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Marine Geophysical Researches

, Volume 17, Issue 4, pp 375–397 | Cite as

Magmatic evolution of the Easter microplate-Crough Seamount region (South East Pacific)

  • Roger Hekinian
  • Peter Stoffers
  • Dietrich Akermand
  • Nicolas Binard
  • Jean Francheteau
  • Colin Devey
  • Dieter Garbe-Schönberg
Article

Abstract

The Easter microplate-Crough Seamount region located between 25° S–116° W and 25° S–122° W consists of a chain of seamounts forming isolated volcanoes and elongated (100–200 km in length) en echelon volcanic ridges oriented obliquely NE (N 065°), to the present day general spreading direction (N 100°) of the Pacific-Nazca plates. The extension of this seamount chain into the southwestern edge of the Easter microplate near 26°30′ S–115° W was surveyed and sampled. The southern boundary including the Orongo fracture zone and other shallow ridges (< 2000 m high) bounding the Southwest Rift of the microplate consists of fault scarps where pillow lava, dolerite, and metabasalts are exposed. The degree of rock alternation inferred from palagonitization of glassy margins suggests that the volcanic ridges are as old as the shallow ridges bounding the Southwest Rift of the microplate. The volcanics found on the various structures west of the microplate consist of depleted (K/Ti < 0.1), transitional (K/Ti = 0.11−0.25) and enriched (K/Ti > 0.25) MORBs which are similar in composition to other more recent basalts from the Southwest and East Rifts spreading axes of the Easter microplate. Incompatible element ratios normalized to chondrite values [(Ce/Yb)N = 1−2.5}, {(La/Sm)N = 0.4−1.2} and {(Zr/Y)N = 0.7−2.5} of the basalts are also similar to present day volcanism found in the Easter microplate. The volcanics from the Easter microplate-Crough region are unrelated to other known South Pacific intraplate magmatism (i.e. Society, Pitcairn, and Salas y Gomez Islands). Instead their range in incompatible element ratios is comparable to the submarine basalts from the recently investigated Ahu and Umu volcanic field (Easter hotspot) (Scientific Party SO80, 1993) and centered at about 80 km west of Easter Island. The oblique ridges and their associated seamounts are likely to represent ancient leaky transform faults created during the initial stage of the Easter microplate formation (≈ 5 Ma). It appears that volcanic activity on seamounts overlying the oblique volcanic ridges has continued during their westward drift from the microplate as shown by the presence of relatively fresh lava observed on one of these structures, namely the first Oblique Volcanic Ridge near 25° S–118° W at about 160 km west of the Easter microplate West Rift. Based on a reconstruction of the Easter microplate, it is suggested that the Crough seamount (< 800 m depth) was formed by earlier (7–10 Ma) hotspot magmatic activity which also created Easter Island.

