Representative compositions of the main host phenocryst phases for melt inclusions are shown in Table  2 , and the range of element concentrations in these minerals are contoured in Fig.  5 .

Results for approximately 200 individual melt inclusions in 19 samples are presented graphically for selected major and trace elements (9 elements out of 28 elements analyzed) in eFig. 1 in comparison with bulk rock compositions and plots for K, Ca, Ti and Sr is given as an example in Fig.  5 .

Changes in the composition of melt inclusions with increasing SiO ₂ content and other inter-element correlation trends follow those of bulk rocks for most elements (Fig.  5 ), except for small but diagnostic deviations observed for some elements at particular stages of the evolution (below)..

By contrast, mixing of two distinct magmas can explain linear variations in whole-rock compositions (shown by the black dashed lines in Fig.  5 ), as well as the more diagnostic evidence from the bimodal distribution of silicate melt inclusions.

For instance, the crystallization of plagioclase from a melt with 64 wt% SiO ₂ could raise the K ₂ O content from 3 to 7 wt% by the time the SiO ₂ content reaches 70 wt% (Fig.  5 , arrow 2).

For instance, a depletion of K in the residual melt of highly crystallized, felsic magma induced a lower K content in the mixed melt (colored dashed lines in Fig.  5 ).

The same combined effect induces a decrease in the silica content of the residual melt (arrow 1 in Fig.  5 ).