Ash From the Changbaishan Qixiangzhan Eruption: A New Early Holocene Marker Horizon Across East Asia

Abstract

Prehistoric Holocene eruptions of Changbaishan volcano in Northeast China are poorly dated, with the exception of the 946 CE Millennium eruption. Poorly refined age estimates for the earlier eruptions present problems for the reconstruction of the eruptive history of the volcano. The Qixiangzhan eruption (QE) is a major controversial event in terms of its eruptive timing (ranging from ~88 to ~4 kyr) and style (effusive or explosive). As a result of the imprecise age estimates for the eruption, a geomagnetic field excursion recorded within the QE comendite has been variably correlated with a number of different excursion events observed elsewhere. In this study, a visible early Holocene tephra was identified in Yuanchi Lake, ~30 km east of the Changbaishan volcanic vent, and was dated to 8831-8100 cal yr BP using Bayesian age modelling. Glass shard compositions enable the correlation of this tephra with the poorly dated QE, as well as with a tephra (SG14-1058) recorded in Lake Suigetsu, in central Japan. These correlations confirm that the QE was explosive and that the ash from the QE can serve as an important early Holocene marker bed across East Asia. In addition, we propose an age of ~8100 cal yr BP for the QE based on the precise date of the Suigetsu SG14-1058 tephra. Our results also confirm that the geomagnetic field excursion recorded in the Qixiangzhan comendite dates to ~8100 cal yr BP.