It was assumed that the fractionation phases were plagioclase with An88, orthopyroxene with Mg#74, and clinopyroxene with Mg#74 (Supplementary Table S4). The plagioclase phenocrysts are generally homogeneous with respect to An content [100 × Ca/(Ca + Na)] except for the rims, although those with reverse zoning are rarely present. However, such a shallow magma chamber has not been observed by a geophysical study except for the small magma bodies located at 4–5 km depth for the andesitic magmas (Mikada et al., 1997). If this was the case, it is expected that plagioclase-rich magma would show a positive Eu anomaly.

Mihara, an active volcano that last erupted in 1986. Earth Sci., 30 October 2018 With these considerations, we concluded that the compositional diversity of the basalts was produced by the mixing of porphyritic magmas with compositionally variable aphyric magmas (Figure 10). Their results showed that the Izu-Tobu magmas were involved in the magma plumbing system at the Izu-Oshima volcano, in particular, before ∼5 ka. doi: 10.1016/j.lithos.2008.12.012, Kuritani, T., Kimura, J.-I., Ohtani, E., Miyamoto, H., and Furuyama, K. (2013). Therefore, to predict future eruptions, it is important to monitor the discharge of porphyritic magma from the magma chamber at 13–18 km depth. It is expected that aphyric magmas with similar compositions to (or slightly more differentiated compositions from) those of the end-member magmas for the 1950–51 eruptions were present in 1986 in the 8–10 km depth magma chamber. Mineral.

Geochem. MAGMA 93, 19–32.

“pl,” “opx,” and “cpx” indicate plagioclase, orthopyroxene, and clinopyroxene, respectively. Because PCA allows us to examine the factors contributing to the variance in the multidimensional data, an increasing number of studies have applied it to high-dimensional geochemical data of volcanic rocks, and successfully resolved the causes of geochemical variations resulting from the heterogeneity of primary magmas and/or magmatic differentiation (e.g., Bosch et al., 2008; Kuritani et al., 2016; Ueki and Iwamori, 2017).

Lett. The An contents of the cores commonly range from 80 to 93 (Figure 3), and those of the rims are 65–75. The plagioclase-melt thermometer of Waters and Lange (2015) with a melt water content of 5 wt.% (Hamada et al., 2011) yields the crystallization temperature of the plagioclase phenocrysts of 890–910°C at 4.4–6.1 kbar, which is much lower than the estimates of 1050–1100°C (Figure 9). Science 163, 926–927. Received: 25 July 2018; Accepted: 10 October 2018;Published: 30 October 2018. Those in the aphyric samples, such as those of the Y1L and 1986–87b, are usually smaller than 0.5 mm in length. The trace element concentrations of primitive mantle are from Sun and McDonough (1989). Trace element concentrations and Sr and Nd isotopic ratios were determined for about 30 representative samples. Geochemical differentiation processes for arc magma of the Sengan volcanic cluster, Northeastern Japan, constrained from principal component analysis. doi: 10.1093/petrology/egg072, Bosch, D., Blichert-Toft, J., Moynier, F., Nelson, B. K., Telouk, P., Gillot, P.-Y., et al. In this process, magmas in the main part of a magma chamber evolve through mixing of the fractionated interstitial melt extracted from the mush zones along the walls of the magma chamber. Jpn. (2008).

Miyazaki, T., and Shuto, K. (1998). This observation suggests that the plagioclase phenocrysts were not in equilibrium with the phenocryst-free Group B2 magmas.

(1969). FIGURE 5.

308, 259–266. To investigate the temporal evolution of the magma plumbing system for the Younger Oshima Group at the Izu-Oshima volcano, we conducted a petrological and geochemical analysis on the representative basaltic products.
The Izu-Oshima volcano, located on the volcanic front of the Izu arc (Figure 1), is one of the most active volcanoes in Japan, and younger volcanism (<∼1.5 ka) has produced mainly basaltic magmas with minor basaltic andesitic magmas. The high absolute value for Na2O (but opposite sign to those for MgO and Fe2O3∗) can also be explained by the fact that Na is an incompatible element during the crystallization of mafic minerals. In den USA offenbarte Google Maps das Missgeschick eines Paketboten.
doi: 10.1016/j.epsl.2015.08.004. Earth Planet. However, no significant eruption occurred between 1951 and 1986. 29, 91–95. Dort hat ein Google Maps-User eine kuriose Entdeckung gemacht. Mihara, and their products were ejected mainly inside the crater. The crystallization pressures and temperatures of the pyroxene phenocrysts were estimated by applying the two-pyroxene geothermobarometer of Putirka (2008) to clinopyroxene (cpx)–orthopyroxene (opx) pairs in Y1Ca, Y1Cb, 1950–51, and 1986–87a.