Revised composite depth scales for ODP sites 198-1209, 198-1210 and 198-1211, Shatsky Rise

We present new revised composite depth scales for Ocean Drilling Program Leg 198 Sites 1209, 1210, and 1211, drilled at Shatsky Rise in the western Pacific Ocean. Reinterpretation of high-resolution physical property data, with the main focus on magnetic susceptibility as the primary parameter for hole-to-hole correlation, revealed that the shipboard composite records had to be revised below 124.87 meters composite depth (mcd) for Site 1209, below 142.45 mcd for Site 1210, and below 88.64 mcd for Site 1211. The revised composite records comprise Paleogene and Cretaceous sediments at all three sites. As a result of the additional adjustments, the revised mcd records of Sites 1209 and 1210 are 13.48 and 2.69 m longer than the original spliced records, respectively. The original splice of Site 1211 has undergone minor adjustments only to match those of Sites 1209 and 1210. Moreover, detailed correlation of sections outside the new spliced records enable samples already taken to be placed into the new revised composite depth scale.

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.

Carbonate and barite content accross the Eocene/Oligocene boundary of ODP Leg 198 sites, Shatsky Rise

The barite and CaCO3 content (in weight percent) of marine sediments can be used to determine spatial and temporal changes in export production (organic and carbonate carbon flux) and/or CaCO3 preservation (inorganic carbon burial). Here we report barite and CaCO3 content in Eocene/Oligocene (E/O) boundary sediments from locations drilled on Shatsky Rise during Ocean Drilling Program Leg 198. Records of these indexes may be used along with other data to determine how the major E/O boundary climatic transition (initiation of Antarctic glaciation and resultant ocean-climate system changes) affected marine export production/preservation at Shatsky Rise. Such data are necessary to elucidate the timing and phasing of changes in the carbon cycle relative to fluctuations in oceanographic conditions across this climatically important interval.

Planktic foraminiferal assemblages in sediments of four ODP Leg 198 holes

A pulse of intense carbonate dissolution occurred during the early late Paleocene at 58.4 Ma. A prominent 5 to 25 cm-thick dark brown clay-rich calcareous nannofossil ooze was found on Shatsky Rise at Sites 1209, 1210, 1211, and 1212 during Ocean Drilling Program Leg 198. The layer corresponds to the lower part of planktonic foraminiferal Zone P4 and coincides with the evolutionary first occurrence of the nannolith Heliolithus kleinpellii, an important component of late Paleocene assemblages and a marker for the base of Zone CP5. The clay-rich layer contains common crystals of phillipsite, fish teeth, and phosphatic micronodules and corresponds to a prominent peak in magnetic susceptibility that probably reflects these high amounts of detrital and authigenic materials. Detailed quantitative analysis of planktonic foraminiferal assemblages across the clay-rich nannofossil ooze layer shows that fundamental changes in faunal composition occurred before, during, and after deposition of the clay-rich ooze. Planktonic foraminifers in the clay-rich layer are characterized by a low-diversity, largely dissolved assemblage dominated by representatives of the genus Igorina (mainly Igorina tadjikistanensis and Igorina pusilla). Conversely, Igorina albeari, morozovellids, acarininids, globanomalinids, subbotinids, and chiloguembelinids are common below the clay-rich layer, almost disappear within it, and reappear in low abundances above the clay-rich layer. These changes in faunal compositions are likely a response to a change in carbonate saturation that caused increased dissolution on the seafloor owing to the shoaling of the lysocline and the carbonate compensation depth.

Faunal turnovers in the central Pacific benthic foraminifera during the Paleocene-Eocene thermal maximum

Although it is well known that the Paleocene/Eocene thermal maximum (PETM) coincided with a major benthic foraminiferal extinction event, the detailed pattern of the faunal turnover has not yet been clarified. Our high-resolution benthic foraminiferal and carbon isotope analyses at the low latitude Pacific Ocean Shatsky Rise have revealed the following record of major faunal transitions: (1) An initial turnover which involved the benthic foraminiferal extinction event (BFE). The BFE, marked by a sharp transition from Pre-extinction fauna to Disaster fauna represented by small-sized Bolivina gracilis, expresses the onset of the PETM and the abrupt extinction of about 30% of taxa. This faunal transition lasted about 45-74 kyr after the initiation of the PETM and was followed by: (2) the appearance of Opportunistic fauna represented by Quadrimorphina profunda, which existed for about 74-91 kyr after the initiation of the PETM. These two faunas, which appeared after the extinction event, are characterized by low diversity and dwarfism, possibly due to lowered oxygen condition and decreased surface productivity. The second pronounced turnover involved the gradual recovery from Opportunistic Fauna to the establishment of Recovery fauna, which coincided with the recovery about 83-91 kyr after its initiation.

Heritability of white matter fiber tract shapes: A HARDI study of 198 twins

Genetic analysis of diffusion tensor images (DTI) shows great promise in revealing specific genetic variants that affect brain integrity and connectivity. Most genetic studies of DTI analyze voxel-based diffusivity indices in the image space (such as 3D maps of fractional anisotropy) and overlook tract geometry. Here we propose an automated workflow to cluster fibers using a white matter probabilistic atlas and perform genetic analysis on the shape characteristics of fiber tracts. We apply our approach to large study of 4-Tesla high angular resolution diffusion imaging (HARDI) data from 198 healthy, young adult twins (age: 20-30). Illustrative results show heritability for the shapes of several major tracts, as color-coded maps.

Plan Krivorogskogo okruga Sofievskogo raĭona kolfonda Nº 198/15 63, ploshchadiʻ︠u︡ 272.0627 gektara

Digital image

Sapientia, 1995, Vol. L, nº 197-198 (número completo)

Contenido: Razón y fe en Santo Tomás de Aquino / Gustavo Eloy Ponferrada – Sobre la verdad práctica en Tomás de Aquino / Joaquín García Huidobro – Supuestos cartesianos y gnoseología tomista / Augusto Furlán – Discusión de la visión del catolicismo en la obra de Hegel / Ignacio E. M. Andereggen – Ciencia, filosofía y religión : a propósito de una obra de H. Margenau / María Ángeles Vitoria – Sobre el alma y su cuerpo / Héctor Jorge Padrón – El bien común político y la filosofía política actual / Jorge Martínez Barrera – El sujeto de la psiquiatría / Mario Enrique Sacchi – Notas y comentarios – Crónicas -- Bibliografía