Geotechnical sampling and testing of gas-charged marine sediments atin situ pressures

Gas-charged marine sediments were sampled using a pressure core barrel and a new technique involving standard wireline sampling procedures. Pressure core barrel sampling provides sediments atin situ pressures with no degassing. Analysis of gas content, geotechnical properties and microfabric were performed for samples atin situ pressures and compared with degassed results. Methane concentrations ranged from 3,450 to 137,140 ppm for pressurized samples. Microfabric analyses reveal highly nonoriented clay particles and grains in degassed samples. Degassing of these methane-rich sediments increases porosities and compression indices, while reducing undrained shear strengths and computed preconsolidation pressures.     

Fatty acids of bacterial origin in contemporary marine sediments

Contributions by bacteria to recent sediments have been recognized as one important source of input for the extractable lipids. It has, however, proved difficult so far to conclusively relate the components identified to the contributing bacteria. This fact is primarily related to the lack of information on both the lipid chemistry of marine bacteria, and of detailed structures of the sedimentary lipids. In this paper a study of the fatty acids from a tropical marine sediment selected because of its high biomass content is reported, and relationships between the sedimentary extracts of the surface layer to fatty acid components of bacteria cultured from the sediment sample are detailed. By selecting specific structural features, a group of fatty acids have been identified as valid markers for bacteria in this environment: these include iso- and anteiso-branched chain acids; 10-methylpalmitic acid; cyclopropyl 17:0 and 19:0 acids of which ▽19:0 (11,12) is unique to bacteria; cis-vaccenic acid; and the 15:1, 17:1 ω6 and ω8 isomers especially when these occur in pairs; iso Δ7–15: 1 and iso Δ9–17:1 are branched unsaturated acids apparently unique to bacteria. Trans-monoene fatty acids are likely to be a direct bacterial input, and the hydroxy acids identified are probably of bacterial cell wall origin. This study, whilst emphasizing the necessity for detailed structural information on fatty acids in order to use them validly as biological markers, considerably extends the range of fatty acids as markers of bacterial input to contemporary sediments.     

Mass transport in rotatory tidal currents

Summary A perturbation method is used to calculate steady non-linear effects in rotatory tidal currents. The inclusion of the Coriolis acceleration leads to a uniquely determined second order current system in the tidal stream. This is shown to be absent in high frequency gravity waves. It is found that particle drift, or mass transport, is critically dependent on this mean current, and consequently on the value off/,f being the Coriolis parameter, and the angular frequency of the oscillation.     

Illite diagenesis in the Vienna Basin,Austria

Summary The fine clay fractions less than 0.2 micron isolated from Tertiary shales of the Vienna Basin, Austria, were characterized mineralogically and chemically (including c.e.c.). Over the depth (885–2802 m) and temperature (45–120 °C) intervals represented mixed layer smectite-illites change from 74/26 to 20/80, the deeper samples showing IM ordering. Inhibition of illitization at about 2700 m is attributed to unusually high Mg content of pore solutions at this depth.Utilizing a chemical-statistical approach, the illite component of each smectite-illite mixed-layer phase has been characterized as to magnitude of interlayer charge, and octahedral and tetrahedral substitutions. The illite compositions fall neatly within the normal illite field defined by Köster.During the initial stage of illitization, smectite to illite transformation proceeds toward phengitic compositions. As illitization continues (greater depth and T), the illite component progressively changes composition with loss of Mg toward that of ideal 50/50 allevardite.

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Illit-Diagenese im Wiener Becken

Zusammenfassung Feintonproben (kleiner 0,2 Mikron) aus neogenen pelitischen Sedimenten aus dem Wiener Becken wurden mineralogisch und chemisch (einschließlich Ionenaustauschkapazität charakterisiert. Die im Teufenbereich zwischen 885–2802 m und Temperature zwischen 45–120 °C angetroffenen Smektit-Illit Mischphasen haben eine Zusammensetuzung von 74/26 bis 20/80, wobei im untersten Teufenbereich IM-Entwicklung vorliegt. Eine verzögerte Illitisierung bei ca. 2700 m wird lokal ungewöhnlich hohen Mg-Konzentrationen der Porenwässer zugeschrieben.Durch Anwendung eines chemisch-statistischen Näherungsverfahrens konnte die illitische Komponente der Smektit-Illit Mischphasen hinsichtlich Zwischenschichtladung sowie oktaedrischen und tetraedrischen Substitutionen charakterisiert werden. Die Zusammensetzungen der Illite liegen innerhald des Illitfeldes nach Köster.Die Umformung Smektit zu Illit zeigt außerdem zu Beginn des Illitisierungsprozesses phengitische Zusammensetzungen der Phasen. Mit zunehmender Tiefe und Temperatur ist weiterhin eine Neubildung von Allevardit zu beobachten.

