Advertisement

Contributions to Mineralogy and Petrology

, Volume 89, Issue 1, pp 90–101 | Cite as

Petrology and geochemistry of Rodrigues Island, Indian Ocean

  • A. N. Baxter
  • B. G. J. Upton
  • W. M. White
Article

Abstract

Rodrigues Island is composed of a differentiated series of transitional-mildly alkaline olivine basalts. The lavas contain phenocrysts of olivine (Fo88−68)±plagioclase (An73−50), together with a megacryst suite involving olivine, plagioclase, kaersutite, clinopyroxene, apatite, magnetite and hercynite-rich spinels. Troctolitic-anorthositic gabbro xenoliths are widely dispersed throughout the lavas and are probably derived from the upper parts of an underlying layered complex: the megacrysts may originate from coarse, easily disaggregated differentiates near the top of this body.

Modelling of major and trace element data suggests that the majority of chemical variation in the lavas results from up to 45% fractionation of olivine, clinopyroxene, plagioclase and magnetite at low pressures, in the ratio 20∶35∶39∶6. The clinopyroxene-rich nature of this extract assemblage is significantly different to that of the xenoliths, and suggests that clinopyroxene-rich gabbros and/or ultrabasic rocks may lie at greater depth.

Sr and Nd isotopic data (87Sr/86Sr 0.70357–070406,143Nd/144Nd 0.51283–0.51289) indicate a mantle source with relative LREE depletion, and emphasise an unusual degree of uniformity in Indian Ocean island sources. A small group of lavas with strong HREE enrichment suggest a garnet-poor source for these, while high overall Al2O3/ CaO ratios imply high clinopyroxene/garnet ratios in refractory residua.

