|TITLE||LATE PLEISTOCENE-HOLOCENE CLIMATIC CYCLES FROM EASTERN TURKEY: LAKE VAN AND LAKE HAZAR SEDIMENT RECORDS|
|AUTHORS||Zeki Bora Ön (1,2)|Mehmet Sinan Özeren (2)|Mehmet Namik Çagatay (3)|Kürsad Kadir Eris (4)|
- Mugla Sitki Koçman Üniversitesi, Geological Engineering Departmenr, Mugla, Turkey
- Istanbul Teknik Üniversitesi, Avrasya Earth Sciences Institute, Istanbul, Turkey
- Istanbul Teknik Üniversitesi, Faculty of Mines, EMCOL, Istanbul, Turkey
- Firat Üniversitesi, Engineering Faculty, Geology Engineering, Elazig, Turkey
|ABSTRACT||To look for a pattern in nature is a humanistic way of trying to find answers to problems of nature. Therefore, since the early 18th century people tried to understand periodic behavior of climate.
Lake Van (1650 m asl) and Lake Hazar (1240 m asl) lie in the Eastern Anatolia high plateau and have Mediterranean climate embedded into continental climate. Lake Van is a dammed lake by the Nemrut volcano, which is one of the many surrounding semi-active volcanoes, and it is the largest soda lake and fourth largest terminal lake of the world. Lake Hazar is a tectonic lake and has alkaline water chemistry. For this study we have investigated the cycles of Lake Van’s and Hazar’s undisturbed drilled sediment core data, which are interpreted as paleoclimate signals.
A 145.5 meters long composite core that spans the last 90,000 years, on Lake Van is drilled within the framework of PALEOVAN project (ICDP) and a 3.48 meters long piston core that spans the last 18,000 years is recovered from Lake Hazar. Carbon dating, 40Ar/39Ar ages, correlation of tephra layers and correlation of the data with MIS gave the age model of Lake Van. For Lake Hazar six 14C ages are used. The geochemical results for Lake Van, obtained by XRF Core Scanner, stable oxygen and carbon isotope data and total organic and inorganic carbon data (with an approximate resolution of 0.4, 315 and 315 years respectively) and the XRF-magnetic susceptibility data for Lake Hazar (with an approximate resolution of 5.3 and 53 years respectively) are subjected to time series analysis, i.e. moving average and detrending the data. Since the data are not evenly spaced, we preferred the Lomb-Scargle periodogram spectral technique to find the periods that lie in the data.
The results of the analyses of the longest continuous continental climate records so far obtained from Anatolia -Lake Van data- show up the presence of the precession of the equinoxes, harmonics of Milankovitch cycles and Dansgaard/Oeschger cycles. Holocene spectral analyses of Lake Van and Hazar give the solar cycles and the so called Bond cycle.|