On the Relationship Between Cathodoluminescence and the Chemical Composition of Scheelite From Geologically Diverse Ore-Deposit Environments
On the Relationship Between Cathodoluminescence and the Chemical Composition of Scheelite From Geologically Diverse Ore-Deposit Environments
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DOI：
10.3749/canmin.1500023
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发表时间：
2016-09
影响因子：
0.9
通讯作者：
Rémy S. Poulin;Andrew M. McDonald;D. Kontak;M. McClenaghan
中科院分区：
文献类型：
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作者：
Rémy S. Poulin;Andrew M. McDonald;D. Kontak;M. McClenaghan
用扫描电子显微镜-能谱仪、化学发光成像和LA-ICPMS技术研究了不同成矿环境(造山金、夕卡岩、斑岩、云英岩、VMS)中白钨矿的阴极发光(CL)响应与化学成分的关系。我们的详细研究集中在一系列矿床环境中的五个白钨矿样本，包括造山带Au、夕卡岩、VMS和云英岩矿床，但利用了一个尚未公布的数据库，其中包括全球39个以上的矿床。结果表明，化学发光观察到的白钨矿分带模式可用于区分不同成矿环境形成的白钨矿。造山型金矿床的白钨矿表现出均一的化学发光响应，而与近源侵入体有关的系统，如斑岩、夕卡岩和云英岩，则表现出强烈的振荡分带作用，单个分带的宽度从30 0μm不等。LA-ICPMS分析结果表明，白钨矿中Mo、Sr、As和ΣREE+Y具有显著的化学变化。化学发光成像和LA-ICPMS数据显示，白钨矿的化学发光响应强度与Mo含量呈显著负相关。虽然观察到了锶、砷和Σ稀土元素+Y的富集性，但都没有表现出与化学发光响应相关的效应。此外，通过扫描电子显微镜能谱分析得到的定性的Mo和W X射线图谱与白钨矿颗粒的LA-ICPMS图谱相对应，依次描绘了在化学发光下观察到的分带模式。这项工作还表明，CL和LA-ICPMS作图的结合是讨论所观察到的CL结构、元素关系、矿物生长历史和共生作用的有力工具。
Abstract The relationship between cathodoluminescence (CL) response and chemical composition of scheelite from a variety of ore-deposit settings ( e.g ., orogenic Au, skarn, porphyry-related, greisens, VMS) was investigated using SEM-EDS, CL imaging, and LA-ICP-MS techniques. Our detailed study concentrates on five samples of scheelite from a range of ore-deposit settings, including orogenic Au, skarn, VMS, and greisen deposits, but draws on a yet unpublished data base of more than 39 deposits world-wide. Results indicate that the scheelite zonation patterns observed under CL can be useful in discriminating between scheelite arising from differing mineralized environments. Scheelite from orogenic Au deposits exhibits a homogenous CL response in contrast to that from proximal intrusion-related systems, such as porphyries, skarns, and greisens that show a strong oscillatory zonation, with individual zones ranging from 300 μm in width. Results from LA-ICP-MS analyses show significant chemical variations in scheelite with respect to Mo, Sr, As, and ΣREE + Y. Maps generated from CL imaging and LA-ICP-MS data reveal a strong negative correlation between the intensity of the CL response in scheelite and Mo content. While enrichments of Sr, As, and ΣREE + Y are noted, none exhibit a correlatable effect with CL response. Furthermore, the qualitative Mo and W X-ray maps produced via SEM-EDS correlate with the corresponding LA-ICP-MS maps of the scheelite grain, successively delineating the zonation patterns observed under CL. This work also demonstrates that the combination of CL and LA-ICP-MS mapping is a powerful tool in the discussion of observed CL textures, elemental relationships, mineral growth history, and paragenesis.