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Auzende JM, Hey RN, Pelletier B, Rouland D, Lafoy Y, Gracia E, Huchon P. Propagating rift west of the Fiji Archipelago (North Fiji Basin, SW Pacific). ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00612] [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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Kleinrock MC, Searle RC, Hey RN. Tectonics of the failing spreading system associated with the 95.5°W Galapagos propagator. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb094ib10p13839] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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3
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Dyment J. Evolution of the Indian Ocean Triple Junction between 65 and 49 Ma (anomalies 28 to 21). ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb00438] [Citation(s) in RCA: 38] [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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Müller RD, Roest WR. Fracture zones in the North Atlantic from combined Geosat and Seasat data. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/91jb02605] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Cormier MH, MacDonald KC. East Pacific Rise 18°-19°S: Asymmetric spreading and ridge reorientation by ultrafast migration of axial discontinuities. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb02382] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Scheirer DS, Macdonald KC. Near-axis seamounts on the flanks of the East Pacific Rise, 8°N to 17°N. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb02769] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Cooper PA, Milholland PD, Duennebier FK. SEISMICITY OF THE GALAPAGOS 95.5°W PROPAGATING RIFT. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb092ib13p14091] [Citation(s) in RCA: 14] [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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Kleinrock MC, Bird RT. Southeastern boundary of the Juan Fernandez microplate: Braking microplate rotation and deforming the Antarctic plate. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb02510] [Citation(s) in RCA: 9] [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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Ito G, McNutt M, Gibson RL. Crustal structure of the Tuamotu Plateau, 15°S, and implications for its origin. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00071] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kleinrock MC, Hey RN. Detailed tectonics near the tip of the Galapagos 95.5°W propagator: How the lithosphere tears and a spreading axis develops. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb094ib10p13801] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kleinrock MC, Hey RN. Migrating transform zone and lithospheric transfer at the Galapagos 95.5°W propagator. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb094ib10p13859] [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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Lonsdale P. Structural Pattern of the Galapagos Microplate and Evolution of the Galapagos Triple Junctions. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb093ib11p13551] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wilson DS, Hey RN. History of rift propagation and magnetization intensity for the Cocos-Nazca sspreading Center. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00762] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Perram LJ, Cormier MH, Macdonald KC. Magnetic and tectonic studies of the dueling propagating spreading centers at 20°40′S on the East Pacific Rise: Evidence for crustal rotations. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/92jb02913] [Citation(s) in RCA: 38] [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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16
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de Moustier C, Kleinrock MC. Bathymetric artifacts in Sea Beam data: How to recognize them and what causes them. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb091ib03p03407] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Miller SP, Hey RN. Three-dimensional magnetic modeling of a propagating rift, Galapagos 95°30′W. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb091ib03p03395] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Naar DF, Hey RN. Fast rift propagation along the East Pacific Rise near Easter Island. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb091ib03p03425] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lonsdale P. Geomorphology and structural segmentation of the crest of the southern (Pacific-Antarctic) East Pacific Rise. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb02756] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sigmundsson F, Einarsson P, Bilham R, Sturkell E. Rift-transform kinematics in south Iceland: Deformation from Global Positioning System measurements, 1986 to 1992. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00155] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Tentler T, Acocella V. How does the initial configuration of oceanic ridge segments affect their interaction? Insights from analogue models. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2008jb006269] [Citation(s) in RCA: 20] [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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22
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Honsho C, Dyment J, Tamaki K, Ravilly M, Horen H, Gente P. Magnetic structure of a slow spreading ridge segment: Insights from near-bottom magnetic measurements on board a submersible. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jb005915] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Nedimović MR, Carbotte SM, Harding AJ, Detrick RS, Canales JP, Diebold JB, Kent GM, Tischer M, Babcock JM. Frozen magma lenses below the oceanic crust. Nature 2005; 436:1149-52. [PMID: 16121179 DOI: 10.1038/nature03944] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Accepted: 06/15/2005] [Indexed: 11/09/2022]
Abstract
The Earth's oceanic crust crystallizes from magmatic systems generated at mid-ocean ridges. Whereas a single magma body residing within the mid-crust is thought to be responsible for the generation of the upper oceanic crust, it remains unclear if the lower crust is formed from the same magma body, or if it mainly crystallizes from magma lenses located at the base of the crust. Thermal modelling, tomography, compliance and wide-angle seismic studies, supported by geological evidence, suggest the presence of gabbroic-melt accumulations within the Moho transition zone in the vicinity of fast- to intermediate-spreading centres. Until now, however, no reflection images have been obtained of such a structure within the Moho transition zone. Here we show images of groups of Moho transition zone reflection events that resulted from the analysis of approximately 1,500 km of multichannel seismic data collected across the intermediate-spreading-rate Juan de Fuca ridge. From our observations we suggest that gabbro lenses and melt accumulations embedded within dunite or residual mantle peridotite are the most probable cause for the observed reflectivity, thus providing support for the hypothesis that the crust is generated from multiple magma bodies.
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Affiliation(s)
- Mladen R Nedimović
- Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, PO Box 1000, Palisades, New York 10964-8000, USA.
