斑岩型矿化指示矿物-白云母

最新一期经济地质学（Economic Geology）杂志有一篇文章为：White Mica Geochemistry: Discriminating Between Barrenand Mineralized Porphyry Systems。作者为美国新墨西哥矿业理工学院Uribe-Mogollon C博士和Maher K.博士从白云母地球化学角度，作为斑岩型矿化的指示矿物。

 实际上，使用白云母地球化学来指导找矿勘查，至少已经开展了十年有余，使用白云母地球化学特征的研究可以至少追溯到2011年。Alva-Jimenez (2011)研究了加拿大不列颠哥伦比亚的Highland Valley斑岩型铜钼矿床， Cohen (2011)则研究了美国内华达州Ann-Mason斑岩型铜矿。斑岩铜矿如内华达州Ann-Mason斑岩型铜矿和Highland Valley斑岩型铜钼矿床的垂直和水平剖面显示，白云母的W-Sn含量随着远离矿体，呈指数的降低；然而随着远离岩体，白云母中Zn, Tl, B, Co, 和 Cs含量增加(Alva-Jimenez, 2011; Cohen, 2011)。

2018年和2020年，Uribe-Mogollon C和Maher K.系统的利用白云母地球化学对美国的蒙大拿州Copper Cliff斑岩铜矿和Grasshopper斑岩型矿床的找矿远景区。Uribe-Mogollon和Maher (2018)发现蒙大拿州Copper Cliff斑岩铜矿白云母中的微量元素比值（比如Cu/Zn）比值可估测距离矿化中心的距离。其使用的方法类似于Wilkinson et al. (2015)提出的绿泥石Ti温度计的方法。

Uribe-Mogollon和Maher (2020)分析了Grasshopper斑岩型矿床的找矿远景区的白云母成分，结合前期获得的Copper Cliff斑岩铜矿的数据，发现了矿化系统和无矿系统的白云母Zn, Cr, B, Tl, Sn, 和 Cs成分存在显著差异。据此，提出了Zn + Cr + B vs. Tl + Sn + Cs判别图解。

Zn + Cr + B vs. Tl + Sn + Cs判别图解（Uribe-Mogollon和Maher, 2020）

参考文献：

1. Alva-Jimenez,T.,2011,Variationin hydrothermal muscovite and chlorite composition in the Highland Valleyporphyry Cu-Mo district, British Columbia, Canada: M.Sc. thesis, Vancouver,University of British Columbia,249p.

2. Cohen,J.F.,2011,Mineralogyand geochemistry of hydrothermal alteration at the Ann-Mason porphyry copperdeposit, Nevada: Comparison of large-scale ore exploration techniques tomineral chemistry: M.Sc. thesis, Corvallis, Oregon, Oregon State University,599p.

3. Uribe-MogollonC, Maher K. White Mica Geochemistry of the Copper Cliff Porphyry Cu Deposit:Insights from a Vectoring Tool Applied to Exploration. Economic Geology.2018;113:1269-95.

4. Uribe-MogollonC, Maher K. White Mica Geochemistry: Discriminating Between Barren andMineralized Porphyry Systems. Economic Geology. 2020.

5. WilkinsonJJ, Chang Z, Cooke DR, Baker MJ, Wilkinson CC, Inglis S, et al. The chloriteproximitor: A new tool for detecting porphyry ore deposits. Journal ofGeochemical Exploration. 2015;152:10-26.

 作者介绍：

Camilo Uribe-Mogollonreceived a Ph.D. degree in earth and environmental sciences in spring of 2019from the New Mexico Institute of Mining and Technology. His dissertation workfocused on the development of porphyry vectoring techniques in phyllic alteredrocks at the Copper Cliff system and Grasshopper prospect in Montana, USA. Hisresearch provided new constraints on the identification of signatures anddistance indicators for mineralized porphyry orebodies based on geochemicalvariations present in white micas within the phyllic alteration zone.

Kierran Maherreceived a Ph.D. in geology in 2005 from Washington State University. He hasworked and consulted in the minerals industry since 1996 and enjoys workingwith students both on academic research and in the classroom, where he hasdeveloped a rigorous mineral deposit curriculum. This teaching effort extendsto short courses presented to students and mining professionals on geochemistryand hydrothermal alteration. He is presently assistant professor of economicgeology at New Mexico Tech.