Expanded GHOST database

In this study we review a global set of alkenone- and foraminiferal Mg/Ca-derived sea surface temperatures (SST) records from the Holocene and compare them with a suite of published Eemian SST records based on the same approach. For the Holocene, the alkenone SST records belong to the actualized GHOST database (Kim, J.-H., Schneider R.R., 2004). The actualized GHOST database not only confirms the SST changes previously described but also documents the Holocene temperature evolution in new oceanic regions such as the Northwestern Atlantic, the eastern equatorial Pacific, and the Southern Ocean. A comparison of Holocene SST records stemming from the two commonly applied paleothermometry methods reveals contrasting - sometimes divergent - SST evolution, particularly at low latitudes where SST records are abundant enough to infer systematic discrepancies at a regional scale. Opposite SST trends at particular locations could be explained by out-of-phase trends in seasonal insolation during the Holocene. This hypothesis assumes that a strong contrast in the ecological responses of coccolithophores and planktonic foraminifera to winter and summer oceanographic conditions is the ultimate reason for seasonal differences in the origin of the temperature signal provided by these organisms. As a simple test for this hypothesis, Eemian SST records are considered because the Holocene and Eemian time periods experienced comparable changes in orbital configurations, but had a higher magnitude in insolation variance during the Eemian. For several regions, SST changes during both interglacials were of a similar sign, but with higher magnitudes during the Eemian as compared to the Holocene. This observation suggests that the ecological mechanism shaping SST trends during the Holocene was comparable during the penultimate interglacial period. Although this "ecology hypothesis" fails to explain all of the available results, we argue that any other mechanism would fail to satisfactorily explain the observed SST discrepancies among proxies.

Rock magentic investigations of ODP Site 162-983

We report natural remanent magnetization (NRM) directions and geomagnetic paleointensity proxies for part of the Matuyama Chron (0.9-2.2 Ma interval) from two sites located on sediment drifts in the Iceland Basin. At Ocean Drilling Program Sites 983 and 984, mean sedimentation rates in the late Matuyama Chron are 15.9 and 11.5 cm/kyr, respectively. For the older part of the record (>1.2 Ma), oxygen isotope data are too sparse to provide the sole basis for age model construction. The resemblance of the volume susceptibility record and a reference d18O record led us to match the two records to derive the age models. This match, based on Site 983/984 susceptibility, is consistent with available Site 983/984 benthic d18O data. Paleointensity proxies were derived from the slope of the NRM versus anhysteretic remanent magnetization plot for alternating field demagnetization in the 30-60 mT peak field range. Paleointensity lows correspond to polarity reversals at the limits of the Jaramillo, Olduvai, Cobb Mountain, and Réunion Subchrons and to seven excursions in NRM component directions. Magnetic excursions (defined here by virtual geomagnetic polar latitudes crossing the virtual geomagnetic equator) are observed at 932, 1048, 1115, 1190-1215 (Cobb Mountain Subchron), 1255, 1472-1480, 1567-1575 (Gilsa Subchron), and 1977 ka. The results indicate that geomagnetic directional excursions, associated with paleointensity minima, are a characteristic of the Matuyama Chron and probably of polarity chrons in general.

Uranium contents and isotope ratios of uranium and strontium in sediments, leachates and pore fluids from ODP Hole 162-984A

Bulk dissolution rates for sediment from ODP Site 984A in the North Atlantic are determined using the 234U/238U activity ratios of pore water, bulk sediment, and leachates. Site 984A is one of only several sites where closely spaced pore water samples were obtained from the upper 60 meters of the core; the sedimentation rate is high (11-15 cm/ka), hence the sediments in the upper 60 meters are less than 500 ka old. The sediment is clayey silt and composed mostly of detritus derived from Iceland with a significant component of biogenic carbonate (up to 30%). The pore water 234U/238U activity ratios are higher than seawater values, in the range of 1.2 to 1.6, while the bulk sediment 234U/238U activity ratios are close to 1.0. The 234U/238U of the pore water reflects a balance between the mineral dissolution rate and the supply rate of excess 234U to the pore fluid by a-recoil injection of 234Th. The fraction of 238U decays that result in a-recoil injection of 234U to pore fluid is estimated to be 0.10 to 0.20 based on the 234U/238U of insoluble residue fractions. The calculated bulk dissolution rates, in units of g/g/yr are in the range of 0.0000004 to 0.000002 1/yr. There is significant down-hole variability in pore water 234U/238U activity ratios (and hence dissolution rates) on a scale of ca. 10 m. The inferred bulk dissolution rate constants are 100 to 1000 times slower than laboratory-determined rates, 100 times faster than rates inferred for older sediments based on Sr isotopes, and similar to weathering rates determined for terrestrial soils of similar age. The results of this study suggest that U isotopes can be used to measure in situ dissolution rates in fine-grained clastic materials. The rate estimates for sediments from ODP Site 984 confirm the strong dependence of reactivity on the age of the solid material: the bulk dissolution rate (R_d) of soils and deep-sea sediments can be approximately described by the expression R_d ~ 0.1 1/age for ages spanning 1000 to 500,000,000 yr. The age of the material, which encompasses the grain size, surface area, and other chemical factors that contribute to the rate of dissolution, appears to be a much stronger determinant of dissolution rate than any single physical or chemical property of the system.