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Ligi M, Bonatti E, Bortoluzzi G, Carrara G, Fabretti P, Gilod D, Peyve AA, Skolotnev S, Turko N. Bouvet Triple Junction in the South Atlantic: Geology and evolution. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999jb900192] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Begnaud ML, McClain JS, Barth GA, Orcutt JA, Harding AJ. Velocity structure from forward modeling of the eastern ridge-transform intersection area of the Clipperton Fracture Zone, East Pacific Rise. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96jb03393] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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26
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Sauter D, Nafziger JM, Whitechurch H, Munschy M. Segmentation and morphotectonic variations of the Central Indian Ridge (21°10′S-22°25′S). ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00884] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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27
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Nicolas A, Boudier F, Ildefonse B. Variable crustal thickness in the Oman ophiolite: Implication for oceanic crust. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00195] [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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28
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Korenaga J, Hey RN. Recent dueling propagation history at the fastest spreading center, the East Pacific Rise, 26°-32°S. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00176] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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29
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Honsho C, Tamaki K, Fujimoto H. Three-dimensional magnetic and gravity studies of the Rodriguez Triple Junction in the Indian Ocean. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/96jb00644] [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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Hey RN, Johnson PD, Martinez F, Korenaga J, Somers ML, Huggett QJ, LeBas TP, Rusby RI, Naar DF. Plate boundary reorganization at a large-offset, rapidly propagating rift. Nature 1995. [DOI: 10.1038/378167a0] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Topographic expression of five fracture zones in the northwestern Pacific Ocean. ACTA ACUST UNITED AC 1993. [DOI: 10.1029/gm077p0121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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34
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Madsen JA, Fornari DJ, Edwards MH, Gallo DG, Perfit MR. Kinematic framework of the Cocos-Pacific Plate Boundary from 13°N to the Orozco TRANSFORM FAULT: RESULTS FROM AN EXTENSIVE MAGNETIC AND SEAMARC II SURVEY. ACTA ACUST UNITED AC 1992. [DOI: 10.1029/91jb01755] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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35
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Macdonald KC, Scheirer DS, Carbotte SM. Mid-Ocean Ridges: Discontinuities, Segments and Giant Cracks. Science 1991; 253:986-94. [PMID: 17775341 DOI: 10.1126/science.253.5023.986] [Citation(s) in RCA: 235] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
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.
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Klaus A, Icay W, Naar D, Hey RN. SeaMARC II Survey of a propagating limb of a large nontransform offset near 29°S along the fastest spreading East Pacific Rise segment. ACTA ACUST UNITED AC 1991. [DOI: 10.1029/91jb00597] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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37
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Fernandez LS, Hey RN. Late Tertiary tectonic evolution of the seafloor spreading system off the coast of California between the Mendocino and Murray Fracture Zones. ACTA ACUST UNITED AC 1991. [DOI: 10.1029/91jb01416] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Hamburger MW, Everingham IB, Isacks BL, Barazangi M. Seismicity and crustal structure of the Fiji Platform, southwest Pacific. ACTA ACUST UNITED AC 1990. [DOI: 10.1029/jb095ib03p02553] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Huchon P, Bourgois J. Subduction-induced fragmentation of the Nazca Plate off Peru: Mendana Fracture Zone and Trujillo Trough revisited. ACTA ACUST UNITED AC 1990. [DOI: 10.1029/jb095ib06p08419] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sempere JC, Gee J, Naar DF, Hey RN. Three-dimensional inversion of the magnetic field over the Easter-Nazca propagating rift near 25°S, 112°25′W. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/jb094ib12p17409] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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45
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Karsten JL, Delaney JR. Hot spot-ridge crest convergence in the northeast Pacific. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/jb094ib01p00700] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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46
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Lonsdale P. The rise flank trails left by migrating offsets of the equatorial East Pacific Rise axis. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/jb094ib01p00713] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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47
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Naar DF, Hey RN. Recent Pacific-Easter-Nazca plate motions. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/gm057p0009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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48
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49
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Kinematic models of the evolution of the Gorda rise and President Jackson Seamount chain. ACTA ACUST UNITED AC 1989. [DOI: 10.1029/gm057p0031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Yonover RN, Sinton JM, Sommer MA, Gibson EK. C-O-H ratios of silicate melt inclusions in basalts from the Galapagos Spreading Center near 95 degrees W: a laser decrepitation mass spectrometry study. GEOCHIMICA ET COSMOCHIMICA ACTA 1989; 53:3145-3154. [PMID: 11539782 DOI: 10.1016/0016-7037(89)90095-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Volatile ratios (primarily of H2O and CO2) in individual silicate melt (glass) inclusions in minerals have been analyzed using laser volatilization and mass spectrometry. A Nd-glass laser was used to produce 50-micrometer diameter pits in silicate melt inclusions. Released volatiles were analyzed directly with a computer-controlled quadrupole mass spectrometer. The detection limits for CO2 and H2O were on the order of 3 x 10(-14) and 3 x 10(-13) moles, respectively. The reproducibility for CO2/H2O was better than +/- 9%. The total range of volatile ratios from vitreous silicate glass inclusions contained in a suite of Galapagos lavas were: 0.018 to 1.193 for CO2/H2O; 0.002 to 0.758 for CO/H2O; 0 to 0.454 for CH4/H2O; and 0 to 0.432 for Ar/H2O. The mean CO2/H2O from the propagating rift (0.245 +/- 0.068) silicate glass inclusions is significantly lower than that of the actively failing rift (0.641 +/- 0.241); this difference probably reflects different degrees of degassing during magmatic histories for the two regions. Relatively undifferentiated failing rift magmas must have relatively short crustal residence times prior to eruption and, therefore, have not undergone significant degassing of CO2, as would appear to be the case for the more highly fractionated propagating rift magmas. The laser-mass spectrometric system described herein has the ability to act as a point-source probing device that can differentiate between the various volatile sites in minerals and rocks (as well as synthetic materials) on a micrometer scale.
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Affiliation(s)
- R N Yonover
- Hawaii Institute of Geophysics, University of Hawaii at Manoa, Honolulu 96822, USA
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