北京市房山区大石河下游上更新统洞穴堆积与地表沉积对比
CORRELATION BETWEEN UPPER PLEISTOCENE CAVE DEPOSITS AND SUPERFICIAL DEPOSITS IN THE LOWER REACHES OF THE DASHI RIVER IN FANGSHAN AREA,BEIJING MUNICIPALITY
-
摘要: 本文把三福村和东岭子的上更新统地层,自上而下划分为三部分。上部:三福村剖面1—5层(东岭子2—3层),为姜黄色黄土,厚2.95~12.25m。产少量哺乳类及软体类化石,并测得黄土热发光年龄1.9万年,层位相当华北区马兰组,时代为晚更新世晚期。中部:三福村剖面6—10层(东岭子4—6层),由三层古土壤夹二层黄土组成,厚6.72~9m。在前者中测得热发光年龄为8.7—10.4万年,后者产北京斑鹿及大量啮齿类化石,其层位与华北区丁村组中上部相当,时代属于晚更新世中期。下部:三福村剖面11—12层(东岭子7—8层),为亚砂土及古土壤层,厚5.81~7m。其底部不整合于中更新统周口店组及东岭子石笋(铀系年龄10—35万年)之上。其层位相当于丁付组下部,时代为晚更新世早期。Abstract: The Upper Pleistocene strata at Sanfucun and Donglingzi are divided in descending order into three parts: The upper part——beds 1—5 of the Sanfucun section(beds 2—3 of the DongHngzi section)——consist of gingeryellow loess, 2.95~12.25m thick, yielding small amounts of mammal and mollusk fossils. The loess has been measured to have a thermoluminescent ago of 19 ka. Its horizon is equivalent to the Malan Formation of North China and its age is late Late Pleistocene. The middle part——beds 6—10 of the Sanfucun section (beds 4—6 of the Donglingzi section)——is composed of three beds of paleosol with two beds of loess, 7.72~9 m in thickness. The former has a thermoluminescent age of 87—104ka; the latter yields such animal fossils as Cervns, Nycereutes, Cricetulus, Micretus and Lepus. The horizon of this part is equivalent to the middle and upper parts of the Dingcun Formation of North China and its age is middle Late Pleistocene. The lower part——beds 11—12 of the Sanfucun section (beds 7—8 of the Donglingzi section)——is made up of sandy clay and paleosol, 5.81~7m in thickness. Its base rests unconformably on the Middle Pleistocene Zhoukoudian Formation and the Shizhongru of Donglingzi (with a uranium series age of over 100—350 Ka). Its horizon is equivalent to the lower of the Dingcun Formation and its age is early Late Pleistocene.