Judgment of metallogenic potential of Kangxiwa pegmatite in Xinjiang: Evidence from zircon U-Pb geochronology, geochemistry and Lu-Hf isotope.

Rare metals, as the strategic key metal minerals, are of great significance to the national security, economic health and sustainable development of our country. They are non-renewable and have unique physical and chemical properties. Through years of basic geological survey and prospecting in West Kunlun region in Xinjiang, a major breakthrough has been made in rare metal prospecting in the Dahongliutan-Bailongshan. In this paper, we conducted a combined study on detailed ziron U-Pb geochronology, Hf isotope, whole -rock major and trace elements in the Kangxiwa non -mineral pegmatites. These pegmatites are rich in SiO2, but poor in Al2O TiO2, MgO and P2O5 and mainly belong to high-potassium calcium -alkali type series rocks. Zircons from the pegmatites are of magmatic origin, with LA-ICP-MS U-Pb ages of 208 +/- 5. 5Ma to 210.3 +/- 2.3Ma, which are consistent with the age of Dahongliutan pluton, indicating that they are the products of the same tectonic event. Furthermore, these pegmatites are characterized by low REE contents (Sigma REE = 4. 21 x 10(-6) similar to 26. 98 x 10(-6)) with HREE loss, obvious negative Eu anomaly (delta Eu = 0. 04 -0. 61), enrichment of Rb, U and K, considerably loss of Nb, La and Zr, and serious loss of Ba, Ti and Sr. The research demonstrates that the Kangxiwa non -mineral pegmatites and the Dahongliutan pluton were formed in the same period, with similar Hf isotope characteristics. According to the metallogenic characteristics of Dahongliutan rare metal deposit, it is predicted that the Quaternary cover area of Kalakashi River north of Kangxiwa beryl-muscovite pegmatite dike zone and the section with higher elevation in Kangxiwa area are favorable areas for further lithium ore prospecting breakthrough.