鄂尔多斯盆地深部热结构特征及其对华北克拉通破坏的启示  

Lithospheric thermal structure of the Ordos Basin and its implications to destruction of the North China Craton

作　　者：黄方[1,2] 何丽娟[2] 吴庆举[1] 

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029

出　　处：《地球物理学报》2015年第10期3671-3686,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金重大研究计划(91114202);中国地震局地球物理研究所基本科研业务专项(DQJB14B09)联合资助

摘　　要：基于二维稳态热传导方程,利用有限元数值模拟方法,选取东西向横穿鄂尔多斯盆地地质与地球物理解释大剖面进行了深部温度场数值模拟研究,得到了华北克拉通西部的鄂尔多斯盆地下伏岩石圈热结构特征.地幔热流变化范围：21.2～24.5mW·m^-2,体现为东高西低特征.壳幔热流比（Qc/Qm）介于1.51～1.84之间,为＂热壳冷幔＂.与华北东部地幔热流对比表明,西部的鄂尔多斯盆地相对处于稳定的深部动力学环境.在岩石圈热结构研究基础上,对克拉通地震岩石圈与热岩石圈厚度差异进行了对比,研究表明：鄂尔多斯盆地西部地震岩石圈与热岩石圈厚度差异约达140km,而东部的汾渭地堑,渤海湾盆地二者差异逐渐减小.华北克拉通自西向东,地震岩石圈厚度与热岩石圈厚度差异不断减小,意味着华北克拉通岩石圈下部的软流圈地幔黏性系数自西向东逐渐降低,本文从地热学角度可能印证了太平洋俯冲脱水作用对华北克拉通的影响.Recently,the destruction of the North China Craton has become a center of active discussion in earth sciences.While its mechanism remains unclear and debatable.Moreover,geothermal research on this subject is relatively few.The Ordos Basin,located in the west of the North China Craton,is a typical intraplate tectonic unit with stable sedimentation since Paleozoic.Jurassic to Cretaceous is an important period of the formation and evolution of this basin,which were affected by the Tethyan and circum-Pacific tectonic domains.In an attempt to understand the deep dynamics of lithospheric destruction of the North China Craton,the thermal structure of a two-dimensional profile（named AB）across the Ordos Basin from west to east hasbeen studied to provide geothermic evidence to addressing this issue.Based on the two-dimensional steady-state heat conduction equation and using the finite element algorithm,thermal modeling along the profile（named AB）across the Ordos Basin has been carried out,resulting in the lithospheric thermal structure in the Ordos Basin west of the North China Craton.Furthermore,in the process of simulated calculation,we constantly adjust the heat flow at the bottom of the model to calculate surface heat flow（named calculated surface heat flow）,which will be used to fit the measured heat flow on the surface of the earth.So the simulation results are convinced because they are constrained by both thermal physical parameters and the measured surface heat flow.The results are as follows：（1）The Moho temperature along the profile ranges from 610 ℃to 700 ℃.The temperature in the east is higher than that in the west.（2）Mantle heat flow values in different tectonic units in the Ordos Basin range from 21.2to 24.5mW·m^-2.In the eastern Ordos Basin mantle heat flow values are high while the values in the western region are relatively low.But mantle heat flow values are smooth and not high overall,showing a stable deep thermal background in the west of the North China Craton.（3）The heat

关 键 词：温度场 热结构 热岩石圈 华北克拉通破坏 鄂尔多斯盆地 

分 类 号：P314[天文地球—固体地球物理学]