甘肃岗岔金矿短波红外找矿应用及伊利石成因矿物学研究

发布时间：2018-05-16 21:38

本文选题：近红外 + 蚀变矿物　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：甘肃岗岔金矿位于秦岭造山带碌曲—成县逆冲推覆构造带西侧北缘,属于夏河—礼县成矿带西段,该矿床具有浅成低温热液矿床特征,勘探工作显示该矿床储量已达中型。目前矿区处于深部找矿工作的初始阶段,亟需一些找矿理论和方法为深部探矿工作提供支持。本文试图采用近红外蚀变矿物分析技术及成因矿物学与找矿矿物学理论和方法为矿区找矿工作提供依据。矿区蚀变矿物分析显示,区内主要蚀变矿物(相对百分含量大于5%)有白云母(多硅白云母)、伊利石、高岭石、地开石、蒙脱石;次要蚀变矿物(相对百分含量小于5%)有绿泥石、绿帘石、方解石、白云石及少量石膏等。根据蚀变矿物空间上分布及含量变化规律,认为近矿蚀变为绢英岩化(蚀变矿物组合为:白云母+伊利石+次生石英等);远矿蚀变为泥化或粘土化(蚀变矿物组合为:高岭石+地开石+蒙脱石等)。矿区同种岩性(凝灰岩或凝灰质砂岩)、同一蚀变类型(绢英岩化)岩芯样品分析表明,矿化段样品光谱的诊断谱带吸收峰较浅,吸收谱线多出现很多“锯齿状”小吸收峰,且光谱整体形态较为“扁平”;而非矿化段样品的诊断谱带吸收峰则较深,且光谱曲线形态上较为“光滑”。矿区绢英岩化带蚀变矿物进一步分析显示,其中的绢云母主要为伊利石和少量白云母。不同产状(矿化段、蚀变但无矿段、非蚀变段)伊利石的能谱成分分析显示,矿化段伊利石具有较高的铁、镁含量;有蚀变而无矿化段及无蚀变段伊利石铁、镁含量较低。区内标型矿物伊利石红外光谱特征峰分析结果表明:矿化段伊利石具有更尖锐的Al-OH吸收峰,且矿区伊利石近红外结晶度变化与样品金品位的变化具很好的正相关性。此外,矿化段样品伊利石Al-OH吸收峰峰位明显向长波方向(大于2200nm)漂移;非矿化段样品伊利石Al-OH吸收峰向短波方向(小于2200nm)漂移,认为导致这类层状铝硅酸盐矿物Al-OH近红外吸收峰峰位漂移现象的可能成因是:矿物中六次配位的Al离子被其它金属离子(如Fe、Mg等)替代,导致矿物中Fe、Mg含量增高而Al含量降低。以上规律对于矿区深部找矿工作具有一定指导意义。
[Abstract]:Gangcha gold deposit is located in the northern margin of Luqu-Chengxian thrust and nappe tectonic belt in Qinling orogenic belt, and belongs to the western section of Xihe-Lixian metallogenic belt. The deposit has the characteristics of epithermal hydrothermal deposit, and the exploration work shows that the deposit reserves have reached medium size. At present, the mining area is in the initial stage of deep prospecting, which needs to be supported by some prospecting theories and methods. This paper attempts to use near infrared alteration mineral analysis technology and genetic mineralogy and prospecting mineralogy theory and method to provide the basis for ore prospecting in mining area. Analysis of altered minerals in the mining area shows that the major altered minerals in the area (the relative content of which is more than 5%) are Muscovite (polysilicon Muscovite, Illite, kaolinite, geocalite, montmorillonite; minor altered minerals (relative content less than 5%) have chlorite, Green curtain stone, calcite, dolomite and a small amount of gypsum, etc. According to the spatial distribution and content variation of altered minerals, It is considered that near ore alteration is sericite (altered mineral assemblage is Muscovite Illite secondary quartz etc.) distant ore alteration becomes muddy or clay (altered mineral assemblage is kaolinite montmorillonite etc.) The analysis of the core samples of the same lithology (tuff or tuff sandstone) and the same alteration type (sericite) shows that the absorption peaks of the diagnostic spectrum of the samples in the mineralized section are relatively shallow, and many "serrated" small absorption peaks appear in the absorption lines. The whole form of the spectrum is "flat", while the absorption peak of the diagnostic band of the non-mineralized sample is deeper, and the spectral curve is more "smooth" in shape. Further analysis of altered minerals in the sericite zone shows that the sericite is mainly Illite and a small amount of Muscovite. The energy spectrum analysis of Illite in different occurrence (mineralized, altered but not mineralized) shows that Illite has higher iron and magnesium content, and Illite iron with alteration but no mineralization and no alteration is lower in magnesium content. The results of infrared spectrum analysis of Illite show that Illite has a more sharp Al-OH absorption peak in the mineralized area and the near infrared crystallinity of Illite has a good positive correlation with the change of gold grade in the sample. In addition, the Al-OH absorption peak of Illite in the mineralized segment drifts towards the long wave direction (> 2200nmm), and the Al-OH absorption peak drifts to the shortwave direction (less than 2200nm) in the non-mineralized segment. It is considered that the possible cause of the near infrared peak shift of Al-OH absorption peak in this kind of layered aluminosilicate minerals is that the six times coordinated Al ions in the minerals are replaced by other metal ions (such as Feo mg, etc.), which results in the increase of Feo mg content and the decrease of Al content in the minerals. The above rules have certain guiding significance for the deep prospecting work in the mining area.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51;P631.7

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