POWTEX Neutron Diffractometer at FRM II - new perspectives for in-situ rock deformation analysis

EGU2012-13521 In Geoscience quantitative texture analysis here defined as the quantitative analysis of the crystallographic preferred orientation (CPO), is a common tool for the investigation of fabric development in mono- and polyphase rocks, their deformation histories and kinematics. Bulk texture measurements also allow the quantitative characterisation of the anisotropic physical properties of rock materials. A routine tool to measure bulk sample volumes is neutron texture diffraction, as neutrons have large penetration capabilities of several cm in geological sample materials. The new POWTEX (POWder and TEXture) Diffractometer at the neutron research reactor FRM II in Garching, Germany is designed as a high-intensity diffractometer by groups from the RWTH Aachen, Forschungszentrum Jülich and the University of Göttingen. Complementary to existing neutron diffractometers (SKAT at Dubna, Russia; GEM at ISIS, UK; HIPPO at Los Alamos, USA; D20 at ILL, France; and the local STRESS-SPEC and SPODI at FRM II) the layout of POWTEX is focused on fast time-resolved experiments and the measurement of larger sample series as necessary for the study of large scale geological structures. POWTEX is a dedicated beam line for geoscientific research. Effective texture measurements without sample tilting and rotation are possible firstly by utilizing a range of neutron wavelengths simultaneously (Time-of-Flight technique) and secondly by the high detector coverage (9.8 sr) and a high flux (�~1x10 7 n/cm2s) at the sample. Furthermore the instrument and the angular detector resolution is designed also for strong recrystallisation textures as well as for weak textures of polyphase rocks. These instrument characteristics allow in-situ time-resolved texture measurements during deformation experiments on rocksalt, ice and other materials as large sample environments will be implemented at POWTEX. The in-situ deformation apparatus is operated by a uniaxial spindle drive with a maximum axial load of 250 kN, which will be redesigned to minimize shadowing effects inside the cylindrical detector. The HT deformatione experiments will be carried out in uniaxial compression or extension and an upgrade to triaxial deformation conditions is envisaged. The load frame can alternatively be used for ice deformation by inserting a cryostat cell for temperatures down to 77 K with a triaxial apparatus allowing also simple shear experiments on ice. Strain rates range between 10-8 and 10-3 s-1 reaching to at least 50% axial strain. The deformation apparatus is designed for continuous long-term deformation experiments and can be exchanged between in-situ and ex-situ placements during continuous operation inside and outside the neutron detector

Causes and consequences of the great strength variability among soft Nankai accretionary prism sediments from offshore SW-Japan

Geophysical Research AbstractsVol. 16, EGU2014-10666, 2014EGU General Assembly 2014© Author(s) 2014. CC Attribution 3.0 License.Causes and consequences of the great strength variability among softNankai accretionary prism sediments from offshore SW-JapanMichael Stipp (1), Kai Schumann (1), Bernd Leiss (2), and Klaus Ullemeyer (3)(1) GEOMAR, Marine Geodynamics, Kiel, Germany ([email protected], [email protected]), (2)Geowissenschaftliches Zentrum, Universität Göttingen, Germany ([email protected]), (3) Institut für Geowissenschaften,Universität Kiel, Germany ([email protected])The Nankai Trough Seismogenic Zone Experiment of the International Ocean Discovery Program (IODP) isthe very first attempt to drill into the seismogenic part of a subduction zone. Offshore SW-Japan the oceanicPhilippine sea plate is subducted beneath the continental Eurasian plate causing earthquakes of magnitude 8.0 to8.5 and related tsunamis with a recurrence rate of 80-100 years. For the tsunamigenic potential of the forearc slopeand accreted sediments their mechanical strength, composition and fabrics have been investigated. 19 drill coresamples of IODP Expeditions 315, 316 and 333 were experimentally deformed in a triaxial cell under consolidatedand undrained conditions at confining pressures of 400-1000 kPa, room temperature, axial shortening rates of0.01-9.0 mm/min, and up to an axial strain of64% (Stipp et al., 2013). With respect to the mechanical behavior,two distinct sample groups could be distinguished. Weak samples from the upper and middle forearc slope ofthe accretionary prism show a deviatoric peak stress after only a few percent strain (< 10%) and a continuousstress decrease after a maximum combined with a continuous increase in pore pressure. Strong samples fromthe accretionary prism toe display a constant residual stress at maximum level or even a continuous stressincrease together with a decrease in pore pressure towards high strain (Stipp et al., 2013). Synchrotron textureand composition analysis of the experimentally deformed and undeformed samples using the Rietveld refinementprogram MAUD indicates an increasing strength of the illite and kaolinite textures with increasing depth downto 523 m below sea floor corresponding to a preferred mineral alignment due to compaction. Experimentallydeformed samples have generally stronger textures than related undeformed core samples and they show alsoincreasing strength of the illite and kaolinite textures with increasing axial strain. Mechanically weak samples havea bulk clay plus calcite content of 31-65 vol.-% and most of their illite, kaolinite, smectite and calcite [001]-polefigures have maxima >1.5 mrd. Strong samples which were deformed to approximately the same amount of strain(up to 40%) have no calcite and a bulk clay content of 24-36 vol.-%. Illite, kaolinite and smectite [001]-pole figuremaxima are mostly <1.5 mrd, except for one sample which was deformed to a considerably higher strain (64%).The higher clay and calcite content and the stronger textures of the mechanically weak samples can be related toa collapsing pore space of the originally flocculated clay aggregates. This process is insignificant in the strongsamples from the prism toe, for which deformation would tend to involve large rock volumes and lead to straindissipation. The weak samples from the forearc slope which become even weaker with increasing strain mayprovoke mechanical runaway situations allowing for earthquake rupture, surface breakage and tsunami generation.Stipp, M., Rolfs, M., Kitamura, Y., Behrmann, J.H., Schumann, K., Schulte-Kortnack, D. and Feeser, V.2013. G-Cubed 14/11, doi: 10.1002/ggge.20290

