Geology and Geochemistry of Sediment-Hosted Hanonu Massive Sulfide Deposit (Kastamonu - Turkey)

Abstract

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.