Extreme isotopic variation documents extensional tectonics in arc magmas from Methana, Greece

M. A. Elburg; I. Smet; P. Van den haute; F. Vanhaecke; M. Klaver; T. Andersen

doi:10.1016/j.lithos.2018.08.029

Extreme isotopic variation documents extensional tectonics in arc magmas from Methana, Greece

M. A. Elburg^*, I. Smet, P. Van den haute, F. Vanhaecke, M. Klaver, T. Andersen

^*Corresponding author for this work

Geology and Geochemistry

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

New Sr-Nd-Hf-Pb isotope data for volcanic rocks from the peninsula of Methana (South Aegean Active Volcanic Arc, Greece) show a wide variation, and more ‘enriched’ isotopic signatures (e.g. elevated ⁸⁷Sr/⁸⁶Sr at 0.705–0.709) than those of other active Aegean volcanic centres, all located on thinner crust. The data set is best explained by polybaric AFC processes, with contaminants similar to country rocks and xenoliths, showing moderately high ⁸⁷Sr/⁸⁶Sr ratios, and with isotopically more evolved lower crust, similar to the pre-Alpine Ios basement. Pb isotope ratios show some minor influence of assimilation of fluid-altered volcanic cumulates. Intermediate lava domes with mafic enclaves were formed during periods of compression, whereas an extensional period saw the deposition of explosive products of bimodal composition, with the more felsic deposits showing the most pronounced influence of crustal assimilation. The latter likely represent stalled magmas from an earlier compressional period, which were remobilised and flushed out by ascending mafic magmas during extension. Recognition of these volcanological, geochemical and isotopic characteristics of deposits associated with extensional tectonics in a modern arc will enable us to use these criteria to infer paleo-tectonics from older volcanic deposits.

Original language	English
Pages (from-to)	386-398
Number of pages	13
Journal	Lithos
Volume	318-319
Early online date	31 Aug 2018
DOIs	https://doi.org/10.1016/j.lithos.2018.08.029
Publication status	Published - Oct 2018

Funding

This research formed part of Smet's PhD work, who was funded by a BOF bursary ; research costs were borne by FWO grants G.0585.06N , G.0669.06 and 1509007N . Hf isotopic analyses were performed at the Vrije Universiteit Amsterdam funded by TransNational Access project 079-TNA3 of Europlanet. Laboratory work was assisted by Mr. Kris Latruwe (Ghent), Mr. Richard Smeets (Amsterdam) and Ms. Siri Simonsen (Oslo). Thin sections were prepared by Mr. Jan Jurceka. Olga Zlatkin and Robert Bolhar are thanked for their constructive reviews. Appendix A

Funders	Funder number
Vrije Universiteit Amsterdam	079-TNA3
Fonds Wetenschappelijk Onderzoek	G.0669.06, 1509007N

Keywords

Aegean Arc
Crustal contamination
Extension
Radiogenic isotopes
Subduction

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.lithos.2018.08.029

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title = "Extreme isotopic variation documents extensional tectonics in arc magmas from Methana, Greece",

abstract = "New Sr-Nd-Hf-Pb isotope data for volcanic rocks from the peninsula of Methana (South Aegean Active Volcanic Arc, Greece) show a wide variation, and more {\textquoteleft}enriched{\textquoteright} isotopic signatures (e.g. elevated 87Sr/86Sr at 0.705–0.709) than those of other active Aegean volcanic centres, all located on thinner crust. The data set is best explained by polybaric AFC processes, with contaminants similar to country rocks and xenoliths, showing moderately high 87Sr/86Sr ratios, and with isotopically more evolved lower crust, similar to the pre-Alpine Ios basement. Pb isotope ratios show some minor influence of assimilation of fluid-altered volcanic cumulates. Intermediate lava domes with mafic enclaves were formed during periods of compression, whereas an extensional period saw the deposition of explosive products of bimodal composition, with the more felsic deposits showing the most pronounced influence of crustal assimilation. The latter likely represent stalled magmas from an earlier compressional period, which were remobilised and flushed out by ascending mafic magmas during extension. Recognition of these volcanological, geochemical and isotopic characteristics of deposits associated with extensional tectonics in a modern arc will enable us to use these criteria to infer paleo-tectonics from older volcanic deposits.",

keywords = "Aegean Arc, Crustal contamination, Extension, Radiogenic isotopes, Subduction",

author = "Elburg, {M. A.} and I. Smet and {Van den haute}, P. and F. Vanhaecke and M. Klaver and T. Andersen",

year = "2018",

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doi = "10.1016/j.lithos.2018.08.029",

language = "English",

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pages = "386--398",

journal = "Lithos",

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T1 - Extreme isotopic variation documents extensional tectonics in arc magmas from Methana, Greece

AU - Elburg, M. A.

AU - Smet, I.

AU - Van den haute, P.

AU - Vanhaecke, F.

AU - Klaver, M.

AU - Andersen, T.

PY - 2018/10

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N2 - New Sr-Nd-Hf-Pb isotope data for volcanic rocks from the peninsula of Methana (South Aegean Active Volcanic Arc, Greece) show a wide variation, and more ‘enriched’ isotopic signatures (e.g. elevated 87Sr/86Sr at 0.705–0.709) than those of other active Aegean volcanic centres, all located on thinner crust. The data set is best explained by polybaric AFC processes, with contaminants similar to country rocks and xenoliths, showing moderately high 87Sr/86Sr ratios, and with isotopically more evolved lower crust, similar to the pre-Alpine Ios basement. Pb isotope ratios show some minor influence of assimilation of fluid-altered volcanic cumulates. Intermediate lava domes with mafic enclaves were formed during periods of compression, whereas an extensional period saw the deposition of explosive products of bimodal composition, with the more felsic deposits showing the most pronounced influence of crustal assimilation. The latter likely represent stalled magmas from an earlier compressional period, which were remobilised and flushed out by ascending mafic magmas during extension. Recognition of these volcanological, geochemical and isotopic characteristics of deposits associated with extensional tectonics in a modern arc will enable us to use these criteria to infer paleo-tectonics from older volcanic deposits.

AB - New Sr-Nd-Hf-Pb isotope data for volcanic rocks from the peninsula of Methana (South Aegean Active Volcanic Arc, Greece) show a wide variation, and more ‘enriched’ isotopic signatures (e.g. elevated 87Sr/86Sr at 0.705–0.709) than those of other active Aegean volcanic centres, all located on thinner crust. The data set is best explained by polybaric AFC processes, with contaminants similar to country rocks and xenoliths, showing moderately high 87Sr/86Sr ratios, and with isotopically more evolved lower crust, similar to the pre-Alpine Ios basement. Pb isotope ratios show some minor influence of assimilation of fluid-altered volcanic cumulates. Intermediate lava domes with mafic enclaves were formed during periods of compression, whereas an extensional period saw the deposition of explosive products of bimodal composition, with the more felsic deposits showing the most pronounced influence of crustal assimilation. The latter likely represent stalled magmas from an earlier compressional period, which were remobilised and flushed out by ascending mafic magmas during extension. Recognition of these volcanological, geochemical and isotopic characteristics of deposits associated with extensional tectonics in a modern arc will enable us to use these criteria to infer paleo-tectonics from older volcanic deposits.

KW - Aegean Arc

KW - Crustal contamination

KW - Extension

KW - Radiogenic isotopes

KW - Subduction

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Extreme isotopic variation documents extensional tectonics in arc magmas from Methana, Greece

Abstract

Funding

Keywords

UN SDGs

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