摘要
重力势能及重力势能差是分析岩石圈内部密度变化所引起的岩石圈平均应力特征的主要方法之一.本文基于全球Crust1.0模型地壳结构,结合常密度、横向变密度和三维变密度三种不同的地幔密度模型,获得了全球尺度更为精细的重力势能及重力势能差分布特征并开展分析.研究结果表明,在北美西部、安第斯山脉、东非、青藏高原等区域表现为重力势能高,呈拉张应力状态;在洋盆、高原周围的盆地等地区表现为重力势能低,呈挤压应力状态.对比分析不同地幔密度模型结果,发现大洋地区洋壳薄,岩石圈地幔密度受构造及热影响变化较大,对重力势能影响大;大陆地区地壳厚度大,对重力势能影响大,地幔密度变化影响相对较小.采用三维变密度地幔模型获得的重力势能差分布和大地水准面异常计算获得的全球重力势能差分布具有相似特征,表明该模型的计算结果更符合全球岩石圈尺度的应力分布特征.三维变密度地幔模型计算的重力势能差显示洋中脊轴部地区趋于零,说明该处岩石圈密度变化对应力影响较小,其拉张应力与洋中脊地区地幔上涌更为相关.
Gravitational potential energy and its differences are one of the main methods to analyze the characteristics of lithospheric mean stress caused by density variation within the lithosphere.In this paper,we analyze the distribution characteristics of global gravitational potential energy and their differences,and also obtain more precise results on global scale based on Crust1.0 model.The results using different mantle density models including constant density,transversal variable density and three-dimensional variable density are compared.The results show that the tensile stress and high gravitational potential energy occur in western North America,the Andes,eastern Africa and Tibetan Plateau,while the compressive stress and low gravitational potential energy occur in the ocean basin and the basin around the plateau.By comparing the results of different mantle density models,we found that the oceanic crust is thin,and the lithospheric mantle density varies greatly under the influence of tectonic movement and heat,which contributes a lot to the gravitational potential energy.In continental region,the thick crust contributes a lot to the gravitational potential energy,but the change of mantle density has relatively less impact.The distribution of the global gravitational potential energy differences obtained by the 3D variable density mantle model is similar to that obtained by the global geoid anomaly,which indicates that the results of this model are more consistent with the global lithospheric stress distribution.The differences of gravitational potential energy calculated by 3D variable density mantle model in the mid-ocean ridge axis tends to zero,indicating that the variation of lithospheric density has little influence on stress,and the tensile stress is more related to mantle upwelling in mid-ocean ridge area.
作者
张倩文
徐亚
王信国
ZHANG QianWen;XU Ya;WANG XinGuo(Key Lab of Petroleum Resource Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;State Key Laboratory of Tibetan Plateau Earth System,Resources and Environment(TPESRE),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第1期77-88,共12页
Chinese Journal of Geophysics
基金
国家自然科学基金(42074092,42174112)
中国科学院青年创新促进会(2016064)资助。
关键词
重力势能
岩石圈密度结构
大地水准面
岩石圈应力
Gravitational potential energy
Lithospheric density structure
Geoid
Lithospheric stress field
