| Deformation on the earth's lithosphere is largely an accommodatory response to the convective processes in the deeper mantle. The accommodation reflects the transfer of deformation from the convective lower mantle through the upper mantle and lower crust to the upper crust and surface. The kinematic, mechanistic and geometric response becomes increasingly complex during the transfer process with the accommodation being increasingly partitioned into shears and faults. Along with the partitioning, there is a concentration in hydrous fluid flow and melt generation and transport. These in turn affect the continuing response to deformation transfer and vice versa. Metallogenesis is one consequence of the multiple interplay between deformation, hydrous fluid and melt activities. Also of importance is the response of the lithosphere in the early earth to mantle convection, the extent to which it varied from the present and the effects any variations have on metallogenetic processes. Methods: Field mapping, microstructural and microtextural analysis, electron microscopy, isotope geochronology, geochemistry. Aims: 1) to quantity natural deformation processes to enable a better understanding of the kinematic and geometrical response of the earth's crust to imposed stresses and strains resulting from mantle flow and their evolution through time, especially in the early earth. 2) to delineate the effects of the above responses in metallogenesis. Present topics: Deformation transfer from lower to upper crust in the destabilization of the Alpine Orogeny in the Aegean area (see also post-doctoral project of A. Lips and Ph.D. project of M. van Koolwijk); deformation and tectonic processes in the early Earth (see also Ph.D. project of K. Beintema); role of melt and hydrous phases in the deformation of the lower crust, crustal deformation mechanisms, strain softening ((also see Ph.D. project of M.J. Zuijderwijk)); deformation processes during the reactivation of crustal shears, kinematic controls within shear zone related metallogenesis (see also Ph.D. project of F. Guerreiro); metallogenesis during orogenic destabilization in the present and early earth. |
