Molybdenum isotope systematics in subduction zones
Molybdenum isotope systematics in subduction zones
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DOI：
10.1016/j.epsl.2016.04.033
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发表时间：
2016-08
影响因子：
5.3
通讯作者：
S. König;M. Wille;A. Voegelin;R. Schoenberg
中科院分区：
文献类型：
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作者：
S. König;M. Wille;A. Voegelin;R. Schoenberg
本研究提供了来自不同俯冲带的弧熔岩的钼同位素数据，其范围在δ 98/95 Mo=− 0.72和+ 0.07‰之间。最重的同位素值观察到的最板流体为主的样品。同位素较轻的签名有关的陆源沉积物俯冲和沉积物熔融成分的相关性增加。我们的观察补充了以前的结论，同位素重钼流体通量可能反映了选择性掺入同位素轻钼的次生矿物内俯冲板。与此解释相一致，与陆源沉积物俯冲和沉积物熔融相一致的低δ 98/95 Mo通量不能简单地与再循环输入信号相关。相反，在沉积物熔融过程中，控制次生矿物的分解可能会释放轻组分，并导致减少δ 98/95 Mo流入亚弧地幔源。板块脱水和含水沉积物熔融之间的自然范围可能导致全球俯冲带岩浆中δ 98/95 Mo的大范围扩散。
This study presents Mo isotope data for arc lavas from different subduction zones that range between δ 98/95 Mo=− 0.72 and+ 0.07‰. Heaviest isotope values are observed for the most slab fluid dominated samples. Isotopically lighter signatures are related to increasing relevance of terrigenous sediment subduction and sediment melt components. Our observation complements previous conclusions that an isotopically heavy Mo fluid flux likely mirrors selective incorporation of isotopically light Mo in secondary minerals within the subducting slab. Analogue to this interpretation, low δ 98/95 Mo flux that coincides with terrigenous sediment subduction and sediment melting cannot be simply related to a recycled input signature. Instead, breakdown of the controlling secondary minerals during sediment melting may release the light component and lead to decreasing δ 98/95 Mo influx into subarc mantle sources. The natural range between slab dehydration and hydrous sediment melting may thus cause a large spread of δ 98/95 Mo in global subduction zone magmas.