Smectite-to-illite alteration in salt-bearing bentonites (The East Slovak Basin)
Smectite-to-illite alteration in salt-bearing bentonites (The East Slovak Basin)
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含盐膨润土中蒙皂石到伊利石的蚀变（东斯洛伐克盆地）
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
A. Biroň
中科院分区：
文献类型：
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作者：
M. Honty;P. Uhlík;V. Šucha;Mária Čaplovičová;J. Franců;N. Clauer;A. Biroň
在东斯洛伐克盆地的深钻孔中，研究了盐环境对火山岩伊利石化的影响。基于X射线衍射分析，得出了在一定深度段内，含盐蒙脱石（SBB）中伊蒙混（I-S）膨胀性总是小于无盐蒙脱石（SFB）的结论。这两种岩性可以很容易地区分水浸出液化学。在2100-2500 m的深度范围内，SBB中的可膨胀性在25-10%的范围内变化，SBB中R1和R3排序可膨胀，SFB中R 0排序可膨胀68-35%。在两个浅SBB样品的膨胀性是接近的SFB，这表明，盐度单独不提高伊利化，但盐度可能会提高它与较高的埋藏温度相结合时。镜质组反射率和RockEval热解在邻近页岩中测量的Tmax证实，SBB中伊利石化的增加不是由于加热和/或侵蚀。由有机质成熟度标定的埋藏和热历史模型表明，相同的热历史在两种岩性（SBB和SFB）中产生了两种不同的膨胀性。利用颗粒厚度测量和K-Ar数据推断了SBB中伊利石化的晶体生长机制。而表面控制的生长是典型的SFB，同时成核和生长的情况下，SBB发挥了更重要的作用。含盐环境对伊利石化的影响尚未完全了解，如果考虑到盐层作为主岩，可能会对放射性废物处置场利用碳酸盐岩作为工程屏障产生严重后果。
The effect of a saline environment on illitization in volcanoclastic rocks is examined in deep boreholes in the East Slovak Basin. Based on X-ray diffraction analysis, it is concluded that illite-smectite (I–S) expandability is always less in the salt-bearing bentonites (SBB) than in the salt-free bentonites (SFB) for a given depth interval. These two lithologies can be distinguished easily by water-leachate chemistry. Within the depth interval 2100–2500 m, the expandability in SBB varies within the range 25–10% expandable with R1 and R3 ordering in SBB and 68–35% expandable with R0 ordering in SFB. In two shallow SBB samples the expandability is close to that of SFB, suggesting that salinity alone does not enhance the illitization; but salinity may enhance it when combined with higher burial temperature. Vitrinite reflectance and Tmax of RockEval pyrolysis measured in adjacent shales confirm that the increased illitization in SBB is not due to heating and/or erosion. The model of burial and thermal history calibrated by organic maturity suggests that the same thermal history produces two different expandabilities in the two lithologies (SBB and SFB). Particle thickness measurements and K-Ar data were used to deduce the crystal growth mechanism of illitization in SBB. Whereas surface-controlled growth is typical for SFB, simultaneous nucleation and growth played a more important role in the case of SBB. The effect of a salty environment on the illitization is not yet fully understood and may have severe consequences for the utilization of bentonites as engineering barriers in radioactive waste disposal sites if salt formations used as host rocks are taken into account.