Key words

Petrology structure volcanism microplate 

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References

  1. Binard, N., Stoffers, P., Hekinian, R., and Searle, R., 1993, Intraplate “en échelon” volcanic ridges West of the Easter microplate: A hot spot origin,Mar. Geol. (submitted).Google Scholar
  2. Bach, W., Hegner, E., Erzinger, J., and Satir, M., 1994, Chemical and isotopic variations along the superfast spreading East Pacific Rise from 6 to 30° S,Contr. Mineral. Petrol. 116, 365–380.Google Scholar
  3. Baker, P. E., Buckley, F., and Holland, J. G., 1974, Petrology and geochemistry of Easter Island,Contr. Mineral. Petrol. 44, 85–90.Google Scholar
  4. Bender, J. F., Langmuir, C. H., and Hanson, G. N., 1984, Petrogenesis of basalt glasses from the Tamayo region, East Pacific Rise,J. Petrol. 25, 213–254.Google Scholar
  5. Bonatti, E., Harrison, C. G. A., Fisher, D. E., Honnorez, J., Schilling, J. G., Stipp, J. J., and Zentilli, M., 1977, Easter volcanic chain (Southeast Pacific): A mantle hot line,J. Geophys. Res. 82, 2457–2478.Google Scholar
  6. Chen, C. Y. and Frey, F. A., 1985, Trace elements and isotopic geochemistry of lavas from Haleakala volcano, East Maui, Hawaii: Implications for the origin of Hawaiian basalts,J. Geophys. Res. 90, 8743–8768.Google Scholar
  7. DeMets, C., Gordon, R. G., Argus, D. F., and Stein, S., 1990, Current plate motions,Geophys. J. Int. 101, 425–478.Google Scholar
  8. Devey, C., Albarède, F., Cheminée, J. L., Michard, A., Muhe, R., and Stoffers, P., 1990, Active hot spot volcanism in the Society islands (West Pacific): Geochemical study,J. Geophys. Res. 95, 5049–5066.Google Scholar
  9. Fisher, R. L. and Norris, R. M., 1960, Bathymetry and geology of Sala y Gomez, Southeast Pacific,Bull. Geol. Soc. Am. 71, 497–502.Google Scholar
  10. Francheteau, J., Patriat, P., Segoufin, J., Armijo, R., Doucoure, M., Yelles-Chaouche, A., Zukin, J., Calmant, S., Naar, D. F., and Searle, R., 1988, Pito and Orongo fracture zones: The nothern and southern boundaries of the Easter microplate (Southeast Pacific),Earth Planet. Sci. Lett. 89, 363–374.Google Scholar
  11. Fontignie, D. and Schilling, J.-G., 1991, 87Sr/86Sr and REE variation along the Easter Microplate boundaries (South Pacific): Application of multivariate statistical analyses to ridge segmentation,Chemical. Geol. 89, 209–241.Google Scholar
  12. Frey, F. A., Green, D. H., and Roy, S. D., 1978, Integrated models of basalts petrogenesis: a study of quartz tholeiites to olivine melilites from southeast Australia utilizing geochemical and experimental petrologic data.J. Petrol. 19, 463–513.Google Scholar
  13. Frey, F. A., Bryan, W. D., and Thompson, G., 1974, Atlantic ocean floor: Geochemistry and petrology of basalts from leg 2 and 3 of Deep-Sea Drilling Project.J. Geophys. Res. 79, 5507–5526.Google Scholar
  14. Gallahan W. E. and Nielsen, R. L., 1992, The partitioning of Sc, Y and rare earth elements between high-Ca pyroxene and natural mafic to intermediate lavas at 1 atmosphere,Geochim. Cosmochim. Acta 56, 2387–2404.Google Scholar
  15. Garbe-Schonberg, C.-D., 1993, Simultaneous determination of 37 trace elements in 28 international rock standards by ICP-Ms,Geostandards Newsletter 17, 81–97.Google Scholar
  16. Green, T. H. and Pearson, N. J., 1985, Rare element partitioning between clinopyroxene and silicate liquid at moderate to high pressure,Contr. Mineral Petrol. 91, 24–36.Google Scholar
  17. Hagen, R. A., Baker, N. A., Naar, D. A., and Hey, R. N., 1990, A SeaMARC II survey of recent submarine volcanism near Easter Island,Marine Geophys. Res. 12, 297–315.Google Scholar
  18. Hanan, B. B. and Schilling, J.-G., 1989, Easter microplate evolution: Pb isotope evidence,J. Geophys. Res. 94, 7432–7448.Google Scholar
