hans-rudoLf WenK

Learn More
a GeoForschungsZentrum Potsdam, Section 4.1, Telegrafenberg, 14473 Potsdam, Germany b Department of Geosciences, Princeton University, Princeton, NJ 08544-1003, USA c Department of Civil and Environmental Engineering, University of California, Berkeley, CA, 94720, USA d Department of Earth and Planetary Science, University of California, Berkeley, CA(More)
a r t i c l e i n f o Keywords: San Andreas Fault SAFOD porosity permeability fault rock composition TEM With transmission electron microscopy (TEM) we observed nanometer-sized pores in four ultracataclastic and fractured core samples recovered from different depths of the main bore hole of the San Andreas Fault Observatory at Depth (SAFOD). Cutting of(More)
Microstructures of deformed calcite in marble from the Bergell Alps are studied by using a microfocused polychromatic synchrotron X-ray beam. The high spatial resolution, together with orientation and strain resolutions, reveals twin plane orientation, multiple twin lamellae, and strain distributions associated with the twins. Single and multiple mechanical(More)
Recent high-pressure studies have shown that an electronic spin transition of iron in ferropericlase, an expected major phase of Earth’s lower mantle, results in changes in its properties, including density, incompressibility, radiative thermal conductivity, electrical conductivity, and sound velocities. To understand the rheology of ferropericlase across(More)
Cubic magnesiow} ustite has been deformed in a diamond anvil cell at room temperature. We present results for (Mg0.4Fe0.6)O, (Mg0.25Fe0.75)O, and (Mg0.1Fe0.9)O up to 37, 16, and 18 GPa, respectively. The diffraction images, obtained with the radial diffraction technique, are analyzed using both single peak intensities and a Rietveld method. For all samples,(More)
A microstructural investigation of stishovite-bearing quartzite from the Vredefort meteorite impact site in South Africa reveals features that are attributed to shock deformation. These include abundant mechanically induced Dauphiné twinning, rhombohedral deformation lamellae and associated residual stresses. Mechanical twins were identified with SEM-EBSD.(More)
Mechanical Dauphiné twinning in quartz has been of long-standing interest, both in single crystals and polycrystalline aggregates. This study investigates texture development in fine-grained quartz rock novaculite with no initial texture using compression experiments conducted in the Paterson gas apparatus to explore the influence of stress and temperature.(More)
a r t i c l e i n f o Increasing use of diffraction methods to study preferred orientation of minerals has established that quartz in deformed rocks not only displays characteristic c-axis orientation patterns, but that there is also generally a distinct difference in the orientation of positive and negative rhombs. In the trigonal quartz crystal structure(More)
It is shown that the deformation state of a granitic rock has a profound impact on the long-term stability of concrete, if used as aggregate due to enhanced susceptibility to the alkali-silica reaction. An investigation of the microstructure of granitic rocks from the Santa Rosa mylonite zone in southern California with transmission electron microscopy and(More)