北京平原第四纪下限问题研究

本文首先回顾了北京平原区第四纪下限的研究历史，指出迄今为止在这一领域存在的问题。根据我国目前的研究进展和北京地区研究现状，按照全国地层委员会的相关标准和要求，确定了划分第四纪下限的5大原则。北京平原区第四系沉积特征复杂，根据多年资料和研究结果，我们提出了划分该界限的方法。广大的北京平原区，不具备完整的第四系剖面露头，生物地层方法划分存在困难；古地麟、热释光及孢粉地质测试为准确定位这一界限提供了可能。对平原区的钻孔而言，笔者发现以古地麟测试结合孢粉分析、岩性特征、地球物理测井以及地球化学测试（碳酸钙分析）等综合手段确定这一界限的证据更有说服力，新5孔应用效果较好。

Discussion on the Lower Boundary of the Quaternary System in Beijing's Plain Area

This paper first views the research history of the lower boundary of the Quaternary System in Beijing's plain area,and points out the problems existing in this field.Five principles for the division of the Quaternary lower boundary have been determined on the basis of the progress of the research in China and the status-quo in the Beijing area,and following the relevant standards and requirements of the National Commission on Stratigraphy.The Quater- nary sediments in Beijing's plain area bear complicated features.Based on the data and research results of many years,the authors propose a method for the division of the lower boundary.The wide Beijing's plain area lacks complete outcrops of the Quaternary,so that it is difficult to make a bio-stratigraphic division.Paleomagnetic,ther- moluminescence and sporopollen tests make it possible to precisely position this boundary.As regards the boreholes in the plain area,the authors have found that it is more convincing to use the integrated means combining the paleo- magnetic testing with sporopollen analysis,lithologic features,geophysical logging,geochemical testing(Ca analysis) etc.,which have yielded good results in the application to the Xin-5 hole.