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Contributions to Mineralogy and Petrology

, Volume 99, Issue 4, pp 446–463 | Cite as

He, Pb, Sr and Nd isotope constraints on magma genesis and mantle heterogeneity beneath young Pacific seamounts

  • David W. Graham
  • Alan Zindler
  • Mark D. Kurz
  • William J. Jenkins
  • Rodey Batiza
  • Hubert Staudigel
Article

Abstract

Pb, Sr and Nd isotope variations are correlated in diverse lavas erupted at small seamounts near the East Pacific Rise. Tholeiites are isotopically indistinguishable from MORB (206Pb/204Pb=18.1–18.5; 87Sr/86Sr=0.7023–0.7028; 143Nd/144Nd=0.51326-0.51308); associated alkali basalts always show more radiogenic Pb and Sr signatures (206Pb/204Pb=18.8–19.2; 87Sr/86Sr=0.7029–0.7031) and less radiogenic Nd (143Nd/144Nd=0.51289–0.51301). The isotopic variability covers ∼80% of the variability for Pacific MORB, due to the presence of small-scale heterogeneity in the underlying mantle. Isotope compositions also correlate with trace element ratios such as La/Sm. Tholeiites at these seamounts have 3He/4He between 7.8–8.7 RA(RA= atmospheric ratio), also indistinguishable from MORB. He trapped in vesicles of alkali basalts, released by crushing in vacuo, has low 3He/4He (1.2–2.6 R)Ain conjunction with low helium concentrations ([He]<5×10−8 ccSTP/g). In many cases post-eruptive radiogenic ingrowth has produced He isotope disequilibrium between vesicles and glass in the alkali basalts; subatmospheric 3He/4He ratios characterize the He dissolved in the glass which is released by melting the crushed powders. The narrow range of 3He/4He in the vesicles of the alkali basalts suggests that low 3He/4He is a source characteristic, but given their low [He] and high (U + Th), pre-eruptive radiogenic ingrowth cannot be excluded as a cause for low inherited 3He/4He ratios. Pb, Sr and Nd isotope compositions in lavas erupted at Shimada Seamount, an isolated volcano on 20 m.y. old seafloor at 17°N, are distinctly different from other seamounts in the East Pacific (206Pb/204Pb=18.8–19.0, 87Sr/ 86Sr≅0.7048 and 143Nd/144Nd≅0.51266). Relatively high 207Pb/204Pb (15.6–15.7) indicates ancient (>2 Ga) isolation of the source from the depleted upper mantle, similar to Dupal components which are more prevalent in the southern hemisphere mantle. 3He/4He at Shimada Seamount is between 3.9–4.8 RA. Because the helium concentrations range up to 1.5×10−6, the low 3He/4He can not be due to radiogenic accumulation of 4He in the magma for reasonable volcanic evolution times. The low 3He/4He may be due to the presence of “enriched” domains within the lithosphere with high (U + Th)/He ratios, possibly formed during its accretion near the ridge. Alternatively, the low 3He/4He may be an inherent characteristic of an enriched component in the mantle beneath the East Pacific. Collectively, the He-Pb-Sr-Nd isotope systematics at East Pacific seamounts suggest that the range of isotope compositions present in the mantle is more readily sampled by seamount and island volcanism than by axial volcanism. Beneath thicker lithosphere away from the ridge axis, smaller degrees of melting in the source regions are less efficient in averaging the chemical characteristics of small-scale heterogeneities.

