Marine Versus Terrigenous Organic Matter

A variety of parameters are used to assess organic matter sotrrces. Btrlk parameters have the advantage that they are representative of total organic matter, whereas molectrlar parameters address only part of the extractable organic matter, which in turn is only a small portion of total organic matter. Some successfirl applications of molectrlar parameters show that the small bitumen fraction may be representative of the total, but there are many other examples where this is not the case. On the other hand, oxidation of marine organic 

Hydrogen Index (HI) values from Rock-Eval pyrolysis (see Sect. 4.5.2) below about 150 mg HC/g TOC are typical of terrigenous organic matter, whereas HI values 

Carbon isotope ratios are principally useful to distinguish between marine and terrestrial organic matter sources in sediments and to identify organic matter from different types of land plants. The stable carbon isotopic composition of organic matter reflects the isotopic composition of the carbon source as well as the discrimination (fractionation) between and 

Fluctuations that have been measured in the 5 G values of sedimentary organic matter over the Earth s history (e g. Schidlowski 1988) can thus be interpreted in terms of the productivity in the water coltrrrm and the availability of DIG in a particular geological time period. In a study of sediments from the central equatorial Pacific Ocean spanning the last 255,000 years it has been demonstrated that the carbon isotopic composition of fossil organic matter depends on the exchange between atmospheric and oceanic GO. Ghanges with time can then be used to estimate past atmospheric carbon dioxide concentratiorrs (Jasper et al. 1994). 

Past Sea-Surface Temperatures (SST) Based on Long-Chain Alkenones 

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