Zircon U-Pb dating and geochemical characteristics of the granites in Kuchuwula-Yingba area of western Inner Mongolia

Zircon U-Pb dating indicates that the granite samples collected from the Kuchuwula-Yingba area of western Inner Mongolia includes the Late Devonian monzonitic granite ((371±2)Ma), Middle Permian K-feldspar granite ((271±1)-(270±1)Ma) and Early Cretaceous monzonitic granite ((133±1)Ma). In combination with the data available, the acidic magmatic activity can be divided into 4 stages:Late Devonian (-371 Ma), Late Carboniferous (313-311 Ma), Early-Middle Permian (282-270 Ma) and Early Cretaceous (133-130 Ma). Geochemically, the Late Devonian monzonitic granites belong to the typical S-type granites, which reflects a post-collisional tectonic setting. On the one hand, these data indicate that magmatic activities occurred before the Carboniferous period in the Zhusileng-Hangwula tectonic zone; on the other hand, they probably exactly reflect the lower limit of the time when Kazakhstan + Tarim + North China plate collided with the Siberian plate. The Middle Permian K-feldspar granites belong to the A-type granites, which reflects a tectonic setting of the crustal extension, having a good correspondence with the strong extension environment of this region in the same period. The geochemical characteristics of the Early Cretaceous monzonitic granites are similar to the features of Late Devonian monzonitic granite, also suggesting a post-collisional tectonic setting in accord with the post-collisional and extensional environment of this region in the same period.