火成岩
地质学
结壳
地球化学
大洋地壳
地幔楔
地幔(地质学)
大陆地壳
岩石学
俯冲
构造学
地震学
作者
Scott S. Turner,C. H. Langmuir
出处
期刊:Science Advances
[American Association for the Advancement of Science (AAAS)]
日期:2024-06-14
卷期号:10 (24)
标识
DOI:10.1126/sciadv.adg6482
摘要
A long-standing paradigm of arc geochemistry is that the trace element compositions of arc lavas arise from two compositionally distinct slab components: an aqueous dehydration fluid from the subducting igneous ocean crust that transports “fluid-mobile” elements, such as barium (Ba), and a sediment melt that supplies thorium (Th) and the light rare earth elements. This two-component framework has been widely called upon to explain global geochemical trends as well as geochemical variations within individual arcs, such as the Marianas. Here, we show that this paradigm is inconsistent with mass balance, due to the low Ba contents of igneous ocean crust, and with experimental data, which show that aqueous fluids from the igneous oceanic crust would be too dilute to substantially affect arc compositions. Observations previously attributed to the sediment melt/igneous-crust-fluid hypothesis are better explained by diverse subducting sediment compositions coupled with ambient mantle wedge heterogeneity, both globally and for the Marianas.
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