Luminescence dating study of eruptions and baked sediments from Changbaishan volcano, Northeastern China

Abstract

Accurate dating of Quaternary eruptions is crucial for understanding volcanic histories, geo-dynamics, volcanic hazards, and the development and evolution of magmatic systems. However, determining the age of young volcanic eruptions remains a very challenging task. In this study, optically stimulated luminescence (OSL) dating is applied to fine-grained quartz (FQ) and polymineral (FM) materials sampled from the tephra deposit and its baked layers from the Heishigou section of the Changbaishan volcano, China. Adiocarbon dating obtained from a charcoal sample adjacent to the tephra layer yields an age of 876–994 cal. AD, referred to as the millennium eruption. OSL dating results show that FQ is the suitable material for dating young volcanic deposits. The OSL ages are in good agreement with both the radiocarbon dating of the tephra layer charcoal and the ages of over 27 tree rings modeled with Oxcal. The FQ in tephra layer displays the highest sensitivity of the OSL signal and the 110 °C thermoluminescence (TL) peak to dose of ionizing radiation, compared to the baked layer and unbaked sediments. Moreover, the heavily baked layers, closest to tephra, exhibit greater sensitivity to dose compared to other less baked layers. The unbaked sediments show lowest sensitivity to dose. Tephra experienced the highest temperatures heating, as suggested by the increase of the sensitivity to dose at increasing baking temperatures, up to ∼800 °C. The quartz grains in the tephra and the baked layers were heated to temperatures of at least 500 °C, sufficient to completely reset their luminescence signals. However, caution is necessary when using OSL dating for pyroclastic flow deposits and quartz from volcanic fields older than 10,000 years due to the potential instability of the medium component in OSL signals and/or incomplete bleaching prior to deposition.