The Pyroclastites Around Southwestern Part of Van Lake (Eatern Anatolia, Turquey): Implications on The Regional Palaeohydrography

Abstract

THE PYROCLASTITES AROUND SOUTHWESTERN PART OF VAN LAKE (EATERN ANATOLIA, TURQUEY): IMPLICATIONS ON THE REGIONAL PALAEOHYDROGRAPHY Located in eastern Anatolia (Turkey), Lake Van is the fourth largest lake in the world. Along the banks of the lake, several lake terraces record Pleistocene variations of the lake levels. In the terraces, the lake deposits are often interbedded with pyroclastites emitted by the volcanoes located on the northern side of the lake. Our research focuses on the south-western part of the lake, where several pyroclastites interbedded with lake deposits allow establishing a regional tephrostratigraphy, which is being Ar/Ar dated. In this area, the study of the pyroclastites allows to understand the impact of volcanism on the palaeohydrography: all the valleys where filled-in with pyroclastites which induced heavy disruptions of the drainage network. Moreover, our research enlightens evidences that volcanic activity was responsible for the enclosure of the lake and that the major transgression of the lake, dated ca. 100 ka, is not only linked to changes in the water balance, but at first linked to volcanic activity.