Southern Tianshan hosts Middle Paleozoic oceanic sediments and mafic volcanic rocks.
Volcanic rocks are associated with marine chert, carbonate, siliceous shale and turbidite.
Volcanic rocks possess geochemical features of OIB with subordinate MORB.
The dominating OIBs were derived from low-degree melting of garnet peridotite.
Wide age range of OIBs and their domination in OPS suggest a relatively large oceanic realm.