Petrogenesis of Middle Devonian diorite at the Xierqu Fe–Cu deposit in the Kalatag district, eastern Tianshan, NW China

Xierqu is a skarn Fe–Cu deposit associated with porphyritic diorite, in the Kalatag district of eastern Tianshan, China. The diorite yields a sensitive high‐resolution ion microprobe U–Pb zircon date of 391 ± 3 Ma interpreted as its age of emplacement. Major element geochemistry shows that the diorite is a calc‐alkaline assaying 16.7–19 wt.% of Al 2 O 3 , with Mg # values of 56.8–67.1, and Al 2 O 3 /(CaO + Na 2 O + K 2 O) (A/CNK) values of...