Harald Behrens

Bio: Harald Behrens is an academic researcher from Leibniz University of Hanover. The author has contributed to research in topics: Viscosity & Glass transition. The author has an hindex of 56, co-authored 235 publications receiving 9492 citations. Previous affiliations of Harald Behrens include Centre national de la recherche scientifique.

H2o solubility in haplogranitic melts: compositional, pressure, and temperature dependence

Abstract: H20 solubility has been determined in haplogranitic melts (system Si02-NaAISi30s- KAISi30s, Qz-Ab-Or) in the range 0.5-8 kbar and 800-1350 0c. Three types of starting materials were used: dry glass cylinders, prehydrated glass pieces, or dry glass blocks surrounded by glass powder. All the starting materials gave consistent results. The H20 contents of the glasses were determined by Karl-Fischer titration. Dissolved H20 was demonstrated to be distributed homogeneously throughout the isobarically quenched melts (glasses) using infrared spectroscopy. The compositional dependence of H20 solubility was mainly determined at 0.5 kbar, 900 and 1000°C; 1 kbar, 850°C; and 4.8 kbar, 800°C. Seventeen compositions containing 25, 35, or 45 wt% normative Qz and with various Or/(Or + Ab) ratios (0.86-0.09, Ab and Or expressed as normative weight percent) were investigated. At 0.5 kbar, H20 sol- ubility was little affected by the anhydrous composition. By contrast, molar H20 solubility in alumino silicate melts was significantly dependent upon anhydrous composition between 1 and 5 kbar. The highest solubility values were obtained for the most Ab-rich melts. This alkali effect has important implications for the physical and chemical properties of granitic melts. The effect of pressure (P) on H20 solubility at P ;:: 3 kbar is greater than that reported in previous studies. Between 3 and 8 kbar at 800 OC,there is a (nearly linear) positive correlation between P and H20 solubility. The effect of temperature (T) on H20 solubility was investigated for a composition QZ2sAb3sOr34 (normative weight percent) in the P-T range 0.5-8 kbar and 800-1350 0C. Water solubility ranged from retrograde (with increas- ing T) at P ~ 4 kbar through temperature independence at approximately 4.5 kbar to prograde at P = 5 kbar. Calculated H20 solubilities using the model of Burnham and Nekvasil (1986) are slightly high at 0.5 kbar and significantly low at 5 kbar, compared with the experimental data. This implies that calculated H20 activities for haplogranitic systems using the H20 content of the melt may be overestimated at high pressure (P ;:: 5 kbar). Using the ther- modynamic model of Silver and Stolper (1985) and assuming a proportion of molecular H20 and OH groups close to that defined for albite melts by Silver and Stolper (1989), we found that the partial molar volume of H20 in a melt with a composition QZ2sAb3sOr34 has to be close to 10-12 cm3/mol to obtain a good agreement between the calculated and the experimentally determined H20 solubility curves in the pressure range 1-8 kbar at 900°C.

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Thermometers and Barometers for Volcanic Systems

Abstract: Knowledge of temperature and pressure, however qualitative, has been central to our views of geology since at least the early 19th century. In 1822, for example, Charles Daubeny presented what may be the very first “Geological Thermometer,” comparing temperatures of various geologic processes (Torrens 2006). Daubeny (1835) may even have been the first to measure the temperature of a lava flow, by laying a thermometer on the top of a flow at Vesuvius—albeit several months following the eruption, after intervening rain (his estimate was 390°F). In any case, pressure ( P ) and temperature ( T ) estimation lie at the heart of fundamental questions: How hot is Earth, and at what rate has the planet cooled. Are volcanoes the products of thermally driven mantle plumes? Where are magmas stored, and how are they transported to the surface—and how do storage and transport relate to plate tectonics? Well-calibrated thermometers and barometers are essential tools if we are to fully appreciate the driving forces and inner workings of volcanic systems. This chapter presents methods to estimate the P-T conditions of volcanic and other igneous processes. The coverage includes a review of existing geothermometers and geobarometers, and a presentation of approximately 30 new models, including a new plagioclase-liquid hygrometer. Our emphasis is on experimentally calibrated “thermobarometers,” based on analytic expressions using P or T as dependent variables. For numerical reasons (touched on below) such expressions will always provide the most accurate means of P-T estimation, and are also most easily employed. Analytical expressions also allow error to be ascertained; in the absence of estimates of error, P-T estimates are nearly meaningless. This chapter is intended to complement the chapters by Anderson et al. (2008), who cover granitic systems, and by Blundy and Cashman (2008) and Hansteen and Klugel (2008), who consider additional methods …

An improved and extended internally consistent thermodynamic dataset for phases of petrological interest, involving a new equation of state for solids

Abstract: The thermodynamic properties of 254 end-members, including 210 mineral end-members, 18 silicate liquid end-members and 26 aqueous fluid species are presented in a revised and updated internally consistent thermodynamic data set. The PVT properties of the data set phases are now based on a modified Tait equation of state (EOS) for the solids and the Pitzer & Sterner (1995) equation for gaseous components. Thermal expansion and compressibility are linked within the modified Tait EOS (TEOS) by a thermal pressure formulation using an Einstein temperature to model the temperature dependence of both the thermal expansion and bulk modulus in a consistent way. The new EOS has led to improved fitting of the phase equilibrium experiments. Many new end-members have been added, including several deep mantle phases and, for the first time, sulphur-bearing minerals. Silicate liquid end-members are in good agreement with both phase equilibrium experiments and measured heat of melting. The new dataset considerably enhances the capabilities for thermodynamic calculation on rocks, melts and aqueous fluids under crustal to deep mantle conditions. Implementations are already available in thermocalc to take advantage of the new data set and its methodologies, as illustrated by example calculations on sapphirine-bearing equilibria, sulphur-bearing equilibria and calculations to 300 kbar and 2000 °C to extend to lower mantle conditions.

Raman spectroscopy of biological tissues

Abstract: This article reviews some of the recent advances in Raman spectroscopy, in areas related to natural tissues and cell biology. It summarizes some of the most widely used peak frequencies and their assignments. The aim of this study is to prepare a database of molecular fingerprints, which will help researchers in defining the chemical structure of the biological tissues introducing most of the important peaks present in the natural tissues. In spite of applying different methods, there seems to be a considerable similarity in defining the peaks of identical areas of the spectra. As a result, it is believed that preparing a unique collection of the frequencies encountered in Raman spectroscopic studies can lead to significant improvements both in the quantity and quality of spectral data and their outcomes. This article is the first review of its kind to provide a precise database on the most important Raman characteristic peak frequencies for researchers aiming to analyze natural tissues by Raman ...

The Rock Physics Handbook

Abstract: Responding to the latest developments in rock physics research, this popular reference book has been thoroughly updated while retaining its comprehensive coverage of the fundamental theory, concepts, and laboratory results. It brings together the vast literature from the field to address the relationships between geophysical observations and the underlying physical properties of Earth materials - including water, hydrocarbons, gases, minerals, rocks, ice, magma and methane hydrates. This third edition includes expanded coverage of topics such as effective medium models, viscoelasticity, attenuation, anisotropy, electrical-elastic cross relations, and highlights applications in unconventional reservoirs. Appendices have been enhanced with new materials and properties, while worked examples (supplemented by online datasets and MATLAB® codes) enable readers to implement the workflows and models in practice. This significantly revised edition will continue to be the go-to reference for students and researchers interested in rock physics, near-surface geophysics, seismology, and professionals in the oil and gas industries.