Genesis of the Bieyesamas Monzogranite of the Altay Mountain, Xinjiang, Northwestern China, and Its Rare Metal Resource Potential

Gengbiao Qiao,Xiaoyan Chen,Wenming Li,Xudong Zhang

doi:10.1155/2021/4430984

Abstract

Lying in the Altay Orogenic Belt in Xinjiang, Northwestern China, the Bieyesamas monzogranite pluton is located in the North Altay Terrane. It is one of the important granitic batholiths with a large amount of rare metal pegmatite dikes. According to LA-ICP-MS zircon U-Pb isotopic dating, the 206Pb/238U weighted average age of the Bieyesamas monzogranite is 451.1 ± 5.1 Ma ( MSWD = 6.0 ), indicating the formation age of Late Ordovician. The Bieyesamas monzogranite has secondary minerals such as garnet and tourmaline. The geochemical analysis shows that the pluton is characterized by high SiO2 (70.45%~75.44%), Al2O3 (14. 04%~17.14%), potassium and alkaline ( K 2 O = 4.20 % ~ 4.78 % , N a 2 O + K 2 O = 7.90 % ~ 8.99 % ), A/CNK (1.16~1.28), and high corundum (2.33%~5.08%) being found in CIPW standard minerals, belonging to high-K calc-alkaline peraluminous series. The pluton is enriched in LREE, depleted in HREE ( LREE / HREE = 5.99 ~ 9.65 ), with obviously negative Eu anomaly ( δ Eu = 0.44 ~ 0.60 ), while the trace elements are characterized by Rb, K, Nb, Ta, Hf, and U enrichment and Ba, Sr, Ti, and Zr depletion, as well as with high differentiation index ( DI = 93.24 % ). Zircon ε Hf t values range from 2.89 to 7.69, with the corresponding two-stage model ages ( T DM 2 ) of 941~1257 Ma. The mineral assemblage, geochemical characteristics, and zircon Hf isotope indicate the pluton experienced the highly fractionated process and belongs to highly fractionated S-type granite, which was formed by partial melting of the Meso- to Neoproterozoic crustal material. In the Bieyesamas monzogranite, the average contents of rare metals are obviously higher ( Li = 550 × 10 − 6 , Be = 10.18 × 10 − 6 , Nb = 18.91 × 10 − 6 , Ta = 2.14 × 10 − 6 , Rb = 500 × 10 − 6 , and Cs = 149.9 × 10 − 6 ) than the other rocks and Clark values of crust, which indicates that the Bieyesamas pluton has the enrichment potential of rare metals. The metallogenic geological conditions are superior in the Bieyesamas area of the Altay Mountain, and rare metal deposits and ore spots are widely distributed. In particular, the newly discovered rare metal deposits are characterized by large-scale mineralization, high grade and industrial utilization value, etc. It is preliminarily predicted that they have reached the medium-scale deposits. Therefore, the Bieyesamas area is one of the key areas for rare metal prospecting breakthroughs in the future, with great potential for rare metal mineral resources.

Highlights

The Altay Orogenic Belt is located in the western part of the Central Asian Orogenic Belt, in the transition zone between the Siberian Block and the Kazakhstan-Jungare Block [1], with a total length of about 2000 km, extending nearly east-west through China, Mongolia, Russia, and Kazakhstan (Figure 1(a)), and stretching about 500 km in northernXinjiang, NW China [2]
Based on the study of the metallogenic geological background, we further explored the prospect of rare metal finding and mineralization potential in the region, which provide new information for the regional tectonic evolution of the Altay Orogenic Belt, and at the same time, it is of great indicative significance for the search and exploration of rare metals in northeastern Altay
The Th content of zircon ranges from 21:5 × 10−6 to 145:4 × 10−6; the U content ranges from 210:0 × 10−6 to 1123:0 × 10−6, with a wide fluctuation range; the Th/U ratio is mainly concentrated in the range of 0.07 to 0.39

Summary

Introduction

The Altay Orogenic Belt is located in the western part of the Central Asian Orogenic Belt, in the transition zone between the Siberian Block and the Kazakhstan-Jungare Block [1], with a total length of about 2000 km, extending nearly east-west through China, Mongolia, Russia, and Kazakhstan (Figure 1(a)), and stretching about 500 km in northernXinjiang, NW China [2]. The Altay Orogenic Belt is located in the western part of the Central Asian Orogenic Belt, in the transition zone between the Siberian Block and the Kazakhstan-Jungare Block [1], with a total length of about 2000 km, extending nearly east-west through China, Mongolia, Russia, and Kazakhstan (Figure 1(a)), and stretching about 500 km in northern. The Altay Orogenic Belt is adjacent to the West Sayan Ridge ancient island arc belt to the north and is bounded to the Junggar Orogenic Belt by the ErtixMainobo suture zone [3] (Figure 1(b)). The Altay Orogenic Belt is an accretionary orogenic belt, which has undergone two-way accretion of the Paleozoic oceanic crust and intracontinental orogeny of the Middle Cenozoic, forming a series of continental blocks, island arcs, and accretionary Geofluids 86° (b) Habahe 88° 49° N (a) Russia Kazakhstan Mongolia China Fig. 1b

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Conclusion