  19. Hekinian, R. and Hoffert, M., 1975, Rate of palagonization and manganese coating on basaltic rocks from the rift valley in the Atlantic Ocean near 36°50′ N,Mar. Geol. 19, 91–109.Google Scholar
  20. Hekinian, R., Thompson, G., and Bideau, D., 1989, Axial and off-axial heterogeneity of basaltic rocks from the East Pacific Rise at 12°38′ N and 11°26′–11°30′ N,J. Geophys. Res. 17, 17,437–17,463.Google Scholar
  21. Hekinian, R., Bideau, D., Stoffers, P., Cheminée, J. L., Muhe, R., Puteanus, D., and Binard, N., 1991, Submarine intraplate volcanism in the South Pacific: Geological setting of the Society and Austral regions,J. Geophys. Res. 96, 2109–2138.Google Scholar
  22. Hekinian, R., Bideau, D., Cannat, M., Francheteau, J., and Hébert, R., 1992, Volcanic activity and crust-mantle exposure in the ultrafast Garrett transform fault near 13°28′ S in the Pacific,Earth Planet, Sci. Lett. 108, 259–275.Google Scholar
  23. Hekinian, R., Bideau, D., Hébert, R., and Niu, Y., 1994, Magmatism in the Garrett Transform Fault,J. Geophys. Res. (in press).Google Scholar
  24. Johnson, K. T. M., Dick, H. J. B., and Shimizu, N., 1990, Melting in oceanic upper mantle: anion microprobe study of diaprides in abyssal peridotites,J. Geophys. Res. 95(B3), 2661–2678.Google Scholar
  25. Langmuir C. H., Vocke, R. D., Jr., Hanson, G. N., and Hart, S. R., 1978, A general mixing equation with applications to Icelandic basalts,Earth Planet. Sci. Let. 37, 380–392.Google Scholar
  26. Mahoney, J. J., Sinton, J. M., Kurz, M. D., Macdougall, J. J., Spencer, K. J., and Lugmair, G. W., 1994, Isotope and trace element characteristics of super-fast spreading ridge: East Pacific Rise, 13°23′ S,Earth Planet. Sci. Lett.,121, 173–193.Google Scholar
  27. Maia, M. and Diament, M., 1991, An analysis of the altimetric geoid in various wavebands in the Central-Pacific Ocean: constraints on the origin of intraplate features,Tectonophysics 190, 133–153.Google Scholar
  28. Mammerickx, J., Anderson, R. N., Menard, H. W., and Smith, S. M., 1975, Morphology and tectonic evolution of the East-Central Pacific,Geol. Soc. Amer. Bull. 86, 111–118.Google Scholar
  29. Menard, H. W., Chase, T. E., and Smith, S. M., 1964, Galapagos Rise in the Southeastern Pacific,Deep-Sea Res. 11, 232–242.Google Scholar
  30. Moore, J. G., 1966, Rate of palagonitization of submarine basalt adjacent to Hawaii,U.S. Geol. Surv. Prof. Pap. 550D, 163–171.Google Scholar
  31. Morgan, W. J., 1972, Deep mantle convection plumes and plate motions,Amer. Ass. Petrol. Geol. Bull. 56, 203–213.Google Scholar
  32. Naar, D. F. and Hey, R. N., 1986, East Rift propagation along the East Pacific Rise near Easter Island,J. Geophys. Res. 91, 3425–3438.Google Scholar
  33. Naar, D. F. and Hey, R. N., 1989, Recent Pacific-Easter-Nazca plate motions, in Evolution of Mid-Ocean Ridges, IUGG, Symposium 8, AGU,Geophysical Monograph 57, 9–30.Google Scholar
  34. Naar, D. F. and Hey, R. N., 1991, Tectonic evolution of the Easter microplate,J. Geophys. Res. 96, 7961–7993.Google Scholar
  35. Okal E. and Casenave, A., 1985, A model for the plate tectonic evolution of the east-central Pacific based on SEASAT investigations,Earth Planet. Sci. Lett. 79, 99–116.Google Scholar
  36. Ottonello, G., 1980, Rare earth abundances and distribution in some spinel peridotite xenoliths from Assab (Ethiopia),Geochim. Cosmochim. Acta. 44, 1885–1901.Google Scholar
  37. Pearce, J. A. and Norry, M. J., 1979, Petrogenetic implication of Ti, Zr, Y, and Nb variations in volcanic rocks,Contr. Mineral. Petrol. 69, 33–47.Google Scholar
  38. Pilger R. H. and Handschumacher, D. W., 1981, The fixed hotspot hypothesis and the origin of the Easter-Sala y Gomez—Nazca trace,Geol. Soc. Am. Bull. 92, 437–446.Google Scholar
