## 5 Discussion
### Petrological Classification and Petrogenesis
It was proposed that late Early Cretaceous granitoids (118-110 Ma) in the Jiaodong Peninsula resulted from the partial melting of continental lower-middle crust followed by crystal fractionation [65]. The microgranular dark enclaves were widely developed in late Early Cretaceous granitoids, such as Sanfoshan pluton [30], Yashan pluton [65], Changshannan pluton [64], Gushan pluton [66] and Weidesan plutons [77], which were considered to be a result of magma mixing between crust-derived and mantle-derived magmas [30, 64, 65, 66, 77]. Likewise, the microgranular dark enclaves were also observed in the Dazeshan pluton in this study. However, all the dark enclaves are dioritic, with SiO\({}_{2}\) concentrations of 52.46-58.06 wt.% (Figure 5a) [64, 65, 66, 77], and they have negative \(\epsilon\)Hf (t) values ranging from -19.6 to -16.1 [78], indicating a crustal derivation for these dark enclaves, although a mantle origin followed by the crustal contamination remains a possibility [79]. Furthermore, the indistinguishable (\({}^{87}\)Sr/\({}^{86}\)Sr)\({}_{i}\) values for the dark enclaves and their host granitoids (Table 2; Figure 8) suggest a cogenetic origin, which may be associated with a common evolution process, such as restite unmixing, crystal accumulation, crystal fractionation or liquid immiscibility, instead of the magma mixing, co-mingling or wall-rock assimilation models [47, 52, 79, 80, 81, 82, 83, 84, 85]. However, the primary igneous rather than metamorphic textures of the enclaves from the Dazeshan pluton (Figure 3) preclude an origin resulting from restite unmixing [69, 84, 86]. In addition, the much higher REE, Zr, Nb and P concentrations in the dark enclaves than those in their host granitoids (Table A1; Figures 6 and 7) rule out their relation to fractional crystallization [80, 87, 88, 82]. Furthermore, a crystal accumulation model is also eliminated because of the greater REE and the moderately negative Eu anomalies (Eu/Eu\({}^{*}\) = 0.45-0.65) in contrast to the positive Eu anomaly shown in the dark enclaves (Table A1; Figure 6) [79, 89, 90]. Thus, it seems that liquid immiscibility is a viable model to explain the origin of the Dazeshan granitoids and their dark enclaves, which is also supported by the major-, trace-, and REE-element composition presented below, except for their identical (\({}^{87}\)Sr/\({}^{86}\)Sr)\({}_{i}\) values (Table 2; Figure 8). Experimental studies show that silicate melts rich in MgO, CaO, P\({}_{2}\)O\({}_{5}\), FeO and TiO\({}_{2}\) tend to split into one immiscible liquid pair, consisting of a quartz-feldspathic acid liquid and an iron-rich intermediate-basic liquid, producing a gap in SiO\({}_{2}\) composition with a linear trend on the oxide against SiO\({}_{2}\) plots [91, 92, 93, 94]. On a Greig pseudoternary phase diagram [SiO\({}_{2}\)-(CaO + MgO + TFE\({}_{2}\)O\({}_{3}\) + TiO\({}_{2}\) + P\({}_{2}\)O\({}_{5}\))-(Na\({}_{2}\)O + K\({}_{2}\)O + Al\({}_{2}\)O\({}_{3}\))], the Dazeshan granitoids and dark enclaves plot within a two-liquid immiscible field (Figure 10). In addition, they show a gap between 56.84 wt.% and 68.25 wt.% in SiO\({}_{2}\) composition, and  
Figure 9: (a) Na-K-Ca and (b) Sr-Rb-Ba plots for the Dazeshan granitoids based on [16]. The published data for middle Early Cretaceous granitoids (132–122 Ma) [64, 65, 66, 67] and Late Early Cretaceous granitoids (118–110 Ma) [49, 50, 68] are also shown in the Figures. Fields of low-Ba–Sr and high-Ba–Sr granitoids are from [76], and the field of adakite is from [17]. the oxides have a decreasing trend against SiO\({}_{2}\) increasing (Figure 5). Thus, the major-element compositional variation between the Dazeshan granitoids and dark enclaves could be related to a liquid immiscible process. Furthermore, the relative contents of trace and REE elements in the silicic rocks and their dark enclaves can also be used to judge if they were derived from a liquid immiscible process [80; 87; 93; 94].