Postdoctor SU Benxun and his teacher QIN Kezhang study geochemistry and geochronology of acidic rocks in the Beishan region.

The dacites and granites from the Beishan region are characterized by highly-fractionated REE, enrichments in LILE, and depletion in Nb, Ta and Sr. The dacites contain zircons with ages ranging from 265 to 748 Ma. These features suggest that they were probably derived from the older lower continental crust and were later on subjected to significant crustal assimilation.

These acidic igneous rocks (except dacites and granites) and coeval mafic–ultramafic intrusions form a bimodal igneous series. This implies that the Beishan region was a Late Paleozoic rift probably developed in association with the early Permian mantle plume activity in the Tarim Basin.

Su et al. Geochemistry and geochronology of acidic rocks in the Beishan region, NW China: Petrogenesis and tectonic implications. Journal of Asian Earth Sciences, 2011, 41(1): 31-43 （Download）

Fig. Zircon U–Pb ages of the mafic–ultramafic intrusions and volcanic rocks in the Eastern Tianshan and Beishan regions. Data sources are illustrated on the map. (Image by SU)