¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy
18O/16O analyses were made on a set of leucite-bearing igneous rocks from a variety of localities around the world. The samples chosen for study all have relatively primitive characteristics, such as low SiO2 contents (42–52 wt.%). Whole-rock δ18O values from the 10–15 m.y. old Australian leucitites...
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ftcaltechauth:oai:authors.library.caltech.edu:117226 2023-05-15T13:52:02+02:00 ¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy Taylor, Hugh P., Jr. Turi, Bruno Cundari, Aldo 1984-08 https://authors.library.caltech.edu/117226/ https://resolver.caltech.edu/CaltechAUTHORS:20221004-127929900.1 unknown Elsevier Taylor, Hugh P., Jr. and Turi, Bruno and Cundari, Aldo (1984) ¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy. Earth and Planetary Science Letters, 69 (2). pp. 263-276. ISSN 0012-821X. doi:10.1016/0012-821x(84)90186-9. https://resolver.caltech.edu/CaltechAUTHORS:20221004-127929900.1 <https://resolver.caltech.edu/CaltechAUTHORS:20221004-127929900.1> Article PeerReviewed 1984 ftcaltechauth https://doi.org/10.1016/0012-821x(84)90186-9 2022-10-06T17:56:57Z 18O/16O analyses were made on a set of leucite-bearing igneous rocks from a variety of localities around the world. The samples chosen for study all have relatively primitive characteristics, such as low SiO2 contents (42–52 wt.%). Whole-rock δ18O values from the 10–15 m.y. old Australian leucitites range from +7.1 to +11.0; however, none of these values represents the original δ18O of the erupted lava, as every sample has undergone some subsolidus18O enrichment. The δ18O values of the primary magmas (≈ +6.5) can be accurately calculated from the δ18O of clinopyroxene mineral separates. However, the leucite mineral separates (pure, stoichiometric KA1Si2O6) have δ18O = +8.8to+10.6, and clearly have not retained their primary igneous oxygen isotopic compositions. The whole-rock δ18O values exhibit a positive correlation with H2O+ contents, and extrapolation to a plausible water content for such a subaerially erupted lava ( <0.5 wt.% H2O) gives a range of primary δ18O values of +5.8 to +6.8. The much less hydrated Bufumbira, Africa and Gaussberg, Antarctica samples have δ18O = +6.7to+7.9and+6.1to+7.0, respectively. These have probably undergone only minor subsolidus18O enrichments. The San Venanzo, Italy, samples are even less hydrated, so their extremely high δ18O values of +10.8 to +12.0 are definitely magmatic values. Those data confirm our earlier conclusions that the leucite-bearing magmas erupted in north-central Italy are unique in having much higher δ18O values than potassic rocks from southern Italy or anywhere else in the world. The northward increase in δ18O in the leucite-bearing rocks of Italy is thus clearly a manifestation of progressively greater interaction between mantle-derived magmas (δ18O = +5.5to+7.5) and the high-18O sedimentary and metasedimentary rocks of the Italian continental crust (δ18O = +15to+25), which were strongly heated during the episode of Tuscan anatectic granitic magmatism. Article in Journal/Newspaper Antarc* Antarctica Caltech Authors (California Institute of Technology) Gaussberg ENVELOPE(89.183,89.183,-66.800,-66.800) Earth and Planetary Science Letters 69 2 263 276 |
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Caltech Authors (California Institute of Technology) |
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ftcaltechauth |
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unknown |
description |
18O/16O analyses were made on a set of leucite-bearing igneous rocks from a variety of localities around the world. The samples chosen for study all have relatively primitive characteristics, such as low SiO2 contents (42–52 wt.%). Whole-rock δ18O values from the 10–15 m.y. old Australian leucitites range from +7.1 to +11.0; however, none of these values represents the original δ18O of the erupted lava, as every sample has undergone some subsolidus18O enrichment. The δ18O values of the primary magmas (≈ +6.5) can be accurately calculated from the δ18O of clinopyroxene mineral separates. However, the leucite mineral separates (pure, stoichiometric KA1Si2O6) have δ18O = +8.8to+10.6, and clearly have not retained their primary igneous oxygen isotopic compositions. The whole-rock δ18O values exhibit a positive correlation with H2O+ contents, and extrapolation to a plausible water content for such a subaerially erupted lava ( <0.5 wt.% H2O) gives a range of primary δ18O values of +5.8 to +6.8. The much less hydrated Bufumbira, Africa and Gaussberg, Antarctica samples have δ18O = +6.7to+7.9and+6.1to+7.0, respectively. These have probably undergone only minor subsolidus18O enrichments. The San Venanzo, Italy, samples are even less hydrated, so their extremely high δ18O values of +10.8 to +12.0 are definitely magmatic values. Those data confirm our earlier conclusions that the leucite-bearing magmas erupted in north-central Italy are unique in having much higher δ18O values than potassic rocks from southern Italy or anywhere else in the world. The northward increase in δ18O in the leucite-bearing rocks of Italy is thus clearly a manifestation of progressively greater interaction between mantle-derived magmas (δ18O = +5.5to+7.5) and the high-18O sedimentary and metasedimentary rocks of the Italian continental crust (δ18O = +15to+25), which were strongly heated during the episode of Tuscan anatectic granitic magmatism. |
format |
Article in Journal/Newspaper |
author |
Taylor, Hugh P., Jr. Turi, Bruno Cundari, Aldo |
spellingShingle |
Taylor, Hugh P., Jr. Turi, Bruno Cundari, Aldo ¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy |
author_facet |
Taylor, Hugh P., Jr. Turi, Bruno Cundari, Aldo |
author_sort |
Taylor, Hugh P., Jr. |
title |
¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy |
title_short |
¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy |
title_full |
¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy |
title_fullStr |
¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy |
title_full_unstemmed |
¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy |
title_sort |
¹⁸o/¹⁶o and chemical relationships in k-rich volcanic rocks from australia, east africa, antarctica, and san venanzo-cupaello, italy |
publisher |
Elsevier |
publishDate |
1984 |
url |
https://authors.library.caltech.edu/117226/ https://resolver.caltech.edu/CaltechAUTHORS:20221004-127929900.1 |
long_lat |
ENVELOPE(89.183,89.183,-66.800,-66.800) |
geographic |
Gaussberg |
geographic_facet |
Gaussberg |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_relation |
Taylor, Hugh P., Jr. and Turi, Bruno and Cundari, Aldo (1984) ¹⁸O/¹⁶O and chemical relationships in K-rich volcanic rocks from Australia, East Africa, Antarctica, and San Venanzo-Cupaello, Italy. Earth and Planetary Science Letters, 69 (2). pp. 263-276. ISSN 0012-821X. doi:10.1016/0012-821x(84)90186-9. https://resolver.caltech.edu/CaltechAUTHORS:20221004-127929900.1 <https://resolver.caltech.edu/CaltechAUTHORS:20221004-127929900.1> |
op_doi |
https://doi.org/10.1016/0012-821x(84)90186-9 |
container_title |
Earth and Planetary Science Letters |
container_volume |
69 |
container_issue |
2 |
container_start_page |
263 |
op_container_end_page |
276 |
_version_ |
1766256229319966720 |