The diverse fluid regimes during melting of the metasedimentary crust have been often discriminated on the basis of the composition of anatectic granitoids, with granites indicating fluid-absent melting conditions and trondhjemitic compositions suggesting the addition of external water in the source region. The lack of abundant metasedimentary-derived trondhjemites in the geological record is supposed to prove the minor role of water-fluxed melting in the crustal maturation. In terms of trace elements, instead, Rb, Sr and Ba contents and their ratios have been commonly used to discriminate dehydration vs. water-fluxed melting scenarios. Here I show that reconciling results of melting experiments, thermodynamic modeling and nanogranitoid study brings out a different picture. Equilibrium thermodynamics cannot properly reproduce melt compositions of the selected benchmark experiments, with the latter having trondhjemitic compositions mainly for the metastable behavior of muscovite during laboratory runs. The formation of sufficient volumes of extractable trondhjemitic melts is related to high pressure melting conditions (≥8 kbar at 700 °C and ≥11 kbar at 750 °C) or K-poor bulk rock compositions, rather than to the only presence of water. At low- to medium-pressure, crustal melts are granites in composition, whatever the fluid regime is. It is inferred that the abundance of anatectic peraluminous granites (compared to metasedimentary-derived trondhjemites) does not imply a dry nature of the orogenic crust. Likewise, the use of LILE (Rb, Sr and Ba) signatures may lead to erroneous conclusions on the fluid regime of the deep continental crust.

经常根据速溶花岗岩的成分来区分介子沉积壳融化过程中的各种流体形态，其中花岗岩表明缺乏流体融化条件，而白垩系组成则表明在源区中增加了外部水。地质记录中缺乏大量的源于沉积的特里杰米德火山岩，这可能证明了水熔融化在地壳成熟中的次要作用。取而代之的是，就痕量元素而言，Rb，Sr和Ba的含量及其比例通常用于区分脱水与水助熔的情况。在这里，我证明了融解实验，热力学建模和纳米颗粒物研究的协调结果带来了不同的画面。平衡热力学不能正确地再现所选基准实验的熔体成分，后者具有通透性成分，主要用于白云母在实验室运行期间的亚稳态行为。足够量的可萃取的四方菊药熔体的形成与高压熔解条件（在700℃下≥8kbar）有关。 °C和750  °C时≥11kbar ）或贫K块状岩石成分，而不是仅存在水。在低压至中压下，无论流体状态如何，地壳熔体的成分都是花岗岩。可以推断，大量的高钙铝质花岗岩（与由沉积成矿的特兰杰米特相比）并不意味着造山壳具有干性。同样，使用LILE（Rb，Sr和Ba）签名可能会得出关于深部大陆壳流体状态的错误结论。