东营市东辛2-4井磁性地层划分对比研究

本文通过东辛2—4井岩心样品的古地磁学研究,整段岩心呈现以正极性为主的混合极性特征。自上而下划分的布容、松山、高斯和吉尔伯特极性时和布容极性时内清晰显示出的哥德堡和布莱克亚时的界限分别位于井深28.0m、161.0m、274.5m和452.0m。据黄河口南北5个钻孔磁性地层的划分对比,长江口、苏北盆地和东营地区,吉尔伯特、高斯和布容极性时的沉积速度较快,松山极性时较慢或近于缺失;黄河口以北至河北地区,高斯极性时地层不发育,吉尔伯特、松山和布容极性时则较厚,表明它们所处的构造单元、地质基础和沉积环境有较大的不同。

MAGNETOSTRATIGRAPHIC CLASSIFICATION AND CORRELATION OF WELL 2-4, DONGXIN, DONGYING

The researches of magnetostratigraphy in well 2-4, Dongxin, Shengli Oil field, clearly shows that there are four polarity epoches: Brunhes, Matuyamu,Gauss and Gilbert. The well is 530.1m deep and the Gilbert Polarity zone has not been drilled through. The age of sediments at 530.1m is about 4.126Ma. According to the magnetostratigraphic classification, we have known that bottom boundaries of Holocene, Upper Pleistocene, Middle Pleistocene, Lower Pleistocene and Upper Pliocene lie at 28.0m, 160.0m, 243.0m, 278.7m and 452.0m respectively. Sediments between 452.0m and 530.1m belong to lower Upper Pliocene system. The average sedimentation rates of lower Upper Pliocene, upper Upper Pliocene, Lower Pleistocene, Middle Pleistocene, Upper Pleistocene and Holocene are 10.8cm/ka, 19.8cm/ka, 1.83cm/ka, 14.4cm/ka, 130.9cm/ka and 224.0 cm/ka respectively. The average sedimentation rates increase greatly from bottom to top in the well except the Lower and Middle Pleistocene. The boundaries of the sediments are quite accurate and reliable, so the well can be used for magnetostratigraphic classification and correlation.