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With 12 Figures     

Microbial lipids of an intertidal sediment—I. Fatty acids and hydrocarbons

A detailed study has been made of the solvent extractable monocarboxylic, dicarboxylic and hydroxylated fatty acids and n-alkanes in a surface intertidal sediment, and the distributions compared to microorganisms cultured from the sediment. Diatoms are shown to contribute most of the monocarboxylic acids, particularly the significant amounts of polyunsaturated acids present, and a small proportion of the n-alkanes. Bacteria contribute between 11 and 14% of the monocarboxylic acids and markers for this, including trans-monounsaturated acids, are proposed. Detritus from the sea-grass Zostera muelleri is a major source of the α-hydroxy-, ω-hydroxy and α,ω-dicarboxylic acids in the sediment and a minor contributor of n-alkanes and long-chain fatty acids.     

Azimuth determination without circle readings

The technical aspects of azimuth determination in the vertical plane of the reference object are given. The programme preparation, field operations and computations of field data are described. The paper includes the results of experimental work close to the local meridian and near the prime vertical. Field operations and results are discussed.     

Updated bathymetric survey of Kick-'em-Jenny submarine volcano

High-resolution bathymetric data obtained in July 1996 during a survey of the Kick-'em-Jenny submarine volcano north of Grenada in the Lesser Antilles revealed changes in the structure of the volcanic edifice compared to previously available surveys. The volcano's summit, at 178 m below sea level, was found to be approximately 18 m farther from the surface than was reported by Bouysse et al. (1988) and others. No dome was observed. Instead, an open crater, surrounded by walls that dropped significantly in elevation from one side to the opposite, suggest that eruptions, earthquakes, rockfalls or explosions may have altered the structure since the last detailed survey. The deepest contour of the volcano's crater was found 106 m below the summit.     

Structural investigations of Australian coals—IV. A characterization of the variation in rank of bituminous coal fractions by elemental analysis and I.R. spectroscopy

A series of seven Permian Australian bituminous coals of varying rank, were examined by quantitative infrared spectroscopy, using absorption coefficients K(cmmg^?1) and elemental analysis in the form of bond equivalence data. Both analytical techniques were found to be complementary in their average structural predictions. The coals were chemically fractionated into Total Solvent Extractables (T.S.E.), Solvent Extractable Humic Acids (S.E.H.A.) and insoluble Kerogens. Molecular condensation was found to decrease for the T.S.E. fractions, and increase as expected, for the insoluble kerogen fractions, as a function of increasing coal rank. The effect of aqueous base extraction upon the kerogen fraction, observable as an increase in oxygen by bond equivalence, could be related to minor changes in I.R. absorption coefficients and difference spectra.     

The Equatorial Undercurrent in the central Atlantic and its relation to tropical Atlantic variability

Seasonal to interannual variations of the Equatorial Undercurrent (EUC) in the central Atlantic at 23°W are studied using shipboard observation taken during the period 1999–2011 as well as moored velocity time series covering the period May 2005–June 2011. The seasonal variations are dominated by an annual harmonic of the EUC transport and the EUC core depth (both at maximum during September), and a semiannual harmonic of the EUC core velocity (maximum during April and September). Substantial interannual variability during the period of moored observation included anomalous cold/warm equatorial Atlantic cold tongue events during 2005/2008. The easterly winds in the western equatorial Atlantic during boreal spring that represent the preconditioning of cold/warm events were strong/weak during 2005/2008 and associated with strong/weak boreal summer EUC transport. The anomalous year 2009 was instead associated with weak preconditioning and smallest EUC transport on record from January to July, but during August coldest SST anomalies in the eastern equatorial Atlantic were observed. The interannual variations of the EUC are discussed with respect to recently described variability of the tropical Atlantic Ocean.