Geophysical Detection of Relict Metasomatism from an Archean (∼3.5 Ga) Subduction Zone
Geophysical Detection of Relict Metasomatism from an Archean (∼3.5 Ga) Subduction Zone
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DOI：
10.1126/science.1178477
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发表时间：
2009-11-20
期刊：
影响因子：
56.9
通讯作者：
Snyder, David B.
中科院分区：
文献类型：
--
作者：
Chen, Chin-Wu;Rondenay, Stephane;Snyder, David B.
板块构造何时在地球上开始一直是不确定的，它在早期大陆组装中的作用也没有被很好地理解。通过合成重合的地震和电性剖面，我们证明了加拿大太古宙奴隶克拉通是俯冲作用形成的。近100公里深度的地震不连续和导电异常之间的空间重叠，以及富含代表交代前缘的次生矿物的地幔捕虏体的出现，支持了岩石圈碎片俯冲和吸积的克拉通组装。尽管克拉通组装的证据很少被保存下来，但这些结果表明，板块构造早在古太古代就开始活动了，类似于35亿年前(GA)。
When plate tectonics started on Earth has been uncertain, and its role in the assembly of early continents is not well understood. By synthesizing coincident seismic and electrical profiles, we show that subduction processes formed the Archean Slave craton in Canada. The spatial overlap between a seismic discontinuity and a conductive anomaly at similar to 100 kilometers depth, in conjunction with the occurrence of mantle xenoliths rich in secondary minerals representative of a metasomatic front, supports cratonic assembly by subduction and accretion of lithospheric fragments. Although evidence of cratonic assembly is rarely preserved, these results suggest that plate tectonics was operating as early as Paleoarchean times, similar to 3.5 billion years ago (Ga).