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Well-crystallized epitaxial YbFe 2 O 4 films were prepared on an α-Al 2 O 3 (001) substrate using an Fe 3 O 4 buffer layer. Fe 3 O 4 has a relatively small lattice mismatch with both YbFe 2 O 4 and α-Al 2 O 3 . Electron diffraction analysis combined with transmission electron microscopy revealed the epitaxial relationship to be α-Al 2 O 3 [110](001) k Fe 3 O 4 [ 211](111) k YbFe 2 O 4 [110](001). Moreover, superlattice spots due the Fe 2+ -Fe 3+ charge order state of YbFe 2 O 4 were clarified. The Fe 2+ /Fe 3+ ratio in YbFe 2 O 4 was nearly stoichiometric. The film exhibited a ferrimagnetic transition at >220 K and a nonlinear current-voltage characteristic at room temperature. These results confirmed the good crystallinity and stoichiometry of the obtained YbFe 2 O 4 films.

In order to clarify the tectono-sedimentary history of Paleozoic Baltica, age spectra of detrital zircon grains from the Ediacaran (Kotlin Regional Stage) and Lower Cambrian sandstones (lowermost Lontova and Lükati formations) in western Estonia in central Baltica were analyzed by LA-ICPMS. The abundant occurrence of Archean to Mesoproterozoic (2800-1000 Ma) zircon grains was confirmed in all samples. The new data provided the following information on the provenance of siliciclastic material as well as a major change in the sedimentary regime of the Paleo-Baltic basin during the Early Cambrian:(1) the Ediacaran-Lower Cambrian Paleo-Baltic basin received abundant terrigenous clastics from the core of Baltica underlain by the Archean-Mesoproterozoic crystalline crust, (2) the exposed surface area of the 1600 Ma Rapakivi granites apparently was more extensive during the Ediacaran-Early Cambrian than at present, (3) a major re-organization of the basin geometry occurred in the middle Early Cambrian (ca 530-515 Ma) in central Baltica, inducing a change in the sediment supply system, (4) in contrast to the total absence of Neoproterozoic detrital zircon grains before the middle Early Cambrian, their sudden appearance at this time, together with consistent occurrence at least until the mid-Devonian, suggests a significant uplift event located in southeast Baltica and/or in a more easterly land domain (e.g., in Sarmatia), (5) possible sources for the Neoproterozoic zircon grains include the peripheral mobile belts with pan-African signatures around Baltica, e.g., the so-called Gondwanan fragments along the Tornquist margin to the southwest and the Timanian belt along the northeastern margin.

To clarify the supply/deposition pattern of terrigenous clastics of Cretaceous Japan, U-Pb and Pb-Pb ages of detrital zircons are analyzed by laser-ablation induced coupled plasma mass spectroscopy （LA-ICPMS） of Lower Cretaceous sandstones in the Chichibu belt, SW Japan. Target rocks include Lower Cretaceous fore-arc sandstones in the Sanchu graben and the Choshi area of the southern Kanto district; e.g. Hauterivian Shiroi Formation, Barremian Ishido Fm, and Aptian-Albian Sanyama Fm in the Sanchu graben, and Barremian Ashikajima Fm, Early Aptian Inubozaki Fm, and Aptian-Albian Nagasakihana Fm in the Choshi area. All these fore-arc sandstones are dominated by Mesozoic （ca. 250-100 Ma） detrital zircons with minimal amount of （300-250 Ma） Permian grains, and Precambrian grains are extremely rare. The similar age spectra of these sandstones suggest a common provenance, despite the current along-arc separation of the Sanchu graben from the Choshi area for ca. 130 km. Hauterivian-Barremian sandstones from both areas are characterized by the abundance of Permian, Triassic, and Jurassic zircons, where as Aptian-Albian sandstone by monotonous dominance of Early Cretaceous grains. This stratigraphic change in zircon age spectra reflects a secular change in the exposure /erosion conditions of older granitoids in the provenance, in remarkable accordance with that of coeval sandstones from other areas; e.g., Ryoseki Formation in Shikoku （fore-arc basin） and Kanmon Group in northern Kyushu /western Honshu （intra-arc basin） . This stratigraphic change commonly detected in the Cretaceous fore-arc and intra-arc records the growth /erosion history of a new crust of the volcanic arc developed along the East Asian margin. The disappearance of older Permian, Triassic, and Jurassic zircons in sandstones during the Barremian-Aptian interval suggests large-scale tectonic erosion along the East Asian active margin. The abundance of

