Abstract: Koru (Çanakkale) barite bearing lead-zinc deposits are typical examples of the lead-zinc deposits occurred in theTertiary volcanic rocks outcropped in the Biga Peninsula. Volcanic rocks around the investigated deposits aredistinguished as; Eocene Akçaalan andesite, Oligocene Adadağı pyroclastics, Miocene Dededağ dacite and PlioQ ucite rnary Karaöm e der basalt.The investigated deposits hosted by Adadağı pyroclastics and show two different mineralization styles such asstock work ore veinlets in the upper parts and ore veins along the fault zones in WNW-ESE direction, in the lowerparts. Galena, sphalerite and barite are the main minerals and accompanied by minor amounts of py rite, chalcopyrite,fahlerz (tennantite), marcasite, chalcosine, covellite, bornite, tenorite and quartz.TFM, T m ICE and TH values measured during the fluid inclusion studies indicate the presence of CaCl2 and MgCl2 inthe mineralizing hy d rothermal fluids, salinity of the hydrothermal solutions is rather relatively high during baritecrystalisation in the early episode of mineralization, while decrased during the sulfide dominated later episode. Thetemperatures of fluids is low (< 80 °C) during the early stage and increased up to 270 °C during the later stage.Sulfide minerals seem to be formed in a temperature range of 120-160 °C.Major element results show that the volcanic rocks in the study area have high potassic calcalcaline composition inthe early stage, while they have medium potassic calcalcaline compositon similar to within plate basalts in the laterstage (Karaöm erler basalt).Trace elements contents of the various rock units show that the lead and zinc in the ore deposits may be drivedfrom Akçaalan andesite, while copper from Dededağ dacite. REE studies show that normalised REE values ofbaritesresemble to sea water. The dispersion of the galena, sphalerite and barite values among those of volcanic rocks andseawater on the CeN/YbN ~ YbN diagram was assumed to be ore forming elements were derived from the surroundingvolcanic rocks by deep circulated sea. water