To investigate the pressure/temperature regime of the Earth´s crust and shallow parts of the upper mantle, at the GFZ three piston cylinder presses are installed and run. Two of the three presses are non-endloaded piston cylinder apparatus ("Johannes-type"), with which pressures up to 2.1 GPa and temperatures up to 1400°C can be reached. Salt/graphite- or natural fluorite/graphite-assemblages (latter for temperatures larger 800°C) are of 2.2 cm diameter. Pressures were calibrated according the equilibrium albite = jadeite + α-quartz. For experiments in the pressure range 2.0-5.0 GPa an endloaded piston-cylinder press ("Boyd & England-type") is used for temperatures up to 1650°C. For pressures up to 4.0 GPa salt/graphite-, salt/steel (as furnace material)-or pyrex-glass/pyrophyllite/graphite (for temperatures higher than 1000°C)-assemblages are of 1.27 cm (1/2 inch) diameter; for higher pressures 0.8 cm diameter salt/graphite-assemblages are used. Largest dimensions of precious metal capsules, natural or synthetic materials are welded within, are of 10 mm length and 6 mm in diameter. Variable experimental designs (e.g. up to four capsules in one run, buffered experiments) are possible. Pressure calibration is relied to the a-quartz -coesite transition. Temperatures are monitored by Ni/CrNi- or Pt/PtRh-thermocouples for both types of apparatus.

Fig. 1: Endloaded piston-cylinder apparatus for pressures up to 5.0 GPa

Fig. 2: Schematic drawing of the sample assembly