桂东南各构造时期含稀土矿物花岗岩岩相学及稀土成矿影响因素探讨

Petrology of Rare Earth Element-Bearing Granites from Different Tectonic Periods in Southeastern Guangxi and a Study on the Factors Influencing Rare Earth Mineralization

摘要: 桂东南位于华南著名的钦杭断裂带西南端，隶属于著名的大容山–十万大山构造–岩浆岩带，是研究扬子板块与华夏板块碰撞造山过程的重要地区。本论文旨在通过桂东南各时期含稀土矿物花岗岩的岩相学等分析探讨该区域各时期花岗岩中稀土矿物的分布、种类及其与花岗岩成因的关联。本论文系统分析了桂东南地区各时期与稀土矿相关的花岗岩的岩相学特征、矿物组合、地球化学性质及构造背景等，揭示了各时期花岗岩的形成构造背景。研究表明发育离子吸附型稀土矿的花岗岩岩体富含堇青石、紫苏辉石及独居石、磷钇矿等稀土副矿物。高初始稀土含量、易风化矿物组合及长期风化历史是成矿的关键因素。本论文通过研究稀土矿物在花岗岩中的分布特征、富集特点及其对源区岩浆演化的指示作用，旨在揭示稀土元素在花岗岩中的地球化学行为及其对花岗岩成分变化的影响机制，研究成果将为稀土资源勘查、花岗岩成因研究及地质构造解析提供重要科学依据。

Abstract: Southeastern Guangxi is located at the southwestern end of the well-known Qinzhou-Hangzhou fault zone and belongs to the famous Darongshan-Shiwandashan tectono-magmatic belt. It is a key area for studying the collisional orogenic process between the Yangtze Block and the Cathaysia Block. This paper aims to investigate the distribution, types, and genetic relationships of rare earth minerals in granites of different periods in southeastern Guangxi through petrological and related analyses. A systematic study is conducted on the petrological characteristics, mineral assemblages, geochemical properties, and tectonic settings of granites associated with rare earth mineralization in different periods in the region, revealing the tectonic backgrounds of granite formation at each stage. The results indicate that granite bodies hosting ion-adsorption type rare earth deposits are enriched in cordierite, hypersthene, and accessory rare earth minerals such as monazite and xenotime. High initial rare earth element contents, easily weathered mineral assemblages, and prolonged weathering history are identified as key factors controlling mineralization. By examining the distribution patterns and enrichment characteristics of rare earth minerals in granites, as well as their implications for source region and magmatic evolution, this study aims to clarify the geochemical behavior of rare earth elements in granitic systems and the mechanisms influencing compositional variations in granites. The findings provide important scientific evidence for rare earth resource exploration, granite genesis studies, and tectonic interpretation.