浙江湖州市青铜桥ZK01孔第四系沉积物磁性特征和古环境意义

Magnetic characteristics of Quaternary sediments and palaeoclimatic significance of ZK01 drill hole in Qingtongqiao, Huzhou city, Zhejiang province

通过对湖州市青铜桥ZK01孔第四系沉积物系统磁性参数测量及分析研究,发现根据磁参数的比值对沉积物中磁性矿物颗粒大小和成分的分析结果,与根据磁化率(κ)、饱和等温剩磁(SIRM)、饱和剩磁矫顽力{(Bo)cr}的分析获得的结果两者有较好的一致性。ZK01孔以24.7m为界,上部磁性矿物浓度高、磁性矿物成分单一,磁性颗粒粒度变化不大;下部磁性矿物浓度低(底部除外),磁性矿物成分和磁性颗粒粒度变化大,沉积物中有多相磁性矿物的存在,并含有超顺磁晶粒混合物。ZK01孔剖面跨越了布容—松山极性带界线,在布容正向极性期,存在2个次级极性倒转事件。剖面可分出五个明显不同的磁性地层段,可能分别对应于不同时期的古气候条件。为进一步查清研究地区第四系地层结构、地层的划分和对比具重要意义。

According to systemic measure and study of magnetic parameters of Quaternary sediments of ZK01 drill hole in Qingtongqiao, Huzhou city, Zhejiang Province, the authors discover that analysis results of grain sizes and types of magnetic minerals in sediments gained by magnetic parameters are in remarkable consistency with those by magnetic susceptibility, saturated isothermal remanence and coercive force of saturation remanence. There are high magnetic mineral quantities, single magnetic mineral types and less changeable grain sizes above 24.7 meters in ZK01 drill hole, and low magnetic mineral quantities （ exception for the bottom sediments）, manifold magnetic mineral types and variable grain sizes with super paramagnetic grain mixtures in sediments under 24.7 meters. ZK01 drill hole section spans the boundary of Brunhes - Matuyama polarity zone. There are two secondary polarity reversal events： Gothenburg reverse polarity excursion and Blake reverse polarity excursion during the Brunbes normal polarity. Five magnetostratigraphic members can be distinguished in this section, which are possibly corresponding to different palaeoclimatic conditions respecfively and have an important geological significance so as to understand Quaternary stratigraphic texture and correlation.