Polarity chron boundaries and interval sedimentation rates of ODP Leg 162 sites

Magnetic polarity stratigraphies for Sites 980-984 are based on shipboard measurements from the pass-through magnetometer after alternating field (AF) demagnetization at a peak field of 25 mT and shore-based stepwise AF demagnetization of discrete samples. The characteristic magnetization component was determined after AF demagnetization removed the steep downward drill-string-related magnetic overprint. Peak AF fields in the 20-30 mT range were required to resolve the component, carried by magnetite, that was used to produce unambiguous Pliocene-Pleistocene magnetic stratigraphies at all five sites. At Sites 980 and 983, magnetic stratigraphies were resolved to the base of the recovered advanced hydraulic piston corer (APC) section, which lies in the Matuyama Chron (1r.2r) and Olduvai Subchron (2n), respectively. At Sites 981 and 982, magnetization intensities decrease sharply in the normal polarity zone corresponding to the Gauss Chron (2An), and magnetic stratigraphies below this level could not be resolved. At Site 984, the resolution of magnetic stratigraphy was curtailed at ~250 meters below seafloor (Olduvai Subchron) by core deformation at the base of the APC section and in the underlying extended core barrel section. As the magnetic stratigraphies at all four sites are unequivocal, polarity chron interpretations can be made without aid from the biostratigraphy. Mean sedimentation rates within polarity chrons have been calculated and Pliocene-Pleistocene biomagnetostratigraphic correlations tested.

Sapientia, 1986, Vol. XLI, nº 162 (número completo)

Contenido: La causa IV : necesidad de la primera causa o acto de Dios / Octavio N. Derisi -- La cuestión del "paso" indebido de las proposiciones especulativas a las prácticas y la respuesta de Tomás de Aquino / Carlos I. Massini -- Significado del pensamiento de Michele Federico Sciacca para el hombre de hoy / Alberto Caturelli -- La sociedad nacional y la sociedad internacional para el análisis de la doctrina social de la Iglesia / Pedro E. Baquero Lazcano -- Notas y comentarios -- Bibliografía

Diário da Constituinte [gravação de vídeo] : [programa n. 162]

Foi testada a porta de detector de metais posicionada na entrada das galerias do Plenário. É um equipamento de segurança com cem por cento de tecnologia nacional. O Deputado Jorge Arbage (PDS-PA) informa que a porta estava dentro do programa estabelecido para as normas de segurança da Assembleia Nacional Constituinte (ANC). O Deputado Mauro Miranda (PMDB-GO) defende emendas em favor da autonomia dos municípios. O Deputado Amaury Muller (PDT-RS) declara que o Poder Executivo não tem respondido os requerimentos de informações do Poder Legislativo e considera isso um desrespeito à soberania da Constituinte. Na sessão O Povo Pergunta, cidadã quer saber o que muda no direito de expressão. O Deputado Ruy Nedel (PMDB-RS) responde que o "direito de dizer" já mudou com a queda da ditadura e cita as figuras da Inconstitucionalidade por Omissão e do Defensor do Povo como formas de mudar o direito de fazer a Constituição ser cumprida. Jair Meneguelli, Presidente da Central Única dos Trabalhadores (CUT), conclama a população a assinar as emendas populares.

Diário da Constituinte [gravação de vídeo] : [programa n. 162 A]

Opinião de cidadãos sobre a proposta de aprovar a nova Constituição através de plebiscito. Dois projetos de resolução, apresentados pelos Deputados Brandão Monteiro (PDT-RJ) e Virgílio Guimarães (PT-MG). estabelecem que, após 90 dias da promulgação da nova Carta, ela seja aprovada por um plebiscito. O Deputado Virgílio Guimarães (PT-MG) considera que a palavra final cabe ao eleitor. O Deputado Alceni Guerra (PFL-PR) quer plebiscitos parciais, por temas. Em debate promovido pelo 1º Secretário da Assembleia Nacional Constituinte Marcelo Cordeiro, líderes partidários fazem um balanço do projeto de Constituição. O Deputado Brandão Monteiro (PDT-RJ) rejeita a ideia de chamar de "monstrengo" a nova Constituição, mas diz que ela precisa de ajustes. O Deputado Luiz Henrique (PMDB-SC) declara ser fundamental o entendimento dos partidos nas questões polêmicas, para que se faça uma Constituição moderna. José Carlos Coutinho (PL-RJ) critica o aproveitamento, no projeto, do texto do substitutivo recusado na Comissão de Educação da Assembleia Nacional Constituinte (ANC). O Senador Carlos Chiarelli (PFL-RS) declara que a negociação é urgente e indispensável. O Deputado Bonifácio de Andrada (PDS-MG) considera que as negociações permitirão o consenso na votação no Plenário. A Deputada Irma Passoni (PT-SP) declara que cada partido deve afirmar seus princípios, mas também trabalhar para uma negociação possível no sentido de alcançar as necessidades atuais da nação brasileira. Cidadãos assinam as emendas populares nos pontos mais movimentados das cidades. As principais emendas populares que estão circulando pelo país tratam dos seguintes temas: direito dos trabalhadores; direitos da mulher; conselho de comunicação; educação.