Browsing by Author "Ozkumus, Serkan"

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Geology and Geochemistry of Sediment-Hosted Hanonu Massive Sulfide Deposit (Kastamonu - Turkey)
(Elsevier, 2018) Gunay, Kurtulus; Donmez, Cahit; Oyan, Vural; Yildirim, Nail; Ciftci, Emin; Yildiz, Hayrullah; Ozkumus, Serkan
Hanonu massive sulfide (HMS) mineralization is the first sediment-hosted massive sulfide deposit discovered in Anatolia (Turkey). Containing more than 1% Cu and with more than 25 million tonnes reserve, the HMS mineralization is located in the Cangaldag Metamorphic Complex (CMC) in the central Pontides within metavolcaniclastic rocks with mafic sill and/or lava interlayers. Rocks related to mineralization were exposed to metamorphism under the greenschist facies conditions. Tectonism and metamorphic processes affected all units including ore. The HMS mineralization consists dominantly of Cu (0.2-6.9%) accompanied by Zn (239 ppm-1%) and comprises massive, banded and disseminated sulfide bodies. The main ore minerals include pyrite, chalcopyrite, with minor sphalerite and magnetite. The regular stratigraphy displaying uninterrupted layers of volcanoclastics contains mafic lava or sills within the sequence with the mineralization initially emplaced within immature clastics and then subjected to metamorphism as a package, which indicates that the ore and wall rocks formed in the same paleotectonic environment. Data obtained from melt models of mafic lava or sills related to the HMS mineralization indicate these rocks formed in back-arc basins from a mixture of 70% depleted MORE; mantle and 30% asthenospheric melt with melting degrees possibly of 8-15%. According to isotope data, lead from the HMS mineralization may be sourced from an arc-related environment, with magmatic activity in the lower crust and upper mantle. Geologic and geochemical data indicate that the HMS mineralization may have formed in a back-arc rift tectonomagmatic environment.
Geology, Geochemistry and Re-Os Geochronology of the Jurassic Zeybek Volcanogenic Massive Sulfide Deposit (Central Pontides, Turkey)
(Elsevier, 2019) Gunay, Kurtulus; Donmez, Cahit; Oyan, Vural; Baran, Cuneyt; Ciftci, Emin; Parlak, Osman; Ozkumus, Serkan
Located in the north of Anatolia, the Pontide Orogenic Belt hosts Turkey's most important volcanogenic massive sulfide (VMS) deposits. Studies completed in the last ten years have discovered new massive sulfide deposits in the Central Pontide zone. The Zeybek VMS deposit is one of these newly-discovered deposits found in the Central Pontides. This deposit is associated with the Cangaldag Metamorphic Complex occurring as east-west-striking tectonic slices. The Cangaldag Metamorphic Complex is an allochthonous mass of metavolcanic, metavolcanidastic and metaclastic rocks in the form of imbricated tectonic slices. Zeybek massive sulfide deposit is located within metaclastic rocks intercalated with mafic sills or lava flows in this complex. The major ore mineral paragenesis in the Zeybek VMS deposit comprises pyrite, chalcopyrite and sphalerite, with lower amounts of bornite, covelline, chalcocite and magnetite. With thirty thousand meters of drilling in the mineralized area, 20 million ton resources with 0.32 wt% Cu were determined. According to the wall-rock mineralization relationships, mineralization style and ore geochemistry of the Zeybek VMS mineralization, it is similar to a mafic-siliciclastic type volcanogenic massive sulfide formation. Re-Os geochronologic studies of chalcopyrites from the Cu-rich massive ore samples obtained a 178 +/- 2.2 Ma (MSWD: 4.1) Re-187/Os-188 against Os-187/Os-188 isochron. Geochemical and isotopical age data associated with the Zeybek VMS deposit indicate that the mineralization occurred in an arc-back arc tectonic environment, which developed in Middle Jurassic age intra-ocean as a result of the closure of north-ward subduction that resulted the closure of the Tethys ocean.