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REE Mineralogy and Resources Chapter 279 183 of the magma; an oxidized mafic source for the magnetite-series, and assimila- tion of organic carbon in the accreted sedimentary rocks in the lower to middle crust (Ishihara and Matsuhisa, 1999) or through subduction processes (Takagi, 2004) for the ilmenite-series. On the other hand, Chappell and White (1974) described two types of granitic suites for the Phaleozoic Lachaln Fold Belt of eastern Australia as follows: I-type granitic rocks derived from source of igne- ous rocks and containing moderate amount of Al2O3 and high amount of Na2O. Sedimentary-type (S-type) results from the partial melting of metasedi- mentary source rocks and having high Al2O3 but low Na2O. A serious debate had arisen over the notion that Paleozoic granitic rocks of I- and S-types (Chappell and White, 1974) correspond approximately to Mesozoic–Cenozoic granitic rocks of the magnetite-series and the ilmenite-series, respectively (Whalen and Chappell, 1988), although Ishihara (1981) pointed out that the ilmenite-series granitic rocks from Japan are composed of both I-type and S-type granitic rocks. The different chemical compositions between the magnetite- and ilmenite- series magmas may cause a slight difference in chemical composition of accessory minerals such as allanite, zircon, and monazite. Hoshino et al. (2006) reported that allanites from granitic rocks in the Japanese island arc are divided into Mn-poor (2wt.%>MnO, 0.14 apfu>Mn) and Mn-rich (2 wt.% < MnO, 0.14 apfu < Mn) types, and the latter occur in Japanese gra- nitic rocks (Fig. 25). In only this section, we use middle rare earth elements (MREEs: Sm-Dy) for convenience. Mn-poor allanites characteristically occur in magnetite-series granitic rocks and are relatively rich in LREE (La-Nd), whereas Mn-rich allanites occurs in ilmenite-series granitic rocks and exhibit enrichment in MREEs (Fig. 26). The relationship between Mn-rich and Mn-poor allanite-(Ce) is expressed by the coupled substitution Mn2++(MREE, HREE)3+ $ Ca2+ + LREE3+ (Hoshino et al., 2006). The Mn-rich allanites charac- teristically occur in Mesozoic ilmenite-series granitic rocks in the Japanese arc and are not observed in granitic rocks in continental margins and intracontinental setting (Hoshino et al., 2006, 2007). This characteristic occurrence of Mn-rich allanite in Mesozoic ilmenite-series granitic rocks is related to sediment compo- sition incorporated during the formation of ilmenite-series granitic magma (Hoshino et al., 2006, 2007). Zircon from granitic rocks in subduction-related magmatic arcs, eg, Japan, are classified into two types: HREE-U-Th-poor and a HREE-U-Th-rich type (Hoshino et al., 2010). The occurrence of two types of zircon is not related to the difference of ilmenite- and magnetite-series, but the HREE-U-Th-rich zircons characteristically occur in granitic pegmatite. On the Y-Hf diagrams (Fig. 27), zircons in the Paleozoic–Mesozoic granitic rocks from the Japanese arc are compared with zircons in various Precambrian–Mesozoic intracon- tinental setting. HfO2 content in zircon from many granitic pegmatites in the intracontinental settings of the Precambrian–Mesozoic era (eg, Cˇerny ́ and Siivola, 1980; Kempe et al., 2004; Lumpkin and Chakoumakos, 1988;PDF Image | HANDBOOK ON THE PHYSICS AND CHEMISTRY OF RARE EARTHS
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