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Contributions to Mineralogy and Petrology

, Volume 69, Issue 2, pp 151–165 | Cite as

Crustal contamination versus enriched mantle: 143Nd/144Nd and 87Sr/86Sr evidence from the Italian volcanics

  • C. J. Hawkesworth
  • R. Vollmer
Article

Abstract

143Nd/144Nd, 87Sr/86Sr, and REE analyses are presented on a wide variety of Pliocene-Recent volcanic rocks from central Italy. 143Nd/144Nd varies from 0.51214–0.51289 and 87Sr/86Sr from 0.7255-0.7036; while the rare earth elements are characterised by light RE enrichment and a significant negative Eu anomaly. These Italian volcanics are tentatively subdivided into three zones: (1) N. Tuscany where the magmas are believed to reflect crustal anatexis. (2) A central zone in which hybrid (crust/ mantle) rocks have been recognised. (3) A southern zone, south of Rome, where mantle-derived magmas are identified which have been largely unaffected by interaction with continental crust. At Roccamonfina, in zone 3, Rb/Sr and Sm/Nd pseudo isochrons are observed but since the calculated ages are 0.5 and 2.0 b.y. respectively it is argued that a simple isochron model is not applicable and that the data are most easily explained by a recent mixing event within the upper mantle. It is envisaged that this occurred during metasomatism of the upper mantle source region by a fluid that had high 87Sr/86Sr and low 143Nd/144Nd and was enriched in K, Rb, and LREE's but relatively depleted in Sr2+ and Eu2+.

