Abstract

The Biga Peninsula is a well known metallogenic province in Turkey that hosts many currently mined Pb-Zn±Cu±Ag deposits. These deposits are hosted by a variety of rocks that range from metamorphic to volcanic and there has been a long debate about the age and origin of these deposits. The present work contributes to the mineralogy and wall rock alteration of the Çataltepe Pb-Zn±Cu±Ag in Lapseki (Çanakkale) from the Biga Peninsula. The Çataltepe Pb-Zn±Cu±Ag deposit is hosted by rocks that range in age from Mesozoic to Tertiary. Mesozoic rock units are generally characterized by Çamlıca metamorphic and Çetmi Melange units. Çamlıca metamorphics consist schists, quartzite, metasandstone, and phyllite with lens- and/or band shaped recrystallized limestone and/or marble intercalations in green schist facies. The Çamlıca metamorphics are tectonically overlain by Çetmi Melange that consists mainly of serpentinized harzburgite. Tertiary rock units are represented by Şevketiye granitoid (granodiorite) and Beyçayır volcanics (porphyritic andesite, augite-bearing andesite, dacitic andesite and dacite) Eocene in age. The mineralization of the Çataltepe Pb-Zn±Cu±Ag deposit is lithologically controlled and hosted mostly along the marble-metasandstone/quartzite contact and within marble itself. Mineralization is rarely seen at the fractures and cracks of the other metamorphic rocks. Microscopic studies reveal a prograde stage characterized by calc-silicate associations of garnet and pyroxene; followed by a retrograde stage characterized by carbonate and epidote that partly replaced the prograde association. Ore minerals consists of brown sphalerite, honey coloured sphalerite, galena, chalcopyrite, pyrite, pyrrhotite, magnetite, valeriite, hematite, marcasite, arsenopyrite, limonite, and bixbyite. Some of these minerals are found in the fractures of garnet crystals. Electron microprobe analysis (EPMA) of garnets show middle compositions on the grossular-andradite solid solutions. Trace elements compositions of sphalerite obtained by EPMA show that brown sphalerite and galena associated with massive ore have significant compositional differences than honey coloured sphalerite and galena associated with disseminated ore represent two distinct stages in ore genesis. Mineralization appears to be epigenetic formed under meso-epithermal (hydrothermal) conditions in more shallow depths relative to a distal Pb-Zn skarn deposit.