The sedimentologic parameters of earthquake related turbidites in Lake Hazar (Turkey) along the East Anatolian Fault Zone

The Lake Hazar (Elazığ) is situated as an inter-mountain basin located on the East Anatolian Fault Zone (EAFZ) which is a major continental left-lateral strike-slip fault in Eastern Turkey. Since most of the major cities in the eastern part of Turkey with high populations are located along or near the EAFZ; studies focused on earthquake risk in the near-future have a significant importance of carrying in terms of socio-economic conditions. Relevant with massive earthquakes during different geologic periods due to local and regional tectonic conditions; occurred earthquakes are measured between 6.7-7.8 Mw in Lake Hazar during the last 50 years.

Therefore, Lake Hazar is considered to be archive as receiving most of the past earthquake records that are considered to be deposited as turbidites along the lake floor. For this reason, this study aims to investigate the earthquake-related turbidites (seismo-turbidites) in Lake Hazar and special interest on their sedimentological parameters. For this purpose; seven sediment cores retrieved from Lake Hazar have been examined by using multi-parameters, including mainly sedimentologic analyses together with physical and geochemical imprints. Grain size parameters of the seismoturbidites such as mean, mode, and median together with sorting and skewness reveal depositional processes during the turbidite deposition along the lake floor. According to lithologic and grain size parameters; deciphered distinct facies variations of seismoturbidites, each of them was indicated various sedimentologic processes related to different depositional dynamics. The geochemical analyses of the seismoturbidite allow us to define the deepwater condition during and after its deposition and the source of the transported sediments.

The formation of laminated seismoturbidites is characterized by the finest-grain size that was presumably formed by suspended deposition under a strong seiche effect in deep parts of the lake. The coarser seismoturbidites represent massive and graded facies that are mainly deposited by traction carpet along the lake slopes as a result of slumps triggered by the earthquakes. The high fluctuation in grain sizes of the coarser seismoturbidites also indicates the existence of seiche effect during/or after the earthquakes that may have resulted in strong grain segregation of the transported sediments from slope to the basin of the lake. This study is supported and funded by TÜBİTAK Project (Grand Number: 119Y251).