Geochemical analysis at ODP Site 207-1259 from the Demerara Rise in the western equatorial Atlantic

Organic carbon-rich shales deposited during the Coniacian-Santonian Oceanic Anoxic Event 3 were drilled during ODP Leg 207 at Demerara Rise. We present integrated high-resolution geochemical records of core intervals from ODP Sites 1259 and 1261 both from nannofossil biozone CC14. Our results reveal systematic variations in marine and detrital sediment contribution, depositional processes, and bottom water redox conditions during black shale formation at two locations on Demerara Rise in different paleo-water depths. A combination of redox proxies (Fe/S, P/Al, C/P, redox-sensitive/sulfide-forming trace metals Mn, Cd, Mo, Ni, V, Zn) and other analytical approaches (bulk sediment composition, P speciation, electron microscopy, X-ray diffraction) evidence anoxic to sulfidic bottom water and sediment conditions throughout the deposition of black shale. These extreme redox conditions persisted and were periodically punctuated by short-termed periods with less reducing bottom waters irrespective of paleo-water depth. Sediment supply at both sites was generally dominated by marine material (carbonate, organic matter, opal) although relationships of detrital proxies as well as glauconitic horizons support some influence of turbidites, winnowing bottom currents and/or variable detritus sources, along with less reducing bottom water at the proposed shallower location (ODP Site 1259). At Site 1261, located at greater paleo-depth, redox fluctuations were more regular, and steady hemipelagic sedimentation sustained the development of mostly undisturbed lamination in the sedimentary record. Strong similarities of the studied deposits exist with the stratigraphic older Cenomanian-Turonian OAE2 black shale sections at Demerara Rise, suggesting that the primary mechanisms controlling continental supply and ocean redox state were time-invariant and kept the western equatorial Atlantic margin widely anoxic over millions of years.

Major, trace and rare earth element concentrations of sediments from ODP Leg 207 sites

The Cretaceous and Paleogene sediments recovered during Ocean Drilling Program Leg 207 can be divided into three broad modes of deposition: synrift clastics (lithologic Unit V), organic matter-rich, laminated black shales (Unit IV), and open-marine chalk and calcareous claystones (Units III-I). The aim of this study is to provide a quantitative geochemical characterization of sediments representing these five lithologic units. For this work we used the residues (squeeze cakes) obtained from pore water sampling. Samples were analyzed for bulk parameters (total inorganic carbon, total organic carbon, and S) and by X-ray fluorescence for major (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, and P) and selected minor (As, Ba, Co, Cr, Cu, Mo, Ni, Pb, Rb, Sr, U, V, Y, Zn, and Zr) elements. Inductively coupled plasma-mass spectrometry analyses for rare earth elements (REEs) were performed on acid digestions of the squeeze cake samples from Site 1258. The major element composition is governed by the mixture of a terrigenous detrital component of roughly average shale (AS) composition with biogenous carbonate and silica. The composition of the terrigenous detritus is close to AS in Units II-IV. For Unit I, a more weathered terrigenous source is suggested. Carbonate contents reach >60 wt% on average in chalks and calcareous claystones of Units II-IV. The SiO2 contribution in excess of the normal terrigenous-detrital background indicates the presence of biogenous silica, with highest amounts in Units II and III. The contents of coarse-grained material (quartz) are enhanced in Unit V, where Ti and Zr contents are also high. This indicates a high-energy depositional environment. REE patterns are generally similar to AS. A more pronounced negative Ce anomaly in Unit IV may indicate low-oxygen conditions in the water column. The Cretaceous black shales of Unit IV are clearly enriched in redox-sensitive and stable sulfide-forming elements (Mo, V, Zn, and As). High phosphate contents point toward enhanced nutrient supply and high bioproductivity. Ba/Al ratios are rather high throughout Unit IV despite the absence of sulfate in the pore water, indicating elevated primary production. Manganese contents are extremely low for most of the interval studied. Such an Mn depletion is only possible in an environment where Mn was mobilized and transported into an expanded oxygen minimum zone ("open system"). The sulfur contents show a complete sulfidation of the reactive iron of Unit IV and a significant excess of sulfur relative to that of iron, which indicates that part of the sulfur was incorporated into organic matter. We suppose extreme paleoenvironmental conditions during black shale deposition: high bioproductivity like in recent coastal upwelling settings together with severe oxygen depletion if not presence of hydrogen sulfide in the water column.

