confined to the area west of Oliktok Point and 

 much of it does not move into the Simpson 

 Lagoon. The Sagavanirktok River sediment out- 

 fall does not seem to move far away from the river 

 mouth. Dispersal patterns of the above clays are 

 largely supported by the known mean current di- 

 rections of waters over the area, which is towards 

 the southwest (Kinney et al., 1972). Such a prev- 

 alence of currents would tend to push the Col- 

 ville River flume away from the Simpson Lagoon 

 area. A similar dispersal of the Sagavanirktok 

 River clay is largely inhibited because Simpson 

 Lagoon lies sheltered between the mainland 

 coast and the barriers and thus is largely in the 

 shadow area for the open marine southwest pre- 

 vailing currents. 



Our studies on clay mineral compositions of 

 sediments from the continental margin and open 

 marine environments of north arctic Alaska have 

 not been completed. However, the preliminary' 

 results do indicate the potential value of this 

 approach in the interpretations of paleogeography 

 and paleocurrent of past depositional basins. The 

 relevance of our clay mineral studies in environ- 

 ment and pollution studies has been discussed by 

 Naidu(1972). 



Sediment Geochemistry and Element Partition 

 Patterns 



The content of organic carbon in the deltaic 

 and adjacent shallow marine sediments of north 

 arctic Alaska is significantly lower (Table 4) than 

 those observed in tropical deltaic sediments 

 (Trask, 1939; Naidu, 1966). This may be due to 

 the verv' low organic productivity in the Alaskan 

 deltaic region as supported by phytoplankton 

 productivity and ^^C primary productivity studies 

 (Alexander and Billington. 1972), and low yearly 

 supply of terrigenous detrital organic matter. It 

 seems improbable that low organic carbon in our 

 sediments is a result of relatively higher oxidative 

 decomposition of organic matter in the region of 

 our study. This conclusion is based on the fact 

 that for most of the year the continental margin 

 environment of north Alaska is covered with ice, 

 and as such it would be expected that the envi- 

 ronment overlying the sediments will be less ven- 

 tilated and thus less oxygenated. Because of the 

 general prevalence of low temperatures in the 



arctic, it is contended that the relatively low or- 

 ganic carbon in the arctic deltaic sediments is 

 probably not due to higher organic decomposition 

 by bacterial activity. 



The progressive increase seaward of sediment 

 organic carbon (Table 5) is contrary to the com- 

 monly observed pattern of organic carbon dis- 

 tributions in marine sediments (Trask, 1939, p. 

 445; Riley and Chester, 1971, p. 380). The gen- 

 erally observed seaward decrease in organic car- 

 bon of marine sediments has been attributed to: (i) 

 seaward decrease of terrigenous organic supply, 

 and (ii) seaward increase in organic decomposi- 

 tion (Riley and Chester, 1971, p. 294 and 380). 

 However, on the basis of the above two factors 

 obviously the observed seaward differences in 

 organic carbon contents in the Beaufort Sea 

 (Table .5) can not be explained. It is believed that 

 in the present situation the regional differences in 

 sediment organic carbon are determined by the 

 variations in lithology. Such a conclusion is sup- 

 ported by the strong negative correlation observed 

 between organic carbon and sand contents of the 

 deltaic and nondeltaic sediments (Table 6; and 

 Naidu and Hood, 1972). Presumably as a result of 

 seaward decrease in sand (Table 1; Naidu and 

 Hood, 1972) there is lesser seaward 'dilution" of 

 sediment organic matter by sand size inorganic 

 mineral particles, as well as concomitant de- 

 crease in oxidative decomposition of organic mat- 

 ter resulting from lower porosity of mud. From the 

 correlations of organic carbon and sediment size 

 grades, it is inferred that the bulk of the organic 

 carbon in the deltaic sediments is associated with 

 the silt fraction (Table 6) whereas in the nondel- 

 taic marine sediments it is concentred in the clay 

 fraction (Naidu and Hood, 1972). Possibly this is 

 related to the differing hvdrodynamical condi- 

 tions of deposition, and the probable result of size 

 fractionations of detrital organic particles as a 

 function of distance from the shore. 



As compared to the nondeltaic shelf and ex- 

 trashelf sediments of the Beaufort Sea, there is 

 notable enrichment of Ca and carbonate in the 

 deltaic sediments (Table .5). Plausibly this is due 

 to the presence of relatively higher contents of 

 calcareous lithogenous and bioclastic compo- 

 nents in the deltaic sediments. The bulk of the Ca 

 appears to be tied up in the carbonate, as attested 

 by a strong covariance between the two (Table 6; 



249 



