近日，长安大学温汉捷团队在对美国内华达州麦克德米特黏土型锂矿含锂矿物的原位分析和成因研究中取得新成果。这一研究成果于2024年3月1日发表在国际顶尖学术期刊《地球化学学报》上。

研究人员综合使用扫描电子显微镜、透射电子显微镜、飞行时间二次离子质谱和核磁共振等仪器技术，对蒙脱石层段的矿物学、原位Li分布和Li键合环境进行了研究。结果表明：蒙脱石具有低结晶度的自生乳白色粘土特征，常充填或包裹火山矿物间隙；锂主要赋存于镁蒙脱石中而非火山矿物中。在凝灰质沉积物样品中，火山玻璃发生了转化，导致其完全消失，变成粘土矿物。

由于镁蒙脱石的八面体位与锂相结合，故称为镁蒙脱石。研究人员认为锂蒙脱石的沉淀发生在高盐碱水环境中，是麦克德米特凝灰岩溶解的结果。球晶方解石和锂蒙脱石的共存也支持了这一结论。总体而言，本研究证实了、锂蒙脱石是主要含锂矿物，增加了对陆内破火山口盆地锂蒙脱石成因模式的认识。

据悉，粘土型锂矿床在应对全球对锂的需求激增方面发挥关键作用。麦克德米特黏土型锂矿床位于美国内华达州，是美国最大的锂矿床，其含矿层序分别为蒙脱石为主层序和伊利石为主层序。然而，前人对蒙脱石占主导的层段内锂的赋存状态和含锂矿物的成因研究尚不深入。

附：英文原文

Title: In-situ analysis and genetic investigation of Li-bearing minerals in McDermitt clay-type lithium deposit, Nevada, USA

Author: Cui, Yi, Wen, Hanjie, Zhou, Zhengbing, Ling, Kunyue, Xu, Lin, Liu, Shirong, Xu, Fei

Issue&Volume: 2024-03-01

Abstract: Clay-type Li deposits are poised to play a pivotal role in addressing the surging global demand for Li. The McDermitt clay-type Li deposit, located in Nevada, is the largest Li deposit in the United States, with Li hosted by a clay-rich sequence of smectite-dominated intervals and illite-dominated intervals, respectively. However, the occurrence of Li and the genesis of Li-bearing minerals within smectite-dominated intervals have not been thoroughly investigated in previous research. Here, we studied the mineralogy, the in-situ Li distribution, and the bonding environments of Li within the smectite intervals using a combination of instrumental techniques including scanning electron microscope, transmission electron microscope, time-of-flight secondary ion mass spectrometry, and nuclear magnetic resonance. Our results indicate that the smectite exhibits low crystallinity characteristics of lacustrine clay authigenesis and is commonly found to fill the interstices among volcanic minerals or envelop them; Li is mainly hosted by Mg-smectite rather than the volcanic minerals. Within the tuffaceous sediment samples, the volcanic glass has undergone a transformation, resulting in its complete disappearance and alteration into clay minerals. Owing to the octahedral sites of Mg-smectite bounded in Li, it is referred to be hectorite. We interpret that the hectorite’s precipitation occurs in a high saline-alkaline water environment, a result of McDermitt tuff dissolution. This conclusion can be supported by the coexistence of spherulitic calcite and hectorite. Overall, this study confirms hectorite as the main Li-bearing mineral and increases the understanding of the genetic model of hectorite formation in intracontinental caldera basins.

DOI: 10.1007/s11631-024-00675-5

Source: https://link.springer.com/article/10.1007/s11631-024-00675-5