浙江地区钻孔古地磁研究

The Magnetostratigraphy of core from Zhengjiang,China

为了研究获得该钻孔沉积年龄,用磁性地层学方法和AMS^(14)C测年结果,分析该钻孔沉积历史。120个样品古地磁结果表明沉积物磁倾角大部分为正倾角,应都属于布容正极性期,存在的负倾角段可能记录了Gothemburg(~12 kyr)、Hilina-Pali(~17 kyr)、Mono Lake(~3 2kyr)极性漂移和Laschamp(~41 kyr)极性事件。表明该钻孔沉积历史约为40kyr。因此利用磁性地层学很好的解决了三角洲地区沉积物缺少有效测年物质的问题。并与岩性地层对比方法进行比较,表明该地区的一层硬黏土层确实为全新世与晚更新世界线。

The earth's magetic field is changing as the time changing,which can be record by the stable sedimentatary substance. So Magnetostratigraphy is a efficient method which get the age of sedimentations when we can not get enough appropriate aging sample. We used this way to study the sedimentary history of the core in Zhe Jiang Province. There are four paleomagnetic polarity excursion,which may be Gothemburg( ~ 12 kyr)、Hilina-Pali( ~ 17 kyr) 、Mono Lake and Laschamp. It is concluded that the bottom the holecore is 40 kyr.We also can find that the hard clay sedimentation which was find in most of this region,record the Gothembury excursion,which really is the interface of Holocene and the late Pleistocene. With the sedimentary age,we can analyse the environment and cliamte form late Pleistocene to now.