Geochronology of Late Cenozoic Volcanism in the Area of Lake Van, Turkey: an Example of Developmental Dynamics for Magmatic Processes (Vol 433, Pg 1031, 2010)

Abstract

An isotope-geochronological study has been performed to examine the products of Late Cenozoic collision volcanism on the northern coast of Lake Van, Turkey. We obtained 45 new K-Ar dates, based on which the principal time characteristics of volcanic activity in the region have been determined. Volcanic activity in the northern coast of Lake Van has lasted similar to 15 myr; it has had an expressed discrete nature, when periods of intense volcanic activity alternated with long-lasting pose periods. Four stages of Neogene-Quaternary volcanism have been identified: Middle Miocene (15.0-13.5 Ma), Late Miocene (10-9 Ma), Pliocene (5.8-3.7 Ma), and Quaternary (1.0-0.4 Ma). The average duration of the stages was 1-2 myr; the stages were separated from each other with periods of inactivity of approximately equal lengths (similar to 3 myr). For each of the Pliocene and Quaternary stages, three additional phases of volcanism have been identified, which were separated from each other with short time intervals (a few hundred thousand years). The last burst of volcanic activity in the study area occurred similar to 400 ka; similar to Quaternary volcanism in general, it was not characterized by a high intensity. An important result of the studies performed was to confirm the existence of a separate Middle Miocene stage of collision volcanism for the Caucasian-Anatolian Segment of the Alpine Fold Belt. New geochronological data generated presented in this paper indicate that Neogene-Quaternary volcanism in this portion of the belt started much earlier (similar to 15 Ma) than assumed by the majority of the previous researchers.