长江三角洲北翼ZKA4钻孔剖面第四纪磁性地层特征及其意义

对长江三角洲北翼南通地区ZKA4钻孔岩心进行了磁性地层学研究,结果表明,302.7 m的岩心记录了布容正向极性时(Brunhes)、松山负向极性时(Matruyama)和部分高斯正极性时(Gauss)。在系统古地磁样品采集、处理和测试的基础上,应用磁性地层、AMS~(14)C加速器测年等方法,结合岩性特征,对ZKA4钻孔剖面进行了详细地层划分,分别确定了下更新统、中更新统、上更新统和全新统的埋深及沉积厚度,其中Q/N界线位于291.72 m处,Qp~1/Qp~2、Qp~2/Qp~3、Qp~3/Qh界线分别定位于189.39 m、132.44 m和26.14 m处。本项研究结果为该区域第四纪地层划分对比、古地理环境演化及岸线变迁等相关研究提供了可靠的地层年代框架。

Characteristics and Implications of the Quaternary Magnetostratigraphy in #br# Borehole ZKA4 from the Northern Flank of Yangtze River Delta

The broehole ZKA4 locates in Nantong area of the northern flank of Yangtze River Delta. Quaternary magnetostratigraphy studies show that the 302.7 m core taken from broehole ZKA4 has recorded Brunhes normal polarity chron, Matruyama reversed polarity chron and Gauss normal polarity chron. After systematic sampling, treating and measuring, the vertical distribution depth of the Lower Pleistocene, Middle Pleistocene, Upper Pleistocene and Holocene in broehole ZKA4 are determined by magnetostratigraphic study, AMS 14C dating and core observation. The Q/N, Qp1/Qp2, Qp2/Qp3 and Qp3/Qh boundary locates at 291.72m, 189.39m, 132.44m and 26.14m respectively. These provide a reliable chronostratigraphic framework for regional research on stratigraphic division and correlation, paleogeographic environment as well as coastline changes in Quaternary.