Keywords

Lithosphere 86Sr Alkali Basalt Ridge Axis Helium Concentration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Allan J, Batiza R (1988) Petrology of lavas from seamounts flanking the East Pacific Rise, 21°N: Implications concerning the mantle source composition for both seamount and adjacent EPR lavas. J Geophys Res (in press)Google Scholar
  2. Allègre CJ, Condomines M (1982) Basalt genesis and mantle structure studied through Th-isotope geochemistry. Nature 299:21–24Google Scholar
  3. Allègre CJ, Turcotte DL (1985) Geodynamic mixing in the mesosphere boundary layer and the origin of oceanic islands. Geophys Res Lett 12:207–210Google Scholar
  4. Allègre CJ, Turcotte DL (1986) Implications of a two component marble-cake mantle. Nature 323:123–127Google Scholar
  5. Allègre CJ, Brevart O, Dupré B, Minster JF (1980) Isotopic and chemical effects produced in a continuously differentiating converting Earth mantle. Phil Trans R Soc Lond A 297:447–477Google Scholar
  6. Allègre CJ, Hamelin B, Dupré B (1984) Statistical analysis of isotopic ratios in MORB: the mantle blob cluster model and the convective regime of the mantle. Earth Planet Sci Lett 71:71–84Google Scholar
  7. Allègre CJ, Dupré B, Lewin E (1986) Thorium/uranium ratio of the Earth. Chem Geol 56:219–227Google Scholar
  8. Allègre CJ, Hamelin B, Provost A, Dupré B (1987) Topology in isotopic multispace and origin of mantle chemical heterogeneities. Earth Planet Sci Lett 81:319–337Google Scholar
  9. Anderson DL (1982) Isotopic evolution of the mantle: a model. Earth Planet Sci Lett 57:13–24Google Scholar
  10. Anderson DL (1985) Hotspot magmas can form by fractionation and contamination of mid-ocean ridge basalts. Nature 318:145–149Google Scholar
  11. Batiza R (1977) Age, volume, compositional and spatial relations of small isolated oceanic central volcanoes. Mar Geol 24:169–183Google Scholar
  12. Batiza R (1980) Origin and petrology of young oceanic central volcanoes: are most tholeiitic rather than alkalic? Geol 8:477–482Google Scholar
  13. Batiza R, Vanko D (1983) Volcanic development of small oceanic central volcanoes on the flanks of the East Pacific Rise inferred from narrow-beam echo-sounder surveys. Mar Geol 54:53–90Google Scholar
  14. Batiza R, Vanko D (1984) Petrology of young Pacific seamounts. J Geophys Res 89:11235–11260Google Scholar
  15. Batiza R, Vanko D (1985) Petrologic evolution of large failed rifts in the eastern Pacific: petrology of volcanic and plutonic rocks from the Mathematician Ridge area and the Guadalupe trough. J Petrol 26:564–602Google Scholar
  16. Carlson RW, Macdougall JD, Lugmair GW (1978) Differential Sm/Nd evolution in oceanic basalts. Geophys Res Lett 5:229–232Google Scholar
  17. Catanzaro EJ, Murphy TJ, Shields WR, Garner EL (1968) Absolute isotopic abundance ratios of common, equal-atom, and radiogenic lead isotopic standards. J Res Natl Bur Stand 72AGoogle Scholar
  18. Church SE, Tatsumoto M (1975) Lead isotope relations in oceanic ridge basalts from the Juan de Fuca-Gorda Ridge area, N.E. Pacific Ocean. Contrib Mineral Petrol 53:253–279Google Scholar
  19. Clarke WB, Jenkins WJ, Top Z (1976) Determination of tritium by mass spectrometric measurement of 3He. Inter J Appl Rad Isotopes 27:515–522Google Scholar
  20. Cohen RS, O'Nions RK (1982) The lead, neodymium and strontium isotopic structure of ocean ridge basalts. J Petrol 23:299–324Google Scholar
  21. Condomines M, Gronvold K, Hooker PJ, Muehlenbachs K, O'Nions RK, Oskarsson N, Oxburgh ER (1983) Helium, oxygen, strontium and neodymium isotopic relationships in Icelandic volcanics. Earth Planet Sci Lett 66:125–136Google Scholar
