On the location of plumes and lateral movement of thermochemical structures with high bulk modulus in the 3‐D compressible mantle

摘要: The two large low shear velocity provinces (LLSVPs) at the base of lower mantle are prominent features in all wave tomography models. Various lines evidence suggest that LLSVPs thermochemical and stable on order hundreds million years. Hot spots igneous province eruption sites tend to cluster around edges LLSVPs. With 3-D global spherical dynamic models, we investigate location plumes lateral movement chemical structures, which composed dense, high bulk modulus material. reasonable values density anomalies, find anomalous material forms dome-like structures with steep edges, can survive for billions years before being entrained. We more occur near rather than top, domes. Moreover, domes have higher temperatures those atop downwelling region (subduction) controls direction speed Domes move away from subduction zones. could remain relatively stationary when distant but would migrate rapidly a new zone initiates above. Generally, segment dome edge be 200 years, while other segments rapid movement. In presence time-dependent subduction, computations maintaining fixity core-mantle boundary longer is challenge.