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The fields of experimental mineralogy, geochemistry and geophysics are currently passing through an exciting evolutionary stage that will lead, in the coming years, to significant improvements in our understanding of the composition, structure and dynamics of the Earth´s interior. This is partly the consequence of a number of recent technological developments that are revolutionising experiments in studies of materials at high pressures and temperatures. The acquisition by the Bayerisches Geoinstitut of a new, unique 5000 tonne multi-anvil high-pressure system that was installed in late 1997 is one example of these developments. As with the existing multi-anvil presses, this new system will enable experiments to be performed up to 25 GPa and 2800°C, which simulate conditions in the Earth at a depth of more than 700 km. The advantage of the new 5000 tonne system is that the size of the samples used in the experiments can be increased significantly. A larger sample size will improve the accuracy of physical property measurements that are made in-situ at high pressures and temperatures, and also enable such measurements to be made at much higher pressures. These physical properties include electrical conductivity, rheology and elasticity. As documented in this Annual Report, significant progress in making such measurements has already been achieved at the Bayerisches Geoinstitut. The electrical conductivities of olivine, wadsleyite and ringwoodite, the most abundant minerals present in the Earth to a depth of 660 km, have now been measured up to 18 GPa and 1400°C. These new results are of great value for refining geophysical models of the electrical conductivity of the Earth´s interior, such models being a principal source of information for understanding mineralogy, composition and temperature as a function of depth. In the last year, it has, for the first time, become possible to perform high-strain deformation experiments on ringwoodite at high pressures and temperatures (16 GPa and 1300°C). Ringwoodite is the most abundant mineral in the transition zone of the Earth´s mantle (depth 410-660 km) and a knowledge of the rheology of this region obtained through deformation experiments is critical for understanding the convective behaviour of the entire mantle. The latter stands as one of the key unresolved issues in the Earth Sciences.

The "third generation" synchrotron radiation sources, which have recently come on line at the European Synchrotron Radiation Facility (ESRF) in France, the Advanced Photon Source (APS) in USA, and SPring-8 in Japan, represent another technological development that is important for the field of experimental Earth Sciences. These facilities now produce X-rays with characteristics that enable a wide range of in-situ experiments to be performed with the aims of investigating crystal structure, equations of state, reaction kinetics, and rheology of crystalline solids and melts under the conditions of the Earth´s deep interior. So far the involvement of the Bayerisches Geoinstitut in such experiments has been limited to crystallographic investigations. It is now planned that our involvement will increase significantly in the future. It is intended, for example, through international collaborations, to utilise synchrotron radiation facilities for novel experiments to investigate the rheological properties of materials (both minerals and melts) at extreme conditions of temperature and pressure.

An indication that the quality of the research and the experimental facilities of the Bayerisches Geoinstitut place us at the forefront of high-pressure research in Europe is provided by the recent decision of the European Union to support the institute for a further two years (1998-2000) as a Large Scale Facility for High-Pressure Research. This funding, which commenced in 1994, enables scientists from other institutes in EU countries to visit the Bayerisches Geoinstitut for periods up to three months in order to utilise the high-pressure experimental facilities. By the end of 1997, 51 scientists from 8 European countries had visited under this scheme, with a total of 1634 man-days of access time being provided.

As we look forward to the coming year, one development is particularly notable in the history of the Bayerisches Geoinstitut. Stephen Mackwell commenced on 1 January 1998 as Professor of Experimental Geophysics of the Solid Earth. The filling of this third professorship represents the final stage in the initial growth of the institute and will enable our research activities to expand into the areas of rheology and mass transport at high temperatures and pressures.

As in previous years, and also on behalf of my colleagues, I would like to thank the Free State of Bavaria as represented by the Staatsministerium für Kultus, Unterricht, Wissenschaft und Kunst as well as the Kommission für Geowissenschaftliche Hochdruckforschung for their continuing support and strong commitment to the Bayerisches Geoinstitut. We also gratefully acknowledge generous support from external funding agencies, in particular the Alexander von Humboldt Foundation, the European Union, and the German Science Foundation, which have also contributed greatly to the development and success of the Institute.