Coupled Trace Element and Sr-Nd-(Pb) Isotopes in Olivine-Hosted Melt Inclusions from the Mariana Arc
| Autor: | Gareth Davies, Igor K. Nikogosian, A.J.J. Bracco Gartner, N. Luciani, Janne M. Koornneef, Tim Elliott |
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| Přispěvatelé: | Geology and Geochemistry, Earth Sciences |
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Koornneef, J M, Nikogosian, I K, Luciani, N, Bracco Gartner, A J J, Elliott, T & Davies, G R 2020, ' Coupled trace element and Sr-Nd-(Pb) isotopes in olivine-hosted melt inclusions from the Mariana arc ', pp. 1357 . https://doi.org/10.46427/gold2020.1357 None |
| Popis: | The Mariana arc forms part of the 2500 km Izu–Bonin–Mariana arc system caused by westward subduction of the Pacific Plate beneath the Philippine Sea Plate over the last ~45 Myr. The magmatism produced in this comparatively simple arc setting records a moderate flux of fluids and sediments from the downgoing plate, however, the low MgO (Here we analyse coupled trace element and Sr-Nd(-Pb) isotope compositions of olivine-hosted MIs in five samples from four islands within the Central Island province: Agrigan (AGR2, AGR6), Pagan (PAG3), Guguan (GUG6) and Sarigan (SAG1). Bulk rock MgO contents range from 4 to 5.7 wt.% [1]. We specifically target melt inclusions in olivine phenocrysts with the highest fortsterite content (Fo = Mg/(Mg+Fe)*100): AGR: 80-86; PAG: 76-81; GUG: 76-88; SAG: 84-88 mol%. Trace element contents and ratios of the selected MIs record marked differences between islands and show larger variability compared to published bulk rock and MI compositions [2]. Ba/La and Th/Nb or La/Sm ratios – indicators of slab fluids versus sediment melts, respectively – confirm that Guguan inclusions are dominated by a fluid component whereas Agrigan and Sarigan reflect a larger sediment contribution. Pagan inclusions show intermediate compositions and a restricted range indicating the influence of both fluids and sediments. Sr-Nd-(Pb) isotope compositions of individual and pooled melt inclusions will be determined by wet chemistry and TIMS techniques using 10^13 Ω amplifier technology [3] to further identify and quantify the recycled components. [1] Elliott et al. (1997). Journal of Geophysical Research, 102: 14991-15019. [2] Kent & Elliott (2002). Chemical Geology, 183: 263-286. [3] Koornneef et al. (2019). Nature Communications 10, 3237 |
| Databáze: | OpenAIRE |
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