Preferential Formation of Chlorite Over Talc During Si‐Metasomatism of Ultramafic Rocks in Subduction Zones
Preferential Formation of Chlorite Over Talc During Si‐Metasomatism of Ultramafic Rocks in Subduction Zones
复制标题
俯冲带超镁铁岩硅交代过程中绿泥石优先于滑石形成
DOI：
10.1029/2022gl100218
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发表时间：
2022
影响因子：
5.2
通讯作者：
H. Marschall
中科院分区：
文献类型：
--
作者：
E. Codillo;F. Klein;H. Marschall
通过超镁铁岩的二氧化硅交代作用形成的滑石被认为在俯冲带过程中发挥着关键作用。然而，滑石粉的形成条件仍然受到很少的限制。我们使用热力学反应路径模型来评估板片-地幔界面滑石的形成，并表明它受到一组有限的压力-温度条件、原岩和流体成分的限制。相比之下，我们的模型预测，在与俯冲带板片-地幔界面相关的条件下，绿泥石的形成是普遍存在的。在挖出的俯冲带地体的岩石记录中，滑石的稀缺和绿泥石的丰富是显而易见的。因此，硅交代过程中滑石粉的形成可能在挥发性循环、应变局部化和控制板界面的解耦-耦合转变中发挥更有限的作用。相反，观察到和预测的绿泥石的普遍存在证实了它在板片-地幔界面过程中的突出作用，之前的研究将其归因于滑石粉。
Talc formation via silica‐metasomatism of ultramafic rocks is believed to play key roles in subduction zone processes. Yet, the conditions of talc formation remain poorly constrained. We used thermodynamic reaction‐path models to assess the formation of talc at the slab‐mantle interface and show that it is restricted to a limited set of pressure–temperature conditions, protolith, and fluid compositions. In contrast, our models predict that chlorite formation is ubiquitous at conditions relevant to the slab‐mantle interface of subduction zones. The scarcity of talc and abundance of chlorite is evident in the rock record of exhumed subduction zone terranes. Talc formation during Si‐metasomatism may thus play a more limited role in volatile cycling, strain localization, and in controlling the decoupling‐coupling transition of the plate interface. Conversely, the observed and predicted ubiquity of chlorite corroborates its prominent role in slab‐mantle interface processes that previous studies attributed to talc.
影响因子：
2.5
作者：
Abers, Geoffrey A.;van Keken, Peter E.;Wilson, Cian R.
通讯作者：
Wilson, Cian R.
影响因子：
3.5
作者：
Klein, Frieder;Bach, Wolfgang;McCollom, Thomas M.
通讯作者：
McCollom, Thomas M.