Entstehung und Ablauf von enormen (bis 600 m) Seespiegelschwankungen im Lake Van (Ostanatolien): Klima vs Geodynamik

• Antragsteller: Professor Dr. Hans-Ulrich Schmincke (†)
• Fachliche Zuordnung: Paläontologie
• Förderung: Förderung von 2018 bis 2022
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 414840187

• Erstellungsjahr: 2022

Zusammenfassung der Projektergebnisse

Two holes were drilled in the Paleovan ICDP Drilling Project through the 200 m thick sediments of 200 m deep Lake Van (eastern Turkey), the largest sodic lake in the world with the purpose to monitor climate changes over some 500 000 years. The lake basin is not only tectonically highly active - viz. a 1990 earthquake with 600 fatalities in Van -, the slopes of two active young volcanoes (Süphan, the largest volcano in Turkey, and historically active Nemrut) extend to the base of the northern and western lake basin. One major objective of our work was to explore to what degree volcanic/tectonic forcing dominated the evolution of the lake basin and volcanic and nonvolcanic sedimentation and controlled extremely variable changes in lake level (as much as 500 m !) through the ca. 500 000 years of the lakes activity vis-à-vis climate forcing. Our work was focused on the analysis of some 350 primary and reworked tephra layers supplied from Süphan and Nemrut and some intralake volcanoes. A major goal of our project was also to physically determine precise physical ages to monitor both the evolution of the volcanic activity and climate variations determined by other groups. Three important results illustrate the interdependance of climate and volcanic activity. 1. Tephra layers are numerous in the time window between historic and ca 14 ka and again after ca 30 ka. We interpret this tephra gap as a result of climate variations, the cold climates around the glacial maximum loading the lithosphere thereby reducing partial melting in the mantle while explosive volcanism strongly increased from both volcanoes after ca 15 000 years following lithosphere unloading. 2. Seismic triggering was an important precursor to volcanic activity as shown by highly faulted intervals including triggered turbidites preceding many volcanic eruptions. 3. The most drastic lake level low stands as much as almost 600 m (!) occurred in two stages between ca 280 and ca. 400 m as shown by seismic data. Our detailed studies of thick tephra intervals in this age range found most of them to be highly reworked and a close temporal correlation with growth of a major morphological ridge in the lake basin probably due to a belt of trachytic intrusions. This correlation of several variables suggests to us that geodynamic forcing throughout the lake`s history influenced lake level as much as climate.

Projektbezogene Publikationen (Auswahl)

• Impact of volcanism on the evolution of Lake Van I: evolution of explosive volcanism of Nemrut Volcano (eastern Anatolia) during the past >400,000 years. Bulletin of Volcanology, 75(5).
  Sumita, Mari & Schmincke, Hans-Ulrich
  
• Impact of volcanism on the evolution of Lake Van II: Temporal evolution of explosive volcanism of Nemrut Volcano (eastern Anatolia) during the past ca. 0.4 Ma. Journal of Volcanology and Geothermal Research, 253, 15-34.
  Sumita, Mari & Schmincke, Hans-Ulrich
  
• Impact of volcanism on the evolution of Lake Van (eastern Anatolia) III: Periodic (Nemrut) vs. episodic (Süphan) explosive eruptions and climate forcing reflected in a tephra gap between ca. 14ka and ca. 30ka. Journal of Volcanology and Geothermal Research, 285, 195-213.
  Schmincke, Hans-Ulrich & Sumita, Mari
  
• Sedimentary evolution and environmental history of Lake Van (Turkey) over the past 600 000 years. Sedimentology, 61(6), 1830-1861.
  Stockhecke, Mona; Sturm, Michael; Brunner, Irene; Schmincke, Hans‐Ulrich; Sumita, Mari; Kipfer, Rolf; Cukur, Deniz; Kwiecien, Ola & Anselmetti, Flavio S.
  
• Seismic stratigraphy of Lake Van, eastern Turkey. Quaternary Science Reviews, 104, 63-84.
  Cukur, Deniz; Krastel, Sebastian; Schmincke, Hans-Ulrich; Sumita, Mari; Çağatay, M. Namık; Meydan, Aysegül Feray; Damcı, Emre & Stockhecke, Mona
  
• Water level changes in Lake Van, Turkey, during the past ca. 600 ka: climatic, volcanic and tectonic controls. Journal of Paleolimnology, 52(3), 201-214.
  Cukur, Deniz; Krastel, Sebastian; Schmincke, Hans Ulrich; Sumita, Mari; Tomonaga, Yama & Namık, Çağatay M.
  
• Peralkaline felsic magmatism at the Nemrut volcano, Turkey: impact of volcanism on the evolution of Lake Van (Anatolia) IV. Contributions to Mineralogy and Petrology, 169(4).
  Macdonald, Ray; Sumita, Mari; Schmincke, Hans-Ulrich; Bagiński, Bogusław; White, John C. & Ilnicki, Sławomir S.
  
• Structural characteristics of the Lake Van Basin, eastern Turkey, from high-resolution seismic reflection profiles and multibeam echosounder data: geologic and tectonic implications. International Journal of Earth Sciences, 106(1), 239-253.
  Cukur, Deniz; Krastel, Sebastian; Tomonaga, Yama; Schmincke, Hans-Ulrich; Sumita, Mari; Meydan, Ayşegül Feray; Çağatay, M. Namık; Toker, Mustafa; Kim, Seong-Pil; Kong, Gee-Soo & Horozal, Senay
  
• Large-volume basaltic hyaloclastite eruption along a propagating land/lake lithosphere fracture at Lake Van (Eastern Anatolia): impact of volcanism on the evolution of Lake Van V. Bulletin of Volcanology, 80(12).
  Schmincke, Hans-Ulrich; Sumita, Mari & Cukur, Deniz