Oxygen isotope evidence for slab-derived fluids in the sub-arc mantle
Oxygen isotope evidence for slab-derived fluids in the sub-arc mantle
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DOI：
10.1038/31679
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发表时间：
1998-06-25
期刊：
影响因子：
64.8
通讯作者：
Stolper, EM
中科院分区：
文献类型：
--
作者：
Eiler, JM;McInnes, B;Stolper, EM
大洋岩石圈的俯冲被认为使地幔中富集了富集在蚀变洋壳及其沉积盖层中的元素（例如H2O、CO2和碱）（1，2）。这种富集通常是从岛弧熔岩的地球化学推断出来的（3）。更直接的证据--例如来自地幔的具有明确地壳起源的样本--是罕见的。地幔衍生矿物中的硅酸盐玻璃包裹体可以具有不同于玄武岩的主元素和微量元素成分（5，6），有时包含Sr，Nd和Pb的“富集”同位素成分，这表明包裹体是俯冲洋壳或沉积物的部分熔融物（6）。或者，这些富碱包裹体中的一些可能是通过将橄榄岩熔融到低程度（可能存在挥发物）而产生的（7）。在这里，我们提出的氧同位素数据从硅酸盐玻璃包裹体地幔橄榄石样品中的岛屿设置。这些数据提供了直接的证据，包体来自于一个来源，丰富的物质从俯冲洋壳，因此，板片衍生的流体已经渗透到亚弧地幔楔。
The subduction of oceanic lithosphere is thought to enrich the mantle in elements concentrated in altered oceanic crust and its sedimentary cover (for example, H2O, CO2 and alkalis)(1,2). This enrichment is generally inferred from the geochemistry of island-arc lavas(3). More direct evidence-such as samples from the mantle with a dear crustal origin(4)-is rare. Inclusions of silicate glass within mantle-derived minerals can have major- and trace-element compositions unlike basalt(5,6) and sometimes contain 'enriched' isotopic compositions of Sr, Nd and Pb, suggesting that the inclusions are partial melts of subducted oceanic crust or sediments(6). Alternatively, some of these alkali-rich inclusions may have been produced by melting peridotites to low degrees (possibly in the presence of volatiles)(7). Here we present oxygen isotope data from silicate glass inclusions obtained from mantle olivine samples in an island-are setting. These data provide direct evidence that the inclusions are derived from a source rich in material from the subducted oceanic crust and therefore that slab-derived fluids have infiltrated the sub-are mantle wedge.