The Huangyangshan A-type granitic pluton, distributed along the thrust fault in the Kalamaili region of East Junggar, Xinjiang, China, consists of alkaline granite containing abundant dioritic enclaves that formed via magma mixing. Both the host granite and the enclaves contain sodic amphiboles. The textural evidence indicates that amphiboles crystallized as a magmatic phase in both units.
We determined major and trace element contents of amphiboles from both units to investigate the compositional variation of the amphiboles during the magma mixing process.
Therefore, the variations of W- and C-site cations can reflect magma evolution. The core and rim of the amphiboles show similar trace element patterns, which also suggests that the amphiboles are late-stage phases. Furthermore, the amphibole-only thermometers yield reasonable estimates that are consistent with petrographic evidence. However, thermometers based on partition coefficients and all the currently available amphibole-based barometers that rely on Al contents or D Al cannot be applied to Fe-rich and Al-poor amphiboles.
Magma mixing is a common magmatic process during formation of granitoids Kumar et al. Previous studies suggest that magma mixing can be important for formation of critical metal deposits e.
If mafic magma injects into felsic magma during magma mixing, microgranular mafic enclaves MMEs would likely form. During this process, amphiboles are usually the major rock-forming minerals. The A site occurs in the center of space between the double-chains of the structure. Cations on the B-site situate at the periphery of the strip of the octahedra C-cations occupy. This complexity gives rise to a complicated classification for amphiboles Hawthorne et al. Owing to the complexity, amphiboles are capable of accommodating a variety of elements with variable ionic charges and radii, including alkali elements, rare earth elements REE , high field strength elements HFSE , and large ion lithophile elements LILE Siegel et al.