Oxygen isotopic composition of interstitial waters from ODP Leg 207 sites

We determined oxygen isotopic compositions of interstitial water (IW) recovered during Ocean Drilling Program Leg 207. Five sites were cored (3200- to 1900-m water depth) on Demerara Rise off Suriname, South America, recovering a Cenomanian-Paleogene sedimentary sequence consisting of black shales and chalks. A total of 115 IW oxygen isotopic analyses are presented.

Size-related stable isotope changes in Late Cretaceous and Recent planktic foraminifera from the western tropical Atlantic

The paleoecology of Cretaceous planktic foraminifera during the Late Cenomanian to Coniacian period (~95-86 Ma) remains controversial since much of the tropical marine record is preserved as chalk and limestone with uncertain geochemical overprints. Here we present delta13C and delta18O data from sieve size fractions of monospecific samples of exceptionally well preserved planktic foraminifera recovered during Ocean Drilling Program Leg 207 (Demerara Rise, western tropical Atlantic). Our results suggest that all species studied (Hedbergella delrioensis, Heterohelix globulosa, Marginotruncana sinuosa, Whiteinella baltica) grew primarily in surface waters and did not change their depth habitat substantially during their life cycle. Comparison of size-related ontogenetic trends in delta13C in Cretaceous and modern foraminifera further suggests that detection of dinoflagellate photosymbiosis using delta13C is confounded by physiological effects during the early stages of foraminifer growth, raising doubts about previous interpretations of photosymbiosis in small foraminifera species. We propose that obligate photosymbiosis involving dinoflagellates may not have evolved until the Campanian or Maastrichtian since our survey of Cenomanian-Coniacian species does not find the delta18O and delta13C size-related trends observed in modern foraminifer-dinoflagellate symbioses.

Geochemistry of Albian to Santonian black shale sequences on the Demerara Rise, South American margin

Ocean Drilling Program Leg 207 recovered thick sequences of Albian to Santonian organic-carbon-rich claystones at five drill-sites on the Demerara Rise in the western equatorial Atlantic Ocean. Dark-colored, finely laminated, Cenomanian-Santonian black shale sequences contain between 2% and 15% organic carbon and encompass Oceanic Anoxic Events 2 and 3. High Rock-Eval hydrogen indices signify that the bulk of the organic matter in these sequences is marine in origin. However, d13Corg values lie mostly between -30 per mil and -27 per mil, and TOC/TN ratios range from 15 to 42, which both mimic the source signatures of modern C3 land plants. The contradictions in organic matter source indicators provide important implications about the depositional conditions leading to the black shale accumulations. The low d13Corg values, which are actually common in mid-Cretaceous marine organic matter, are consequences of the greenhouse climate prevailing at that time and an associated accelerated hydrologic cycle. The elevated C/N ratios, which are also typical of black shales, indicate depressed organic matter degradation associated with low-oxygen conditions in the water column that favored preservation of carbon-rich forms of marine organic matter over nitrogen-rich components. Underlying the laminated Cenomanian-Santonian sequences are homogeneous, dark-colored, lower to middle Albian siltstones that contain between 0.2% and 9% organic carbon. The organic matter in these rocks is mostly marine in origin, but it occasionally includes large proportions of land-derived material.

Stable oxygen and carbon isotope ratios of foraminifera and test results after different sample cleaning procedures from ODP Leg 207 sediments

We report oxygen and carbon stable isotope analyses of foraminifers, primarily planktonic, sampled at low resolution in the Cretaceous and Paleogene sections from Sites 1257, 1258, and 1260. Data from two samples from Site 1259 are also reported. The very low resolution of the data only allows us to detect climate-driven isotopic events on the timescale of more than 500 k.y. A several million-year-long interval of overall increase in planktonic 18O is seen in the Cenomanian at Site 1260. Before and after this interval, foraminifers from Cenomanian and Turonian black shales have d18O values in the range -4.2 per mil to -5.0 per mil, suggestive of upper ocean temperatures higher than modern tropical values. The d18O values of upper ocean dwelling Paleogene planktonics exhibit a long-term increase from the early Eocene to the middle Eocene. During shipboard and postcruise processing, it proved difficult to extract well-preserved foraminifer tests from black shales by conventional techniques. Here, we report results of a test of procedures for cleaning foraminifers in Cretaceous organic-rich mudstone sediments using various combinations of soaking in bleach, Calgon/hydrogen peroxide, or Cascade, accompanied by drying, repeat soaking, or sonication. A procedure that used 100% bleach, no detergent, and no sonication yielded the largest number of clean, whole individual foraminifers with the shortest preparation time. We found no significant difference in d18O or d13C values among sets of multiple samples of the planktonic foraminifer Whiteinella baltica extracted following each cleaning procedure.

