张瑞成　吕金波

的上部，孔深145.87 m。揭露新生界埋深141.69 m，其中第四系埋深115.03 m，地层沉积特征差异性明显。通过对第四系与新近系（Q/N）界限附近（埋深100～129 m）岩芯精细描述，并选取49件孢粉含量较高的样品共同研究，结果表明该地区由新近纪时期孢粉组合主要为木本植物花粉的湿热环境逐步转变为第四纪孢粉组合以松为主的针叶林的干凉气候环境。结合钻孔上部地层共同分析得出，早更新世和中更新世沉积层很薄;永定河受气候与环境的共同影响，在晚更新世大兴地区多次泛滥形成冲洪积扇，寒冷的气候造成永定河冲洪积物加速沉积，将大兴隆起掩埋，形成了北京平原。

关键词：新-10孔;Q/N界限;冲洪积扇;永定河;北京平原

Study on xin-10 hole and its regional geological significance in Daxing District of Beijing Plain

ZHANG Ruicheng1， LV Jinbo2

（1. Beijing Institute of Geological， Beijing 100195， China;

2. Beijing Institute of Geology survey， Beijing 100195， China）

Abstract： The xin-10 hole constructed by the project of Beijing Multi-Parameter 3D Geological Survey is located in the west of Xiaoputou village， Dahongmen， Daxing District ， in the upper part of Daxing uplift， with a depth of 145.87 m. The burial depth of Cenozoic is 141.69 m， of which the burial depth of Quaternary is 115.03 m. The sedimentary difference is obvious. Based on the detailed description of the core near the Q/N boundary （100 -129 m depth） and the study of the 49 samples selected with high sporopollen content， the results show that the humid and hot environment of Neogene sporopollen assemblage was mainly woody plant pollen， which gradually changed to the dry and cool climate of coniferous forest dominated by pine in Quaternary. Combined with the analysis of the upper strata of the borehole， it is concluded that the sedimentary layer of early Pleistocene and Middle Pleistocene is very thin. Influenced by the climate and environment， Yongding River inundated many times in Daxing area in the late Pleistocene to form the alluvial proluvial fan. The cold climate accelerated the deposition of the alluvial proluvial materials of the River， buried Daxing uplift and formed the Beijing plain.

Keywords： xin-10 hole; Q / N boundary; alluvial proluvial fan; Yongding River; Beijing Plain

北京平原属于华北平原的重要的一部分，平原区永定河、滹沱河、黄河等河流交错纵横，为华北平原的发育提供了充分的物源。

新生代新近纪天坛组沉积之后，永定河冲洪积物向东南越过大兴隆起进入廊坊-固安凹陷，证明第四纪大兴隆起逐渐被埋没，在第四纪时期冲积扇广泛发育，北京地区以永定河冲积扇为主（袁宝印等，2002;郭高轩等，2013;张瑞成等，2008），现今的北京城坐落于冲积扇之上。目前研究仍存在一定问题，第四纪以来的北京地区沉积演化特征与气候变化特征的研究并不详尽，如北京地区冲积扇规模、范围与形成时间等。

為了进一步研究北京地区第四纪以来气候与沉积变化规律，2007年北京市地质矿产勘查开发局完成了《北京市多参数立体地质调查报告》，重点开展了对北京平原区的调查。……