摘要
年纹层发育的湖泊沉积物可以提供独立的、绝对定年的时间标尺,为重建高分辨率的区域古地磁场长期变化主曲线提供了难得的条件;基于长而连续的湖泊沉积物年纹层时间标尺建立的区域磁偏角和磁倾角长期变化参考曲线大大增强了岩芯对比和古地磁定年结果的精确性。此外,满足特定条件的湖泊沉积物还可以提供古地磁场强度长期变化的记录并有助于反映宇宙成因核素(如14C、10Be等)产生速率的变化、太阳活动等信息;目前,湖泊沉积物纹层年代学时间标尺及古地磁研究程度较高的主要是瑞典、芬兰和北美一些地区,区域古地磁场长期变化主曲线的地理分布并不均匀,因此在全球范围内寻找长序列的、连续的年纹层发育的湖泊进行古地磁研究可以更好地理解仪器观测记录以前的地磁场行为。
The varved lake sediments are invaluable because it is possible to build independent, absolute and high-resolution varve chronology based on varve-counting. The high-resolution varve chronology can be used to reconstruct the highest resolution record of regional paleomagnetic secular variations. The correlations and paleomagnetic dating of lake sediments are improved greatly by declination secular variation and inclination secular variation derived from the varved lake sediments. In addition, if the varved lake sediments meet with some special criterions, it is possible to use the secular variation of paleomagnetic intensity to correlate and date the lake sediments, sometimes even to provide some information about the production rate of cosmogenic nuclides (e.g.^(14)C,^(10)Be) and solar activity. At present, the geographic distributions of regional paleomagnetic secular variations records based on the varved lake sediments are sparse and asymmetric,more research is made on some varved lake sediments in Sweden, Finland and North American. It is very important and significant to find much more lakes, which possess long and continuous varved sediments, to reconstruct high-resolution varve chronology and regional paleomagnetic records.
出处
《地质科技情报》
CAS
CSCD
北大核心
2004年第4期35-40,共6页
Geological Science and Technology Information
基金
国家自然科学青年基金资助项目(40302023)
中科院知识创新工程重要方向项目(KZCX3-SW-145)
