CLAY MINERALOGICAL APPROACH TO THE SLIP-SURFACE FORMATION IN THE O'DOKORO LANDSLIDE, NIIGATA, CENTRAL JAPAN
CLAY MINERALOGICAL APPROACH TO THE SLIP-SURFACE FORMATION IN THE O'DOKORO LANDSLIDE, NIIGATA, CENTRAL JAPAN
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日本中部新泻县 ODokoro 滑坡滑面形成的粘土矿物学方法
DOI：
10.11362/jcssjclayscience1960.11.107
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Keizo Sasaki
中科院分区：
文献类型：
--
作者：
K. Egashira;K. Matsuo;S. Gibo;Shinya Nakamura;Yaming Zhou;Hidemasa Inoue;Keizo Sasaki
对新泻县O‘dokoro滑坡进行了矿物学分析。O‘dokoro滑坡发生在剪切带上，位于Itoigawa-Shizuoka构造线以西5公里处，位于蛇纹岩混杂岩中。基岩蛇纹岩体的片状蛇纹岩样品的粒度分布中粘土含量小于20%，粘土组分由含少量滑石的反钙辉石组成。没有检测到其他矿物，也没有注意到与粒度分数的矿物学差异。相反，从断层裂隙煤层中采集的粘土物质(断层粘土)显示，粘土含量为50%，预计与滑动面具有矿物学相似性。粘土组分以蛭石和绿泥石为主，并伴有蒙皂石、滑石和角闪石。未鉴定出安替戈石，表明绿泥石的蠕化作用取得了进展。断层粘土中的绿泥石被认为是镁绿泥石或镁铁绿泥石，可能是镁铁质矿物蛇纹岩作用形成的。蛭石可能是通过断裂作用由绿泥石转化而来的。剪切带中O‘dokoro滑坡滑动面的形成与矿物膨胀性的增加有关。
Samples were collected form the O'dokoro landslide in Niigata prefecture for the mineralogical analysis. The O'dokoro landslide occurs in the sheared belts, located 5 km west from the Itoigawa-Shizuoka Tectonic Line and is positioned in the serpentinite melange. Lamellar serpentinite sample from the bedrock serpentinite bodies contained less than 20% of clay in the particle-size distribution, and the clay fraction consisted of antigorite with a small amount of talc. No other minerals were detected and no mineralogical difference with the particle-size fraction was noticed. In contrast, the clayey material (the fault clay) sampled from the fault-fractured seams which is expected to have a mineralogical similarity to the slip surface, showed the clay content of 50%. The clay fraction was dominated by vermiculite and chlorite accompanied by smectite, talc and amphiboles. Antigorite was not identified, and progress of vermiculization of chlorite was indicated. Chlorite in the fault clay was regarded as Mg- or MgFe-chlorite and was possibly formed by serpentinization of mafic minerals. Vermiculite was probably transformed from chlorite by faulting. Argillation and the increase in the swellability of minerals were proposed to make favorable the slip-surface formation in the O'dokoro landslide in the sheared belts.