The alkaline rocks located in the Hatu area of Dulan county in the middle section of the East Kunlun Orogenic Belt have a relatively high content of light rare earth elements (LREE). This study conducted scanning electron microscopy (SEM) petrographic methods, zircon U-Pb dating, and geochemical work on two REE-mineralized alkaline rock outcrops, providing support for further work and study in the mining area. The REE-mineralized alkaline rocks are composed of alkali feldspar syenite, hornblende alkali feldspar syenite, and quartz alkali feldspar syenite. SEM analysis indicates that the REE are mainly hosted in REE-bearing minerals such as chevkinite, parisite, allanite, and monazite. The alkali feldspar syenite and hornblende alkali feldspar are enriched in REE, with a content of 994 × 10−6~5054 × 10−6. The zircon U-Pb dating results show that the ages of the two REE-mineralized alkaline rock are 423.6 ± 2.7 Ma and 431.2 ± 5.3 Ma, respectively. Geochemical analysis indicates that the Hatu alkaline rocks can be classify as A-type granite, and are characterized by evidence of a mixture of materials from the crust and mantle. Considering the regional tectonic history, it is primarily inferred that the Hatu REE-mineralization alkaline rocks were formed after the closure of the Proto-Tethys Ocean Basin and the Eastern Kunlun region experienced extensional tectonic stage, resulting in the upwelling of asthenospheric material and heating of crustal material. This study provides theoretical support for regional geochemical research and further exploration efforts in the Hatu area.
Zhan et al. (Sat,) studied this question.