Bysanttilaisten ja Akhaian ruhtinaskunnan väliset sotatoimet vuosina 1259-83 : Tapaustutkimus myöhäis-bysanttilaisesta sodankäynnistä

In my master thesis I analyse Byzantine warfare in the late period of the empire. I use military operations between Byzantines and crusader Principality of Achaia (1259–83) as a case study. Byzantine strategy was based (in “oriental manner”) on using ambushes, diplomacy, surprise attacks, deception etc. Open field battles that were risky in comparison with their benefits were usually avoided, but the Byzantines were sometimes forced to seek open encounter because their limited ability to keep strong armies in field for long periods of time. Foreign mercenaries had important place in Byzantine armies and they could simply change sides if their paymasters ran out of resources. The use of mercenaries with short contracts made it possible that the composition of an army was flexible but on the other hand heterogeneous – in result Byzantine armies were sometimes ineffective and prone to confusion. In open field battles Byzantines used formation that was made out from several lines placed one after another. This formation was especially suitable for cavalry battles. Byzantines might have also used other kinds of formations. The Byzantines were not considered equal to Latins in close combat. West-Europeans saw mainly horse archers and Latin mercenaries on Byzantine service as threats to themselves in battle. The legitimacy of rulers surrounding the Aegean sea was weak and in many cases political intrigues and personal relationships can have resolved the battles. Especially in sieges the loyalty of population was decisive. In sieges the Byzantines used plenty of siege machines and archers. This made fast conquests possible, but it was expensive. The Byzantines protected their frontiers by building castles. Military operations against the Principality of Achaia were mostly small scale raids following an intensive beginning. Byzantine raids were mostly made by privateers and mountaineers. This does not fit to the traditional picture that warfare belonged to the imperial professional army. It’s unlikely that military operations in war against the Principality of Achaia caused great demographic or economic catastrophe and some regions in the warzone might even have flourished. On the other hand people started to concentrate into villages which (with growing risks for trade) probably caused disturbance in economic development and in result birth rates might have decreased. Both sides of war sought to exchange their prisoners of war. These were treated according to conventional manners that were accepted by both sides. It was possible to sell prisoners, especially women and children, to slavery, but the scale of this trade does not seem to be great in military operations treated in this theses.

Sapientia, 2000, Vol. LV, nº 207 (número completo)

Contenido: Il Dio dei filosofi e il Dio dei teologi in Guglielmo di Ockham / Alessandro Ghisalberti – La Trinidad divina y la deificación del hombre por el nacimiento del hijo en el alma, según los escritos del maestro Eckhart / Brian J. Farrelly – Suárez y Descartes sobre la noción de verdades eternas y su relación con Dios / Bernardo Cantens – Interacción mente-cuerpo y libre arbitrio en Descarles / Enrique Chávez-Arvizo – Razón y verdad : Hobbes y el Aquinate / María L. Lukac de Stier – Pascal y la crisis de la razón / Francisco Leocata – La contribución de Jacques Maritain a la teología natural / Juan J. Álvarez – Ontología de lo social / Abelardo Pithod – Réflexions sur une introduction à la métaphysique / Yves Floucat – El conocimiento divino del ente futuro contingente / Gabriel Delgado – Insegnamento sociale cristiano : magistero e scienze umane / Enrique Colom – Aquinas on Aristotle and creation : use or misuse? / Timothy L. Smith – La verdad, raíz de la libertad / Gustavo Eloy Ponferrada – Besoin de Dieu et désir de Dieu : l’illusion d’une mort / Michel Mahé – El ser a merced de la afectividad / Mario Enrique Sacchi – Notas y comentarios -- Bibliografía

Diário da Constituinte [gravação de vídeo] : [programa n. 207 A]

