Radial X-Ray Diffraction at the Extreme Conditions Beamline of PETRA III: In-Situ Texture Analysis of a Mixture of Perovskite and Ferropericlase to 1100 K and 40 GPa

Solid-state convection in the Earth interior is associated with the development of seismic anisotropy in many regions of the mantle. One of the main causes of observed seismic anisotropies is plastic deformation of the constituent minerals by dislocation glide, which produces lattice preferred orientation (LPO). If one has a sound understanding of the relationship between deformation and the development of anisotropy, observed anisotropies can be used to infer the dynamic state in the deep Earth. However, due to substantial experimental difficulties, direct in-situ determinations of LPO development at lower mantle conditions are extremely scarce in the literature and are typically limited to single phases. Thus little is known about the interactions between phases during deformation and questions remain as to what phase or phases control deformation and what phase or phases are responsible for observed anisotropies. This lack of information significantly limits our ability to interpret observations of seismic anisotropy in terms of mantle flow models. Substantial experimental progress is needed to investigate deformation of mixtures of lower mantle minerals at relevant pressures and temperatures. In order to extend our capability to deform complex multiphase mineral aggregates at simultaneous high pressures and temperatures exceeding 30 GPa at 1000 K a new experimental setup has been recently developed at the Extreme Conditions Beamline (ECB) P02.2 of PETRA III synchrotron in Hamburg. The new setup is dedicated to perform X-ray diffraction in radial geometry using a modified resistive-heated diamond anvil cell (RH-RDAC). The sample environment is heated by a graphite heater surrounding the sample assembly and diamonds. The DAC is enclosed in a dedicated vacuum vessel to preserve the diamonds and other sensitive components from oxidation at high temperature.Here we present in detail the features and the performance of this setup. We will also discuss results of experimental observations of texture and stress development during deformation up to 40GPa at 1000 K in a simplified lower mantle aggregate of Mg-Pv and Fp. A preliminary analysis of the experiment indicates that Mg-Pv develops a 100 texture and exhibits qualitatively lower stresses than observed in previous room temperature measurements