江苏兴化ZK10孔第四纪多重地层研究

Quaternary multistratigraphic study of Borehole ZK10,Xinghua, Jiangsu Province

通过对江苏兴化ZK10孔岩石地层、生物地层、磁性地层及年代地层的研究,确定了该孔第四纪年代地层序列:1第四纪底界置于松山/高斯极性世分界处,埋深212m,距今2.58Ma。下更新统包括五队镇组下段、中段及上段的中下部,对应孢粉组合Ⅰ-1和Ⅰ-2。2早、中更新世界线与布容/松山极性世界线吻合,距今0.78Ma,埋深约120m,位于孢粉Ⅰ-2与Ⅱ带的分界处。中更新统包括五队镇组上段顶部、小腰庄组下段及上段的中下部。五队镇组是包含下、中更新统的跨时岩石地层单位。3中、晚更新世界线埋深81.5m,120ka BP左右,置于孢粉带Ⅱ与Ⅲ-1的分界处,与小腰庄组和灌南组分界线基本吻合。上更新统包括小腰庄组上段上部及灌南组。小腰庄组是包含中、上更新统的跨时地层单位。上更新统包括Ⅲ-1、Ⅲ-2、Ⅳ和Ⅴ孢粉带。4晚更新世与全新世界线埋深12.25m,距今10ka BP左右,位于Ⅴ与Ⅵ孢粉带分界处。全新统为淤尖组,对应孢粉Ⅵ带。

Borehole ZK10 is located in Xinghua City, Jiangsu Province. Based on litho-, bio -, magneto- and chronostratigraphic study of the core sediments, the authors established its Quaternary chronological framework：①The lower boundary of Quaternary, con-sistent with the G/M boundary at 2.58Ma,was found at 212m in depth. The Lower Pleistocene in this core was composed of the lower, middle members and lower to mid-parts of the upper member of the Wuduizhen Formation, and corresponded to the pollen zones I -1 and I -2.②The Early/Middle Pleistocene boundary, in accord with the M/B boundary at 0.78Ma, was found at 120m. This was defined at the boundary between the pollen zones I -1 and H . The Middle Pleistocene was composed of the top part of upper member of Wuduizhen Formation and the lower member and the lower- to mid-parts of the upper member of the Xiaoyaozhuang Formation. The Wuduizhen Formation was a time-transgressive lithostratigraphical unit across the Lower/Middle Pleistocene.③The Middle/Late Pleistocene boundary at 120ka BP was found at the depth of 81.5m. It lay on the boundary between the pollen zones H and n -1, and essentially coincided with the boundary between Xiaoyaozhuang Formation and Guannan Formation. The latter was another time- transgressive unit crossing both the Middle and Upper Pleistocene. The Upper Pleistocene was composed of the pollen zones n_1, n-2, w and V .④The Late Pleistocene/Holocene boundary, about 10ka BP, 12.25m, lay on the pollen boundary between zones V and ^. Lithostratigraphically, Holocene deposits belong to the Yujian Formation and correspond to the pollen zone ^.