摘要
北京平原地处山前冲洪积扇分布区,区内湖泊密布,河流纵横,沉积环境多样。由于第四系三维结构的复杂性,对第四系进行地层划分有一定的难度。前人根据不同的资料对北京平原第四系进行过地层划分,建立了泥河湾组、周口店组、马兰组等多个岩石地层单位。这些地层单位主要是依据沉积凹陷钻孔岩心中的孢粉、有孔虫、介形虫等化石和少量的古地磁数据划分的,实际上仍是年代地层单位。由于这些地层单位划分依据不统一,识别标志不清晰,因此难以得到广泛的共识。近十余年来,随着资料的积累和对第四系三维结构的认识提高,特别是古地磁测年技术的普及,为北京平原第四纪地层的划分奠定了基础。本文依据40余个钻孔的古地磁测试数据,初步厘定了下更新统底界、中更新统底界、上更新统底界3个等时面。依据工程地质勘察、水文地质钻孔、考古发掘和泥炭调查等资料编绘了平原区全新统等厚度图。
Beijing plain, located in the piedmont alluvial fan area, has lots of lakes and rivers in its administrative area. Because of the variability of sedimentary environment, the three- dimensional structure is very complex. Due to the complexity of the threedimensional structure of the Quaternary strata, the Quaternary stratigraphic division is relatively difficult to some extent. Some researcher have established the lithostratigraphic units such as Nihewan Group, Zhoukoudian Group and Malan Group based on some geological data from different sources. These stratigraphic units are mainly based on fossil pollen, foraminifera, and Ostracoda in sedimentary sag drill holes, and a small amount of paleomagnetic data, and are actually the chronostratigraphic units. Because the units are not uniform and the identification mark is not clear, it is difficult to get a broad consensus. In the past 10 years, the increaseof the accumulation of data, the understanding of the three-dimensional structure of the Quaternary, and especially the popularity of the ancient magnetic prospecting technology have laid the foundation for the division of the Quaternary strata in Beijing plain.Based on paleomagnetic data from more than 40 drill holes, the authors initially established the bottom boundaries of lower, middle and upper Pleistocene series. According to the engineering geological prospecting, hydrogeological drilling, archaeological excavations and peat investigation materials, the authors compiled a Holocene isopach map for Beijing Plain.
出处
《中国地质》
CAS
CSCD
北大核心
2016年第3期1055-1066,共12页
Geology in China
基金
中国地质调查局项目(1212011301290)资助~~
关键词
北京平原
第四纪沉积物
三维地层结构
第四纪地层划分
Beijing Plain
Quaternary sediments
3D geological structure
Quaternary strata division
