Earth Sciences

Special Issue

Energy&Environment

  • Submission Deadline: 30 January 2015
  • Status: Submission Closed
About This Special Issue
Epithermal Fluid Inclusion Systematics In Ophiolite-RelatedListwaenites From The Izmir-Ankara-Erzincan Suture Zone

The İzmir-Ankara-Erzincan Suture Zone (İAESZ) -between Pontides and Anatolide-Tauride Platform- is charcterized by various rock types, which are derived from an ophiolitic suite. Remnants of an oceanic litosphere, built from ultramafic-mafic rocks and radiolarian cherts, mudstone and pelagic limestones,represent the northern branch of a Tethyan ocean, which developed during Triassic-Jurassic-Cretaceous times. Ultramafic rocks of ophiolitic slices are partly or entirely serpentinitized.Ultramafic rocks (harzburgite, dunite) have 30-45% SiO2, 7-10% Fe2O3, 35-45% MgO and 0.1-1% CaO contents, whereas listwaeniteshave 91-95% SiO2, 5-7% Fe2O3 and 0.1-1%CaO contents. Local iron mineralization is characterized by Fe2O3 contents of 36%.Listwaenites are composed commonly of quartz, chalcedony, chlorite, mineral pseudomorphs of mafic minerals and Cr-spinel and limonite with occasional carbonate minerals, such as calcite, dolomite, and ankerite. Serpentinized ultramafic rocks were replaced by listwaenites, which formed by alteration of ultramafic rocks by hydrothermal solutions along shear planes and thrust zones.Silica-rich hydrothermal solutions seem to have played a larger role than carbonate-rich solutions. In quartz found in the listwaenites, different forms of silica could be distinguished within the epithermal deposits. They consist of large, clear euhedral quartz crystals and banded botryoidal quartz and finely crystalline euhedral quartz crystals having dark air-filled voids, and are not likely suitable for fluidinclusion analyses. Zoned quartz crystals contain primary inclusions defining growth zones, and these also contain irregular, primary inclusions with about constant liquid to-vapor. Consistent inclusions have approximately low temperature (≤200⁰C), low pressure and salinity (0-3,5 % NaCl equivalent), (Bodnar et al., 1985). The earlier fine-grained quartz contains rare or no inclusions while the later quartz forms coarse grained crystals (Fig. 1). This suggests that the silicification took place at different and periodical intervals. The geochemical analyses show that there was no precious-metal precipitation during listwaenite formation. The listwaenitization is likely to be a result of low temperature fluids with low salinity and low pressure.
Guest Editors
  • Hsin-Min Chang

    Science Department, National Open University, Taipei, Taiwan

  • Na-na Li

    North China Electric Power University, Beijing, China