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渤海湾的海陆交互相沉积对研究海陆环境变化、新构造活动及华北平原的演化历史等均有重要意义,而建立可靠的年代地层框架是上述研究的前提。对取自渤海湾西岸天津市深度为203.57 m的BZ2钻孔进行了详细的磁性地层学研究,结果表明,钻孔岩心包含4个正极性段,分别可与标准极性柱中布容(Brunhes)、贾拉米洛(Jaramillo)、奥尔都维(Olduvai)和高斯(Gauss)正极性世对比;获得的3个负极性段则与松山(Matuyama)和凯纳(Kaena)事件对应,从而获得钻孔岩心底部年龄约为3.18 MaBP。磁性界限之间平均沉积速率的相对一致性,指示了渤海湾在晚上新世以来总体稳定的下沉趋势。
The sea-land interaction facies deposition in the Bohai Bay is of great significance for the study of the changes in the land-sea environment, neotectonic activity and the evolution history of the North China Plain. Establishing a reliable chronostratigraphic framework is the prerequisite for the above study. A detailed magnetic stratigraphy study was conducted on a BZ2 borehole taken from the depth of 203.57 m in Tianjin on the west coast of the Bohai Gulf. The results show that the core of the borehole contains four positive polarity segments, which can be respectively matched with Brunhes ), Jaramillo, Olduvai, and Gauss positive polarities; the three negative polarity segments obtained correspond to the Matuyama and Kaena events and thus The bottom of the borehole was obtained at about 3.18 Ma BP. The relative consistency of the average deposition rate between the magnetic boundaries indicates an overall stable downward trend in the Bohai Bay since the late Pliocene.