天津市西青区辛口镇郑庄子C6(C7)钻孔3.5 Ma以来的地层年代及沉积环境演化

Stratigaphic chronology since 35 ka and sedimentary environment evolution revealed by borehole C6(C7)in Xiqing district,Tianjin

对位于天津市西青区的C6(C7)钻孔进行了磁性地层学、^(14)C测年、沉积旋回、孢粉地层学和有孔虫、介形类研究,研究结果表明:①第三系与第四系界限(N/Q)埋深323.90 m,早更新世与中更新世界限(Qp1/Qp2)埋深98.0 m,中更新世与晚更新世界限(Qp2/Qp3)埋深61.59 m,更新世与全新世界限(Qp/Qh)埋深18.50 m。②晚更新世发生两次大范围海侵沉积事件,第一次发生于晚更新世早期,距今约85 ka—70 ka,相当于区域上的沧州海侵,埋深为38.15 m—47.18 m;第二次发生于晚更新世晚期,距今约39 ka—22 ka,相当于区域上的献县海侵,埋深为18.50 m—24.60 m。③全新世发生一次大范围海侵沉积事件,距今8 ka-5 ka,相当于区域上的黄骅海侵,埋深为3.37 m—15.95 m。

This paper studied the magneto-stratigraphy,^(14)C,dating,sedimentary cycle,pollen stratigraphy,microbiota perforated and microbiotaostracoda in Borehole C6(C7),which is located inXiqing District,Tianjin.The results show that:1)depth of the boundary of the Tertiary and the Quaternary(N/Q)is buried to 323.90 m,the depth of Early Pleistocene and Middle Pleistocene(Qp1/Qp2)boundaries to 98.0 m,the depth of Middle Pleistocene and late Pleistocene(Qp2/Qp3)boundaries to 61.59 m,the depth of late Pleistocene and the Holocene(Qp3/Qh)boundaries to 18.5 m;2)There are two large-scale transgression deposition events during Late Pleistocene.The first occurred in the early stage of late Pleistocene,about 85 to 70 ka ago,corresponding to Cangzhou Transgression with bury depth of 38.15 to 47.18 m.The second occurred in the late stage of late Pleistocene,about 39 to 22 ka ago,corresponding to Xianxian Transgression with bury depth of 18.50 to 24.60 m.The large-scale Deposition event during the Holocene about 5 to 8 ka ago with bury depth of is 3.37 to 15.95 m corresponding to Huanghua Transgression.