关键词: ¹⁴C测年, 炭化木, 天池火山

Abstract: The largest eruption of the Tianchi Volcano in historical period had not been recorded in historical document. Therefore,the determination of the accurate date of this largest eruption event is of great importance to the estimation of the eruption interval,the evaluation of the eruption risk and the hazard prediction of the future eruption. Basing on the systematical ¹⁴C dating of a well-preserved large carbonized wood,Liu Ruo-xin et al (1997) concluded that the largest historical eruption of the Tianchi Volcano occurred in 1215?15 AD. However,this conclusion has evoked much controversy. Horn et al (2000) suggested that the eruption time of Tianchi Volcano should be in 969?20 AD as determined from the age of a slab of carbonized wood collected from the North Korean side in a pumice fallout deposit. Earlier,Dunlap (1996) reported a wiggle-matched age of 1039?18 AD determined at the University of Arizona. Moreover,some experts favor 870?170 AD,which was the average of 53 radiocarbon ages of carbonized wood collected from the ignimbrite. In this paper,the eruption time of the Tianchi Volcano has been studied through detailed field investigation and careful selection of representative profile for collecting radiocarbon samples. The radiocarbon dates of 16 samples of carbonized wood including a piece of bark collected from ignimbrite around the Tianchi Volcano show that it is reasonable to consider the age of 1215?15 as the eruption time of the Tianchi Volcano. All of the radiocarbon ages of the carbonized wood are older than the true age of volcanic eruption,the largest deviation from which is 800yr,but the age of the bark is close to that of the Tianchi Volcano eruption. This may imply that the age of bark sample may provide better constraint on the date of volcanic eruption. The radiocarbon ages of black ignimbrites from Heishihe River,Pumice Forest,and Jinjiang Gorge show that they are also the product of 1215?15 AD eruption.

Key words: radiocarbon dating, carbonized wood, Tianchi Volcano