S‐type granitic gneiss is a major rock type in exposed Phanerozoic basement areas. However, it is hardly used to decipher the metamorphic evolution of such areas formed by the collision of tectonic plates. It is demonstrated by thermodynamic modelling of the metamorphism of common to evolved S‐type granite that mineralogical key patterns can elucidate the baric nature of granitic gneiss. Low‐ to medium‐grade granitic gneiss shows increasing and decreasing contents of potassic white mica and biotite, respectively, with rising pressure. Pressures above c. 12 kbar (500°C) result in considerable amounts of Na‐rich clinopyroxene. A relatively precise peak‐pressure estimate can be obtained by the determination of the Si content in potassic white mica but only for water pressures below 13–15 kbar. Thus, eclogite facies granitic gneiss can only be recognized by the presence of Na‐rich clinopyroxene. Silicon contents in biotite might have a geobarometric potential as potassic white mica. Titanium minerals in S‐type granitic gneiss are of limited baric potential.

中文翻译：

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S型花岗片麻岩的主要模式，用于定义生代基底岩层的钡（低压至高压）性质

S型花岗片麻岩是裸生代地下层地区的主要岩石类型。但是，几乎没有用它来解释由构造板块碰撞形成的这种区域的变质演化。通过对演化为S型花岗岩的常见变质作用的热力学建模证明，矿物学上的关键特征可以阐明花岗片麻岩的轻质性。中低等级的花岗片麻岩显示，随着压力的升高，钾白云母和黑云母的含量分别增加和减少。高于c的压力。12 kbar（500°C）会产生大量的Na富集的次氯环丁烯。通过测定钾白云母中的硅含量可以获得相对精确的峰值压力估算值，但仅适用于水压低于13–15 kbar的情况。因此，只有存在富钠的斜辉石才能识别出榴辉岩相的花岗岩片麻岩。黑云母中的硅含量可能具有高钾潜力，如钾白云母。S型花岗片麻岩中的钛矿物具有有限的重矿潜力。