31-03-78 



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22-11-78 



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 25 



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CG 



STATION 5 



FIGURE 7. Evolution of the saturated hydrocarbons. 



sterane compounds (CnH2n-G) eluted between n-C26 and n-C31, and m/e 

 191 characteristic of pentacyclic triterpane compounds (CnH2n-8) 

 eluted over n-C30 (Fig. 8 and 9) . This relative enrichment in cyclo- 

 paraffins is confirmed by the mass spectrometry analysis of the 

 fraction (Hood and O'Neal - 1958). Among the saturated hydrocarbons, 

 (n+iso) -alkanes show a rapid diminution after March 31, 1978, and a 

 stabilization thereafter ; cycloparaf f ins , principally 2-, 3- and 4- 

 membered rings show an enrichment, and 5- and 6-membered rings are 

 fairly stabilized (Fig. 10) . 



119 



