The pyretic sulphide deposits of the lahanos mine area, eastern black sea region, Turkey

Abstract

The Lahanos pyritic sulphide deposit is one of the important copper deposits occurring within the submarine volcanic environment of the Eastern Pontus Ore province. It is situated 10 miles to the south of Espiye, Giresun Vilayeti. Petrographic study of the Lahanos rocks, despite their heavy alteration, shows that they belong mainly to the calc alkaline and tholeiitic basalt suites, and in addition, there are some high-alumina basalts. The intense igneous activity took place during the Mesozoic and the early and middle Tertiary periods. This phase of igneous activity culminated in the intrusion of syntectonic granites, tonolites and adamellites, and was followed by aplitic and hydrothermal phases, in the Pontid Geosyncline. The ore mineralisation, associated with dacites, is characterised by large quantities of pyrite associated with other base metal sulphides such as chalcopyrite, sphalerite, galena and other sulphides and sulphosalts. Field, underground and borehole evidence shows that the Lahanos ore body displays a zonal arrangement, which is similar to the well documented "Kuroko" type ore deposits in Japan. The results of detailed chemical and mineralogical study of the ore and country rock are given and the temperature of formation is estimated. Comparative details are given for the Murgul and Karadere deposits. The evidence supports an epigenetic hydrothermal origin for this "strata bound" deposit, but the volcanicity alone is inadequate to explain the source of the base metals, which are probably derived from the granites. The role of pyroclastic horizons of restricted permeability as a control of precipitation is discussed.