  39. Poreda R. J., Schilling, J. G., and Craig, H., 1993, Helium isotope ratios in Easter microplate basalts,Earth Planet. Sci. Lett. 119, 319–329.Google Scholar
  40. Prinzhofer, A., Lewin, E., and Allégre, C. J., 1989, Stochastic implications of melting of the marble-cake mantle. Evidence from local study of the East Pacific Rise at 12°50′ N,Earth Planet. Sci. Lett. 92, 189–206.Google Scholar
  41. Rusby, R. I., 1992, Gloria and other geophysical studies of the tectonic pattern and history of the Easter microplate, southeast Pacific, from Parson, L. M., Murton, B. J., and Browning, P. (eds),Ophiolites and their Modern Oceanic Analogues. Geol. Soc. Spec. Publication60, 81–106.Google Scholar
  42. Rusby, R. I. and Searle, R. C., 1993, Intraplate thrusting near the Easter microplate,Geology 21, 311–314.Google Scholar
  43. Schilling, J.-G., Sigurdsson, H., Davis, A. N., and Hey, R. H., 1985, Easter microplate evolution,Nature 317, 325–331.Google Scholar
  44. Scientific Party, 1993, SO80, Geology of young submarine volcanoes west of Easter Island, South East Pacific,Marine Geology (submitted).Google Scholar
  45. Schnetzler C. C. and Philpotts, J. A., 1970, Partition coefficient of rare-earth elements igneous matrix material and rock forming mineral phenocryst. II,Geochim. Cosmochim. Acta 34, 331–340.Google Scholar
  46. Searle, R. C., Francheteau, J., and Cornaglia, B., 1993, New observations on mid-plate volcanism and the tectonic 22history of the Pacific plate, Tahiti to Easter microplate,Earth Planet Sci. Lett. (in press).Google Scholar
  47. Searle, R. C., Rusby, R. I., Engeln, J., Hey, R. N., Zukin, J., Hunter, P. M., LeBas, T. P., Hoffmann, H.-J., and Livermore, R., 1989, Comprehensive sonar imaging of the Easter microplate,Nature 341, 701–705.Google Scholar
  48. Sinton, J. M., Smaglik, S. M., Mahoney, J. J., and Macdonald, K. C., 1991, Magmatic processes at superfast spreading oceanic ridges: Glass variations along the East Pacific Rise, 13° S–23° S,J. Geophys. Res. 96, 6133–6155.Google Scholar
  49. Stoffers, P.et al., 1989, Geology of Macdonald “hot spot”: Recent submarine eruptions in the South Pacific,Mar. Geophys. Res. 11, 101–112.Google Scholar
  50. Stoffers, P.et al., 1992, Cruise Report SONNE 80a-Midplate III Oceanic Volcanism in the South Pacific,Berichte-Reports, Geol.-Palœont. Inst., Univ. Kiel. 58, 128 pp.Google Scholar
  51. Sun S.-S. and MacDonough, 1989, Chemical and isotopic systematics of oceanic basalts: Implications for mantle compositions and processes, in:Magmatism in the Ocean Basins, eds. Saunder, A. D. and Norry, M. C.,Geol. Soc. Spec. Publication 42, 313–345.Google Scholar
  52. Tarney, J., Wood, D. A., Saunders, A. D., Cann, J. R., and Varet, J., 1980, Nature of mantle heterogeneity in North Atlantic: evidence from deep sea drilling.Phil. Trans. R. Soc. Lond. A297, 179–202.Google Scholar
  53. Thompson, G., Bryan, W. B., and Humphris, S. E., 1989, Axial volcanism on the East Pacific Rise, 10–12 NT, in:Magmatism in the Ocean Basins, eds. Saunders, A. D. and Norry, M. C.,Geol. Soc. Spec. Publication 42, 181–200.Google Scholar
  54. Weaver, J. S. and Langmuir, C. H., 1990, Calculation of phase equilibrium in mineral-melt systems,Comput. Geosci. 16, 1–19.Google Scholar

Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Roger Hekinian
    • 1
  • Peter Stoffers
    • 2
  • Dietrich Akermand
    • 3
  • Nicolas Binard
    • 4
  • Jean Francheteau
    • 5
  • Colin Devey
    • 2
  • Dieter Garbe-Schönberg
    • 2
  1. 1.FREMER, Centre de BrestPlouzanéFrance
  2. 2.Geologisch-Palaontologisches InstitutUniversitat KielKielFRG
  3. 3.Mineralogisch-Petrographisches InstitutUniversitat KielKielFRG
  4. 4.U. S. Geological SurveyMenlo ParkUSA
  5. 5.Université de Bretagne Occidentale, (GDR 910)BrestFrance

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