700 AURHENius [chap. 25 



Arrhenius, 1962). The synthesis experiments mentioned above also indicate that 

 precipitation of aluminum species from solution in sea-water would form 

 zeohtes rather than phyllosihcates. Finally, microcrystalline zeohte is found 

 within dissolving skeletons of sihceous organisms in sediments without signi- 

 ficant quantities of igneous silicates. This suggests that the high concentrations 

 of dissolved sihca from biotic sources at the sediment-water interface (cf. 

 Table VI) induce the formation of the zeohtes in these cases. On the other 

 hand, phillipsite is frequently observed in intimate physical association with 

 pyi'oclastics or their remnants on the deep-ocean floor, suggesting that the 

 solution from which the zeolite crystallized is derived directly from the pyro- 

 clastic aluminosihcates (Murray and Renard, op. cit.). 



A third mode of formation of zeolites, known to operate on the deep-ocean 

 floor, is the interaction between sea-water or interstitial water and hot basaltic 

 lava dm-ing its intrusion. This phenomenon, together with extensive palagonit- 

 ization of the glass and serpentinization of oh vine, is beautifully illustrated in 

 the basalt found at the bottom of the experimental Mohole drilled at Guadalupe 

 Island in 1961. 



Phyllosihcates frequently form a major part of the non-biotic fraction in 

 pelagic sediments. Some are clearly terrigenous, with kaolinite the major 

 representative. In solutions containing alkah or alkaline earth ions, kaohnite 

 is a stable phase at only a relatively high concentration of hydrogen ion ; it is 

 thus precluded as a mineral forming in the ocean. Oinuma et al. (1959; see 

 also Kobayashi et al, 1960) have demonstrated higher concentrations of this 

 mineral on the continental shelf than in the pelagic areas of the Western Pacific. 

 Fui'ther, the investigations by Correns (1937) and Yeroshchev-Shak (1961a) 

 indicate considerably higher kaolinite content in Atlantic sediments than in the 

 Pacific. This agrees with the greater influx of terrigenous material in the 

 Atlantic, indicated independently by deposition rates and by the chemical 

 composition of the sediment (Goldberg and Arrhenius, 1958). 



Other phyllosihcate species are obviously halmeic, while a third group, 

 comprising much of the poorly crystallized material with a grain size less than 

 a few microns, is of uncertain origin. Highly ordered polymorphs like biotite 

 and chlorite prevail in relatively large grain sizes (3-30 (jl) in areas receiving 

 considerable terrigenous material from metamorphic rocks. However, in the 

 finer fraction of these sediments the crystaUinity decreases, and disordered 

 IM mica species^ dominate. Some of these may have come directly from the 

 continents; their coexistence with coarser, ordered polymorphs seems to indi- 

 cate that the disordered mica species are partly diagenetic alteration products. 

 Rimsaite (1957) has reported progressive alteration of different mica species. 



On the basis of the high boron content and the bonding of the boron in the 

 grain-size fraction containing the iMd micas, Arrhenius (1954 and 1954a) sug- 

 gested that these micas have crystallized from solution in the ocean with boron 



1 The term illite has been used as a group name for these minerals, together with mixed 

 layer structures (Grim, Dietz and Bradley, 1949). Yoder (1957) has pointed out the need 

 for a modified terminology. 



