## 3 Sampling Strategy, Analytical Methods, and Results
### Major Element Composition: EPMA Results
#### 3.4.1 Amphibole  
Although new classifications and nomenclature schemes for amphibole minerals have been developed in recent years based on more accurate measurements [45; 46; 47], the nomenclature scheme for the calcic amphibole group has remained largely unchanged. Cations of amphibole were calculated based on a 23-oxygen-atom basis, following the procedure outlined in [45] (see Table S1 of the electronic supplement). Since the valence state of Fe has not been measured, the Fe\({}^{3+}\)/\(\Sigma\) Fe ratio was calculated by constraining the sum of specific cations to a particular value and assuming electroneutrality for the entire formula [47]. The various cation sums and constraints proposed for this calculation are discussed in detail in [45; 47; 48; 49].  
The amphiboles analyzed in this study are all calcic ((Ca + Na)\({}_{\rm B}\geq\) 1.0, typically, Ca\({}_{\rm B}\geq\) 1.5). See Figure 4a,b for further classification. amphiboles in the fine-grained hornblende gabbro (Type 1: D17-B1-02) are classified as magnesiohorrhleende, while others are categorized as magnesio-hatsingite (\({}^{\rm VI}\)Al \(\geq\) Fe\({}^{3+}\)) or pargasite (\({}^{\rm VI}\)Al \(<\) Fe\({}^{3+}\)). The magnesium number (Mg# = 100 Mg/(Mg + Fe\({}^{2+}\)) varies between 59.39 and 72.15, and SiO\({}_{2}\) contents range from 38.60 to 48.48 wt.% and Al\({}_{2}\)O\({}_{3}\) from 7.57 to 15.24 wt.%, with TiO\({}_{2}\) (0.55-2.98 wt.%), FeO\({}^{7}\) (9.86-14.70 wt.%), MgO (11.27-14.84 wt.%), CaO (10.84-13.83 wt.%), Na\({}_{2}\)O (0.73-2.48 wt.%), and K\({}_{2}\)O (0.33-1.61 wt.%) [45].  
Figure 5 shows the compositional profiles of the amphiboles analyzed in this study. At the rims, amphiboles exhibit similar concentrations of Mg#, SiO\({}_{2}\), and TiO\({}_{2}\) (Figure 5). Some positive or negative peaks are caused by cleavage or fractures. The Type 2 amphibole shows a slight decrease in Mg#, SiO\({}_{2}\), and TiO\({}_{2}\), nearly constant Al\({}_{2}\)O\({}_{3}\), and a slight increase  
Figure 4: Mineral compositions of representative amphiboles and clinopyroxenes from the Sanggeda intrusion. (**a**,**b**) Classification of amphiboles according to the nomenclature of [45]. (**c**) Data for clinopyroxene from homblende cumulate enclaves plotted on the enstatite–ferrosilite–diopside–hedenbergetic quadrilateral of [50]. Except for Type 1, hollow and solid symbols represent crystals dispersed in the matrix and cumulate enclaves, respectively.  
in K\({}_{2}\)O toward the rim (Figure 5a). The Type 3C grain shows a progressively decreasing Mg# and K\({}_{2}\)O content from core to rim, while SiO\({}_{2}\), TiO\({}_{2}\), and Al\({}_{2}\)O\({}_{3}\) contents remain uniform (Figure 5b). The Type 4 amphibole shows a lower Mg# in the core, which then increases toward the edge of the crystal (Figure 5c,d). The Type 4P amphibole shows a large variation in Mg# at the edge, consistent with the narrow zoning observed at the edge of the amphibole under the microscope.  
Figure 5: Major element compositional profiles across amphibole crystals of various types: (**a**) Type 2; (**b**) Type 3C; (**c**) Type 4P; (**d**) Type 4C. The red arrows in the figure indicate the starting and ending positions of the profiles, whether rim to core or rim–core–rim.  
Representative amphibole analyses were plotted in bivariate diagrams against Mg# (Figure 6). The Mg# of the Type 1 amphibole (approximately 65-68) is at an intermediate level, with higher SiO\({}_{2}\) and lower Al\({}_{2}\)O\({}_{3}\) and K\({}_{2}\)O contents compared to other types of amphiboles. The Type 2 amphibole has higher TiO\({}_{2}\) and Na\({}_{2}\)O contents, lower Al\({}_{2}\)O\({}_{3}\), CaO, and K\({}_{2}\)O contents, and similar SiO\({}_{2}\) contents. The Type 3 and 4 amphiboles show a wide Mg# range (about 59-72) but relatively similar major element compositions.