Keywords

Magnetite Olivine Indian Ocean Apatite Mantle Source 
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.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Abbey S (1980) Studies in “standard samples” for use in the general analysis of silicate rocks and minerals. Part 6: 1979 edition of “useable” values. Geol Surv Canada Paper 80-14Google Scholar
  2. Baxter AN (1972) Magmatic evolution of Mauritius, western Indian Ocean. Ph.D. Thesis, University or Edinburgh, ScotlandGoogle Scholar
  3. Baxter AN (1975) Petrology of the Older Series lavas from Mauritius, Indian Ocean. Geol Soc Am Bull 86:1449–1458Google Scholar
  4. Baxter AN (1976) Geochemistry and petrogenesis of primitive alkali basalt from Mauritius, Indian Ocean. Geol Soc Am Bull 87:1028–1034Google Scholar
  5. Baxter AN (1978) Ultramafic and mafic nodule suites in shieldforming lavas from Mauritius, Indian Ocean. J Geol Soc London 135:565–581Google Scholar
  6. Benjamin T, Heuser WR, Burnett DS (1978) Laboratory studies of actinide partitioning relevant to244Pu chronometry. Proc Lunar Planet Sci Conf 9th:1393–1406Google Scholar
  7. Benjamin T, Heuser WR, Burnett DS, Seitz MG (1980) Actinide crystal — liquid partitioning for clinopyroxene and Ca3(PO4). Geochim Cosmochim Acta 44:1251–1264Google Scholar
  8. Bird ML (1971) Distribution of trace elements in olivines and pyroxenes an experimental study. PhD thesis, University of Missouri, RollaGoogle Scholar
  9. Carter JL (1970) Mineralogy and chemistry of the Earth's upper mantle based on the partial fusion — partial crystallisation model. Geol Soc Am Bull 81:2021–2034Google Scholar
  10. Clague DA, Beeson MH (1980) Trace element geochemistry of the East Molokai Volcanic Series, Hawaii. Am J Sci 280-A: 820–844Google Scholar
  11. Clague DA, Frey FA (1982) Petrology and trace element geochemistry of the Honolulu volcanics, Oahu: Implications for the Oceanic Mantle below Hawaii. J Petrol 23:447–504Google Scholar
  12. De Laeter JR, Hosie DJ (1978) The abundance of barium in stony meteorites. Earth Planet Sci Lett 38:416–420Google Scholar
  13. Drake MJ (1975) The oxidation state of europium as an indicator of oxygen fugacity. Geochim Cosmochim Acta 39:55–64Google Scholar
  14. Dupré B, Allegre CJ (1983) Pb-Sr isotope variation in Indian Ocean basalts and mixing phenomena. Nature 303:142–146Google Scholar
  15. Ewart A, Bryan WB, Gill JB (1973) Mineralogy and geochemistry of the younger volcanic islands of Tonga, S.W. Pacific. J Petrol 14:429–465Google Scholar
  16. Exley RA, Smith JV (1982) The role of apatite in mantle enrichment processes and in the petrogenesis of some alkali basalt suites. Geochim Cosmochim Acta 46:1375–1384Google Scholar
  17. Frey FA, Green DH, Roy DS (1978) Integrated models of basalt petrogenesis: a study of quartz tholeiites to olivine melilites from southeastern Australia utilising geochemical and experimental petrological data. J Petrol 19:463–513Google Scholar
  18. Gunn BM (1971) Trace element partitioning during olivine fractionation of Hawaiian basalts. Chem Geol 8:1–13Google Scholar
  19. Henderson P (1982) Inorganic Geochemistry; Pergamon Press, pp 353Google Scholar
  20. Hofmann AW, White WM (1982) Mantle plumes from ancient oceanic crust. Earth Planet Sci Lett 57:421–436Google Scholar
  21. Irving AJ (1978) A review of experimental studies of crystal/liquid trace element partitioning. Geochim Cosmochim Acta 42:743–770Google Scholar
  22. Kay RW (1979) Zone refining at the base of lithospheric plates: A model for a steady-state asthenosphere. Tectonophysics 55:1–9Google Scholar
  23. Kesson SE (1973) The primary geochemistry of the Monaro alkaline volcanics, southeastern Australia — Evidence for upper mantle heterogeneity. Contrib Mineral Petrol 42:93–108Google Scholar
  24. Lindstrom DJ (1976) Experimental study of the partitioning of the transition metals between clinopyroxene and coexisting silicate liquids. Ph.D. thesis, University of OregonGoogle Scholar
  25. McDougall I, Compston W (1965) Strontium isotope composition and potassium-rubidium ratios in some rocks from Reunion and Rodriguez, Indian Ocean. Nature 207:252–253Google Scholar
  26. McDougall I, Upton BGJ, Wadsworth WJ (1965) A geological reconnaiscence of Rodriguez Island, Indian Ocean. Nature 206:26–27Google Scholar
  27. McKenzie D, Sclater JG (1971) The evolution of the Indian Ocean since the late Cretaceous. Geophys JR Astron Soc 25:437–528Google Scholar
  28. Mason B (1979) Data of Geochemistry. Chapter B: Cosmochemistry. Part 1: Meteorites. US Geol Surv Prof Pap:1–132Google Scholar
