Paleoenvironmental changes in the western Mediterranean since the last glacial maximum: High resolution multiproxy record from the Algero-Balearic basin

The present study uses a multiproxy approach in order to further understand the evolution of climate responses in the western Mediterranean as of the Last Glacial Maximum. Sediments from ODP Site 975 in the Algero-Balearic basin have been analysed at high resolution, both geochemically andmineralogicallly. The resulting data have been used as proxies to establish a sedimentary regime, primary marine productivity, the preservation of the proxies and oxygen conditions. Fluctuations in detrital element concentrations were mainly the consequence of wet/arid oscillations. Productivity has been established using Ba excess, according to which marine productivity appears to have been greatest during cold events Heinrich 1 and Younger Dryas. The S1 time interval was not as marked by increases in productivity as was the eastern Mediterranean. In contrast, the S1 interval was first characterized by a decreasing trend and then by a fall in productivity after the 8.2 ky BP dry-cold event. Since then productivity has remained low. Here we report that there was an important redox event in this basin, probably a consequence of the major oceanographic circulation change occurring in the western Mediterranean at 7.7 ky BP. This circulation change led to reventilation as well as to diagenetic remobilization of redox-sensitive elements and organic matter oxidation. Comparisons between our paleoceanographic reconstruction for this basin and those regarding other Mediterranean basins support the hypothesis that across the Mediterranean there were different types of responses to climate forcing mechanism. The Algero-Balearic basin is likely to be a key area for further understanding of the relationships between the North Atlantic and the eastern Mediterranean basins.

(Table 1) Porewater analysis with respect to gypsum from different ODP holes

The stability of gypsum in marine sediments has been investigated through the calculation of its saturation index at the sediment in situ temperature and pressure, using the entire ODP/IODP porewater composition database (14416 samples recovered from sediments collected during 95 ODP and IODP Legs). Saturation is reached in sediment porewaters of 26 boreholes drilled at 23 different sites, during 12 ODP/IODP Legs. As ocean bottom seawater is largely undersaturated with respect to gypsum, the porewater Ca content or its SO4 concentration, or both, must increase in order to reach equilibrium. At several sites equilibrium is reached either through the presence of evaporitic gypsum layers found in the sedimentary sequence, and/or through a salinity increase due to the presence of evaporitic brines with high concentrations of Ca and SO4. Saturation can also be reached in porewaters of seawater-like salinity (~ 35 per mil), provided sulfate reduction is limited. In this case, saturation is due to the alteration of volcanogenic material which releases large amounts of Ca to the porewaters, where the Ca concentration can reach 55 times its seawater value as for example at ODP Leg 134 site 833. At a few sites, saturation is reached in hydrothermal environments, or as a consequence of the alteration of the basaltic basement. In addition to the well known influence of brines on the formation of gypsum, these results indicate that the alteration of sediments rich in volcanogenic material is a major process leading to gypsum saturation in marine sediment porewaters. Therefore, the presence of gypsum in ancient and recent marine sediments should not be systematically interpreted as due to hypersaline waters, especially if volcanogenic material is present.

Skhem-chertezh kolfonda "Zem - Trud" uchastok N 161

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Vykopirovka s plana uchastka kolonizat︠s︡ionnogo fonda N 975b Khersonskogo okruga Skadovskogo raĭona, pod nazvaniem "1 Kustovoe Obʻedenenie" prenaznachennogo Narkomzemom dli︠a︡ perselenii︠a︡ evreev

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Sapientia, 1986, Vol. XLI, nº 161 (número completo)

Contenido: La causa III : los principios de causalidad eficiente y final / Octavio N. Derisi -- El conocimiento trascendental de Dios y la metafísica de la naturaleza / Edgardo Castro -- Aportes para una caracterización del silogismo práctico / Federico Mihura Seeber -- El dinamismo ético-social y la educación del hombre según Aristóteles / Silvana Filippi -- Pintura y significación / Raúl Echauri -- Notas y comentarios -- Bibliografía

Diário da Constituinte [gravação de vídeo] : [programa n. 161]

O Artigo 12º do projeto da Comissão de Sistematização, que trata dos direitos do homem e da mulher, é um dos que tem recebido grande número de emendas. O Deputado Bernardo Cabral (PMDB-AM) comenta sobre as emendas. Informações sobre requisitos para validar as emendas populares. O Senador Fernando Henrique Cardoso (PMDB-SP) informa que nunca no Brasil houve uma Constituição com tanta participação popular. O Deputado Aldo Arantes (PC do B-GO) afirma que a mobilização popular e a pressão democrática são necessárias para que possamos ter uma Constituição avançada, pois os grupos conservadores exercem muita pressão na Assembleia Nacional Constituinte (ANC). Orestes Quércia, Governador de São Paulo, diz que é preciso que todos, de alguma forma, participem do processo de elaboração da Constituição. Engenheiros debatem propostas com os constituintes. Mateus Schneider, Presidente do Clube de Engenharia, esclarece que a intenção é contribuir com informações técnicas aos constituintes, deixando de lado a questão ideológica. O Deputado Flávio Palmier (PMDB-RJ) comenta que o Clube traz ideias para dialogar com os constituintes, sem se colocar como lobista. Propostas do Clube: definição de empresa nacional, proibição dos contratos de risco, reserva de mercado para informática, defesa dos recursos minerais do país. A Deputada Raquel Cândido (PFL- RO) considera que a proposta mais interessante dos engenheiros diz respeito à industrialização de matérias-primas no país. O Deputado Nelson Seixas (PMDB-SP) considera que o Brasil deve expandir as reservas de mercado.