To reconstruct the detailed paleogeographic configuration of the Cretaceous arc-trench system in East Asia, shallow marine sandstones from the Ryoke, Sanbagawa, and Chichibu belts in western Shikoku are investigated with age spectra by U-Pb dating detrital zircons with LA-ICPMS. The mid-Cretaceous Shuki and Nigyu formations, unconformably covering the preCretaceous accretionary complex of the Chichibu belt, contain abundant detrital zircons from the Jurassic to Early Cretaceous ages, with small quantities of Permian and Triassic detrital zircons. These age spectra are almost identical to those previously obtained from other coeval formations elsewhere in the Chichibu belt （the Monobegawa Group） , which represent the Cretaceous forearc setting. The common age spectra suggest that the provenance of the Cretaceous fore-arc domain had ubiquitous compositions of rocks for nearly 1,000 km along the arc, and that Jurassic to Early Cretaceous granitoids were predominant, with associated small quantities of older pre-Jurassic granitoids. From the Ryoke belt, the Campanian （Late Cretaceous） Yamanouchi Formation of the Izumi Group, unconformably covering the mid-Cretaceous Ryoke granitoids, also has a similar age spectrum. This confirms that the provenance of the fore-arc remained more or less the same at least until the Late Cretaceous. The most intriguing age spectrum was obtained from the Maana Formation, which occurs as a klippe sitting on top of the southern Sanbagawa belt. As well as other dated sandstones, Maana sandstone contains Early Cretaceous to Jurassic zircons; nonetheless it accompanies not only Permo-Triassic zircons but also abundant Paleoproterozoic （2400-1600 Ma） grains. This unique age spectrum is correlative solely with those from the Tetori/Jinzu groups in the Hida belt, whose depositional setting has featured provenance with the Precambrian basement. This suggests that the Maana Fm was primarily deposited at the continent side of all the Paleozoic accretionary complexes and their highpressure metamorphosed equivalents of SW Japan; i.e., the back-arc side of the Cretaceous arctrench system in East Asia. As to the age spectrum of detrital zircons, in addition to lithofacies,

The overall configuration of the Cretaceous subduction-related arc-trench system in Japan is preserved in the current distribution of the relevant orogenic components; i.e., the coeval set of accretionary complexes formed at the trench （Sanbosan and North Shimanto belts） , high-P/T meta-ACs along the Wadati-Benioff zone （Sanbagawa and Shimanto metamorphic belts） , arc batholiths （Ryoke-Sanyo and San-in belts） , and fore-arc basin strata （Ryoseki-Monobegawa and Izumi groups） . To document the sediment distributary pattern within the Cretaceous arctrench system and the composition of relevant provenance, detrital zircon dating was conducted for the Upper Cretaceous sandstones （Atogura and Tochiya formations） from the northern Kanto Mountains. These strata occur immediately to the south of Median Tectonic Line of SW Japan, and as klippe with unknown origin. The results of U-Pb dating by LA-ICPMS show that three sandstones have common age spectra with four major age groups; i.e., 120-150 Ma （Early Cretaceous） , 170-200 Ma （Jurassic） , 250-300 Ma （Permian） , and 1600-2200 Ma （Paleoprotero-zoic） , with minor amounts of much older grains up to 2900 Ma （Archean） . These age spectra are unique, when compared to other coeval Cretaceous fore-arc and/or intra-arc sandstones in Japan. The Early Cretaceous grains were obviously derived from a proximal source to the depositional site, probably the Cretaceous volcanic arc of the Ryoke-Sanyo belt in SW Japan. The dominant grains of the Jurassic and Permian ages were probably derived from coeval plutonic belts in the provenance, whereas the Paleoproterozoic grains were probably derived from continental blocks in East Asia with crusts of corresponding ages, such as the North and South China blocks. Except for the Cretaceous arc source, Jurassic and Permian granitoids are extremely rare in