Abstract
O- and Sr-isotope data are reported for cordieritebearing dacites and andesites forming part of the Neogene volcanic province of SE Spain. The almandine-bearing biotite-cordierite-labradorite dacite from the Cerro del Hoyazo with its numerous inclusions of metamorphic and igneous rocks has been studied in some detail. A syngenetic derivation of the Hoyazo dacite magma and part of its inclusions (interpreted as restite) by means of anatexis of (semi-)pelitic rocks has previously been proposed.
δ 18O values and 87Sr/86Sr ratios, thought to be closely representative of the original magmas, vary from +12.2 to +15.6 and 0.7095 to 0.7171, respectively. The metamorphic rock inclusions have δ 18O values (+13.0-+16.2) comparable to the range for the volcanics. These results support an anatectic origin for the entire suite of cordierite-bearing volcanics. The inclusions of basic igneous rocks in the Hoyazo dacite have, in comparison with the dacite, lower δ 18O values (+11.1-+13.1) and equal to lower 87Sr/86Sr ratios (0.7081–0.7112), confirming an independent origin.
The six analysed samples of the Hoyazo dacite show a strong linear correlation of 87Sr/86Sr versus 87Rb/86Sr which, if interpreted as an isochron, yields an age of 210±17 Ma. Similar linear arrays for samples from the Mazarrón and Mar Menor areas yield nearly concordant ages. Samples for the Vera area define a 535±22 Ma line. These linear correlations may be interpreted either as (1) mixing lines, in which case the indicated ages have no geological meaning, or (2) true isochrons dating pre-eruptional events of the parent (meta-)sediments.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Bellon H, Bordet P, Montenat C (1983) Chronologie du magmatisme néogene des Cordilleres bétiques (Espagne méridionale). Bull Soc Geol France 25:205–217
Carmichael ISE, Turner FJ, Verhoogen J (1974) Igneous Petrology. McGraw Hill, New York, pp 739
Chappell BW, White AJR (1974) Two contrasting granite types. Pacific Geol 8:173–174
Clayton RN, Mayeda TK (1963) The use of bromine pentafluoride in extraction of oxygen from oxides and silicates for isotopic analysis. Geochim Cosmochim Acta 27:43–52
Faure G, Bowman JR, Elliot DH, Jones LM (1974) Strontium isotope composition and petrogenesis of the Kirkpatric basalt, Queen Alexandra Range, Antarctica. Contrib Mineral Petrol 48:153–169
Gill J (1981) Orogenic andesites and plate tectonics. Springer-Verlag, New York Heidelberg Berlin, pp 390
Javoy M (1977) Stable isotopes and geothermometry. J Geol Soc Lond 133:609–636
Longstaffe FJ, Clark AH, McNutt RH, Zentilli M (1983) Oxygen isotopic compositions of Central Andean plutonic and volcanic rocks, latitudes 26°–29° south. Earth Planet Sci Lett 64:9–18
López Ruiz J, Badiola RE (1980) La region volcanica neogena del sureste de Espana. Estudios Geol 36:5–63
Magaritz M, Whitford DJ, James DE (1978) Oxygen isotopes and the origin of high-87Sr/86Sr andesites. Earth Planet Sci Lett 40:220–230
McIntyre GA, Brooks C, Compston W, Turek A (1966) The statistical assessment of Rb-Sr isochrons. J Geophys Res 71:5459–5468
Nobel FA, Andriessen PAM, Hebeda EH, Priem HNA, Rondeel HE (1981) Isotopic dating of the post-alpine Neogene volcanism in the Betic Cordilleras, southern Spain. Geol Mijnbouw 60:209–214
O'Neil JR, Shaw SE, Flood RH (1977) Oxygen and hydrogen isotope compositions as indicators of granite genesis in the New England Batholith, Australia. Contrib Mineral Petrol 62:313–328
Peccerillo A, Taylor SR (1976) Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, northern Turkey. Contrib Mineral Petrol 58:63–81
Roddick JC, Compston W (1977) Strontium isotopic equilibration: A solution to a paradox. Earth Planet Sci Lett 34:238–246
Taylor HP (1978) Oxygen and hydrogen isotope studies of plutonic granitic rocks. Earth Planet Sci Lett 38:177–210
Taylor HP, Turi B (1976) High-18O igneous rocks from the Tuscan magmatic province, Italy. Contrib Mineral Petrol 55:33–54
Whitford DJ, Jezek PA (1977) Geochemistry of Cenozoic and Recent lavas from the Banda arc, Indonesia. Carnegie Inst Wash Yearb 76:845
Zeck HP (1968) Anatectic origin and further petrogenesis of almandine-bearing biotite-cordierite-labradorite-dacite with many inclusions of restite and basaltoid material, Cerro del Hoyazo, SE Spain. Thesis, Amsterdam University
Zeck HP (1970) An erupted migmatite from Cerro del Hoyazo, SE Spain. Contrib Mineral Petrol 26:225–246
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Munksgaard, N.C. High δ18O and possible pre-eruptional Rb-Sr isochrons in cordierite-bearing Neogene volcanics from SE Spain. Contr. Mineral. and Petrol. 87, 351–358 (1984). https://doi.org/10.1007/BF00381291
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00381291