Age of a late Quaternary (13.6 cal kyr BP) eruption and associated marker tephra of the Tengchong volcanoes, Yunnan Province, southwestern China

摘要

The Tengchong volcanoes in western Yunnan Province are some of the youngest volcanoes in China, and determining their eruption ages would further our understanding of their genesis and historical activity. In this study, the age of a late Quaternary eruption of Dayingshan volcano was obtained by dating organic-rich sediments that envelope a 5-cm-thick visible tephra layer found in the Yubi peat section. Compositionally, the purified glass shards extracted from the layer by density separation are calc-alkaline trachyandesite and trachyte/trachydacite, which is consistent with the composition of the Dayingshan lava. An age-depth model of the Yubi section was constructed from accelerator mass spectrometry (AMS)C-14 dating of peat samples and Poisson models of deposition (P sequence) functions, using OxCal with the IntCal 13 database. This yielded an age for the tephra layer of 13,642 +/- 84 cal yr BP. A nearly identical tephra layer occurs in the Qinghai Crater Lake sediments. The Yubi tephra is now a reliable age and stratigraphic marker layer, useful for regional paleoclimate and tephrochronology research.