Study in relation with increase for the Greater Accuracy of Climatic and Environmental Information obtained from Ice cores

众所周知，格陵兰冰芯所获得的过去气候和环境信息在时间尺度上具有很高的分辨率。但在底部岩芯，深度-年龄尺度的误差估计增加到20%或更大。这是由于减薄和变形层，以及材料的扩散。此外，在南极内陆地区的低积累率是一个较低的分辨率比格陵兰芯恢复。为了提高岩心气候环境信息（即时间尺度）的准确性，进行了变形试验、ECM测量和笼形水合物数浓度调查。流动扰动已被证明会改变格陵兰核心下部的层序。2-样品上的三维ECM信号变得沿沿着层干扰。此外，通过使用含有混浊带的样品进行机械测试，但不能得到特定的发现。另一方面，笼形水合物在空间上的分布反映了浅层冰中气泡和积雪孔隙空间的分布，因此具有层状结构。利用南极富士穹深岩芯薄片，在显微镜下对笼形水合物进行了计数。从1200 ~ 2400 m深度范围内选取了21块样品。笼形水合物的数浓度呈周期性变化。周期表示层的厚度。实测值与D-J模型计算的年厚度基本一致。新方法可用于提高冰芯时标的精度。

It has well known that the past climatic and environmental information obtained from Greenland ice cores is high resolution in time scale. However, error estimate of depth-age scale increases to 20 % or more at a bottom core. It is due to thinning and deformation of layer, and diffusion of material. Also, core recovered at inland area of Antarctica where is low accumulation rate is a lower resolution than in Greenland core. In order to increase for accuracy of climatic and environmental information (namely, time scale) of the core, a deformation test, ECM measurement and investigation of number concentration of clathrate hydrate were carried out. Flow disturbances have been shown to alter layer order in the lower part of the Greenland cores. 2-dimensional ECM signals on the sample became to disturb along the layers. Also, a mechanical test was carried out by use a sample that contains cloudy bands, but particular finding could not be made. On the other hand, it is considered that distribution of clathrate hydrate in space reflects air bubble distribution in shallower ice and pore space in firn, and therefore, has layer structure. Clathrate hydrate was accounted under microscope by use of thin section of the Dome Fuji deep core, Antarctica. The samples were selected 21 pieces from depth between 1200〜2400 m. The number concentration of clathrate hydrate changes periodically. The period means thickness of layer. And the measured values agreed with the annual thickness that was calculated by D-J model. The new method will be able to use for increase of accuracy of ice core time scale.