Sedimentary evolution of Lake Van Eastern Turkey

Authors: Deniz Cukur Sebastian Krastel Filiz DemirelSchlüter Emin Demirbağ Caner Imren Frank Niessen Mustafa Toker PaleoVanWorking Group

Publish Date: 2012/09/04

Volume: 102, Issue: 2, Pages: 571-585

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Abstract

This paper presents results of a multichannel seismic reflection survey at Lake Van and provides constraints on the sedimentary evolution of the lake The geophysical data of the lake confirm the existence of three physiographic provinces a shelf a slope and a deep relatively flat basin The most prominent features identified on the shelf and slope are clinoforms submerged channels as well as closely spaced lake floor depressions reflecting a highly variable lakelevel history The morphological depressions are interpreted as resulting from subaquatic erosion by channelized sedimentladen currents into horizontally bedded fan sediments Submerged channels on the eastern shelf are interpreted as meanderingslope channels probably as a consequence of a lakelevel fall that exposed the shelf area Clinoforms on the Eastern fan may represent relict deltas formed during stationary or slightly rising lakelevel intervals Merging subsurface imaging interpretation with morphological studies of exposed sediments reveals lakelevel fluctuations of several hundreds of meters during the past ca ~550 ka The lake has three prominent basins Tatvan Deveboynu and the Northern basin separated by basement ridges eg the Northern ridge The seismic units in the Tatvan and Northern basins are dominated by alternations of wellstratified and chaotic reflections while the Deveboynu basin subsurface consists mainly of chaotic units The chaotic seismic facies are interpreted as massflow deposits probably triggered by earthquakes and/or rapid lakelevel fluctuations The moderatetohighamplitude wellstratified facies seen in the deeper parts of the basins are interpreted as lacustrine deposits intercalated with tephra layers The occurrence of a clinoform in the deepest part of the lake suggests a major flooding stage of Lake Van more than ~400 ka ago Seismic profiles from the deepest part of the lake basin show remarkably uniform and continuous stratigraphic units without any major erosional feature following the flooding event indicating that the lake was never completely dry afterward and therefore significantly older than previously suggestedWe would like to thank Prof Sefer Örcen and his team from Yüzüncü Yil University Van for the possibility to use the university boat and logistic support The boat crew is thanked for their untiring commitment which made the cruise a great success Two anonymous reviewers are acknowledged with thanks for their constructive comments and suggestions The IHS Kingdom® software was used for seismic data interpretation and mapping Financial support was provided by the Deutsche Forschungsgemeinschaft Project KR22229

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