摘要
针对北京地区岩石地层密度资料较为粗略的现状,系统采集了标准地层剖面岩石标本和平原区各大流域第四系大样共1669块,使用DX-600Z全自动电子密度计测试了密度,分析了常见岩石的密度及不同时代地层的密度特征,首次将北京区域地层密度细分到组级,绘制了系密度和组密度曲线,划分了密度界面,得到如下结论:(1)全区岩石密度范围为1.845~3.364 g/cm^3,岩石平均密度从大到小依次是片麻岩、白云岩、灰岩、火山岩、侵入岩、泥岩、砾岩、砂岩、页岩和第四系砂黏土,平均密度分别为2.766 g/cm^3、2.761 g/cm^3、2.725 g/cm^3、2.696 g/cm^3、2.667 g/cm^3、2.651 g/cm^3、、2.620 g/cm^3、2.581 g/cm^3、2.475 g/cm^3、1.581 g/cm^3.(2)不同时代地层密度平均值从大到小依次是:蓟县系、太古界、侏罗系、寒武系、三叠系、侵入岩、侏罗-白垩系、长城系、二叠系、青白口系、石炭系、白垩系和第四系,平均密度分别为2.792 g/cm^3、2.756 g/cm^3、2.733 g/cm^3、2.719 g/cm^3、2.703 g/cm^3、2.669 g/cm^3、2.662 g/cm^3、2.658 g/cm^3、2.628 g/cm^3、2.548 g/cm^3、2.474 g/cm^3、2.202 g/cm^3、1.581 g/cm^3.(3)全区沉积地层存在6个明显的密度界面,分别是:第四系与白垩系、白垩系与侏罗-白垩系,石炭系与奥陶系、寒武系与青白口系、青白口系与蓟县系、蓟县系与长城系,密度差分别为0.621 g/cm^3、0.460 g/cm^3、0.102 g/cm^3、-0.171 g/cm^3、0.244 g/cm^3、-0.134 g/cm^3.地层之间普遍存在的密度差异为利用重力方法研究沉积盆地基底构造以及开展地热、地下水和页岩气等资源勘查提供了物理基础.
In view of the relatively rough current situation of the rock stratum density data in Beijing area,1669 pieces of rock specimens from standard stratum sections and Quaternary large samples from major watersheds in the plain area were collected systematically.The density was tested by DX-600Z full-automatic electronic densimeter.The density of common rocks and the density characteristics of strata in different times were analyzed.For the first time,the stratum density in Beijing area was subdivided into groups,the series density and group density curves were drawn,and the density interfaces were divided.The following conclusions are drawn:(1)the rock density in the whole region ranges from 1.845 to 3.364 g/cm^3.the average rock density is gneiss,dolomite,limestone,volcanic rock,intrusive rock,mudstone,conglomerate,sandstone,shale and quaternary sand clay from large to small.the average density is 2.766 g/cm^3,2.761 g/cm^3,2.725 g/cm^3,2.696 g/cm^3,2.667 g/cm^3,2.651 g/cm^3,2.620 g/cm^3,2.581 g/cm^3,2.475 g/cm^3 and 1.581 g/cm^3,respectively(2)The average values of strata density in different eras are Jixian,Archean,Jurassic,Cambrian,Triassic,intrusive rocks,Jurassic-Cretaceous,Changcheng,Permian,Qingbaikou,Carboniferous,Cretaceous and Quaternary in descending order.The average density is 2.792 g/cm^3,2.756 g/cm^3,2.733 g/cm^3,2.719 g/cm^3,2.703 g/cm^3,2.669 g/cm^3,2.662 g/cm^3,2.658 g/cm^3,2.628 g/cm^3,2.548 g/cm^3,2.474 g/cm^3,2.202 g/cm^3,1.581 g/cm^3,respectively.(3)There are six obvious density interfaces in the sedimentary strata of the whole region,namely:Quaternary and Cretaceous,Cretaceous and Jurassic-Cretaceous,Carboniferous and Ordovician,Cambrian and Qingbaikou,Qingbaikou and Jixian,Jixian and Changcheng,with density differences of 0.621 g/cm^3,0.460 g/cm^3,0.102 g/cm^3,-0.171 g/cm^3,0.244 g/cm^3,-0.134 g/cm^3,respectively.The common density difference between strata provides a physical basis for studying the basement structure of sedimentary basins and carrying out resource exploration such as geothermal,groundwater and shale gas by gravity method.
作者
雷晓东
裴艳东
关伟
李巧灵
薛洪林
LEI Xiao-dong;PEI Yan-dong;GUAN Wei;LI Qiao-ling;XUE Hong-lin(Beijing Institute of Geo-exploration Technology,Beijing 100120,China;Tianjin Center,China Geological Survey,Tianjin 300170,China)
出处
《地球物理学进展》
CSCD
北大核心
2020年第3期836-844,共9页
Progress in Geophysics
基金
中国地质调查局项目(12120114033901,DD20160229-07/09/W11)
北京市财政专项(PXM2019-158307-000009)联合资助.
关键词
物性
密度界面
岩石
地层
北京
Physical properties
Density interface
Rock
Stratum
Beijing