Keywords

Rare Earth Mineral Resource Volcanic Rock Earth Element Source Region 
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. Appleton, J.D.: The petrology of the potassium-rich lavas of the Roccamonfina Volcano, Italy. Ph. D. thesis, University of Edinburgh (1970)Google Scholar
  2. Appleton, J.D.: Petrogenesis of potassium-rich lavas from the Roccamonfina Volcano, Roman Region, Italy. J. Petrol. 13, 425–456 (1972)Google Scholar
  3. Barberi, F., Innocenti, F., Mazzuoli, F.: Contributo alla conscenza chimico-petrografica e magmatologica delle rocce intrusive, vulcaniche e filoniane del Campigliese (Toscana). Mem. Soc. Geol. Ital. 6, 643–681 (1967)Google Scholar
  4. Barberi, F., Innocenti, F., Ricci, C.A.: Il magmatismo nell'Appennino Centro Settentrionale (‘La Toscana Meridonale’). Spec. Issue Rend. Soc. Ital. Mineral. Petrol. 27, 1–45 (1971)Google Scholar
  5. Brooks, C., James, D.E., Hart, S.R.: Ancient lithosphere: its role in young continental volcanism. Science 193, 1086–1094 (1976)Google Scholar
  6. Burri, C.: Vulcano Vesbico e Monte Vulture: analgoie nella loro evolutione magmatica. Rend. Accad. Sci. Fis. Mat. 28, 131–142 (1961)Google Scholar
  7. Capaldi, C., Civette, L., Gasparini, R.: Volcanic history of the island of Ischia (South Italy). Bull. Volcanol. 40, 11–22 (1976)Google Scholar
  8. Carter, S.R., Evensen, N.M., Hamilton, P.J., O'Nions, R.K.: Continental volcanics derived from enriched and depleted source regions: Nd and Sr isotope evidence. Earth. Planet. Sci. Lett. 37, 401–408 (1978)Google Scholar
  9. Cox, K.G., Hawkesworth, C.J., O'Nions, R.K., Appleton, J.D.: Isotopic evidence for the derivation of some Roman Region volcanics from anomalously enriched mantle. Contrib. Mineral. Petrol. 56, 173–180 (1976)Google Scholar
  10. De Paolo, D.J., Wasserburg, G.J.: Nd isotopic variations and petrogenetic models. Geophys. Res. Lett. 13, 249–252. (1976a)Google Scholar
  11. De Paolo, D.J., Wasserburg, G.J.: Inferences about magma sources and mantle structure from variations of 143Nd/144Nd. Geophys. Res. Lett. 12, 743–746 (1976b)Google Scholar
  12. Drake, M.J., Weill, D.F.: Partition of Sr, Ba, Ca, Y, Eu2+, Eu3+, and other REE between plagioclase feldspar and magmatic liquid: an experimental study. Geochim. Cosmochim. Acta 39, 689–712 (1975)Google Scholar
  13. Dupuy, C.: Contribution a l'etude des fractionments Geochimiques des Alcalins, des Alcalino-Terreux et du Gallium au cours des processus magmatiques. D. Sc. thesis. Univ. Montpellier (1970)Google Scholar
  14. Dupuy, C., Allegre, C.J.: Fractionment K/Rb dans les suits ignimbriteques de Toscane. Un example de rejuvenation crustale. Geochim. Cosmochim. Acta 36, 437–458 (1972)Google Scholar
  15. Erlank, A.J.: Upper mantle metasomatism as revealed by Potassic Richterite bearing peridotite xenoliths from kimberlites. EOS 57, p. 597 (1976)Google Scholar
  16. Gast, P.W.: Trace element fractionation and the origin of tholeiitic and alkaline magma types. Geochim. Cosmochim. Acta 32, 1057–1086 (1968)Google Scholar
  17. Giese, P., Morelli, C., Steinmetz, L.: Main features of crustal structure in western and southern Europe based on data of explosion seismology. Tectonophysics 20, 367–379 (1973)Google Scholar
  18. Hawkesworth, C.J., Norry, M.J., Roddick, J.C., Baker, P.E., Francis, P.W., Thorpe, R.S.: 143Nd/144Nd, 87Sr/86Sr, and incompatible element variations in calc-alkaline andesites and plateau lavas from South America. Earth Planet. Sci. Lett. 42, 45–57 (1979)Google Scholar
  19. Hawkesworth, C.J., O'Nions, R.K., Pankhurst, R.J., Hamilton, P.J., Evensen, N.M.: A geochemical study of island-arc and back-arc tholeiites from the Scotia Sea. Earth Planet. Sci. Lett. 36, 253–262 (1977)Google Scholar
  20. Hooker, P.J., O'Nions, R.K., Pankhurst, R.J.: Determination of REE in USGS standard rocks by mixed-solvent ion exchange and mass-spectrometric isotope dilution. Chem. Geol. 16, 189–196 (1975)Google Scholar
  21. Hurley, P.M., Fairbairn, H.W., Pinson, W.H.: Rb-Sr isotopic evidence in the origin of potash-rich lavas from Western Italy. Earth Planet. Sci. Lett. 5, 301–306 (1966)Google Scholar
  22. Kramers, J.D.: Lead and strontium isotopes in Cretaceous kimberlites and mantle-derived xenoliths from southern Africa. Earth Planet. Sci. Lett. 34, 419–431 (1977)Google Scholar
  23. Kyser, T., O'Neil, J.R.: Oxygen isotope relations among oceanic tholeiites, alkali basalts, and ultramafic nodules. U.S.G.S. Open-File Report 78–701 237–240 (1978)Google Scholar
  24. Langmuir, C.H., Vocke, R.D., Hanson, G.N., Hart, S.R.: A general mixing equation with applications to Icelandic basalts. Earth Planet. Sci. Lett. 37, 380–392 (1978)Google Scholar
  25. Mitchel, R.H., Brunfelt, A.D.: Rare earth element geochemistry of kimberlite. In: Physics and Chemistry of the Earth. 9, 671–685 (1975)Google Scholar
  26. O'Nions, R.K., Hamilton, P.J., Evensen, N.M.: Variation in 143Nd/144Nd and 87Sr/86Sr ratios in oceanic islands. Earth Planet. Sci. Lett. 34, 13–22 (1977)Google Scholar
  27. Richard, P., Shimizu, N., Allegre, C.J.: 143Nd/146Nd a natural tracer — an application to oceanic basalts. Earth Planet. Sci. Lett. 31, 269–278 (1976)Google Scholar
  28. Sheppard, S.M.F., Dawson, J.B.: Hydrogen, Carbon and Oxygen isotope studies of megacryst and matrix minerals from Lesothan and South Africa kimberlites. In: Physics and Chemistry of the Earth. 9, 747–764 (1975)Google Scholar
  29. Taylor, H.P. Jr., Turi, B.: High 18O igneous rocks from the Tuscan magmatic province, Italy. Contrib. Mineral. Petrol. 55, 33–54 (1976)Google Scholar
  30. Thompson, R.N.: Primary basalts and magma genesis III. Alban Hills, Roman comagmatic province, Central Italy. Contrib. Mineral. Petrol. 60, 91–108 (1977)Google Scholar
  31. Turi, B., Taylor, H.P. Jr.: Oxygen isotope studies of potassic volcanic rocks of the Roman Province, Central Italy. Contrib. Mineral. Petrol. 55, 1–31 (1976)Google Scholar
  32. Vollmer, R.: Rb-Sr and U-Th-Pb systematics of alkaline rocks: the alkaline rocks from Italy. Geochim. Cosmochim. Acta 40, 283–295 (1976)Google Scholar
  33. Vollmer, R.: Isotopic Evidence for genetic relations between acid and alkaline rocks in Italy. Contrib. Mineral. Petrol. 60, 109–118 (1977)Google Scholar

Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • C. J. Hawkesworth
    • 1
  • R. Vollmer
    • 1
  1. 1.Department of Earth SciencesUniversity of LeedsLeedsGreat Britain

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