The formation and preservation of compositional heterogeneities inside the Earth affect mantle convection patterns globally and control the long-term evolution of geochemical reservoirs. However, the distribution, nature, and size of reservoirs in the Earth’s mantle are poorly constrained. Here, we invert measurements of travel times and amplitudes of seismic waves interacting with mineralogical phase transitions at 400–700-km depth to obtain global probabilistic maps of temperature and bulk composition. We find large basalt-rich pools (up to 60% basalt fraction) surrounding the Pacific Ocean, which we relate to the segregation of oceanic crust from slabs that have been subducted since the Mesozoic. Segregation of oceanic crust from initially cold and stiff slabs may be facilitated by the presence of a weak hydrated layer in the slab or by weakening upon mineralogical transition due to grain-size reduction.

中文翻译：

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地幔过渡带玄武岩储层

地球内部成分异质性的形成和保存影响全球地幔对流模式并控制地球化学储层的长期演化。然而，地幔中储层的分布、性质和规模很难得到约束。在这里，我们反转了 400-700 公里深度处与矿物学相变相互作用的地震波传播时间和振幅的测量值，以获得温度和体积成分的全球概率图。我们在太平洋周围发现了大型的富含玄武岩的矿池（玄武岩含量高达 60%），这与自中生代以来俯冲的洋壳与板块的分离有关。