O Grupo do Consenso e o Grupo dos 32 apresentarão conjuntamente emendas ao substitutivo do Relator Bernardo Cabral (PMDB-AM) sobre saúde, comunicação, educação e sistema tributário. O Deputado Fernando Bezerra Coelho (PMDB-PE) declara que só mediante autorização do Congresso haverá aumento de carga tributária. O Senador Almir Gabriel (PMDB-PA) esclarece que se pretende fazer prevalecer a criação do Sistema Único de Saúde e a institucionalização da seguridade social com recursos próprios. Os dois Grupos não conseguiram chegar ao consenso em relação aos seguintes pontos: Reforma Agrária, Tribunal Constitucional, mandato presidencial, sistema eleitoral, destinação constitucional das Forças Armadas e sistema de governo. O Senador José Fogaça (PMDB-RS) acredita que não se pode produzir um sistema de governo que seja dos vencedores contra os vencidos, sendo necessário o debate até atingir o consenso da totalidade ou de uma grande maioria dos constituintes. Foram apresentadas cerca de 2.400 emendas ao substitutivo do Relator Bernardo Cabral. O Senador Marco Maciel (PFL-PE) solicita a prorrogação do prazo de entrega das emendas, visando estender as negociações e criar entendimentos sobre os pontos de divergência na Assembleia Nacional Constituinte (ANC). Na Sessão Plenária da Comissão de Sistematização da ANC, continua a discussão de emendas populares com propostas para a criação de novos Estados. O Deputado Virgílio Galassi (PDS-MG) defende a subdivisão territorial do país, em especial a criação do Estado do Triângulo.

Diário da Constituinte [gravação de vídeo] : [programa n. 207]

O prazo para emendas ao substitutivo está terminando. O Deputado Inocêncio Oliveira (PFL-PE) acredita que o texto atual não representa a maioria da Assembleia Nacional Constituinte (ANC). O Deputado José Carlos Coutinho (PL-RJ) informa que os direitos do povo são prioridade, antes das questões relativas ao Estado. A Deputada Beth Azize (PSB-AM) declara que há questões confusas e que o texto constitucional deve ser claro e entendido por todos os brasileiros. O Grupo dos 32 (Trinta e dois) sugere ao Relator que estabeleça um período de transição entre o presidencialismo e o parlamentarismo. O Deputado Israel Pinheiro Filho (PMDB-MG) esclarece que, no corpo da Constituição, seria colocado um parlamentarismo puro e nas disposições transitórias se discriminariam as etapas de implantação do sistema. Membros do Grupo dos 32 se posicionam em relação a Reforma Agrária. O Deputado Israel Pinheiro Filho (PMDB-MG) informa que a questão da imissão de posse virou tabu. O Deputado José Sarney Filho (PFL-MA) declara ser a favor da criação da justiça agrária. Os Deputados Ricardo Izar (PFL-SP) e José Elias Moreira (PTB-MS) são contrários à imissão de posse imediata. O Deputado Ronaro Corrêa (PFL-MG) defende a criação do Banco Nacional do Hectare. O Deputado Doreto Campanari (PMDB-SP) informa que o governo tem vários meios de aumentar a tributação para ter condições de comprar terras e entregá-las a quem precise. No Plenário da Assembleia Nacional Constituinte, continua a discussão de emendas populares sobre liberdade para o espiritismo, eleições diretas e monarquia. O Deputado Luiz Inácio Lula da Silva (PT-SP) defende a emenda popular que estabelece eleições diretas para presidente em 1988.

Orçamento de 2013 : contingenciamento de despesas do Executivo : Decreto nº 8.021 (29/05) : Portaria MP 207 (31/05)

Seguem-se observações preliminares sobre o contingenciamento de 2013, baseadas na 1ª Avaliação de receitas e despesas, anunciada somente em 22 de maio por conta da sanção tardia do orçamento; nos limites de pagamento e de movimentação e empenho das dotações do Executivo do Decreto 8.021/13, de 29 de maio, e da Portaria Ministério do Planejamento 207, de 31 de maio, assim como nas previsões constantes da proposta e da Lei aprovada.

Generation of 207-femtosecond pulses from a ytterbium figure-of-eight fibre laser

We report the generation of 207-fs pulses with 1.2mW average power at 1036 nm directly from a passively mode-locked Yb-doped fibre laser with a nonlinear optical loop mirror for mode-locking and pairs of diffraction gratings for intracavity dispersion compensation. These results imply a 4-fold reduction in pulse duration over previously reported figure-of-eight cavity passively mode-locked Yb-doped fibre lasers. Stable pulse trains are produced at the fundamental repetition rate of the resonator, 24.0MHz. On the other hand, this laser offers a cleaner spectrum and greater stability and is completely self-starting.