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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