- abstract:
The Quaternary Southwest Japan Arc is a product of subduction of the hot, young Philippine Sea Plate beneath the Eurasian Continental Plate. The magmas erupted from the Southwest Japan Arc belong to a category of magmas commonly referred to as "adakites" or "adakitic magmas". These magmas show trace element evidence for interaction with garnet at depth, and may be associated with partial melting of subducted altered oceanic crust. Also found throughout the southern Sea of Japan region are alkali basalts with little apparent connection to the subduction zone. We have determined major element, trace element, and Sr, Nd, Pb, and U-Th isotopic compositions for a bimodal suite of lavas erupted at the Daisen volcanic field in the Southwest Japan Arc. These magmas consist of mildly alkaline basalts and a calcalkaline intermediate suite, separated by a ~10 wt.% silica gap. The intermediate magmas show trace element and isotopic evidence for interaction with garnet, consistent with partial melting of the hot, young (~20 Ma) Philippine Sea Plate. The Daisen intermediate magmas are distinct from other adakitic magmas in their radiogenic isotopic characteristics, consistent with a significant contribution (~25%) from subducted Nankai Trough sediments. Our data suggest that the basalts erupted at the Daisen volcanic field are not parental to the intermediate magmas, and contain a small contribution of EM1-like mantle common in Sea of Japan alkali basalts but not apparent in the Daisen intermediate magmas.
- summary:
In summary, the Daisen intermediate lavas are most likely generated by partial melting of the subducted Philippine Sea plate mixed with Nankai Trough sediment, while the basalts are generated by partial melting of hybrid mantle composed primarily of subarc mantle that has been metasomatized by sediment‐derived melts, mixed with an ancient enriched mantle (EM1) component. Sediment relamination at the base of the arc crust could contribute to the strong sedimentary influence in the trace element and isotopic characteristics of the intermediate magmas.
- doi: 10.1002/ggge.20176
- modified at 17 h ago
@article{20150910133315-072654,
author = "Feineman, M and Moriguti, Takuya and Yokoyama, Tetsuya and Terui, S. and Nakamura, E.",
title = "Sediment-enriched adakitic magmas from the Daisen volcanic field, Southwest Japan",
journal = "Geochemistry, Geophysics, Geosystems",
year = "2013",
number = "8",
volume = "14",
pages = "3009-3031",
note = "Feineman, Maureen and Moriguti, Takuya and Yokoyama, Tetsuya and Terui, Sakiko and Nakamura, Eizo",
doi = "10.1002/ggge.20176",
}| caption | ID | assembly | stone | ||
|---|---|---|---|---|---|
| Table 1: Major and trace element concentrations and isotopic ratios in selected Daisen Lavas pub | 20180914092450-141269 | major-trace-isotope (Feineman et al., 2013) | 26 | ||