FeTiMM - A new oxybarometer for mafic to felsic magmas
FeTiMM - A new oxybarometer for mafic to felsic magmas
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DOI：
10.7185/geochemlet.1740
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发表时间：
2017-01-01
影响因子：
4.9
通讯作者：
Audetat, A.
中科院分区：
文献类型：
--
作者：
Arato, R.;Audetat, A.
岩浆的氧化状态是一个很难重建的关键参数。最常见的方法是通过磁铁矿-钛铁矿氧压法。然而，许多天然岩浆不含钛铁矿，阻碍了该技术的应用。在这里，我们提出了一种新的方法，允许fO（2）被重建的基础上磁铁矿和硅酸盐熔体之间的Fe和Ti的分配。我们称之为FeTiMM的新方法适用于无钛铁矿和含钛铁矿的样品，甚至适用于缓慢冷却的侵入岩，如花岗岩。FeTiMM在109个实验中进行了校准，这些实验涵盖了从玄武岩到流纹岩组成的广泛的氧逸度、温度、压力和硅酸盐熔体范围，并且返回的fO（2）值在0.5个对数单位内与除五种情况外的所有情况下的独立约束fO（2）值一致。对19个英安岩到流纹岩组成的天然样品进行的第一次测试同样成功。因此，FeTiMM在地球科学的各个学科中为许多新的应用打开了大门，包括火山学，火成岩学，实验地球化学和矿石地质学领域。
The oxidation state of magmas is a key parameter that is notoriously difficult to reconstruct. The most common approach is via magnetite-ilmenite oxybarometry. However, many natural magmas do not contain ilmenite, preventing application of this technique. Here we present a new method that allows fO(2) to be reconstructed based on the partitioning of Fe and Ti between magnetite and silicate melt. The new method, which we call FeTiMM, is applicable to both ilmenite-free and ilmenite-bearing samples, and even to slowly cooled intrusive rocks such as granites. FeTiMM was calibrated on 109 experiments covering a wide range of oxygen fugacities, temperatures, pressures and silicate melts ranging from basaltic to rhyolitic composition, and returned fO(2) values that agree within 0.5 log units with independently constrained fO(2) values in all but five cases. A first test on 19 natural samples of dacitic to rhyolitic compositions was equally successful. FeTiMM thus opens the door for numerous new applications in various disciplines of Earth Sciences, including the fields of volcanology, igneous petrology, experimental geochemistry and ore geology.