  22. Craig H, Lupton JE (1976) Primordial neon, helium and hydrogen in oceanic basalts. Earth Planet Sci Lett 31:369–385Google Scholar
  23. Dodson M (1973) Closure temperature in cooling geochronological and petrological systems. Contrib Mineral Petrol 40:259–274Google Scholar
  24. Duncan RA, McCulloch MT, Barsczus HG, Nelson DR (1986) Plume versus lithospheric sources for melts at Ua Pou, Marquesas Islands. Nature 322:534–538Google Scholar
  25. Dupré B (1983) Structure et évolution du manteau terrestre étudiées à l'aide des traceurs isotopiques couples Sr-Pb. Thesis, University of Paris VIIGoogle Scholar
  26. Dupré B, Echeverria LM (1984) Pb isotopes of Gorgona Island (Colombia): isotopic variations correlated with magma type. Earth Planet Sci Lett 67:186–190Google Scholar
  27. Dupré B, Lambret B, Rousseau D, Allègre CJ (1981) Limitations on the scale of mantle heterogeneities under oceanic ridges: lead and strontium isotope variations in the FAMOUS and CYAMEX areas. Nature 294:552–555Google Scholar
  28. Fisher DE (1979) He and Xe in deep-sea basalts as a measure of magmatic differentiation. Nature 282:825–827Google Scholar
  29. Frey FA, Clague DA (1983) Geochemistry of diverse basalt types from Loihi Seamount, Hawaii: petrogenetic implications. Earth Planet Sci Lett 66:337–355Google Scholar
  30. Galer SJG, O'Nions RK (1986) Magmagenesis and the mapping of chemical and isotopic variations in the mantle. Chem Geol 56:45–61Google Scholar
  31. Gardner JV, Dean WE, Blakely RJ (1984) Shimada Seamount: an example of recent mid-plate volcanism. Geol Soc Amer Bull 95:855–862Google Scholar
  32. Gerlach DC, Hart SR, Morales VWJ, Palacios C (1986) Mantle heterogeneity beneath the Nazca plate: San Felix and Juan Fernandez islands. Nature 322:165–168Google Scholar
  33. Gerling EK (1940) On the solubility of helium in melts. C R (Dokl) Acad Sci USSR 27:22Google Scholar
  34. Göpel C, Manhes G, Allègre CJ (1985) U-Pb systematics in iron meteorites: uniformity of primordial lead. Geochim Cosmochim Acta 49:1681–1695Google Scholar
  35. Graham DW (1987) Helium and lead isotope geochemistry of oceanic volcanic rocks from the East Pacific and South Atlantic. PhD Diss, MIT/WHOIGoogle Scholar
  36. Graham DW, Jenkins WJ, Kurz MD, Batiza R (1987) Helium isotope disequilibrium and geochronology of glassy submarine basalts. Nature 326:384–386Google Scholar
  37. Grove TL, Bryan WB (1983) Fractionation of pyroxene-phyric MORB at low pressure: an experimental study. Contrib Mineral Petrol 84:293–309Google Scholar
  38. Gurnis M (1986) Stirring and mixing by plate-scale flow: large persistent blobs and long tendrils coexist. Geophys Res Lett 13:1474–1477Google Scholar
  39. Hamelin B, Allègre CJ (1985a) Large-scale regional units in the depleted upper mantle revealed by an isotope study of the South-West Indian Ridge. Nature 315:196–199Google Scholar
  40. Hamelin B, Allègre CJ (1985b) Lead isotopic composition of high temperature peridotites from Lherz, Lanzo, Beni-Bousera and the genesis of isotopic heterogeneities in the Earth's mantle. EOS 66:1114Google Scholar
  41. Hamelin B, Manhes G, Albarede F, Allègre CJ (1985) Precise lead isotope measurements by the double spike technique: a reconsideration. Geochim Cosmochim Acta 49:173–182Google Scholar
  42. Hart SR (1984a) A large-scale isotope anomaly in the southern hemisphere mantle. Nature 309:753–757Google Scholar
  43. Hart SR (1984b) Helium difffusion in olivine. Earth Planet Sci Lett 70:297–302Google Scholar
  44. Hart SR (1988) Heterogenous mantle domains: signatures, genesis and mixing chronologies. Earth Planet Sci Lett (in press)Google Scholar
