冲绳海槽中部火山事件的环境磁学记录

对冲绳海槽中部DH180岩心沉积物进行了AMS14C测年、磁化率、非磁滞剩余磁化强度和饱和等温剩余磁化强度等试验,在含火山物质高的两段层位各磁学参数发生了异常变化。在57.5~82.5和212.5~252.5 cm深度处磁化率、非磁滞剩余磁化强度和饱和等温剩余磁化强度表现出增大的变化趋势,饱和度则出现相对减小的变化趋势。根据磁学参数异常变化的位置和测年数据,对所记录的两次火山事件发生年代进行了计算,它们分别为距今约12.6和6.2 ka,最近一次火山喷发的年代与K-Ah火山喷发的年代基本一致。

Environmental magnetism record of volcano ejecting events in the middle Okinawa Trough

Multiple experiments measurements, such as AMS ¹⁴C dating, magnetic susceptibility, anhyster esis remanent magnetization and saturation remanent magnetization, were made on 64 samples of the DH 180 core sediment taken from the middle Okinaw a Trough.Magnetic parameters verified singularly at the two layers that sediments contain more volcanic matter.The magnetic susceptibility, the anhysteresis remanent magnetization and the saturation remanent magnetization show an increasing tendency, and the saturation shows a decreasing tendency oppositely at the depths from 57.5 to 82.5 cm and from 212.5 to 252.5 cm.The time of volcano ejecting events was calculated based on the data of datings at the depths of magnetic parameters changing evidently.It happened at 12.6 and 6.2 ka respectively, and the time of the last volcano ejecting event was consistent with K-Ah volcano ejecting events.