Physical properties and sedimentology of 4 profiles fom the South Atlantic

Ultrasonic P wavc transmission seismograms recorded on sediment cores have been analyzed to study the acoustic and estimate the clastic properties of marine sediments from different provinces dominated by terrigenous, calcareous, amI diatomaceous sedimentation. Instantaneous frequencies computed from the transmission seismograms are displayed as gray-shaded images to give an acoustic overview of the lithology of each core. Ccntirneter-scale variations in the ultrasonic waveforms associated with lithological changes are illustrated by wiggle traces in detail. Cross-correlation, multiple-filter, and spectral ratio techniques are applied to derive P wave velocities and attenuation coefficients. S wave velocities and attenuation coefficients, elastic moduli, and permeabilities are calculated by an inversion scheme based on the Biot-Stoll viscoelastic model. Together wilh porosity measurements, P and S wave scatter diagrams are constructed to characterize different sediment types by their velocity- and attenuation-porosity relationships. They demonstrate that terrigenous, calcareous, and diatomaceous sediments cover different velocity- and attenuation-porosity ranges. In terrigcnous sediments, P wave vclocities and attenuation coefficients decrease rapidly with increasing porosity, whereas S wave velocities and shear moduli are very low. Calcareous sediments behave similarly at relatively higher porosities. Foraminifera skeletons in compositions of terrigenous mud and calcareous ooze cause a stiffening of the frame accompanied by higher shear moduli, P wave velocities, and attenuation coefficients. In diatomaceous ooze the contribution of the shear modulus becomes increasingly important and is controlled by the opal content, whereas attenuation is very low. This leads to the opportunity to predict the opal content from nondestructive P wave velocity measurements at centimeter-scale resolution.

Distribution of desmoscolecida (Nematoda) in surface sediments of the Iberian Deep-Sea, North Atlantic (Table 1)

1. Desmoscolecida from the continental slope and the deep-sea bottom (59-4354 m) off the Portuguese and Moroccan coasts are described. 18 species were identified: Desmoscolex bathyalis sp. nov., D. chaetalatus sp. nov., D. eftus sp. nov., D. galeatus sp. nov., D. lapilliferus sp. nov., D. longisetosus Timm, 1970, D. lorenzeni sp. nov., D. perspicuus sp. nov., D. pustulatus sp. nov., Quadricoma angulocephala sp. nov., Q. brevichaeta sp. nov., Q. iberica sp. nov., Q. loricatoides sp. nov., Tricoma atlantica sp. nov., T. bathycola sp. nov., T. beata sp. nov., T. incomposita sp. nov., T. meteora sp. nov., T. mauretania sp. nov. 2. The following new terms are proposed: "Desmos" (ring-shaped concretions consisting of secretion and concretion particles), "desmoscolecoid" and "tricomoid" arrangement of the somatic setae, "regelmaessige" (regular), "unregelmaessige" (irregular), "vollstaendige" (complete) and "unvollstaendige" (incomplete) arrangement of somatic seta (variations in the desmoscolecoid arrangement of the somatic setae). The length of the somatic setae is given in the setal pattern. 3. Desmoscolecida identical as to genus and species exhibit no morphological differences even if forthcoming from different bathymetrical zones (deep sea, sublitoral, litoral) or different environments (marin, freshwater, coastal subsoil water, terrestrial environment). 4. Lorenzen's (1969) contention that thearrangement of the somatic setae is more significant for the natural relationships between the different genera of Desmoscolecida than other characteristics is further confirmed. Species with tricomoid arrangement of somatic setae are regarded as primitive, species with desmoscolecoid arrangement of somatic setae are regarded as more advanced. 5. Three new genus are established: Desmogerlachia gen. nov., Desmolorenzenia gen. nov. and Desmofimmia gen. nov. - Protricoma Timm, 1970 is synonymized with Paratricoma Gerlach, 1964 and Protodesmoscolex Timm, 1970 is synonymized with Desmoscolex Claparede,1863. 6. Checklists of all species of the order Desmoscolecida and keys to species of the subfamilies Tricominae and Desmoscolecinae are provided. 7. The following nomenclatorial changes are suggested: Desmogerlachia papillifer (Gerlach, 1956) comb. nov., D .pratensis (Lorenz, 1969) comb. nov., Desmotimmia mirabilis (Timm, 1970) comb. nov., Paratricoma squamosa (Timm, 1970) comb. nov., Desmolorenzenia crassicauda (Timm, 1970) comb. nov., D. desmoscolecoides (Timm, 1970) comb. nov., D. eurycricus (Filipjev, 1922) comb. nov., D. frontalis (Gerlach, 1952) comb. nov., D. hupferi (Steiner, 1916) comb. nov., D. longicauda (Timm, 1970) comb. nov., D. parva (Timm, 1970) comb. nov., D. platycricus (Steiner, 1916) comb. nov., D. viffata (Lorenzen, 1969) comb. nov., Desmoscolex anfarcficos (Timm, 1970) comb. nov.

