisciplinary geophysical studies in the equatorial Atlantic Ocean, the region where some of the most prominent transform discontinuities have been developing. Here we present the results of the data analysis in the vicinity of the Chain FZ, on the South American Plate. The crustal structure across the Chain FZ, at the contact between ∼10 and 24 Ma oceanic lithosphere, is sampled along seismic reflection and refraction profiles. We observe that the crustal thickness within and across the Chain FZ ranges from ∼4.6-5.9 km, which compares with the observations reported for slow-slipping transform discontinuities globally. We attribute this presence of close to normal oceanic crustal thickness within FZs to the mechanism of lateral dike propagation, previously considered to be valid only in fast-slipping environments. Furthermore, the combination of our results with other data sets enabled us to extend the observations to morphotectonic characteristics on a regional scale. Our broader view suggests that the formation of the transverse ridge is closely associated with a global plate reorientation that was also responsible for the propagation and for shaping lower-order Mid-Atlantic Ridge segmentation around the equator.
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Affiliation(s)
- Milena Marjanović
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Satish C. Singh
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Emma P. M. Gregory
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Ingo Grevemeyer
- GEOMAR Helmholtz Centre of Ocean Research Kiel, RD4—Marine GeodynamicsKielGermany
| | - Kevin Growe
- Applied Geophysics ProgramTU Delft, ETH Zürich, RWTH AachenAachenGermany
| | - Zhikai Wang
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Venkata Vaddineni
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Muriel Laurencin
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | - Hélène Carton
- Université de Paris, Institut de Physique du Globe de Paris, CNRSParisFrance
| | | | - Christian Filbrandt
- GEOMAR Helmholtz Centre of Ocean Research Kiel, RD4—Marine GeodynamicsKielGermany
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Cannat M, Cann J, Maclennan J. Some Hard Rock Constraints on the Supply of Heat to Mid-Ocean Ridges. MID-OCEAN RIDGES 2013. [DOI: 10.1029/148gm05] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Searle RC, Escartín J. The Rheology and Morphology of Oceanic Lithosphere and Mid-Ocean Ridges. MID-OCEAN RIDGES 2013. [DOI: 10.1029/148gm03] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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7
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Macdonald KC. Linkages Between Faulting, Volcanism, Hydrothermal Activity and Segmentation on Fast Spreading Centers. FAULTING AND MAGMATISM AT MID-OCEAN RIDGES 2013. [DOI: 10.1029/gm106p0027] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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8
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Hayes DE, Kane KA. Long-lived mid-ocean ridge segmentation of the Pacific-Antarctic Ridge and the Southeast Indian Ridge. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb01562] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Magde LS, Detrick RS. Crustal and upper mantle contribution to the axial gravity anomaly at the southern East Pacific Rise. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb02869] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Ito GT, Lin J. Mantle temperature anomalies along the past and paleoaxes of the Galápagos spreading center as inferred from gravity analyses. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb02594] [Citation(s) in RCA: 63] [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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11
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Kane KA, Hayes DE. Long-lived mid-ocean ridge segmentation: Constraints on models. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb01561] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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12
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Cormier MH, Macdonald KC, Wilson DS. A three-dimensional gravity analysis of the East Pacific Rise from 18° to 21°30′S. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00243] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Appelgate B, Shor AN. The northern Mid-Atlantic and Reykjanes Ridges: Spreading center morphology between 55°50′N and 63°00′N. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb03459] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Toomey DR, Jousselin D, Dunn RA, Wilcock WSD, Detrick RS. Skew of mantle upwelling beneath the East Pacific Rise governs segmentation. Nature 2007; 446:409-14. [PMID: 17377578 DOI: 10.1038/nature05679] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 02/08/2007] [Indexed: 11/08/2022]
Abstract
Mantle upwelling is essential to the generation of new oceanic crust at mid-ocean ridges, and it is generally assumed that such upwelling is symmetric beneath active ridges. Here, however, we use seismic imaging to show that the isotropic and anisotropic structure of the mantle is rotated beneath the East Pacific Rise. The isotropic structure defines the pattern of magma delivery from the mantle to the crust. We find that the segmentation of the rise crest between transform faults correlates well with the distribution of mantle melt. The azimuth of seismic anisotropy constrains the direction of mantle flow, which is rotated nearly 10 degrees anticlockwise from the plate-spreading direction. The mismatch between the locus of mantle melt delivery and the morphologic ridge axis results in systematic differences between areas of on-axis and off-axis melt supply. We conclude that the skew of asthenospheric upwelling and transport governs segmentation of the East Pacific Rise and variations in the intensity of ridge crest processes.
