Volume 25, Issue No. 1, 2000

The low hydrothermal alteration of serpentinites from the ophiolite complexes in Turkey has formed listwaenites with either mineralized or non-mineralized and scattered through the three-ophiolite belts in Anatolia, Turkey. The listwaenite occurrences and associated mineralization in Turkey are reviewed, taking into account the location and description used in literature. The geology and geochemistry of the listwaenites in east central Anatolia serve as a reference to illustrate the characteristics of listwaenite formation and precious metal concentrations in ophiolite belts of Turkey. The late Cretaceous (Pre-Maastrichtian) alteration of serpentinite bodies in the Divrig˘i and Kuluncak ophiolitic mŽlanges, in east central Anatolia has formed two distinct types of listwaenite. The earliest is silica-carbonate listwaenite (type I), which is dominated by silica+calcite+dolomite+ankerite±magnesite. Later, carbonate listwaenite (type II) comprise calcite+dolomite+ankerite±magnesite, and lack any significant introduction of silica. In the Divrig˘i and Kuluncak ophiolitic mŽlanges the most of the silica-carbonate (type I) and carbonate (type II) listwaenite are formed along thrust fault zones. In clearly fault-related listwaenites, thrust fault(s) acted as pathway for hydrothermal fluids. In non fault-related listwaenites, hydrothermal fluids moved along highly serpentinized microfractured, stockworked and porous ultramafic rocks. The hydrothermal fluids involved in the formation of carbonate (type II) listwaenite differed from those that formed silica-carbonate (type I) listwaenite, which was enriched in SiO₂, as well as CO₂, Ca and H₂O, whereas those that formed carbonate listwaenite were SiO₂ deficient, and enriched only in CO₂, Ca and H₂O.