David García Pérez y Carolina Olivares Chávez (Eds). La persistencia de los clásicos. Supplementum IV, Noua Tellus, Anuario del Centro de Estudios Clásicos. Universidad Nacional Autónoma de México, Instituto de Investigaciones Filológicas, México, 2012, 126 pp.

Fil: Zamperetti Martín, Deidamia Sofía. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Susana Zanetti y otros, Las cenizas de la huella. Linajes y figuras de artista en torno al modernismo. Rosario, Beatriz Viterbo Editora, 1997, 126 págs.

Fil: Basile, María Teresa Gabriela. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Susana Zanetti y otros, Las cenizas de la huella. Linajes y figuras de artista en torno al modernismo. Rosario, Beatriz Viterbo Editora, 1997, 126 págs.

Fil: Basile, Teresa. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

David García Pérez y Carolina Olivares Chávez (Eds). La persistencia de los clásicos. Supplementum IV, Noua Tellus, Anuario del Centro de Estudios Clásicos. Universidad Nacional Autónoma de México, Instituto de Investigaciones Filológicas, México, 2012, 126 pp.

Fil: Zamperetti Martín, Deidamia Sofía. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Age and petrographic characterization of volcanic ash from ODP Leg 198 and Leg 126 sites

In this study of volcanic ash retrieved from Shatsky Rise during Ocean Drilling Program Leg 198, the texture and composition of the volcanic components (glass and crystals) were used to fingerprint ash layers for detailed correlation. Correlations among ash layers in holes drilled at the same site as well as between sites, including sites on different parts (highs) of the rise, were tested. Although high-to-high correlations failed, intrahigh correlations were more successful. Our data suggest a significantly different source for some pyroclastic debris, especially at Site 1208, possibly associated with pumice rafts carried northward from the Izu-Bonin arc by the Kuroshio Current. Other ashes are consistent with rhyolitic to dacitic air fall ash from Asian arc volcanoes. We were not able to texturally distinguish between air fall ash and pumice-raft fallout but suspect that the latter is associated with higher percentages of vesiculated ash components, as we demonstrate occur in more proximal Izu-Bonin pyroclastic deposits.

Geochemistry and structural formulas of heavy minerals from sands and sandstones of ODP Leg 126 samples

Lower Oligocene to Pleistocene volcaniclastic sands and sandstones recovered around the Izu-Bonin Arc during Ocean Drilling Program Leg 126 were derived entirely from Izu-Bonin Arc volcanism. Individual grains consist of volcanic glass, pumice, scoria, basaltic or andesitic fragments, plagioclase, pyroxene, and minor olivine and hornblende. In Pliocene-Pleistocene samples plagioclase and heavy minerals in the volcaniclastic sands and sandstones are present in the following abundances: plagioclase > orthopyroxene > clinopyroxene > pigeonite > olivine. In contrast, plagioclase and heavy minerals found in Oligocene-Miocene samples occur in the following order: plagioclase > clinopyroxene > orthopyroxene > hornblende. The low concentration of Al, Ti, and Cr in calcium-rich clinopyroxenes in Oligocene to Holocene sediments suggests that the sources of the volcaniclastic detritus were nonalkalic igneous rocks. There are, however, some distinctive differences in the chemical composition of pyroxene between the Pliocene-Pleistocene and Oligocene-Miocene volcaniclastic sands and sandstones. Orthopyroxene belongs to the hypersthene-ferrohypersthene series (Fe-rich) in Pliocene-Pleistocene sediments, and the bronzitehypersthene series (Mg-rich) in Oligocene-Miocene sediments. Clinopyroxene is characterized by augite and pigeonite in Pliocene-Pleistocene sediments, and by the diopside-augite series in Oligocene-Miocene sediments. Mineral assemblages and mineral chemistry of the volcaniclastic sands and sandstones reflect those of the volcanic source rocks. Therefore, the observed changes in mineralogy record the historical change in volcanism of the Izu-Bonin Arc. The mineralogy is consistent with the geochemistry of the volcaniclastic sands and sandstones and the geochemistry of forearc volcanic rocks of the Izu-Bonin Arc since the Oligocene.