Structural analysis and tectonic evolution of the metamorphites in the Keban (Elazığ) vicinity

The study area includes an area about 300 km2 around Keban town situated in the west of Elazığ on the Eastern Taurus Region with a distance of 45 km far from Elazığ. The aim of this study is to investigate geological features and tectonic evolution of Keban metamorphites which are rather complex due to intensive tectonic activities. Directed to this purpose, a systematic measuring of linear and planar structures in the metamorphites and cover units which outcrop in the study area was carried out. The measured orientations were plotted and represented on maps and analysed in terms of contour diagrams. Many rock samples were examined for paleontologicaL petrographical and microtectonical purposes. Depending on the information and the data obtained from above studies, Stratigraphy of Keban metamorphites, its relation with the other units and directions and tectonic evolution of the stresses were tried to evaluated. The oldest unit in the study area is Early Permian aged Arapgir recrystallised limestones which is placing in the base of Keban metamorphites. These units are overlain conformably by Late Permian aged Nimri formation. This formation which is composed of calc-schist, bedded dolomitic limestone and crystallised limestones is shown gradually transition to the Permian-Triassic Keban marbles. These three units which are following each other uninterrupted, deposited in shallow marine environments. Keban marbles are overlain conformably by Late Triassic aged Delimehmet formation. This formation is shown over of Keban marbles everywhere in the studyarea. Delimehmet formation is indicated flysh characteristic and predominated by elastics with metadiabase intercalations. It is deposited in an active and partially deep marine environment. In relation with closing of south branch of Neo-Tethyan Ocean the Keban metamorphiteş were folded ( Fl, F2 folds ) and also metamorphised during a period Late Cretaceous. The Munzur limestones which are Late Triassic-Late Cretaceous aged and are outcropping in the east of the study area overlie Keban metamorphiteş with a tectonic contact and Ulupmar quartz diorite unit of Elazığ magmatics with an intrusive contact. These limestones were come thrusted from NE to SW approximately 40 - 50 km to their present condition, after Santonian. The cover units of Keban metamorphitesorderly from older to younger are; Early Paleocene aged Kuşçular formation, Thanetian-Lutetian aged Seske formation, Lutetian-Late Oligocene aged Kırgeçit formation, Aquitanian aged Alibonca formation, Late Miocene aged Karabakir formation, and Plio-Quaternary (?) aged Hamurlu formation. The contact of Santonian-Campanian aged Elazığ magmatics and its overlying Late Campanian-Early Maestrichtian aged Sağdıçlar formation with Keban metamorphiteş has tectonic relation. The Late Cretaceous-Paleocene aged Keban magmatics cut all of the older units. In addition, plane of thrust which is between Keban metamorphiteş and Munzur limestones, is cutted by Keban magmatics. The Keban metamorphiteş where folded at least in three stages, depending on Alpin Orogeny. The strike of these deformation phases, orderly from older to younger are; E-W, N-S and NE-SW. The E-W striking deformation phase also produced a metamorphism in greenschist facies. In the study area which were affected from late tectonic activities, Middle Miocene or younger aged blocky faults (Soğanlı Fault ) that strike about NE-SW and NW-SE and a right-strike slip fault with a thrust fault combination (Kırklar fault ) that strikes about N-S / NE-SW were developed. This fault is converted into overthrust fault which is approximately an E-W strike in the south (Hor Overthrust Fault ). Key Words : The Metamorphiteş of Keban, Superposed Folds, Geologic Evolution, Structural analysis, block-faulting.