EGU2020-7557
https://doi.org/10.5194/egusphere-egu2020-7557
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Recent seismic events preserved in lacustrine sediments from the SE Tibetan Plateau

Yongbo Wang1, Xuezhi Ma1, and Zhenyu Ni2
Yongbo Wang et al.
  • 1Capital Normal University, College of Resource Enviroment and Tourism, China (yongbowang@cnu.edu.cn)
  • 2Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, China

Large earthquakes are regarded as important contributors to long-term erosion rates and considerable hazard to infrastructure and society, which were difficult to track because of the long recurrence time exceeding the time span of historical records. Geological records, especially the continuously accumulated lacustrine sediments, hold the potential to capture signals of prehistoric seismic events, which has been barely reported from the Tibetan Plateau. Here we present lacustrine sediment records recovered from Basom Tso in Southeastern Tibetan Plateau, in which two seismic events were preserved. Sediment lithology, grain size composition, magnetic susceptibility and XRF scanning induced element compositions showed dramatic variations in two turbidite-like sediment segments. Particularly, the grain size showed an abrupt increase at the bottom of the Turbidites which was followed by a fining-up pattern and covered by a fine clay cap, expressing similar sedimentary processes caused by the seiche effect triggered by seismic events. Consistent patterns were recorded in the element contents as well, i.e. obvious bias in the counts of Fe, Zr, Ti, Ca. In addition, scuh pattern were preserved in sediment cores from different part of the lake basin, indicating a basin wide event layer. Finally, according to the dating results from 137Cs and 14C, the two Turbidites were formed around 1950 A.D. and during the late18th/early 19th century respectively. Such information was further confirmed by historical earthquake records that Chayu Earthquake (M=8.6, 1950 A.D.) and Nyingchi Earthquake (M=6.75, 1845 A.D.) have possibly responsible for the slump of underwater sediments and the formation of these two turbidites.

How to cite: Wang, Y., Ma, X., and Ni, Z.: Recent seismic events preserved in lacustrine sediments from the SE Tibetan Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7557, https://doi.org/10.5194/egusphere-egu2020-7557, 2020