青海乌兰地区花岗伟晶岩矿物学特征及其地球化学组成

青海省乌兰县地处青海省中部、柴达木盆地东部地区,位于欧龙布鲁克—乌兰华力西期稀有、钨(铋、稀土、宝玉石)成矿带,通过对该地区花岗伟晶岩矿物学和地球化学特征研究分析,探究该地区稀有金属的成矿潜力。研究结果表明,该地区花岗伟晶岩的矿石矿物为钾长石、斜长石,石英、白云母和黑云母以及少量的金属矿物和石榴石,其成因类型主要为A型花岗岩,具有高Si2O、过Al、富Na、高全碱、富稀有及稀土元素的特点,并且稀土元素的富集程度差别较大,可达4~12倍,轻重稀土元素分馏明显,轻稀土元素相对富集,重稀土元素相对亏损,Eu和Ce均表现为负异常,微量元素K、Sr、Ti等元素亏损,Rb、Ta、Nb等元素强烈富集,该研究认识对于理解该地区花岗岩成因及找矿方向具有重要的地质意义。

Mineralogical characteristics of granitic pegmatites and its geochemistry composition in the Ulan area, Qinghai

Ulan County is located in the central part of Qinghai Province, the eastern part of Qaidam Basin, is situated in the rare and tungsten (bismuth, rare earths, and precious stones) metallogenic belt of the Oronbrook-Ulan Hualixi stage. The mineralogical and geochemical aspects of granitic pegmatites were studied and analyzed to explore the mineralization potential of rare earth metals. The results shows that the ore minerals of granitic pegmatites and its genetic types is mainly A-type granite, characterized by high Si2O, peraluminous, rich-agpaitic, high total alkali, rare and rare earth elements, the enrichment degree of rare earth elements varies greatly, up to 4-12 times, the fractionation of light and heavy rare earth elements are obvious, the light rare earth elements are relatively enriched, the heavy rare earth elements are relatively deficient, Eu and Ce show negative anomalies, trace elements such as K, Sr and Ti are deficient, and Rb, Ta and Nb are strongly enriched. This research understanding has important geological significance for understanding the genesis of granite in the region and the direction of mineralization search.