Abstract: Along a belt streching from Cyprus, Southeast Anatolia, Zagros and to the Oman Mountain, a linear trough was formed during Upper Cretaceous as the northern edge of the Arabian Craton subsided and allochthonousophiolite blocks were carried in from the north. From Upper Cretaceous to Miocene, shallow marine sedimentary rocksdeposited over the allochthonous units. However, volcanic activity continued up to the Eocene or Oligocene time alonga second belt loceted to the north of the trough. In this study the geoioy of this second belt, which is called SoutheastAnatolian Ophiolite belt, is examined around the Efgani - Maden region and by using chemical characteristics of thevaiconic rocks, its tectonic evolution is evaluated.In the Ergani - Maden region along the Southeast Anatolian ophiolite belt, crops out as the oldest rocks, Guleman group which consists of gradational peridotite, banded gabbro and basalt units. The Guleman group has beenmetamorphosed under greenschist facies conditions. Chemical composition of the volcanic rocks of the Guleman groupresembles to those of low potassium tholeiites of the midoceanic ridges.Maden group, overlying the Guleman group unconformably with a discontinious conglomerate at its base, iscomposed of basaltic volcanics, volcaniclastics, mudstones and pelagic limostones. In the Mâden group, which is Maastrichtien - Upper Eocene in age, the lower volcanic - sediment unit and the upper volcanic unit have been separated.This group has been metamorphosed under prehnite •• pumelliyite facies conditions. The chemical composition of thevolcanic rocks of the Maden group resembles to those of islaand - arc tholeiites.