Pontid kuşağında Artvin bölgesinin jeokimyası, petrojenezi ve masif sülfit mineralizasyonları

Abstract

ÖZET Pontid - Küçük Kafkaslar magmatik kuşağının ortasında yer alan Artvin yakın yöresi magmatik petroloji ve bununla ilgili masif sülfit birikimleri açısından incelenmiştir. Taban Jura veya daha yaşlı kayaçlardan ve metamorf itlerden oluşmaktadır. Bu seri yer bilimciler tarafından Alt Bazik Seri diye adlandırılmıştır.Bu birimi Artvin Granitoyidi kesmektedir. Granitoyidlerin üzerine bir taban konglomerası ile cevherli dasit lav ve tüfleri gelmekte ve bunları mor dasitler kesmektedir. Bu birimleri bazalt, kireçtaşı, tüf ardalanmalı volkano-tortul seri uyumlu olarak üstler. üst Kretase yaşlı birimler yer yer Paleosen yaşlı birimlere geçiş gösterirler. Taban konglomerası ile başlayan Orta Eosen yaşlı f iliş fasiyesindeki kayaçlar alttaki birimleri uyumsuz olarak üstler. Eosen sonrası yerleşen genç kuvarslı diyoritler ve hornblend dasitler en genç birimleri oluşturmaktadır. Artvin yakın yöresi bir ada yayı ortamını belirtmektedir. Bundan dolayı bölgede yoğun bir granitizasyon ve buna eşlik eden dasidik volkanizma oluşmuş, bunlara bağlı olarak çok yoğun magmatik hidrotermal olaylar etkin olmuştur. Bu dasidik volkanizmaya bağlı olarak Artvin yakın yöresinde masif ve damar tipi birçok sülfit mineralizasyonu oluşmuştur. Bunlar genel olarak Cu - Zn - Pb bileşimlidir. Bundan başka sahada birkaç küçük Mn zuhuru da izlenmektedir. Bu Cu - Zn - Pb cevherleşmelerin en önemlileri Kuvars- han, trsahan, Sinkot, Seyitler, Kafkasor, Eski Gümüşhane, Ormanlı zuhurlarıdır. Bu cevherleşmeler köken olarak volka nik bir merkez civarındaki kırıklardan itibaren yükselen hidrotermal sıvılardan meydana gelmiştir. Cevherleşmeler dasidik piroklastlarla eş zamanlı çökelmiş veya içine yerleş miştir. Cevher minerallerinin 400'-350°C civarında bir ısıda oluşmaya başladığı daha sonra ısının düşmesiyle jel yapılı piritlerin oluştuğu anlaşılmaktadır. Daha sonra cev herleşmeyle eş yaşlı veya daha genç olan kırmızı biyomikrit ler cevherleşmeyi örtmektedir. Eosen sonuna kadar bölgede çökeller oluşmayı sürdürmüş ve daha sonra bölge tektonik olaylar sonucu kıvr ımlanmış, kırılmıştır. vıGeochemistry, Petrogenesis and Massive Sulphide Mineralizations of the Artvin District of the Pontid Belt, NE Turkey. SUMMARY Artvin district which is located in between Pontid and Lasser Caucassus has been investigated for magma tic petrology and related polymetallic massive sulphide depositions. The base of the succession which comprieses the basic lavas and their metamorphics, are of Jurasssic age. These are named as `Lower Basic Series` by previous authors. The `Lower basic series` are cut by the Artvin granitoid. This granitoid is overlain by ore-bearing dacites and tuffs. All these are cut by purple-colored dacites. this successions is conformably overlain by the volcano-sedimantary series. In some places the units of Upper Cretaceous ages show graduation into the Paleocene formations. Flych -like formations of Middle Eocene age unconformibly overlie the older formations. The younger Q-diorites and hornblende dacites of Post Eocene age are the youngest formations of the area studied. Artvin area indicates an island arc enviroment. Resulted granitization and associated dacites caused the intensive magma tic hydrothermal activities. Related to this dacitic volcanism many massive or vein type sulphide mineralizations deposited. These generally are of Cu-Zn-Pb composition. Some Mn mineralization whith limited size are also seen. The most impotant massive sulphides are the Kuvarshan, İr sahan, Sinkot, Seyitler, Kafkasor, Eski Gümüşhane and Ormanlı mineralizations. These deposits are related to the hydrothermal fluids which were dischargeced from conduits around the volcanic centers and are contemporaneous with the depositions of dacitic pyroclastics. Starting temperature of the deposition of the ore minerals is around 400-350°C. Presence of colloform pyrites also indicate the pyrite gel depositions at lower temperatures. Contemporary and younger reddish biomicrites overlie the ore formations. Depositions continued at the end of Eocene time. After Eocene, the area were faulted and folded because of the regional compresional stresses. vii

Geochemistry, Petrogenesis and Massive Sulphide Mineralizations of the Artvin District of the Pontid Belt, NE Turkey. SUMMARY Artvin district which is located in between Pontid and Lasser Caucassus has been investigated for magma tic petrology and related polymetallic massive sulphide depositions. The base of the succession which comprieses the basic lavas and their metamorphics, are of Jurasssic age. These are named as `Lower Basic Series` by previous authors. The `Lower basic series` are cut by the Artvin granitoid. This granitoid is overlain by ore-bearing dacites and tuffs. All these are cut by purple-colored dacites. this successions is conformably overlain by the volcano-sedimantary series. In some places the units of Upper Cretaceous ages show graduation into the Paleocene formations. Flych -like formations of Middle Eocene age unconformibly overlie the older formations. The younger Q-diorites and hornblende dacites of Post Eocene age are the youngest formations of the area studied. Artvin area indicates an island arc enviroment. Resulted granitization and associated dacites caused the intensive magma tic hydrothermal activities. Related to this dacitic volcanism many massive or vein type sulphide mineralizations deposited. These generally are of Cu-Zn-Pb composition. Some Mn mineralization whith limited size are also seen. The most impotant massive sulphides are the Kuvarshan, İr sahan, Sinkot, Seyitler, Kafkasor, Eski Gümüşhane and Ormanlı mineralizations. These deposits are related to the hydrothermal fluids which were dischargeced from conduits around the volcanic centers and are contemporaneous with the depositions of dacitic pyroclastics. Starting temperature of the deposition of the ore minerals is around 400-350°C. Presence of colloform pyrites also indicate the pyrite gel depositions at lower temperatures. Contemporary and younger reddish biomicrites overlie the ore formations. Depositions continued at the end of Eocene time. After Eocene, the area were faulted and folded because of the regional compresional stresses. vii