## 2 Geological Setting and Sampling  
The Jiaodong Peninsula, on the East China continental margin, is bounded by the Pacific Plate to the east and separated from the Luxi Block in NCC by the NNE-trending TLF to the west (Figure 1a,b) [6]. It can be separated into Sulu terrane in the southeast and Jiaobei terrane in the northwest based on the lithospheric-scale ENE- to NE-oriented WQYF [32; 33]. The Jiaobei terrane basement rocks consist of Mesoarchean-Neoarchean Jiaodong Group TTG gneiss with Neoarchean amphibolites and mafic granulites [34; 35], Palaeoproterozoic Jingshan and Fenzishan Groups, including metasedimentary marbles, calc-silicate rocks, and amphibolites [36; 37] undergoing a c. 1.8 Ga amphibolite- to granulite-facies metamorphism [35; 38], and the Neoproterozoic Penglai Group, consisting of slates, marbles and quartzites [39]. The crystalline basement in the Sulu terrane mainly includes Neoproterozoic and Palaeoproterozoic basement rocks of YC [40; 41; 42], which underwent a c. 244-220 Ma ultrahigh-pressure (UHP) metamorphic event [43; 44]. Coesite-bearing cogite, granitic geniss, marble and quartzite composed the UHP metamorphic rocks [36; 45], which were overprinted by the 220-205 Ma amphibolite to granulite-facies metamorphism locally [46]. The Palaeo-Pacific plate subduction resulted in the large scale Mesozoic magmatism in the Jiaodong Peninsula (Figure 1b) [8]. These Mesozoic magmatic rocks mainly occurred during two major episodes [47]: (a) Late Jurassic monzogranite and biotite granite (166-149 Ma) [3; 48] and (b) Early Cretaceous (130-110 Ma) porphyritic-like monzogranite, granodiorite and syenogranite [49; 50]. In addition, in the Jiaodong Peninsula, a great number of Mesozoic mafic dykes also occurred [51; 52]. The Dazeshan granitic pluton, with an area of c. 25 km\({}^{2}\), intruding into the southwest part of the Late Jurassic Linglong batholith in Jiaobei terrane (Figure 1), is a sheet-like NE- to NNE-trending intrusive body (Figure 2a,b). It is composed of massive and homogeneous monzogranites, showing the sharp contact with the host rock (Figure 2c,d). These monzogranites are medium- to coarse-grained and light flesh-pink in appearance (Figure 2e) and generally show typically porphyritic-like texture with a large amount of megacrysts of K-feldspar (Figure 2e). In addition, microgranular dark enclaves occur widely but are scarce (less than 1%) in these monzogranites (Figure 2f). They range from a few centimeters to decimeters in size (Figure 2f) and are oval to tabular in shape, commonly showing abrupt contacts with their host granitoids (Figure 2g,f). Some enclaves contain K-feldspar megacrysts (Figure 2h), suggesting that the granitic and mafic magmas were coeval. Samples for this paper, consisting of monzogranites and their dark enclaves, were collected from the Dazeshan granitic pluton, the locations of which are given in Figure 2b. Figure 2: (**a**) Geological map of the Dazeshan pluton, illustrating its location and relation with Linglong batholith. (**b**) Enlarged geological map of Dazeshan granitoids illustrating sample locations. (**c,d**) Contact between fine-grained biotite granite and porphyritic-like monzogranite. (**e**) Porphritic-like monzogranite with megacrysts of K-feldspar. (**f**) Dark microgranular enclaves in host monzogranites. (**g**) Tabular enclaves with abrupt contacts with their host. (**h**) Oval dark enclaves containing K-feldspar megacrysts. The main mineralogy of monzogranite includes plagioclase (32-36%), K-feldspar (30-33%), quartz (22-25%), biotite (3-6%) and amphibole (<3%), with few accessory minerals of sphere, apatite and zircon (Figure 3a-c). K-feldspar is generally subhedral, with inclusions of biotite, plagioclase and quartz (Figure 3d). The dark enclaves are dioritic in composition and usually show fine-grained subhedral equigranular textures (Figure 3e,f). The minerals are mainly of plagioclase, hornblende and quartz, without or with K-feldspar and biotite, and the accessory minerals are apatite, zircon, magnetite and titanite (Figure 3f).