The Carboniferous volcanic rocks in the Aqishan-Yamansu metallogenic belt, Xinjiang, NW China, are sodium-rich volcanic rocks (spilite-keratophyre series). Plagioclases in the sodium-rich volcanic rocks of the Yamansu Formation (C,y) are albites with a small number of oligoclases. Two types of albite (the early Abl and the late Ab(2)) were identified. The Ab(2) is not only different from Abl in morphology and texture, but also in element contents: from Ab(1) to Ab(2), Al2O3 and Ca0 decreased, Na20 increased, An values decreased and Ab values increased. Plagioclases in the sodium-rich volcanic rocks of the Tugutu Bulak Formation (C2tgt) are also albites with a small number of oligoclases. However, the plagioclases of the Tugutu Bulak Formation generally have lower Na2O contents and higher An values than that of the Yamansu Formation. The trace element characteristics of in situ LA-ICP-MS show that Ab2 has a larger range of trace elements, higher Al, Sr, Ca, Ba, Y, Rb, lower LREE/HREE and au than Abl. Moreover, the Ab2 has higher favorable metallogenic elements contents, such as Fe, Co, Ni, Cu, V and Zn, which indicates that more sodium-rich fluids and more ore-forming elements are involved in the formation of Ab(2). These are consistent with the microscopic characteristics of the coexistence of metallic minerals (such as magnetite) and Ab2, which reveals that Ab2 may be related to alteration and mineralization in the Aqishan-Yamansu metallogenic belt. The SHRIMP zircon U-Pb dating of andesite from Tugutu Bulak Formation in the southern Kangguer area is 313. 9 5. 8Ma. It can be inferred that the sodium-rich volcanic rocks also formed in the Late Carboniferous. There is a spatial and temporal coupling relationship between marine sodium-rich volcanic rocks and deposits in the belt, which reminds that attention should be paid to the sodium-rich volcanic rocks in the direction of prospecting and exploration.
