Hydrothermal white mica in the Highland Valley district, British Columbia, is present in high-temperature alteration assemblages in early halo veins and in intermediate-temperature sericitic alteration assemblages in D-type veins. Pale-gray white micas characterize early halo veins in the Valley and Bethsaida zone porphyry Cu-Mo deposits, whereas pale-green white micas form texturally similar vein halos along the margin of the Valley deposit and at the Alwin vein. White micas in the Bethlehem porphyry Cu-Mo deposit form part of a sericitic alteration assemblage associated with D-type veins that overprinted K-silicate–altered rocks. Cation compositions in white micas indicate phengitic compositions trending toward aluminoceladonite. Pale-gray phengitic white micas intergrown with bornite-chalcopyrite-molybdenite contain elevated Na, indicating higher formation temperatures than those that characterize phengitic white micas formed during hydrolytic alteration. Bethlehem phengitic white micas have cation compositions similar to those of pale-green phengitic white micas at the Valley deposit margin, Bethsaida zone margin, and the Alwin vein. The Al-OH absorption wavelengths in pale-gray phengitic white micas are shorter than in pale-green phengitic white mica or phengitic white mica in the sericitic assemblage. In the phengitic white micas, alkali elements substituting in the interlayered site are positively correlated, whereas higher-valence elements substituting into the octahedral site show a greater variability. The data confirms that hydrothermal white-mica chemistry varies between paragenetic stages of a porphyry Cu deposit and between multiple porphyry deposits in a district.

中文翻译：

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加拿大不列颠哥伦比亚省高地山谷斑岩铜钼区中热液白云母的化学变化

不列颠哥伦比亚省高地山谷地区的热液白云母存在于早期晕圈静脉的高温蚀变组合中，并存在于D型静脉的中温浆液蚀变组合中。浅灰色的白色云母是Valley和Bethsaida地区斑岩型Cu-Mo矿床的早期晕脉特征，而浅绿色的白色云母沿着Valley矿床的边缘和Alwin脉形成质地相似的脉晕。伯利恒斑岩型铜钼矿床中的白色云母是与覆盖硅酸钾改变的岩石的D型脉相关的浆液性蚀变组合的一部分。白云母中的阳离子组成表明，苯酚类成分倾向于铝硅藻土。浅灰色的白色云母与斑铜矿-黄铜矿-辉钼矿共生，含有较高的Na，与形成在水解蚀变过程中形成的白云母的特征相比，这表明形成温度更高。伯利恒显性白云母在谷沉积矿床边缘，伯特赛达地带边缘和阿尔文脉中的阳离子组成与浅绿色显性白云母类似。在浆液性组合中，浅灰色的白色云母中的Al-OH吸收波长短于浅绿色的白色云母或白色云母中的Al-OH吸收波长。在显性白云母中，在层间位点取代的碱金属元素呈正相关，而在八面体位点取代的高价金属元素则表现出较大的变异性。