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.