摘要
文章讨论了末次冰期及全新世以来冲绳海槽中部偏东处的沉积物岩芯Z14-6中^(10)Be的历史记录,并与冲绳海槽北部钻孔DGKS9603的^(10)Be记录进行对比。重力柱状岩芯Z14-6取于冲绳海槽水下739m(27°07′N,127°27′E),全长8.96m。选取了晚更新世末次冰期和全新世的层段(2～175cm,年代跨度为0.37～29.3kaB.P.)中12个层位,利用加速器质谱法测定了^(10)Be的含量。Z14-6孔^(10)Be的平均含量为6.10×10~8 atoms/g,最高值(8.71×10~8atoms/g)出现在6.3kaB.P.层位,末次冰期^(10)Be含量总体上处于低值。与DGKS9603孔(28°08.869′N,127°16.238′E;水深1100m,岩芯长585cm)的数据比较,Z14-6孔中^(10)Be含量普遍较低。Z14-6孔的^(10)Be沉积通量平均值为1.04×10~9 atoms/cm^2·ka,最高值(1.36×10~9 atoms/cm^2·ka)出现在6.3kaB.P.层位,最低值(6.45×10~8 atoms/cm^2·ka)出现在9.27kaB.P.层位。Z14-6孔所处水深较浅,黑潮流在末次冰期时并未流经Z14-6孔海区,所以其^(10)Be沉积通量只相当于^(10)Be的大气平均生产率(1.21×10~9 atoms/cm^2·ka)。Z14-6孔中^(10)Be沉积通量降低可能与几个低温事件有关,Z14-6孔在约3kaB.P.和9kaB.P.存在^(10)Be通量减弱现象,因此推测黑潮产生较大变动。Z14-6孔在全新世一些时段的^(10)Be沉积通量峰值显著高于末次冰期时的沉积通量峰值,表明当时黑潮对该海域已发生影响。
The ^10Be records in sediment Core Z14-6 from the eastern side of the middle Okinawa Trough （27°07＇N, 127°27＇E ; water depth： 739m; core length： 8.96m）during the last glacial period and the Holocene are discussed and compared with the ^10Be records in sediment Core DGKS9603 （28°08. 869＇N, 127°16. 238＇E; water depth： 1100m ,core length： 585cm）from the North Okinawa Trough. ^10Be concentrations in 12 layers in the core section of 2- 175cm whieh covers the chronologic range of 0.37 -29.3kaB. P. were determined using Accelerating MassSpectrometry （AMS）. The average ^10Be concentration was 6. 10×10s atoms/g, with the maximum 8.71×10s atoms/g occurring at 6.3kaB. P. The ^10Be concentrations in the last glacial were generally low and also lower than those in DGKS9603. The average sedimentation rate of ^10Be in Z14-6 was 1.0gxl09 atoms/cm^2 ·ka,with the maximum 1.36×109 atoms/cm^2 ·ka occurred at 6.3kaB. P. and minimum 6.45×l0s atoms/cm^2· ka at 9.27kaB. P. layers, respectively. Due to the shallow water depth, the Kuroshio did not flow through Z14-6 during the last glacial, therefore the average sedimentation rate of ^10Be in Z14-6 was at the level of the global mean ^10Be atmospheric production rate（1.21x109 atoms/cm^2·ka）. The decreases of sedimentation rate of ^10Be may be related to the low temperature events,among which are Younger Dryas（YD）and Heinrich event H1. ^10Be sedimentation rate of Z14-6 significantly decreased at about 3kaB. P. and 9kaB. P., suggesting large variations of the Kuroshio Current. The peak values of ^10Be sedimentation rate of Z14-6 in the Holocene were considerably higher than those during the last glacial period,indicating that the influence of the Kuroshio Current on Z14-6 site had occurrad
出处
《第四纪研究》
CAS
CSCD
北大核心
2012年第3期417-422,共6页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:40173027
40176018
90411014和4042115001)资助
