40Ar-39Ar age of tin mineralization in the Beilekuduk tin metallogenic belt, East Junggar, Xinjiang (NW China)
新疆东准噶尔贝勒库都克锡矿带锡成矿的40Ar-39Ar年龄

The Beilekuduk tin metallogenic belt in the eastern Junggar of Xinjiang is the first one discovered in northern China with four independent tin deposits, from east to west, named Sareshik, Beilekuduk, Ganliangzi, and Kamst, respectively. These tin deposits can be divided into two groups in terms of their ore type and gangue mineral compositions. The ores in Sareshik tin deposit are quartz type, and the gangue minerals are predominately composed of quartz, with minor feldspar, but almost no muscovite. Whereas the other three tin deposits are greisen type, and mainly composed of quartz and feldspar, with minor muscovite. In this paper, the 40Ar-39Ar dating results are reported for muscovites from Kamst, Ganliangzi, Beilekuduk tin deposits. The three samples of muscovite in equilibrium with cassiterite yield very flat age spectra. The 40Ar/36Ar-39Ar/36Ar normal isochron ages are well concordant with their corresponding plateau ages, ranging from 305 to 315Ma. These results, together with the Re-Os isochron age of the Sareshik tin deposit we previously reported well constrain the mineralization ages for the four tin deposits, and hence confirm that they certainly belong to the same tin metallogenic belt. Moreover, the coincident ages of the tin ores and their granite wallrocks indicate the most likely genetic relationship between tin mineralization and granitic magmatism in the studied region.