8. CONCLUSIONS
This work adds to the growing catalogue of research describing the
cumulate origins of intermediate and silicic plutons and geochemical and
textural evidence of phase separation in these systems (Bachl et
al. , 2001, Barnes et al. , 2019, Claiborne et al. , 2006,
Claiborne et al. , 2010, Cornet et al. , 2022, Fiedrichet al. , 2017, Garibaldi et al. , 2018, Gelman et
al. , 2014, Hartung et al. , 2017, Payacán et al. , 2023,
Schaen et al. , 2018, Tavazzani et al. , 2020, Walker Jret al. , 2007). The textures and chemistry of the samples suggest
that the range in chemical compositions recorded by SMB samples is
consistent with phase separation by repacking-accommodated compaction.
Trace element modeling suggests that 24% of the mass has crystallized
magma of uniform composition before unmixing occurs, explaining the
composition of the majority of SMB. We find in the cumulates that the
trapped melt fraction is correlated with wt % SiO2 and
incompatible trace elements and inversely correlated with depth, fabric
intensity, and compatible trace elements. We argue that the batholith is
the result of partial-crystallization and subsequent mechanical phase
separation by repacking-driven compaction of repeated injections of
similar magmas over the course of about two million years as indicated
by zircon age dates by previous researchers (Claiborne et al .,
2006, 2010, Walker Jr et al ., 2007).