Türkiye Jeoloji Bülteni

Paleokarst Related Zn-Pb Mineralization of Aladağ Mountains

Abstract: The Zn-Pb occurrences of the Aladağ Mountains are in the southeastern part of the Zamanti District of the Middle Taurus, Turkey. The mineralization depends neither on the stratigraphyof the host rocks nor on any magmatic activity. The occurrences are hosted by paleokarst features, developed at the post Cretaceous emergence surfaces in Permian ,and Jurassic limestone series. The distribution ,and shape of the ore deposits arc influenced by the local fracturing ,and paleokarstification related to the varying lithology.The orebodies were deposited as fillings of karstic networks ,and open-spaces in fracture zones. The mineralized material consists in general of chemically / mechanically transported fragments. Replacementof the wall rock represents an important process of mineralization only in structure-controlled weaknesszones in massive Limestones. The sulfide paragenesis consisting almost entirely of sphalerite, galenite ,and pyrite/marcasite, is rare in all occurrences due to oxidation processes. The oxidic ores contain predominantly smithsonite, hemimorphite, hydrozincite, Zn-Al-silicates ,and high amounts of limonite. The filling-type ores occurring in layers ,and/or as cement of clastic sediments reveal very heterogenous compodition ,and structures (mainly geopetal arrangement) with characteristic variations in different karst zones.The detritus between clay ,and pebble size are derived from -stratigraphically ,or tectonically- overlyingophiolitic ,and older sedimentary source rocks. The insoluble residues of the karstified limestones areonly of little importance.The main period of the karst filling ,and karst mine ralization is very probably of Eocene age. Resultson the ore deposition, from regional down to micros copic scale, considering also our geochemical datapoint to an epigenetic origin for the mineralization through remobilisation by exogene processes.