‹nler Yaylas› Pb-Zn yataklar›; Do¤u Karadeniz Bölgesi’nin iç kesimlerinde yayg›n olarak gözlenen damar tipi yataklar›n tipik örneklerindendir. Yörede, Üst Kretase yafll› volkanitler, Tersiyer yafll› Granitoyitler, Eosen ve PliyoKuvaterner yafll› volkanitler yüzeylemektedir. Yöredeki kurflun-çinko yataklar›; Üst Kretase yafll› volkanitler içinde, yaklafl›k D-B do¤rultulu ve üç cevher damar› fleklinde olup, bu damarlar yaklafl›k olarak KB-GD do¤rultulu faylarla kesilip ötelenmifllerdir. ‹ncelenen örneklerde cevher minerali olarak; sfalerit, galenit, pirit, kalkopirit, fahlerz ve ender olarak da kalkosin ve kovellin, gang minerali olarak ise kuvars ve kalsit gözlenmifl olup sfalerit ve galenit enyayg›n cevher mineralleridir. Opak cevher mineralleri, en son evrede oluflmufl kuvars kristalleri aras›ndaki boflluklarda kristallenmifl olup, kuvarslardan daha sonra oluflmufllard›r. Sfalerit ve galenitlerdeki kükürt izotoplar› bileflimi (δ 34S); -3.9 ile +0.4 ‰ CDT aras›nda de¤iflmekte olup, bu de¤erlerden yararlan›larak, hidrotermal çözeltilerdeki H2S’in izotopsal bilefliminin -5.0 ‰ civar›nda oldu¤u hesaplanm›flt›r. Bu kürükt izotoplar› de¤erleri do¤rudan ma¤- matik faaliyetlerle iliflkili de¤erlere göre hafif olup, sülfürlü minerallerin bileflimindeki kükürtün yöredeki Tersiyer yafll› granitoyitler ve genç volkniklerle do¤rudan iliflkili ma¤matik köenli kükürt olmaktan daha çok, epijenetik hidrotermal çözeltilerce Üst Kretae yafll› volkanik kayaçlardan çözülmüfl kükürt oldu¤u kabul edilebilir. Mineral oluflturucu çözeltiler içindeki suyun oksijen izotoplar› bileflimi, kuvarslarda analiz edilmifl δ 18O de¤erleri ve s›v› kapan›m incelenmeleri s›ras›nda ölçülmüfl homojenleflme s›cakl›¤› de¤erleri kullan›larak hesaplanm›flt›r. Bu hesaplanan δ 18O (+4.2 ile +6.7‰; SMOW) de¤erleri ve s›v› kapan›mlar›nda analiz edilmifl δ D de¤erleri (-83.0 ile -59.0‰;SMOW), δ 18O -δ D diyagramlar› üzerinde ma¤matik kökenli su kutusu içinde veya meteorik su çizgisi taraf›nda konumlanmakta olup mineral oluflturucu çözelti içinde ma¤matik kökenli suyun hakim oldu¤u ve az miktarda metorik suyun da kar›flm›fl olabilece¤ini belirtmektedir.

‹nler Yaylas› lead and zinc deposits are the typical examples of the vein type lead-zinc deposits occur within the Eastern Black Sea Region in Turkey. In the study area; Upper Cretceous volcanics, Tertiary granitoids, Eocene and Plio-Quaternary aged volcanics are outcropped. Ore deposit are developed as ore veins along the the faults in the Upper Cretaceous volcanics. Three ore veins in E-W direction were identified and they were cut and displaced by NW-SE trending faults. Microscopic studies revealed that the ore veins contain sphalerite, galena, pyrite, chalcopyrite, fahlore group minerals, chalcosite and covellite as ore minerals, and quartz and calcite as gangue minerals. Sphalerite and galena are dominant. Opaque minerals occur among the quartz crystals. This indicates that suifide mineralisation occurred later than quartz crystalization. The sulphur isotope composition (δ 34S) of sphalerite and galena ranges from -3.9 to +0.4 ‰ CDT and that of H2S in hydrothermal fluids was calculated around -5.0 ‰. These sulphur isotope values are light compared to that of direct magmatic activities and it may be assumed that the sulphur in the sulfide minerals was possibly leached from the Upper Cretaceous volcanics by epigenetic hydrothermal fluids, rather than having direct magmatic relation to Tertiary granitoids and the younger volcanics occuring in the area. The oxygene isotope composition of the water in the mineralising fluid was calculated using the δ 18O values analysed in quartz and homogenisation temperature values measured during the fluid incluison studies. The calculated δ 18O values ( +4.2 to +6.7 ‰ (SMOW)) and δ D values analysed in inclusion fluid (-83.0 to -59.0 ‰ (SMOW)) plot in or at the meteoric water line side of the the magmatic water box on the δ D - δ 18O diagram and indicate that mineralising fluid was dominated by magmatic water and minor amount of meteoric water might have been mixed.