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Oxygen isotope heterogeneity of arc magma recorded in plagioclase from the 2010 Merapi eruption (Central Java, Indonesia)статья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 30 декабря 2016 г.
- Авторы: BORISOVA A.Y., Gurenko A.A., Martel C., Kouzmanov K., Cathala A., Bohrson W.A., Pratomo I., Sumarti S.
- Журнал: Geochimica et Cosmochimica Acta
- Том: 190
- Год издания: 2016
- Издательство: Pergamon Press Ltd.
- Местоположение издательства: United Kingdom
- Первая страница: 13
- Последняя страница: 34
- DOI: 10.1016/j.gca.2016.06.020
- Аннотация: Chemical and isotopic compositions of magmatic crystals provide important information to distinguish between deep juvenile and crustal contributions. In this work, high-resolution multicollector secondary ion mass spectrometry data reveal strong variations of d18O values in three plagioclase crystals (800–1700 lm) from two representative basaltic andesite samples of the 2010 Merapi eruption (Central Java, Indonesia). The d18O values (from 4.6‰ to 7.9‰) are interpreted to reflect oxygen isotope heterogeneity in the melt composition during plagioclase growth. The lowest d18O values (4.6–6.6‰) are found in anorthite-rich cores (An82–97), whereas higher d18O values (5.7–7.9‰) are found in anorthite-poorer zones (An33–86), typically in crystal rims. Combining these new plagioclase d18O data with d18O of calc-silicate crustal xenoliths erupted between 1994 and 1998, the composition of glass inclusions hosted by the anorthite-rich plagioclase (An82–92), available experimental data, and the results of thermodynamic modeling using the Magma Chamber Simulator code, we conclude that the abundant anorthite-rich cores crystallized from a mantle-derived hydrous basaltic to basaltic trachyandesite melt that recharged a deeper (200–600 MPa) magma storage zone, whereas lower anorthite zones crystallized at shallower levels (100–200 MPa). The oxygen isotope variations in the plagioclase are explained by a two-stage model of interaction of the hydrous, mafic mantle derived magma (1) with old crustal rocks depleted in 18O due to high temperature alteration that yielded the low d18O values in the anorthite-rich cores at deep levels (13–20 km), and later (2) with 18O-enriched carbonate material that yielded the high d18O values in anorthite-poorer zones at shallow levels (4.5–9 km). Thermodynamic modeling is consistent with 18 wt.% assimilation of crustal calc-silicate material at 925–950 C and 100–200 MPa by the 2010 Merapi basaltic andesite magma prior to eruption. Timescales for plagioclase phenocryst growth and residence in the magmatic plumbing system are 634 years. The combined data thus reveal efficient magma recharge and crustal assimilation processes that characterize the open-system magma storage and transport systems associated with the 2010 Merapi eruption.
- Добавил в систему: Борисова Анастасия Юрьевна