High δ18O and possible pre-eruptional Rb-Sr isochrons in cordierite-bearing Neogene volcanics from SE Spain

Niels Munksgaard

Research output: Contribution to journalArticleResearchpeer-review

Abstract

O- and Sr-isotope data are reported for cordierite bearing 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. 

δ18O 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 δ18O values (+ 13.0- + 16.2) comparable to the range for the volcanics. These results support an anateetic 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 δ18O 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 Mazarron 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.

Original languageEnglish
Pages (from-to)351-358
Number of pages8
JournalContributions to Mineralogy and Petrology
Volume87
Issue number4
DOIs
Publication statusPublished - Oct 1984
Externally publishedYes

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Bearings (structural)
cordierite
Spain
dacite
Neogene
volcanology
inclusions
Metamorphic rocks
Igneous rocks
metamorphic rocks
andesite
igneous rocks
biotite
labradorite
restite
almandine
Isotopes
magma
Sediments
sediments

Cite this

@article{0592916079b14ade996ada599ba04bfb,
title = "High δ18O and possible pre-eruptional Rb-Sr isochrons in cordierite-bearing Neogene volcanics from SE Spain",
abstract = "O- and Sr-isotope data are reported for cordierite bearing 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.  δ18O 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 δ18O values (+ 13.0- + 16.2) comparable to the range for the volcanics. These results support an anateetic 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 δ18O 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 Mazarron 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.",
author = "Niels Munksgaard",
year = "1984",
month = "10",
doi = "10.1007/BF00381291",
language = "English",
volume = "87",
pages = "351--358",
journal = "Contributions to Mineralogy and Petrology",
issn = "0010-7999",
publisher = "Springer-Verlag London Ltd.",
number = "4",

}

High δ18O and possible pre-eruptional Rb-Sr isochrons in cordierite-bearing Neogene volcanics from SE Spain. / Munksgaard, Niels.

In: Contributions to Mineralogy and Petrology, Vol. 87, No. 4, 10.1984, p. 351-358.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - High δ18O and possible pre-eruptional Rb-Sr isochrons in cordierite-bearing Neogene volcanics from SE Spain

AU - Munksgaard, Niels

PY - 1984/10

Y1 - 1984/10

N2 - O- and Sr-isotope data are reported for cordierite bearing 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.  δ18O 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 δ18O values (+ 13.0- + 16.2) comparable to the range for the volcanics. These results support an anateetic 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 δ18O 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 Mazarron 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.

AB - O- and Sr-isotope data are reported for cordierite bearing 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.  δ18O 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 δ18O values (+ 13.0- + 16.2) comparable to the range for the volcanics. These results support an anateetic 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 δ18O 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 Mazarron 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.

U2 - 10.1007/BF00381291

DO - 10.1007/BF00381291

M3 - Article

VL - 87

SP - 351

EP - 358

JO - Contributions to Mineralogy and Petrology

JF - Contributions to Mineralogy and Petrology

SN - 0010-7999

IS - 4

ER -