234 



Sediments 



lated to temperature of accumulation of the 

 sediments (Chilingar, 1953; Chave, 1954). 



Among the trace elements titanium clearly 

 bears a close relationship to iron (Fig. 197) 

 with a Fe,03-to-TiO., ratio of 7.5 (Fig. 198), 

 slightly lower than that for red clays (Revelle, 

 Bramlette, Arrhenius, and Goldberg, 1955, 

 Fig. 8). Barium relative to titanium is much 

 less abundant in basin than in deep-sea sed- 

 iments. Although the barium-to-titanium 

 ratio may serve as an index of surface 

 organic productivity in the deep-sea region 

 (Arrhenius, 1952; Goldberg, 1954), this use 

 in the continental borderland is comphcated 

 by other as yet unknown factors. In fact, 

 the ratio of barium to titanium presents a 

 rapid and continuous seaward increase and 

 thus is inversely proportional to both pro- 

 ductivity of surface waters and rate of de- 

 position of detrital sediments. Strontium, 

 with its nearly constant CaO-to-SrO ratio of 

 230 (Fig. 198) (or Ca/Sr = 195), is more 

 abundant relative to calcium than in lime- 

 stones (Kulp, Turekian, and Boyd, 1952) 

 and less abundant than in deep-sea sedi- 

 ments. Manganese is understandably much 

 less than in red clay. The abundance of 

 chromium with depth in several cores (Fig. 

 197) closely parallels calcium and strontium, 

 but no reason for this behavior is suggested. 

 Lead also roughly parallels manganese in 

 basin as in deep-sea sediments (Goldberg, 

 1 954). Vanadium, as discussed by Krauskopf 

 (1955), is probably present in clay minerals 

 rather than in organic matter; this source is 

 also suggested by its greater abundance in 

 red clay than in basin sediments. 



Comparison of the analyses of basin 

 muds with averages for shales and igneous 

 rocks (Tables 17 and 18) reveals many simi- 

 larities, with few cations differing by a factor 

 more than 2 and only calcium by one of 

 more than 3. 



H, Color. The terrigenous marine sedi- 

 ments that include Blue Mud and Green 

 Mud were named and described by Murray 

 and Renard (1891, pp. 229-230, 236-237) 

 on the basis of samples obtained aboard 

 H.M.S. Challenger. Blue Mud was de- 

 scribed as blue or slate-colored owing to 

 organic matter but having a red or brown 

 oxidized surface layer. Calcium carbonate 

 ranged from a trace to 34.3 per cent and 

 averaged 12.5 per cent. Hydrogen sulfide 

 was characteristically present. The rate of 

 deposition was considered fairly rapid. Blue 

 Mud of this definition covers 46,000,000 sq 

 km, occurring in the deeper water surround- 

 ing continents and in enclosed or partially 

 enclosed seas. The depth for 58 samples 

 ranged from 230 to 5 100 meters and averaged 

 2580 meters. In contrast, Green Mud was 

 defined as green to gray in color, possibly 

 owing to green amorphous matter and 

 glauconite that formed because of the slow 

 rate of accumulation of detrital sediment. 

 Calcium carbonate ranged from a trace to 

 56.2 per cent, averaging 25.5 per cent. It 

 covers an area of less than 2,200,000 sq km 

 off" bold exposed coasts with no large rivers. 

 The depth for 22 samples ranged from 200 

 to 2320 meters and averaged 940 meters. 



Rather than having to refer to the basin 

 sediments only as green or yellow-green. 



1.0 



o 



iZO.5 



0.0 



% FeA 



0.2 



O 



10 



0.0, 



20 



% CaO 



40 



Figure 1 98. Plots showing close 

 relationship between TiO. and 

 Fe_,0, and between SrO and 

 CaO in basin and continental 

 slope sediments. 



