中亚造山带天河石花岗岩及相关铷矿床的主要特征与研究进展

铷是重要的"关键金属"矿产资源,是未来各国资源争夺的焦点。虽然我国铷矿资源总量丰富,但主要为低品位难以加工利用的花岗岩型铷矿床,而以铁锂云母、锂云母和铯沸石等作为矿石矿物的高品位易加工花岗伟晶岩型铷矿床非常有限。因此,富铷花岗岩及相关铷矿床的形成过程、元素分异机制以及铷在不同矿物相中的赋存状态和控制因素是铷矿床成矿机制研究和找矿工作的关键。本文在对花岗(伟晶)岩铷矿主要研究进展进行综述的基础上,简介中亚造山带东、西段典型天河石花岗岩及相关铷等稀有金属矿床的主要特征和时空分布,并对未来研究重点进行了展望。本文认为,中亚造山带是全球最重要的天河石花岗岩和相关稀有金属矿床成矿域,其西段大量发育三叠纪天河石花岗岩,而东段大量发育晚侏罗至早白垩世天河石花岗岩。两者形成时代和构造背景分别与古亚洲洋向古特提斯洋构造域,以及古亚洲洋向古太平洋构造域的巨大转折相对应,铷等稀有金属成矿潜力巨大,值得开展深入的年代学、岩石学和矿床成因研究。

Advances and general characteristics of the amazonite granite and related rubidium deposits in Central Asian Orogenic Belt

Rubidium (Rb) is regarded as one of the most economically important of the "critical metals", and it is anticipated to be of the focus of international natural resource competition in the future. Although potential Rb resources are abundant in China, they predominantly occur in low-grade granite-hosted deposits that are difficult to exploit. High-grade pegmatite-hosted Rb deposits in which zinnwaldite, lepidolite, and pollucite occur as ore minerals are limited. Characterizing the processes that form Rb mineralization in Rb-rich granites and related deposits, the differentiation of metallogenic elements, and the factors controlling occurrence state of Rb in different minerals is, therefore, crucial to understanding the metallogenic mechanism and development of robust prospecting models for Rb deposits. On the base of reviews on research advances in granite- and pegmatite-type Rb deposits, this contribution focuses on principal characters, temporal and spatcial distribution of amazonite granites and related Rb deposits in western and eastern segment of Central Asian Orogenic Belt (CAOB). Meanwhile, this contribution also gives research prospects in magmatism and mineralization geochronology, mineralization processes from magma to hydrothermal, and possible formation processes on high grade orebodies. It is proposed that CAOB contains majority of amazonite granites and related Rb deposits in the world. Amazonite granites and related Rb deposits from the western of CAOB are accumulated mainly in Triassic related to tectonic regime transformation from the Paleo-Asian Oceanic tectonic domain to Paleo-Tethys Ocenanic tectonic domain, while from the eastern of the CAOB they are accumulated in Late-Jurassic to Early Cretaceous related to tectonic regime transformation from the Paleo-Asian Ocean tectonic domain to Paleo-Pacific Ocean tectonic domain. The Triassic and Late-Jurassic to Early Cretaceous are two critical periods for amazonite granitic magmatism and Rb mineralization for the western and eastern CAOB repectively, and deserve further studies especially on geochronology, petrology, and metallogeny.