An experimental study of the behaviour of cerium/molybdenum ratios during subduction: Implications for tracing the slab component in the Lesser Antilles and Mariana Arc
An experimental study of the behaviour of cerium/molybdenum ratios during subduction: Implications for tracing the slab component in the Lesser Antilles and Mariana Arc
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俯冲过程中铈/钼比率行为的实验研究：追踪小安的列斯群岛和马里亚纳弧板片成分的意义
DOI：
10.1016/j.gca.2017.05.025
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发表时间：
2017
影响因子：
5
通讯作者：
Skora S
中科院分区：
文献类型：
--
作者：
Skora S
弧岩浆的地球化学特征非常明显，这是俯冲板片中微量元素富集成分进入上覆地幔楔熔体的结果。然而，它并不总是简单的区分这些板片成分同化地壳岩石在随后的分化，因为这两个水库可以共享相似的地球化学特征。这促使了新工具的开发，例如结合Ce/Mo测量使用的98 Mo/95 Mo分析。地表环境中δ98/95 Mo的变化导致俯冲Mo同位素组成的变化。大多数诊断这些是非常同位素重钼在海洋黑色页岩，如那些在小安的列斯群岛附近钻探。然而，俯冲组合总是复杂和不同的熔融行为和对比δ98/95 Mo的各种地壳组件可能会相互抵消，需要更详细的调查的行为Mo和Ce在下行slate.This研究致力于确定可能的主机Mo和Ce在沉积物和玄武岩在弧下深处。使用来自小安的列斯群岛岛弧的合成富碳黑色页岩和钙质沉积物成分进行了新的熔化实验（3 GPa，800-900 °C）。此外，新的分析钼浓度和Ce/Mo数据先前发表的部分熔融研究蚀变洋壳和火山碎屑（马里亚纳弧）。我们的研究表明，硫化物和在较小程度上金红石是主要的主机为钼榴辉岩，而存在或不存在的独居石（贫钙沉积物），绿帘石（富钙沉积物）和碳酸盐（富碳酸钙沉积物）控制沉积物中的Ce浓度。氧化还原条件被发现是非常重要的铈/钼比的板组件来自这些岩性，因为它们对硫化物和绿帘石的稳定性的影响。它进一步表明，金红石只有主机钼在适当的还原条件下，与以前的研究一致。测得的Ce/Mo与我们的实验结果相结合，从而放置在俯冲板相岩石学和氧化还原条件的重要约束。
Arc magmas are very distinct in their geochemical signatures, a consequence of trace element enriched components from the subducting slab that are incorporated into melts of the overlying mantle wedge. However, it is not always straightforward to distinguish such slab components from assimilation of crustal rocks during subsequent differentiation, given that both reservoirs can share similar geochemical characteristics. This has prompted the development of new tools, such as98Mo/95Mo analyses used in combination with Ce/Mo measurements. The diverse range of δ98/95Mo in the surface environment gives rise to variable isotopic compositions of subducted Mo. Most diagnostic of these is the extremely isotopically heavy Mo in marine black shales, such as those drilled in the vicinity of the Lesser Antilles. However, subducting assemblages are invariably complex and differing melting behaviours and contrasting δ98/95Mo of various crustal components may counter-balance one another, requiring a more detailed investigation of the behaviour of Mo and Ce in the down-going slab.This study is dedicated to identifying possible hosts for Mo and Ce in sediments and basalt at sub-arc depths. New melting experiments were performed (3 GPa, 800–900 °C), using synthetic carbon-rich black shale and calcareous sediment compositions from the Lesser Antilles arc. In addition, new analyses of Mo concentrations and Ce/Mo data of previously published partial melting studies on altered oceanic crust and volcaniclastics (Mariana Arc) are presented. Our study suggests that sulfide and to a lesser extent rutile are the major hosts for Mo in eclogites, whereas the presence or absence of monazite (Ca-poor sediments), epidote (Ca-rich sediments) and carbonate (CaCO3-rich sediments) controls Ce concentrations in sediments. Redox conditions are found to be of great importance for the Ce/Mo ratios of slab components derived from these lithologies because of their influence on sulfide and epidote stability. It is further shown that rutile only hosts Mo at suitably reducing conditions, in concordance with previous studies. The combination of measured Ce/Mo with our experimental results thus places important constrains on phase petrology and redox conditions in the subducted slab.
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DOI：
--
发表时间：
1982
期刊：
影响因子：
--
作者：
B. Tucholke;R. Houtz;W. Ludwig
通讯作者：
W. Ludwig
大西洋白垩纪黑色页岩地球化学（DSDP Legs 11、14、36 和 41）☆
影响因子：
3.9
作者：
H. Brumsack
通讯作者：
H. Brumsack
解决小安的列斯群岛弧的沉积物俯冲和地壳污染：He-O-Sr 同位素组合方法
DOI：
--
发表时间：
2002
期刊：
影响因子：
--
作者：
M. V. Soest;D. Hilton;C. Macpherson;D. Mattey
通讯作者：
D. Mattey
影响因子：
5.8
作者：
H. Freymuth;T. Elliott;M. V. Soest;S. Skora
通讯作者：
H. Freymuth;T. Elliott;M. V. Soest;S. Skora
太平洋板块最古老部分的古纬度和构造重建：比较研究
影响因子：
5.8
作者：
R. Larson;M. Steiner;E. Erba;Y. Lancelot
通讯作者：
Y. Lancelot