Abstract

Clay minerals in basalt sills from the northern East Pacific Rise, covered by Upper Pleistocene clayey–sandy–silty sediments (turbidites, hemipelagites, and diatom oozes) sampled from DSDP Holes 477, 478, and 481A, were studied by X-ray methods based on the modeling of diffraction patterns. Trioctahedral smectites formed in thin (0.1–0.5 and 1.8–4 m) fissured sills that are well permeable for water delivered from the water-saturated host sediments heated by the sills. Smectites in basalts are found in the interstices (20–40 vol % in the rock and up to 50–80 vol % in hyalobasalts). They replace olivine and fill cracks and vesicles. Plagioclase and clinopyroxene are generally unaltered. The structure of smectites is characterized by different height of layers depending on the composition of cations in the interlayers and the degree of their hydration. The different-height layers either make up individual smectite phases or alternate in different proportions and with a high degree of segregation in the mixed-layer structures. Under conditions of a prolonged cooling, thick (43 m) sills are distinguished from the thin varieties by the formation of trioctahedral minerals (smectite–chlorite, chlorite, defective chlorite, and talc). They are found mainly in the interstices that make up 3–7 vol % of the rock.

中文翻译：

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东太平洋上升带沉积物覆盖的玄武岩基岩中的粘土矿物

摘要

基于X射线方法，研究了东太平洋北部北部玄武岩窗台上的粘土矿物，这些土壤矿物由DSDP洞477、478和481A中采样的上更新世粘土质-桑迪-粉质沉积物（浊积石，半铁矿和硅藻软泥）覆盖。衍射图的建模。在薄的（0.1-0.5和1.8-4m）裂痕基岩中形成的三八面体蒙脱石对于由基岩加热的含水饱和宿主沉积物输送的水具有很好的渗透性。在空隙中发现玄武岩中的蒙脱石（岩石中占20％至40％（体积），透明质岩中高达50％至80％（体积））。它们代替橄榄石并填充裂缝和囊泡。斜长石和斜环茂通常不变。蒙脱石的结构的特征在于层的高度不同，这取决于中间层中阳离子的组成及其水合程度。不同高度的层要么组成单个蒙脱石相，要么以不同的比例交替出现，并且在混合层结构中具有高度的偏析性。在长时间冷却的条件下，厚（43 m）的门槛与三面体矿物（蒙脱石－亚氯酸盐，亚氯酸盐，次氯酸盐和滑石粉）的形成与稀薄品种有所区别。它们主要存在于占岩石3–7 vol％的空隙中。厚（43 m）的门槛与稀薄的门槛的区别在于形成了三八面体矿物（绿土－亚氯酸盐，亚氯酸盐，次氯酸盐和滑石粉）。它们主要存在于占岩石3–7 vol％的空隙中。厚（43 m）的门槛与稀薄的门槛的区别在于形成了三八面体矿物（绿土－亚氯酸盐，亚氯酸盐，次氯酸盐和滑石粉）。它们主要存在于占岩石3–7 vol％的空隙中。