Estimation of the Al,Si distribution of feldspars from the lattice translations Tr[110] and Tr[110]

A method is proposed to estimate the Al,Si distribution of alkali feldspars from two lattice translations, called Tr[110] and Tr[1¯10], which are the repeat distances in the [110] and [1¯10] directions. The Al content t₁0 of the T₁0 tetrahedral site is estimated from Tr[1¯10], whereas Tr[110] measures t₁m, the Al content of the T₁m site. In order to simplify the estimation procedure, the line separation =2 (131)-2 (1¯31) is given as a function of t₁0 and t₁0-t₁m.     

Die Trocknung des Klärschlammes durch Verdunstung

Zusammenfassung Es werden Bau und Bemessung der Beete, sowie die bisherigen Forschungsarbeiten beschrieben, insbesondere die Verdunstungs- und Trocknungsvorg?nge. Eingehende Versuche über die natürliche Trocknung des Schlammes durch Verdunstung im Freien sind durchgeführt worden. Es werden Formeln für Trocknungsdauer und Beetbelastung entwickelt und einige Vorschl?ge für die Praxis angegeben.

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Summary The dimensioning and construction of drying beds are described, as is previous research, in particular the evaporation and drying processes. Detailed studies on the natural thermal drying of sludge through evaporation in the open air were carried out. Formulas for the drying period and bedloading were developed and several suggestions for the practice are given.

     

Preservation of hydrocarbons and biomarkers in oil trapped inside fluid inclusions for >2 billion years

Oil-bearing fluid inclusions occur in a ca. 2.45 Ga fluvial metaconglomerate of the Matinenda Formation at Elliot Lake, Canada. The oil, most likely derived from the conformably overlying deltaic McKim Formation, was trapped in quartz and feldspar during diagenesis and early metamorphism of the host rock, probably before ca. 2.2 Ga. Molecular geochemical analyses of the oil reveal a wide range of compounds, including CH₄, CO₂, n-alkanes, isoprenoids, monomethylalkanes, aromatic hydrocarbons, low molecular weight cyclic hydrocarbons, and trace amounts of complex multi-ring biomarkers. Maturity ratios show that the oil was generated in the oil window, with no evidence of extensive thermal cracking. This is remarkable, given that the oils were exposed to upper prehnite-pumpellyite facies metamorphism (280-350 °C) either during migration or after entrapment. The fluid inclusions are closed systems, with high fluid pressures, and contain no clays or other minerals or metals that might catalyse oil-to-gas cracking. These three attributes may all contribute to the thermal stability of the included oil and enable survival of biomarkers and molecular ratios over billions of years. The biomarker geochemistry of the oil in the Matinenda Formation fluid inclusions enables inferences about the organisms that contributed to the organic matter deposited in the Palaeoproterozoic source rocks from which the analysed oil was generated and expelled. The presence of biomarkers produced by cyanobacteria and eukaryotes that are derived from and trapped in rocks deposited before ca. 2.2 Ga is consistent with an earlier evolution of oxygenic photosynthesis and suggests that some aquatic settings had become sufficiently oxygenated for sterol biosynthesis by this time. The extraction of biomarker molecules from Palaeoproterozoic oil-bearing fluid inclusions thus establishes a new method, using low detection limits and system blank levels, to trace evolution through Earth’s early history that avoids the potential contamination problems affecting shale-hosted hydrocarbons.     

Experimental insight into spalling behavior of concrete tunnel linings under fire loading

New experimental insight into the spalling behavior of concrete in fire conditions is presented in this paper. Spalling was recorded by a high-speed camera. The slow-motion sequences allow us to determine the size, shape, and velocity of the spalled-off pieces. With this information at hand, the released energy associated with every spalling event is computed and compared to the energies associated with pore-pressure and thermal-stress spalling. This comparison provides new insight into the impact of the various thermal, mechanical, and hydral processes controlling concrete spalling.