  29. Morgan WJ (1978) Rodriguez, Darwin, Amsterdam...., a second type of hot spot island. J Geophys Res 83:5355–5360Google Scholar
  30. Nakamura N (1974) Determination of REE, Ba, Fe, Mg, Na, and K in carbonaceous and ordinary chondrites. Geochim Cosmochim Acta 38:757–775Google Scholar
  31. Norrish K, Hutton JT (1969) An accurate x-ray spectrographic method for the analysis of a wide range of geological samples. Geochim Cosmochim Acta 33:431–453Google Scholar
  32. O'Nions RK, Hamilton PJ, Evenson NM (1977) Variations in143Nd/144Nd and87Sr/86Sr ratios in oceanic basalts. Earth Planet Sci Lett 34:13–22Google Scholar
  33. Pearce JA, Norry MJ (1979) Petrogenetic implications of Ti, Zr, Y and Nb variations in volcanic rocks. Contrib Mineral Petrol 69:33–47Google Scholar
  34. Ringwood AE (1966) The chemical composition and origin of the Earth. In: PM Hurley (ed) Advances in Earth Science. MIT Press, Cambridge, MassGoogle Scholar
  35. Roeder PL, Emslie RF (1970) Olivine-liquid equilibrium. Contrib Mineral Petrol 29:275–289Google Scholar
  36. Schilling JG, Winchester JW (1969) Rare earth contribution to the origin of Hawaiian lavas. Contrib Mineral Petrol 23:27–37Google Scholar
  37. Schilling JG, Bergeron MB, Evans R (1980) Halogens in the mantle beneath the North Atlantic. Philos Trans R Soc London A297:147–178Google Scholar
  38. Seward TM (1971) The distribution of transition elements in the system CaMgSi2O6-Na2Si2O5-H2O at 100 bars. Chem Geol 7:73–95Google Scholar
  39. Shaw DM (1970) Trace element fractionation during anatexis. Geochim Cosmochim Acta 34:237–243Google Scholar
  40. Shima M (1979) The abundances of titanium, zirconium and hafnium in stony meteorites. Geochim Cosmochim Acta 43:353–362Google Scholar
  41. Sun SS (1980) Lead isotope study of young volcanic rocks from mid-ocean ridges, ocean islands and island arcs. Philos Trans R Soc London A297:409–445Google Scholar
  42. Sun SS, Nesbitt RW (1978) Petrogenesis of archean ultrabasic and basic volcanics: Evidence from Rare Earth Elements. Contrib Mineral Petrol 65:301–325Google Scholar
  43. Sweatman TR, Long JVP (1969) Quantitative Electron-probe microanalysis of Rock-Forming Minerals. J Petrol 10:332–379Google Scholar
  44. Thirlwall MF (1979) The petrochemistry of the British Old Red Sandstone Province. Ph.D. Thesis, University of Edinburgh, ScotlandGoogle Scholar
  45. Thompson RN (1982) Magmatism of the British Tertiary Volcanic Province. Scott J Geol 18:49–107Google Scholar
  46. Upton BGJ, Wadsworth WJ (1972) Aspects of magmatic evolution on Reunion Island. Philos Trans R Soc London A271:105–130Google Scholar
  47. Upton BGJ, Wadsworth WJ, Newmann TC (1967) The petrology of Rodriguez Island, Indian Ocean. Geol Soc Am Bull 78:1495–1506Google Scholar
  48. Walsh JN, Buckley F, Barker J (1981) The simultaneous determination of the rare earth elements in rocks using inductively coupled plasma source spectrometry. Chem Geol 33:141–153Google Scholar
  49. Wass SY, Henderson P, Elliott CJ (1980) Chemical heterogeneity and metasomatism in the upper mantle: evidence from rare earth and other elements in apatite-rich xenoliths in basaltic rocks from eastern Australia. Philos Trans R Soc London A297:333–346Google Scholar
  50. Wasserburg GJ, De Paolo DJ (1979) Models of Earth Structure Inferred From Neodymium and Strontium Isotopic Abundances. Proc Natl Acad Sci USA 76:3594–3598Google Scholar
  51. Watkins ND, Gunn BM, Nougier J, Baksi AK (1974) Kerguelen: Continental Fragment or Oceanic Island? Geol Soc Am Bull 85:201–212Google Scholar
  52. White WM, Patchett J (1983) Hf-Nd-Sr isotopes and incompatible element abundances in island arcs: Implications for magma origins and crust-mantle evolution. Earth Planet Sci Lett (in press)Google Scholar
  53. Wood DA, Joron JL, Treuil M, Norry MJ, Tarney J (1979) Elemental and Sr isotope variations in basic lavas from Iceland and the surrounding ocean floor. Contrib Mineral Petrol 70:319–339Google Scholar
  54. Wright TL, Doherty PC (1970) A linear programming and least squares computer method for solving petrologic mixing problems. Geol Soc Am Bull 81:1995–2008Google Scholar
  55. Zielinski RA (1975) Trace element evaluation of a suite of rocks from Reunion Island, Indian Ocean. Geochim Cosmochim Acta 39:713–734Google Scholar

Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • A. N. Baxter
    • 1
  • B. G. J. Upton
    • 2
  • W. M. White
    • 3
  1. 1.Department of GeologyCity of London PolytechnicLondon
  2. 2.Department of GeologyEdinburgh UniversityEdinburgh
  3. 3.Max-Planck-Institut für ChemieMainzFRG

Personalised recommendations