  45. Hofmann AW, Hart SR (1978) An assessment of local and regional isotopic equilibrium in the mantle. Earth Planet Sci Lett 38:44–62Google Scholar
  46. Hofmann AW, White WM (1982) Mantle plumes from ancient oceanic crust. Earth Planet Sci Lett 57:421–436Google Scholar
  47. Jaeger JC (1957) The temperature in the neighborhood of a cooling intrusive sheet. Amer J Sci 255:306–318Google Scholar
  48. Jambon A, Weber H, Braun O (1986) Solubility of He, Ne, Ar, Kr and Xe in a basalt melt in the range of 1250–1600° C: geochemical implications. Geochim Cosmochim Acta 5:401–408Google Scholar
  49. Jenkins WJ (1974) Helium isotope and rare gas oceanology. PhD Diss, McMaster UniversityGoogle Scholar
  50. Jost W (1952) Diffusion in solids, liquids and gases. Academic Press, New York NY, 558 ppGoogle Scholar
  51. Kay RW, Sun S-S, Lee-Hu CN (1978) Pb and Sr isotopes in volcanic rocks from the Aleutian Islands and Pribilof Islands. Alaska. Geochim Cosmochim Acta 42:263–273Google Scholar
  52. Kirsten T (1968) Incorporation of rare gases in solidifying enstatite melts. J Geophys Res 73:2807–2810Google Scholar
  53. Kurz MD (1982) Helium isotope geochemistry of oceanic volcanic rocks: implications for mantle heterogeneity and degassing. PhD Diss, MIT/WHOIGoogle Scholar
  54. Kurz MD, Jenkins WJ (1981) The distribution of helium in oceanic basalt glasses. Earth Planet Sci Lett 53:41–54Google Scholar
  55. Kurz MD, Jenkins WJ (1982) Helium partitioning in basalt glass: reply to comment. Earth Planet Sci Lett 59:439–440Google Scholar
  56. Kurz MD, Jenkins WJ, Hart SR (1982a) Helium-isotopic systematics of oceanic islands and mantle heterogeneity. Nature 297:43–46Google Scholar
  57. Kurz MD, Jenkins WJ, Schilling J-G, Hart SR (1982b) Helium isotopic variations in the mantle beneath the central North Atlantic Ocean. Earth Planet Sci Lett 58:1–14Google Scholar
  58. Kurz MD, Jenkins WJ, Hart SR, Clague D (1983) Helium isotopic variations in volcanic rocks from Loihi Seamount and the island of Hawaii. Earth Planet Sci Lett 66:388–406Google Scholar
  59. Kurz MD, Gurney JJ, Jenkins WJ, Lott DE (1987) Helium isotopic variability within single diamonds from the Orapa kimberlite pipe. Earth Planet Sci Lett 86:57–68Google Scholar
  60. Langmuir CH, Bender JF (1984) The geochemistry of oceanic basalts in the vicinity of transform faults: observations and implications. Earth Planet Sci Lett 69:107–127Google Scholar
  61. Langmuir CH, Bender JF, Batiza R (1986) Petrological and tectonic segmentation of the East Pacific Rise, 5°30′N–14°30′N. Nature 322:422–429Google Scholar
  62. LeBas MJ, LeMaitre RW, Streckeisen A, Zanettin B (1986) A chemical classification of volcanic rocks based on the total alkali-silica diagram. J Petrol 27:745–750Google Scholar
  63. Lott DE, Jenkins WJ (1984) An automated cryogenic charcoal trap system for helium isotope mass spectrometry. Rev Sci Instrum 55:1982–1988Google Scholar
  64. Lupton J (1983) Terrestrial inert gases: isotope tracer studies and clues to primordial components in the mantle. Ann Rev Earth Planet Sci 11:371–414Google Scholar
  65. Lux G (1987) The behavior of noble gases in silicate liquids: solution, diffusion, bubbles and surface effects, with applications to natural samples. Geochim Cosmochim Acta 51:1549–1560Google Scholar
  66. Macdonald GA, Katsura T (1964) Chemical composition of Hawaiian lavas. J Petrol 5:82–133Google Scholar
  67. Macdougall JD, Lugmair GW (1986) Sr and Nd isotopes in basalts from the East Pacific Rise: significance for mantle heterogeneity. Earth Planet Sci Lett 77:273–284Google Scholar
