nary data from a geochemical-mineralogical 

 study of carbonate rocks in the Brooks Range, 

 presently being undertaken by the Alaska State 

 Geological Survey (Mowatt et al., in progress), 

 indicate the common presence of copper as- 

 sociated with these rocks at levels slightly to 

 moderately above reported averages for analogous 

 rocks elsewhere. This coupled with the fact of 

 known extensive, high-grade copper mineraliza- 

 tion in parts of the Brooks Range (e.g. the 

 Bornite-Ruby Creek deposits) in carbonate rocks 

 seems to corroborate the suggested correlations 

 we observe in the sediments of north arctic 

 Alaska. 



The possible argillaceous association of Cu is 

 inferred indirectly from the strong covariances of 

 Cu with K, Li, Rb and illite, and the presumption 

 that illite is the predominant clay mineral in the 

 clay fraction (Table 3). This further suggests that 

 much of this "illite" actually represents detrital 

 micaceous materials, and further that a consider- 

 able portion of this may well be vermiculitic and 

 represent altered/weathered trioctahedral mica 

 which would be anticipated to be somewhat 

 higher in octahedral copper than dioctahedral 

 micas. Illite resulting from the prograde recon- 

 stitutive sequence (diagenetic and anchi- 

 metamorphic) smectite —* mixed-layer 

 smectite/illite -^ illite, suggested by Hower and 

 various coworkers (Velde and Hower, 1963; 

 Hower and Mowatt, 1966; Maxwell and Hower, 

 1967), would not be expected to contain as much 

 Cu in octahedral sites as illite representing "de- 

 graded" micas, due to the differing geologic envi- 

 ronments associated with micas as opposed to 

 smectites. Admittedly smectites associated with 

 alteration zones proximal to hydrothermal Cu 

 mineralization would be exceptions to the forego- 

 ing generalizations. 



Interelement correlations have a potential use 

 in understanding differences in elemental abun- 

 dances between different environments (Table 5), 

 provided the distributions of the elements are 

 governed by similar geochemical rules, and in- 

 volve the same sediment phases. At this stage of 

 our study we can not conclusively say what the 

 geochemical factors are that determine the differ- 

 ences observed between the chemistry of the del- 

 taic, nondeltaic shelf, and the extrashelf sedi- 

 ments. It is strongly suspected that lower rates of 



sedimentation and higher salinities of interstitial 

 waters in the offshore nondeltaic area contribute 

 to the relatively higher alkali contents observed in 

 that area as compared to the delta. 



Considering all factors, it is concluded that the 

 seaward increase in both Fe and Mn (Table 5) is 

 most probably due to simultaneous seaward de- 

 crease in the solubility of Fe and Mn. It is also 

 concluded that the differences observed in the Fe 

 and Mn contents between the deltaic and nondel- 

 taic shelf sediments are not due to possible differ- 

 ences in the rates and amounts of mobilization 

 and precipitation of Fe and Mn from interstitial 

 waters in the above two environments. This con- 

 clusion is arrived at after considering the factors 

 that govern the mobilization and precipitation of 

 elements from interstitial waters (Riley and Ches- 

 ter, 1971, p. 404-407). The factors which point to 

 the insignificant role of interstitial waters in this 

 context are the relatively higher contents of or- 

 ganic carbon and plausibly higher rates of 

 sedimentation in the deltaic region, as compared 

 to the nondeltaic area. 



The above interpretations on element partition 

 patterns are chiefly based on correlation coeffi- 

 cient calculations for the gross sediments, and 

 thus we present them with some reservations. 

 However, to better understand the geochemistry, 

 and to predict the paitition patterns of the ele- 

 ments with more confidence, it would be neces- 

 sary to analyze elements in different sediment 

 phases. The lithogenous (lattice-bound), non- 

 lithogenous (adsorbed/exchangeable phases), 

 and various biogenous and chemogenous compo- 

 nents of the sediments would have to be analyzed. 

 Our future plans call for such a detailed study. 



Elemental concentrations cited in Table 4 and 

 5 should be useful as baseline data to detect any 

 chemical pollution in the deltaic and marine envi- 

 ronments of north arctic Alaska. 



ACKNOWLEDGEMENTS 



We wish to thank Joe A. Dygas for his help in 

 analyzing the carbonate contents in sediments. 

 The statistical analysis and the X-ray analysis 

 were kindly conducted by Bob Tucker and Mrs. 

 Namok C. Veach, respectively. 



Icebreaker ship support was provided by the 

 U.S. Coast Guard. The help of Dr. Peter Barnes 



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