Bulk rock elastic moduli at high pressures, derived from the mineral textures and from extrapolated laboratory data

The elastic anisotropy of bulk rock depends on the mineral textures, the crack fabric and external parameters like, e.g., confining pressure. The texture-related contribution to elastic anisotropy can be predicted from the mineral textures, the largely sample-dependent contribution of the other parameters must be determined experimentally. Laboratory measurements of the elastic wave velocities are mostly limited to pressures of the intermediate crust. We describe a method, how the elastic wave velocity trends and, by this means, the elastic constants can be extrapolated to the pressure conditions of the lower crust. The extrapolated elastic constants are compared to the texture-derived ones. Pronounced elastic anisotropy is evident for phyllosilicate minerals, hence, the approach is demonstrated for two phyllosilicate-rich gneisses with approximately identical volume fractions of the phyllosilicates but different texture types

Neutron time-of-flight texture measurements in Dubna: Status and developments

The multidetector texture diffractometer SKAT (from Russian: Spektrometer Kolitshestvennovo Analiza Tekstury) at the pulsed reactor IBR-2 in Dubna, Russia, started operation in March 1997 and is open for users from all countries. Application of time-of-flight (TOF) diffraction to texture measurements offers the opportunity to record complete diffraction patterns, i.e., to measure several pole figures simultaneously. To allow high spectral resolution for measurements on polyphase geological samples with many diffraction patterns, the instrument was placed at the end of an over 100m long flight path. In this paper, we will summarize advantages and disadvantages of the SKAT, as well as intended improvements.conferenc

2-Aminoacetophenon: Verursachende Komponente der ,untypischen Alterungsnote" (,Naphthalinton", ,Hybridton") bei Wein

Research Note2-aminoacetophenone: Causal component of 'untypical aging flavour' ('naphthalene note', 'hybrid note') of wineFrom wines (Vitis vinifera cvs Müller-Thurgau, Riesling, Silvaner) with an untypical aging note (also called 'naphthalene note' or 'hybrid note') 2-aminoacetophenone could be identified as the causal compound by GC-MS technique, after enrichment of the aroma constituents and fractionated separation of the extracts. This aroma compound known as 'foxy' smelling component of Labruscana grapes has not been found in V. vinifera evs up to now.

Untersuchungen über den Einfluß der Entsäuerung mit Calciumcarbonat auf die flüchtigen Inhaltsstoffe von Traubenmost und Wein

Investigations on the influence of deacidification with calciumcarbonate on the volatile constituents of grape must and wineChanges in the volatile constituents of musts and wines occurring during their chemical deacidification with calciumcarbonate were examined by use of GC-MS techniques. Owing to a change in pH, caused by CaC03 addition, an increase in the concentration of some monoterpenes, which are essential for the specific aroma of the varieties Morio-Muskat and Gewürztraminer, could be observed. This increase, concerning the monoterpene alcohols citronellol, nerol, geraniol and others, is due to the encymic hydrolysis of terpene glycosides present in must and wine

3, 7-Dimethyl-1,7-octandiol - eine neue Terpen-Komponente des Trauben- und Weinaromas

Mit Hilfe der GC-MS-Kopplung identifizierten wir zum erstenmal 3,7-Dimethyl-1,7-octandiol (Hydroxycitronellol) im Aromaextrakt von Traubenmost und Wein verschiedener Rebsorten. Diese Komponente konnte bisher in pflanzlichen Produkten nicht nachgewiesen werden.3,7 -Dimethyl-1,7-octandiol- a new terpene compound of the grape and wine volatilesFor the first time 3,7-dimethyl-1,7-octandiol (hydroxycitronellol) was identified (GC-MS) in the aroma extract of grape musts and wines of various varieties. This component had not previously been found in any plant product