北京大学学报自然科学版 ›› 2025, Vol. 61 ›› Issue (2): 403-410.DOI: 10.13209/j.0479-8023.2025.011

上一篇    

特提斯构造域大地水准面异常来源初探

闫沛龙, 张南   

  1. 北京大学地球与空间科学学院大陆动力学与资源工程研究所, 北京 100871
  • 收稿日期:2024-02-22 修回日期:2024-04-17 出版日期:2025-03-20 发布日期:2025-03-20
  • 通讯作者: 张南, E-mail: nan_zhang(at)pku.edu.cn
  • 基金资助:
    国家自然科学基金(92155204)资助

Preliminary Investigation on the Origin of Geoid Anomalies in the Tethys Tectonic Domain

YAN Peilong, ZHANG Nan   

  1. Institute of Continental Dynamics and Resource Engineering, School of Earth and Space Sciences, Peking University, Beijing 100871
  • Received:2024-02-22 Revised:2024-04-17 Online:2025-03-20 Published:2025-03-20
  • Contact: ZHANG Nan, E-mail: nan_zhang(at)pku.edu.cn

摘要:

针对特提斯构造域大尺度重力场响应问题, 通过对全球大地水准面的球谐谱和核函数分析, 将全球地震层析成像模型作为地幔结构, 进行大地水准面正演计算, 探究由特提斯洋动力过程产生的地幔结构与当今特定球谐阶数的特提斯域大地水准面异常之间可能的联系。全球大地水准面观测的球谐谱分析结果表明, 特提斯构造域的大地水准面异常具有球谐7阶的波长尺度。通过全球大地水准面核函数的分析, 初步约束特提斯构造域大地水准面异常的密度源深度。最后, 通过全球地球动力学数值模拟计算, 测试并验证地幔425~1000 km深度处的球谐7阶密度异常与特提斯构造域大地水准面异常在印度尼西亚、缅甸、青藏高原及扎格罗斯地区具有很好的对应性, 认为目前观测到的球谐7阶大地水准面异常指示位于地幔425~1000 km深度的特提斯洋中–东段的板片残余信号。

关键词: 大地水准面, 特提斯构造域, 球谐谱, 核函数, 地球动力学数值模拟

Abstract:

Regarding the large-scale gravity field response in the Tethyan tectonic domain, this work aims to connect specific wavelength of geoid anomaly with the mantle structure caused by Tethys evolution. To acheive this, spherical harmonic spectrum analysis and kernel analysis on global geoid are employed, and the global geoid is further calculated by forward modeling with the mantle structure obtained by global seismic tomography. Density structure in our geoid calculation is obtained by seismic tomography. Through spherical harmonic analysis of global geoid observation, the geoid anomalies of the Tethyan tectonic domain exhibit a spherical harmonic degree 7 wavelength scale. Analysis of geoid kernels provides initial constraints on the density source depth of Tethyan geoid anomalies. Finally, through global geodynamic numerical modeling, the degree 7 density anomaly at depths of 425–1000 km in the mantle corresponds well with the Tethyan geoid anomalies in the Indonesian, Burmese, Tibetan Plateau, and Zagros regions. Preliminarily, the observed degree 7 geoid anomalies indicate slab remnants in the central and eastern segments of the Tethys at depths of 425–1000 km in the mantle.

Key words: geoid, Tethyan tectonic domain, spherical harmonic spectrum, kernel function, geodynamic numerical modelling