三十年前地震学家们发现核幔边界之上存在分布不均的超低速区(ultralow velocity zones,简为ULVZs),通常和大低速省(large low shear velocity provinces,简为LLSVPs)紧密相连。虽然认识其成因对于理解核幔边界的热和化学状态乃至于深部地球的演化历史至关重要,但是目前尚未有定论。硅酸盐熔体常被用来解释ULVZs的成 Seventy years ago seismologists found that there are ultralow velocity zones (ULVZs) that are unevenly distributed above the core-mantle boundary and are usually closely linked to the large low shear velocity provinces (LLSVPs) . Although the understanding of its origin is crucial for understanding the thermal and chemical states of the core-mantle boundary and even the evolutionary history of the deep earth, it has not yet been decided. Silicate melt is often used to explain the ULVZs into