  68. Marty B, Ozima M (1986) Noble gas distribution in oceanic basalt glass. Geochim Cosmochim Acta 50:1093–1097Google Scholar
  69. McKenzie D (1985a) 230Th-238U disequilibrium and the melting processes beneath ridge axes. Earth Planet Sci Lett 72:149–157Google Scholar
  70. McKenzie D (1985b) The extraction of magma from the crust and mantle. Earth Planet Sci Lett 74:81–91Google Scholar
  71. McKenzie D, O'Nions RK (1984) Mantle reservoirs and ocean island basalts. Nature 301:229–231Google Scholar
  72. Natland JH, Melson WG (1980) Compositions of basaltic glasses from the East Pacific Rise and Siqueiros Fracture Zone, near 9°N. In: B.R. Rosendahl et al. Init Rep DSDP 54, US Government Printing Office, Washington, pp 705–723Google Scholar
  73. Natland JH, Macdougall JD (1986) Parental abyssal tholeiites and alkali basalts at the East Pacific Rise near 9°N and the Siqueiros Fracture Zone. EOS 67:410–411Google Scholar
  74. Newman S, Finkel RC, Macdougall JD (1983) 230Th-238U disequilibrium systematics in oceanic tholeiites from 21°N on the East Pacific Rise. Earth Planet Sci Lett 65:17–33Google Scholar
  75. O'Hara MJ (1985) Importance of the ‘shape’ of the melting regime during partial melting of the mantle. Nature 314:58–62Google Scholar
  76. Oxburgh ER, Turcotte DL (1968) Mid-ocean ridges and geotherm distribution during mantle convection. J Geophys Res 73:2643–2661Google Scholar
  77. Palacz ZA, Saunders AD (1986) Coupled trace element and isotope enrichment in the Cook-Austral-Samoa islands, southwest Pacific. Earth Planet Sci Lett 79:270–280Google Scholar
  78. Polvé M, Allègre CJ (1980) Orogenic Iherzolite complexes studied by 87Rb/86Sr: a clue to understand the mantle convection processes? Earth Planet Sci Lett 51:71–93Google Scholar
  79. Porcelli DR, O'Nions R, O'Reilly SY (1986) Helium and strontium isotopes in ultramafic xenoliths. Chem Geol 54:237–249Google Scholar
  80. Poreda R (1982) Helium partitioning in basalt glass: comment on a paper by MD Kurz and WJ Jenkins. Earth Planet Sci Lett 59:437–438Google Scholar
  81. Reisberg L, Zindler A (1986) Extreme isotopic variations in the upper mantle: evidence from Ronda. Earth Planet Sci Lett 81:29–45Google Scholar
  82. Richardson SH, Erlank AJ, Duncan AR, Reid DL (1982) Correlated Nd, Sr and Pb isotope variation in Walvis Ridge basalts and implications for evolution of their mantle source. Earth Planet Sci Lett 59:327–342Google Scholar
  83. Richter FM (1986) Simple models for trace element fractionation during melt segregation. Earth Planet Sci Lett 77:333–344Google Scholar
  84. Richter FM, Ribe N (1979) Importance of advection in determining the local isotopic composition of the mantle. Earth Planet Sci Lett 43:212–222Google Scholar
  85. Ringwood AE (1982) Phase transformations and differentiation in subducted lithosphere: implications for mantle dynamics, basalt petrogenesis, and crustal evolution. J Geol 90:611–643Google Scholar
  86. Rison W, Craig H (1982) Helium 3: coming of age in Samoa. EOS 63:1144Google Scholar
  87. Rison W, Craig H (1983) Helium isotopes and mantle volatiles in Loihi seamount and Hawaiian Island basalts and xenoliths. Earth Planet Sci Lett 66:407–426Google Scholar
  88. Shaw H (1980) The fracture mechanisms of magma transport from the mantle to the surface. In: R Margraves (ed) Physics of magmatic processes. Princeton Univ Press, Princeton, NJGoogle Scholar
  89. Shirey SB, Bender JF, Langmuir CH (1987) Three-component isotopic heterogeneity near the Oceanographer transform, Mid-Atlantic Ridge. Nature 325:217–223Google Scholar
  90. Smith T (1987) Geology and volcanic development of a near-ridge seamount and new evidence for the diversity of origin of seamount hydloclastites: results from integrated ALVIN/ANGUS and laboratory study. MS Thesis, Washington UniversityGoogle Scholar
