We appreciate the interest of Anenburg & O’Neill in our study on the petrology of the Kaiserstuhl Volcanic Complex (Braunger et al., 2018). Parts of this study are concerned with the redox conditions in the Kaiserstuhl magmas and Anenburg & ÓNeill criticize our introduction of what we called a silica-activity-corrected Fayalite–Magnetite–Quartz-Buffer (FMQ*), as ‘this is a contradiction in terms. For a buffer to shift by several log units would mean that it is not a buffer’. We introduced FMQ* to ‘compensate’ for the very low silica activities in the melts from which some of the Kaiserstuhl rocks were derived. However, the use of FMQ* as a reference buffer leads to confusion and some misinterpretations and is indeed inappropriate to express redox conditions in magmas in a meaningful manner. As Anenburg & O’Neill state, it is very important to distinguish between fO₂-involving mineral equilibria that may be used to calculate fO₂ for a magma from which these minerals crystallized under assumed equilibrium conditions (oxygen sensors) and an experimental charge that actually imposes fO₂ on a synthetic system (oxygen buffer). We thank Anenburg & O’Neill (2019) for their clear statement and agree with their criticism. However, we also want to state here that the calculated redox conditions are correctly illustrated in Figure 18b of Braunger et al. (2018) and show that the oxygen fugacity for the various Kaiserstuhl rocks generally falls 1 to 3 log units above the FMQ-buffer. The uncertainty for the lower limit of redox conditions for some of the rocks (e.g. melilite–haüynites, haüyne–melilitites and especially carbonatites) is caused by only rough constraints on their silica activity, rather than by disequilibrium between the minerals used for calculation (as inferred by Anenburg & O’Neill).

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回答Anenburg＆O'Neill对Braunger，S.，Marks，MAW，Walter，BF，Neubauer，R.，Reich，R.，Wenzel，T.，Parsapoor，A.和Markl，G.（2018）的评论）。德国西南部凯泽斯图尔火山群的岩石学：交代和氧化的岩石圈地幔对生成碳酸盐岩的重要性。岩石学报59，1731–1762

我们感谢Anenburg＆O'Neill对我们对Kaiserstuhl火山复合体岩石学的研究的兴趣（Braunger et al。，2018）。这项研究的部分内容与Kaiserstuhl岩浆中的氧化还原条件有关，Anenburg＆ÓNeill批评我们引入了所谓的经二氧化硅活性校正的方铁石-磁铁矿-石英缓冲液（FMQ *），因为“这是一个矛盾。条款。对于一个缓冲区移动几个对数单位，将意味着它不是一个缓冲区。我们引入了FMQ *来“补偿”熔体中极低的二氧化硅活度，而这些熔岩中的一些Kaiserstuhl岩石是从熔岩中产生的。但是，将FMQ *用作参考缓冲区会导致混淆和一些误解，并且确实不适合以有意义的方式在岩浆中表达氧化还原条件。作为Anenburg＆O'Neill州，区分f O ₂非常重要涉及的矿物平衡，可用于计算岩浆的f O ₂，这些矿物在假定的平衡条件下从这些晶体中结晶出来（氧气传感器），而实验电荷实际上将f O ₂施加在合成系统上（氧气缓冲液）。我们感谢Anenburg＆O'Neill（2019）的明确声明，并同意他们的批评。但是，我们在这里也要指出，Braunger等人的图18b中正确地说明了计算的氧化还原条件。（2018年），结果表明，各种Kaiserstuhl岩石的氧逸度通常比FMQ缓冲液高1-3个log单位。某些岩石（例如，陨石-海因石，海因-硅镁石，尤其是碳酸盐岩）的氧化还原条件下限的不确定性，仅是由于其二氧化硅活性的粗略限制，而不是由用于计算的矿物之间的不平衡引起的（如由Anenburg＆O'Neill推断）。