The A-type granites and tin mineralization in the eastern Junggar, Xinjiang: Constraints from geochronology and geochemistry

<p indent="0mm"> Four independent tin deposits, named Kamst, Ganliangzi, Beilekuduk, and Sareshike, are associated with alkali-rich (alkali-feldspar or alkaline) granites within the Kalamaili orogenic belt in the eastern Junggar, Xinjiang. In order to deeply reveal the genesis of the tin deposits and associated granites, by using methods for the high-precision in-situ U-Pb dating of zircon grains and analyzing elemental and isotopic compositions of granites and fluorite, we have obtained ages of plutons including the Karasay <sc>(300±2 Ma),</sc> Kamst <sc>(301±2 Ma),</sc> Ganliangzi <sc>(296±3 Ma),</sc> and Beilekudouk <sc>(300±2 Ma),</sc> as well as the elemental and Nd isotopic compositions of the granites associated with tin deposits and the fluorite found in the Ganliangzi tin deposit. The systematic comparison of isotopic ages indicates that both the tin deposits and associated granites were formed during the late Carboniferous post-collisional evolution stage in the eastern Junggar. Based on characteristics of highly developed alkali-feldspar, high Ga contents, and low Al contents in the granites associated with tin deposits, it is believed that they belong to the typical A-type granite. The fluorite and A-type granites have consistent characteristics in rare earth and incompatible elements, and respective ε_Nd(t) values of 5.5±0.1 and 5.0±0.4, confirming that there is a proprovenance relationship between the tin deposits and associated granites. Therefore, the tin deposits in the eastern Junggar, Xinjiang are magmatic hydrothermal ones associated with the A-type granite.