594 



KAPLAN AND RITTENBERG 



[CHAP. 23 



measurements prom])tecl Emery and Rittenberg to suggest the use of 10.0 as 

 an average. Since nitrogen analysis can be simply and quickly carried out by 

 the Kjeldahl method, this procedure is frequently used for estimation of total 

 organic matter and the organic content is then taken as 1 7 times the nitrogen 

 content of the sediment. Care must be taken in the interpretation of nitrogen 

 values because the C'/N ratio usually increases with depth of burial (nitrogen is 

 preferentially lost by tlie sediment). 



The studies on specific groups of organic substances in marine sediments are 



HYDROCARB. x lO' PHEOPHYTIN x lO' ORG. MATTER 

 O oi O O TO -t» o r>o 



CaCO, 



-(^ o 





NORMAL DETRITAL 



o o o 



r 



LOS ANGELES 

 BASIN 



NEARSHORE 

 BASINS 



MIDDLE 

 BASINS 



OFFSHORE 

 BASINS 



CONTINENTAL 

 SLOPE 



DEEP-SEA 

 FLOOR 



Fig. 3. Curves showing rates of accumulation of various components of southern California 

 basin sediments. Note the similarities and differences between curves for absohite 

 rates of deposition and for the percentage compositions given in Fig. 2. Values for 

 organic matter are at the surface of the sediment. (From Emery, 1960, fig. 208.) 



largely fragmentary although many of the major constituents present in the 

 plankton of the overlying waters have been detected in recent marine deposits. 

 The review of Vallentyne (1957) shows that more work has been done on the 

 muds of lakes than on oceanic sediments and demonstrates the inadequacy of 

 our state of knowledge. Only in the last two decades have adequate techniques 

 become available for separating and identifying individual com])onnds rather 

 than groups or families of organic substances. 



Two objectives have recently led to the intensive study of organic substances. 

 The first is to obtain information of use to paleontology and perhaps to give 



