川西甲基卡锂矿基地典型岩石及矿物反射波谱特征研究

四川甲基卡矿田是中国乃至于世界上锂矿资源最集中的地区之一,目前对甲基卡锂矿床的光谱学认识还很欠缺。本文运用地物波谱仪对甲基卡地区野外采集的典型岩石及矿物开展波谱测试,建立了研究区样品的波谱数据库,总结了黑云母片岩、十字石片岩、十字石堇青石片岩、角岩、二云母花岗岩、含锂辉石伟晶岩、不含锂辉石伟晶岩、石英脉、长石斑晶、锂辉石、云母、绿柱石的波谱特征。研究结果表明:围岩与岩体波谱特征差异较大,围岩反射率一般在0. 2以下,吸收特征不明显,岩体反射率一般在0. 5以下,具有1413 nm、1911 nm、2197 nm三处不同程度的吸收特征;其中含矿伟晶岩、不含矿伟晶岩及花岗岩可以通过1413 nm及2197 nm等处的吸收特征进行区分;锂辉石及绿柱石具有独特的波谱特征,可以直接用于找矿。本文开展的甲基卡型锂矿地面波谱研究,对其高光谱遥感填图及地质找矿具有重要的指导意义。

Spectral Reflectance Characteristics of Rocks and Minerals in Jiajika Lithium Deposits in West Sichuan

BACKGROUND:The Sichuan Jiajika ore field is one of the most concentrated areas of lithium resources in China and even in the world. At present, the understanding of the spectroscopy of the Jiajika lithium deposit is still very poor.
OBJECTIVES:To better understand the spectra of lithium ore deposits and provide the basis for hyperspectral study of lithium ore deposits by spectrum measurement of typical rocks.
METHODS:Spectra of typical rocks and minerals collected in Jiajika area were measured by Analytical Spectral Devices (ASD) Field Spec-4 Spectroradiometer and a spectral library of this area was built. The spectral characteristics of rocks and minerals including biotite schist, grenatiteschist, grenatite cordieriteschist, hornstone, granite, pegmatite containing spodumene, pegmatite without spodumene, quartz vein, feldspar, spodumenemono, biotite, aquamarine were analyzed.
RESULTS:The results indicated that there were differences in spectral characteristics between rock masses and surrounding rocks. The reflectance of surrounding rocks was less than 0.2, and absorption characteristics was not obvious, whereas the reflectance of rock masses was less than 0.5, and there were three absorption features at 1413 nm, 1911 nm, 2197 nm. In addition, granite, pegmatite containing spodumene, and pegmatite without spodumene can be discriminated by their unique spectra on 1413 nm and 2197 nm. The unique spectral characteristics of spodumene and aquamarine can be applied for ore exploration.
CONCLUSIONS:The research on the surface spectroscopy of the Jiajika type lithium ore deposit carried out in this paper has important guiding significance for hyperspectral remote sensing mapping and geological prospecting.