Stable isotope record of Uvigerina peregrina from the Mediterranean Sea

Based on the glacial to postglacial delta13C differences between endobenthic Uvigerina peregrina species from the Alboran basin and from other mediterranean basins, changes in the fertility of the western part of this basin during the last deglaciation are reconstructed. As a result of particulate organic carbon (POC) rain from the highly productive upwelling cell along the northwestern margin of the Alboran basin, U. peregrina is presently depleted by about 1.6per mil with respect to the measured delta13C values of bottom water SumCO2 and by about 0.9per mil with respect to specimens from other areas of the western Mediterranean or from the Gulf of Cadiz within the Mediterranean Outflow Water. The Uvigerina delta13C difference between the Alboran Sea and the Gulf of Cadiz (Delta delta13C), was close to 0per mil at the beginning of the last deglaciation and during the late glacial time. This suggests that highly fertile systems set in the Alboran Sea near 16 kyr B.P. Two rapid increases in the Delta delta13C offset are recorded near 15 kyr and 11 kyr B.P. Fluctuations around 1.1 to 1.2per mil occurred during the early Holocene, and a maximum was reached near 9 kyr B.P. After 4 kyr the Delta delta13C offset decreased to its present-day average value of 0.9per mil. Changes in the intensity of surficial production cannot account for all the observed fluctuations, especially in the early Holocene time. A strong decrease in the intermediate and deep water ventilation of the Alboran basin may have occurred near 8-9 kyr, in phase with the last stagnant phase in the eastern Mediterranean and the deposition of Sapropel S1. As a result, the redistribution and remineralization at depth of the produced organic matter was incomplete. The POC rain reaching the sediment was locally intensified and caused the lowering of the delta13C values of endobenthic foraminifers such as U. peregrina. The benthic 13C signal suggests that the difference between the Alboran Sea and the Gulf of Cadiz was at its maximum. At the same time, an important modification in the water masses structure may have occurred near 9-8 kyr B.P. The deepening of the permanent pycnocline probably related to a thicker Atlantic jet at a stage of high sea level stand is recorded by the replacement of the right coiling N. pachyderma dominance (coincident with a shallow pycnocline) by the G. inflata dominance (coincident with a deep pycnocline). Diatom abundances were strongly reduced indicating an important modification of the productive system. The glacial-postglacial evolution of productivity within the Alboran basin was therefore more complex than in the adjacent Atlantic Ocean and opposite to the global one which displays a general increase in productivity during glacial time. Although it is the global budget of paleoproductivity that would drive the partitioning of carbon within the ocean, local or regional discrepancies with the global glacial-interglacial model must be addressed. Local winds and regional atmospheric pressure systems, which are the forcing factors for circulation and exchange with the Atlantic, control the fertile systems of the Alboran basin.

Phytoplanktonic microfossil groups of sediments from the South and Equatorial Atlantic

Individual planktonic microfossil species, or assemblage groups of different species, are often used to, qualitatively and/or quantitatively, reconstruct past (sub)surface-water conditions of the world's oceans and seas. Until now, little information has been available on the surface sediment distribution patterns and paleoenvironmental reconstruction potential of coccolith, calcareous dinoflagellate cyst and organic-walled dinoflagellate cyst assemblages of the South and equatorial Atlantic, especially at the species level. This paper (i) summarizes the distributions of these three phytoplanktonic microfossil groups in numerous Atlantic surface sediments from 20°N-50°S and 30°E-65°W and determines their relationship with the physicochemical and trophic conditions of the overlying (sub)surface-waters, and (ii) determines the synecology of the three phytoplankton groups by carrying out statistical analyses (i.e. detrended and canonical correspondence analyses) on all groups simultaneously. Ecological relationships are additionally strengthened by statistically comparing the distribution patterns of the phytoplankton groups with those of planktonic foraminifera (Pflaumann et al. 1996; Niebler et al. 1998), as the ecological preferences of the latter are much better known. Many of the analyzed phytoplanktonic microfossil species or groups of species in the surface sediments do show restricted distributions which primarily reflect the environmental conditions of the upper water masses above them (e.g. sea-surface temperature, productivity, stratification). The acquired 'reference' data sets are large and diverse enough to allow future development of transfer functions for the reconstruction of past surface-water conditions, and show that there is still an enormous paleoenvironmental reconstruction potential concealed in many fossil coccolith and dinoflagellate cyst assemblages.

Reference list of 265 sources used for the discovery of relationships between data clusters and metadata properties

Visual cluster analysis provides valuable tools that help analysts to understand large data sets in terms of representative clusters and relationships thereof. Often, the found clusters are to be understood in context of belonging categorical, numerical or textual metadata which are given for the data elements. While often not part of the clustering process, such metadata play an important role and need to be considered during the interactive cluster exploration process. Traditionally, linked-views allow to relate (or loosely speaking: correlate) clusters with metadata or other properties of the underlying cluster data. Manually inspecting the distribution of metadata for each cluster in a linked-view approach is tedious, specially for large data sets, where a large search problem arises. Fully interactive search for potentially useful or interesting cluster to metadata relationships may constitute a cumbersome and long process. To remedy this problem, we propose a novel approach for guiding users in discovering interesting relationships between clusters and associated metadata. Its goal is to guide the analyst through the potentially huge search space. We focus in our work on metadata of categorical type, which can be summarized for a cluster in form of a histogram. We start from a given visual cluster representation, and compute certain measures of interestingness defined on the distribution of metadata categories for the clusters. These measures are used to automatically score and rank the clusters for potential interestingness regarding the distribution of categorical metadata. Identified interesting relationships are highlighted in the visual cluster representation for easy inspection by the user. We present a system implementing an encompassing, yet extensible, set of interestingness scores for categorical metadata, which can also be extended to numerical metadata. Appropriate visual representations are provided for showing the visual correlations, as well as the calculated ranking scores. Focusing on clusters of time series data, we test our approach on a large real-world data set of time-oriented scientific research data, demonstrating how specific interesting views are automatically identified, supporting the analyst discovering interesting and visually understandable relationships.

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.