Alunite, Natroalunite and Hydrated Halloysite in Carlsbad Cavern and Lechuguilla Cave, New Mexico
Alunite, Natroalunite and Hydrated Halloysite in Carlsbad Cavern and Lechuguilla Cave, New Mexico
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新墨西哥州卡尔斯巴德洞穴和 Lechuguilla 洞穴中的明矾石、钠明矾石和水合埃洛石
DOI：
10.1346/ccmn.1996.0440616
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发表时间：
1996
影响因子：
2.2
通讯作者：
N. Güven
中科院分区：
文献类型：
--
作者：
V. Polyak;N. Güven
明矾石-钠明矾石固溶体系列的成员与瓜达卢佩山脉洞穴（即卡尔斯巴德洞穴和 Lechuguilla 洞穴）内沉积物中的水合埃洛石密切相关。明矾石和钠明矾石晶体由立方体菱形组成；晶体直径范围为 0.5 至 8 µm。这种矿物组合存在于基岩袋、溶液空腔填充物、地面沉积物和墙壁残留物内的沉积物中。洞穴明矾石和钠明矾石的硫稳定同位素值（δ34S，CTD）为负值[+0.1至-28.9每米尔（‰）； n = 12，平均值 = 16.8‰]，与其他研究人员报告的洞穴石膏和天然硫值相当。这些洞穴沉积物中明矾石/钠明矾石与水合埃洛石的结合表明，形成洞穴的水中含有高浓度的硫酸。这些矿物的形成与碳酸盐岩石的挖掘有关，这些碳酸盐岩石形成了卡尔斯巴德洞穴、Lechuguilla 洞穴和瓜达卢佩山脉的其他洞穴。当含硫酸的水暴露于富含粘土的沉积物时，粘土矿物和石英转化为明矾石/钠明矾石和水合埃洛石。
Members of an alunite-natroalunite solid solution series occur in intimate association with hydrated halloysite in deposits within caves of the Guadalupe Mountains, namely Carlsbad Cavern and Lechuguilla Cave. The alunite and natroalunite crystals consist of cube-like rhombs; crystal diameters range from 0.5 to 8 µm. This mineral association is found in sediments within bedrock pockets, solution cavity fills, floor deposits and wall residues. Sulfur stable isotope values (δ34S, CTD) for cave alunite and natroalunite are negative [+0.1 to −28.9 per mill (‰); n = 12 and mean = 16.8‰] and are comparable to the cave gypsum and native sulfur values reported by other investigators. The association of alunite/natroalunite with hydrated halloysite in these cave deposits suggests that the cave-forming waters contained significant concentrations of sulfuric acid. Formation of these minerals is related to the excavation of the carbonate rocks that formed Carlsbad Cavern, Lechuguilla Cave and other caves of the Guadalupe Mountains. The sulfuric acid-bearing waters, when exposed to clay-rich sediments, converted clay minerals and quartz to alunite/natroalunite and hydrated halloysite.