. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 736 GRIFFIN AND GOLDBERG [CHAP. 26 montmorillonite whereas they are distinctly different from true montmoril- lonite. A true montmorillonite has its excess negative charge located in the octahedral layer and little, if any, negative charge in the tetrahedral layer. The micas, on the other hand, will have a high net negative charge in the tetrahedral layer. Furthermore, the net charge on the montmorillonite will be much smaller than that on the micas. So it would be expected that the stripped illite and chlorite would upon
. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. 736 GRIFFIN AND GOLDBERG [CHAP. 26 montmorillonite whereas they are distinctly different from true montmoril- lonite. A true montmorillonite has its excess negative charge located in the octahedral layer and little, if any, negative charge in the tetrahedral layer. The micas, on the other hand, will have a high net negative charge in the tetrahedral layer. Furthermore, the net charge on the montmorillonite will be much smaller than that on the micas. So it would be expected that the stripped illite and chlorite would upon entry into a proper environment revert back to better crystalline mica and. Fig. 6. Concentration gradients of clay minerals in the North Pacific. chlorite by sorption and "fixation" of K+ and Mg2+. The phenomenon of K+ "fixation" is well established and a voluminous literature on the subject has been developed by soil scientists (Volk, 1938; Barshad, 1954). Recently, Weaver (1958) used the phenomenon to differentiate montmorillonite from stripped micas. He showed that the montmorillonite would not "fix" K+ and then collapse, whereas stripped micas would readily "fix" K+ and collajjse. An examination of the 17 A peak from diffraction tracings taken from the surface sediment in the east to west traverse across the North Pacific lends support to the hypothesis that the 17 A material is sorbing K+ and Mg2+ and collapsing. In nearshore sediments the 17 A peak is sharp. However, further from land, the peak broadens and loses intensity because of random inter- layer collapse. In the mid-oceanic areas the peaks disappear (Fig. 7). At first glance this striking correlation of the 17 A peak broadening and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hill, M. N. (Maurice Nev
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