广西北海涠洲岛火山最后喷发活动时代

广西北海涠洲岛是我国最大的第四纪火山岩海岛。近些年来随着我国核电事业的不断发展,涠洲岛火山最后喷发时代和对区域核电厂址的潜在火山灾害,受到了国内外地学界和核电工业界的广泛关注。我们通过对涠洲岛南部地区射汽岩浆喷发的基浪堆积物的野外地质地貌考察,研究了火山喷发物的岩性特征、沉积结构和堆积规模。同时,对系统采集于不同堆积部位的喷发物样品和上覆的黄土样品进行了电子自旋共振(ESR)年代测试分析,结合前人光释光(OSL)测年结果,得出涠洲岛火山最后一次喷发的时间为晚更新世晚期至全新世早期,距今约13～33ka。

The chronology of last eruption of Weizhou Island volcano in Northern Bay of Guangxi Province

The Weizhou Island is the biggest volcanic island in the Northern Bay of South China. With the recent development of nuclear power plants along the coastline in China, more and more attention has been paid to the potential volcanic hazards form Weizhou Island volcano in site evaluation for nuclear installation in adjacent region. In this paper we conducted field investigation on the volcanic surge deposits from the last phreatomagmatic eruption of Weizhou Island volcano, and collected a series of chronology dating samples. In laboratory we picked out quartz grains and performed Electron Spin Resonance (ESR) analysis of both volcanic deposit samples and loess sample which overlays on the top of the volcanic deposits in the field. The ESR ages determined by this study, combined with the Optically Stimulated Luminescence (OSL) ages from the previous study are in agreement within error range, and reveal that the last eruption occurred in about 13~33ka.