  91. Sleep NH (1984) Tapping of magmas from ubiquitous mantle heterogeneities: an alternative to mantle plumes. J Geophys Res 89:10,029–10,041Google Scholar
  92. Spera F (1981) Carbon dioxide in igneous petrogenesis II. Fluid dynamics of mantle metasomatic processes. Contrib Mineral Petrol 77:56–65Google Scholar
  93. Staudigel H, Zindler A, Hart SR, Leslie T, Chen C-Y, Clague D (1984) The isotope systematics of a juvenile intraplate volcano: Pb, Nd and Sr isotope ratios of basalts from Loihi seamount, Hawaii. Earth Planet Sci Lett 69:13–25Google Scholar
  94. Stille P, Unruh DM, Tatsumoto M (1986) Pb, Sr, Nd and Hf isotopic constraints on the origin of Hawaiian basalts and evidence for a unique mantle source. Geochim Cosmochim Acta 50:2303–2319Google Scholar
  95. Subbarao KV, Clark GS, Forbes RB (1973) Strontium isotopes in some seamount basalts from the northeastern Pacific Ocean. Can J Earth Sci 10:1479–1484Google Scholar
  96. Sun SS (1980) Lead isotopic study of young volcanic rocks from mid-ocean ridges, ocean islands and island arcs. Phil Trans R Soc Lond A 297:409–445Google Scholar
  97. Sun SS, Hanson GN (1975) Evolution of the mantle: geochemical evidence from alkali basalt. Geol 3:297–302Google Scholar
  98. Taras BD, Hart SR (1987) Geochemical evolution of the New England Seamount chain: isotopic and trace element constraints. Chem Geol 64:35–54Google Scholar
  99. Tatsumoto M (1978) Isotopic composition of lead in oceanic basalts and its implication for mantle evolution. Earth Planet Sci Lett 38:63–87Google Scholar
  100. Watson B (1982) Melt infiltration and magma evolution. Geol 10:236–240Google Scholar
  101. White WM (1985) Sources of oceanic basalts: radiogenic isotopic evidence. Geol 13:115–118Google Scholar
  102. White WM, Hofmann AW (1982) Sr and Nd isotope geochemistry of oceanic basalts and mantle evolution. Nature 296:821–825Google Scholar
  103. White WM, Hofmann AW, Puchelt H (1987) Isotope geochemistry of Pacific mid-ocean ridge basalt. J Geophys Res 92:4881–4893Google Scholar
  104. Wright E, White WM (1986) The origin of Samoa: new evidence from Sr, Nd and Pb isotopes. Earth Planet Sci Lett 81:151–162Google Scholar
  105. Zindler A, Hart SR (1986a) Chemical geodynamics. Ann Rev Earth Planet Sci 14:493–571Google Scholar
  106. Zindler A, Hart SR (1986b) Helium: problematic primordial signals. Earth Planet Sci Lett 79:1–8Google Scholar
  107. Zindler A, Hart SR, Frey F, Jakobsson SP (1979) Nd and Sr isotope ratios and rare earth element abundances in Reykjanes Peninsula basalts: evidence for mantle heterogeneity beneath Iceland. Earth Planet Sci Lett 45:249–262Google Scholar
  108. Zindler A, Jagoutz E, Goldstein S (1982) Nd, Sr and Pb isotopic systematics in a three-component mantle: a new perspective. Nature 298:519–523Google Scholar
  109. Zindler A, Staudigel H, Batiza R (1984) Isotope and trace element geochemistry of young Pacific seamounts: implications for the scale of upper mantle heterogeneity. Earth Planet Sci Lett 70:175–195Google Scholar

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • David W. Graham
    • 1
  • Alan Zindler
    • 2
  • Mark D. Kurz
    • 1
  • William J. Jenkins
    • 1
  • Rodey Batiza
    • 3
  • Hubert Staudigel
    • 4
  1. 1.Woods Hole Oceanographic InstitutionWoods Hole
  2. 2.Lamont-Doherty Geological ObservatoryPalisadesUSA
  3. 3.Department of Geological SciencesNorthwestern UniversityEvanstonUSA
  4. 4.Scripps Institution of OceanographyLa JollaUSA

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