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Affiliation(s)
- Douglas R Toomey
- Department of Geological Sciences, University of Oregon, Eugene, Oregon 97403, USA.
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15
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Chen YJ. Influence of the Iceland mantle plume on crustal accretion at the inflated Reykjanes Ridge: Magma lens and low hydrothermal activity? ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2001jb000816] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Briais A. Temporal variations of the segmentation of slow to intermediate spreading mid-ocean ridges 1. Synoptic observations based on satellite altimetry data. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jb000533] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Gaherty JB. Seismic evidence for hotspot-induced buoyant flow beneath the Reykjanes Ridge. Science 2001; 293:1645-7. [PMID: 11533487 DOI: 10.1126/science.1061565] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Volcanic hotspots and mid-ocean ridge spreading centers are the surface expressions of upwelling in Earth's mantle convection system, and their interaction provides unique information on upwelling dynamics. I investigated the influence of the Iceland hotspot on the adjacent mid-Atlantic spreading center using phase-delay times of seismic surface waves, which show anomalous polarization anisotropy-a delay-time discrepancy between waves with different polarizations. This anisotropy implies that the hotspot induces buoyancy-driven upwelling in the mantle beneath the ridge.
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Affiliation(s)
- J B Gaherty
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Abelson M, Baer G, Agnon A. Evidence from gabbro of the Troodos ophiolite for lateral magma transport along a slow-spreading mid-ocean ridge. Nature 2001; 409:72-5. [PMID: 11343114 DOI: 10.1038/35051058] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The lateral flow of magma and ductile deformation of the lower crust along oceanic spreading axes has been thought to play a significant role in suppressing both mid-ocean ridge segmentation and variations in crustal thickness. Direct investigation of such flow patterns is hampered by the kilometres of water that cover the oceanic crust, but such studies can be made on ophiolites (fragments of oceanic crust accreted to a continent). In the Oman ophiolite, small-scale radial patterns of flow have been mapped along what is thought to be the relict of a fast-spreading mid-ocean ridge. Here we present evidence for broad-scale along-axis flow that has been frozen into the gabbro of the Troodos ophiolite in Cyprus (thought to be representative of a slow-spreading ridge axis). The gabbro suite of Troodos spans nearly 20 km of a segment of a fossil spreading axis, near a ridge-transform intersection. We mapped the pattern of magma flow by analysing the rocks' magnetic fabric at 20 sites widely distributed in the gabbro suite, and by examining the petrographic fabric at 9 sites. We infer an along-axis magma flow for much of the gabbro suite, which indicates that redistribution of melt occurred towards the segment edge in a large depth range of the oceanic crust. Our results support the magma plumbing structure that has been inferred indirectly from a seismic tomography experiment on the slow-spreading Mid-Atlantic Ridge.
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Affiliation(s)
- M Abelson
- Geological Survey of Israel, 30 Malkhey Yisrael Street, Jerusalem 95501, Israel.
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Martínez F, Fryer P, Becker N. Geophysical characteristics of the southern Mariana Trough, 11°50′N-13°40′N. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jb900117] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Martínez F, Taylor B, Goodliffe AM. Contrasting styles of seafloor spreading in the Woodlark Basin: Indications of rift-induced secondary mantle convection. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jb900068] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Ma LY, Cochran JR. Bathymetric roughness of the Southeast Indian Ridge: Implications for crustal accretion at intermediate spreading rate mid-ocean ridges. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97jb01280] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Sempéré JC, Cochran JR. The Southeast Indian Ridge between 88°E and 118°E: Variations in crustal accretion at constant spreading rate. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/97jb00171] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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24
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Seismological evidence for three-dimensional melt migration beneath the East Pacific Rise. Nature 1997. [DOI: 10.1038/40831] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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25
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Shaw WJ, Lin J. Models of ocean ridge lithospheric deformation: Dependence on crustal thickness, spreading rate, and segmentation. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00949] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Barth GA, Mutter JC. Variability in oceanic crustal thickness and structure: Multichannel seismic reflection results from the northern East Pacific Rise. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00814] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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Kincaid C, Sparks DW, Detrick R. The relative importance of plate-driven and buoyancy-driven flow at mid-ocean ridges. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb01184] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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