{"title":"北美地下最深地幔中俯冲物质重新分布的低速异质体","authors":"Jonathan Wolf , Mingming Li , Maureen D. Long","doi":"10.1016/j.epsl.2024.118867","DOIUrl":null,"url":null,"abstract":"<div><p>The origins and composition of seismic low-velocity heterogeneities atop the core-mantle boundary (CMB) remain poorly understood. It is also debated whether they are static features or whether they can be displaced and modified by mantle convection, although recent seismological and geodynamic evidence suggests the latter. In this work, we perform the first simultaneous analysis of SPdKS waves to characterize low-velocity heterogeneity and seismic anisotropy, which is evidence for deformation, at the base of the mantle. We find seismic velocity heterogeneity and seismic anisotropy that are co-located with, or adjacent to, each other. Our study region, the lowermost mantle beneath North America, has been shaped by long-term subduction. Through geodynamic modeling simulations, we show that the sinking of subducted slabs to the lowermost mantle can trigger formation of hot thermal anomalies near subducted slabs, where chemical heterogeneities can accumulate. The thermochemical anomalies can cause reduction of seismic velocity while the slab-induced flow can cause seismic anisotropy, potentially explaining our seismic observations.</p></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":null,"pages":null},"PeriodicalIF":4.8000,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Low-velocity heterogeneities redistributed by subducted material in the deepest mantle beneath North America\",\"authors\":\"Jonathan Wolf , Mingming Li , Maureen D. Long\",\"doi\":\"10.1016/j.epsl.2024.118867\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The origins and composition of seismic low-velocity heterogeneities atop the core-mantle boundary (CMB) remain poorly understood. It is also debated whether they are static features or whether they can be displaced and modified by mantle convection, although recent seismological and geodynamic evidence suggests the latter. In this work, we perform the first simultaneous analysis of SPdKS waves to characterize low-velocity heterogeneity and seismic anisotropy, which is evidence for deformation, at the base of the mantle. We find seismic velocity heterogeneity and seismic anisotropy that are co-located with, or adjacent to, each other. Our study region, the lowermost mantle beneath North America, has been shaped by long-term subduction. Through geodynamic modeling simulations, we show that the sinking of subducted slabs to the lowermost mantle can trigger formation of hot thermal anomalies near subducted slabs, where chemical heterogeneities can accumulate. The thermochemical anomalies can cause reduction of seismic velocity while the slab-induced flow can cause seismic anisotropy, potentially explaining our seismic observations.</p></div>\",\"PeriodicalId\":11481,\"journal\":{\"name\":\"Earth and Planetary Science Letters\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":4.8000,\"publicationDate\":\"2024-07-04\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Earth and Planetary Science Letters\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0012821X24003005\",\"RegionNum\":1,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Earth and Planetary Science Letters","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0012821X24003005","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Low-velocity heterogeneities redistributed by subducted material in the deepest mantle beneath North America
The origins and composition of seismic low-velocity heterogeneities atop the core-mantle boundary (CMB) remain poorly understood. It is also debated whether they are static features or whether they can be displaced and modified by mantle convection, although recent seismological and geodynamic evidence suggests the latter. In this work, we perform the first simultaneous analysis of SPdKS waves to characterize low-velocity heterogeneity and seismic anisotropy, which is evidence for deformation, at the base of the mantle. We find seismic velocity heterogeneity and seismic anisotropy that are co-located with, or adjacent to, each other. Our study region, the lowermost mantle beneath North America, has been shaped by long-term subduction. Through geodynamic modeling simulations, we show that the sinking of subducted slabs to the lowermost mantle can trigger formation of hot thermal anomalies near subducted slabs, where chemical heterogeneities can accumulate. The thermochemical anomalies can cause reduction of seismic velocity while the slab-induced flow can cause seismic anisotropy, potentially explaining our seismic observations.
期刊介绍:
Earth and Planetary Science Letters (EPSL) is a leading journal for researchers across the entire Earth and planetary sciences community. It publishes concise, exciting, high-impact articles ("Letters") of broad interest. Its focus is on physical and chemical processes, the evolution and general properties of the Earth and planets - from their deep interiors to their atmospheres. EPSL also includes a Frontiers section, featuring invited high-profile synthesis articles by leading experts on timely topics to bring cutting-edge research to the wider community.