26. CLAY-MINERAL DISTRIBUTIONS IN THE 

 PACIFIC OCEAN 



J. J. Griffin and E. D. Goldberg 



1. Introduction 



The clay minerals are often the jjredominant components of the calcium- 

 carbonate-free phases of marine sediments, yet only very limited studies have 

 been made on their areal and depth distributions. Many significant problems in 

 marine geochemistry await resolution as to their compositions, origins or modes 

 of formation, such as the use of clay minerals in geochronology, source areas for 

 detrital components in marine sediments, and changes with time of the reactants 

 and products within the major sedimentary cycle. 



Grim (1953) has summarized much of the earlier work and concludes that 

 many of the reported analyses suffer on the basis of incomplete or inadequate 

 data. Determinations made prior to 1944-45 did not involve the glycerine or 

 ethylene glycol solvation technique (MacEwan, 1944; Bradley, 1945) for the 

 analysis of montmorillonite. Electron microscopic and diffraction techniques in 

 combination are today definitive for the identification of halloysite (Bates, 

 Hildebrand and Swineford, 1950; Studer, in litt. 1960). Finally, information on 

 mixed layer clay minerals and the variation in types of illite, chlorite and 

 montmorillonite were unknown to the pioneer workers. Thus the efforts of 

 Revelle (1944) on the Carnegie samples and Correns (1937) on the Meteor 

 material from the Atlantic are difficult to interpret and collate with modern 

 analyses. 



All of the analyses in the recent literature are restricted to samples recovered 

 close to land and with a small areal distribution. Zen (1957) has studied the clay 

 minerals in the sediments off the coast of Peru and Chile; Grim, Dietz and 

 Bradley (1949), the Gulf of California and the Pacific Ocean off the California 

 coast; Pinsac and Murray (1960), and Murray and Harrison (1956), the Gulf of 

 Mexico (Sigsbee Deep and environs); Murray and Sayyab (1955), the Atlantic 

 coast; and Suzuki and Kitazaki (1954) and Oinuma and Kobayashi (1957), the 

 coastal Japanese area. There are a host of other investigations on even more 

 restricted areas including seas, estuarine environments, bays, etc. 



In order to obtain general background information for marine sedimentation 

 problems on an oceanic basis, clay-mineral analyses were made on materials 

 covering the entire Pacific Ocean. Although the density of the samples is 

 relatively low, the clay-mineral suites were found not to change markedly from 

 one location to another, and it is felt that the coverage is probably adequate 

 for a general distributional pattern. Many of the samples have been subjected 

 to other analyses: quartz contents (Rex and Goldberg, 1958); chemical com- 

 position (Goldberg and Arrhenius, 1958); and rates of sedimentation (Goldberg 

 and Koide, 1962). Most of the materials were collected by expeditions of the 

 Scripps Institution of Oceanography. 



[^MS received December, 1960] 728 



