Bitumen isotopic composition

Sulfur, carbon and hydrogen stable isotope ratios of pyrite, kerogens, and bitumens of two high-sulfur Monterey formation samples from the onshore Santa Maria Basin in California were determined. Kerogens from these were pyrolyzed at 300°C for periods of 2, 10 and 100 hours in closed systems and the yields and isotopic compositions of S-containing fractions (residual kerogens, bitumens and hydrogen sulfide) were determined. 

Two Type II-S kerogens (as defined by Orr (i)) from the onshore Santa Maria Basin Monterey formation were pyrolyzed in this study to determine (a) the distribution of sulfur and its isotopic composition among the various products formed during artificial maturation, and (b) maturation trends reflected in the sulfur isotopic and elemental S/C ratios of kerogens, and in the variation of C and H isotopes. In addition, S isotopes in pyrites, kerogens and bitumens from the two Monterey shale samples were examined to speculate on the mode of S incorporation into Santa Maria Basin sediments. 

Dowling L. M., Boreham C. J., Hope J. M., Marry A. M., and Summons R. E. (1995) Carbon isotopic composition of ocean transported bitumens from the coastline of Austraba. Org. Geochem. 23, 729—737. 

The correlation of the carbon isotope composition (<5 C) of the oil and bitumen fractions of all eventual source rock conditions , in view of the large variety of the latter, allows us to point out the sources of the hydrocarbons which supplied the one or other reservoir and thereby to better direct the prospecting activities. 

In order to study the process of generation and migration of the hydrocarbons, one needs data on their phase composition, the mineral transformations associated with the transformation of the organic matter and the carbon isotope composition of the carbonates, bitumens and oils. 

The distribution and isotopic composition of sulfur in solid bitumens... 

Table 2. Sulfur contents and isotopic compositions for three sandstone samples containing solid bitumens from the Subu...

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