Organic matter thermal alteration

BLACK CARBON AND THERMALLY ALTERED (PYROGENIC) ORGANIC MATTER CHEMICAL CHARACTERISTICS AND THE ROLE IN THE ENVIRONMENT... 

Spectroscopic techniques have received increased attention for the study of natural organic matter (NOM) over the past decades (Hatcher et al., 2001 Abbt-Braun et al., 2004). Such techniques allow the determination of molecular speciation in many cases without the need for extractions, derivatization, or hydrolysis. Spectroscopy is generally less selective in nature than for example chemical extraction techniques, even of chemically or thermally recalcitrant compounds (Frimmel et al., 2002 Haberstroh et al., 2006), though important restrictions for specific bonds apply for some spectroscopic techniques. Equally important are the potentials to investigate the spatial relationships between NOM and mineral phases, surface properties and alteration, and micro-scale heterogeneity within NOM. With improved capabilities and access to synchrotron facilities, worldwide efforts in applying an entire range of powerful spectroscopic tools have proliferated in all areas of science. 

Temperature is the main "driving force" of the geochemical pro esses to a point that a thermal alteration index (an indication of the maximum temperature the sample has reached) can be used to say if the organic matter is mature to produce oil or gas. 

Ishiwatari, R., Ishiwatari, M., Rohrback, B. G., and Kaplan, I. R. (1977). Thermal alteration experiments on organic matter from recent marine sediments in relation to petroleum genesis. Geochim. Cosmochim. Acta 41, 815-828. 

Huizinga B.J.,Tannenbaum E., Kaplan I.R. (1987) The role of minerals in the thermal alteration of organic matter—IV. Generation of re-alkanes, acyclic isoprenoids and alkenes in laboratory experiments. Geochim. Cosmochim. Acta 51, 1083-97. 

Deeper in the sediment, thermal alteration of organic matter generates methane and higher order... 

Thermal maturation The alteration of sedimentary organic matter by the effects of heating. Maturation implies that the altered OM reaches a stage where its thermal breakdown will produce liquid or gaseous hydrocarbons. 

UCM Unresolved complex mixture of hydrocarbons that is a result of the gradual thermal alteration of the initial biological organic matter during formation of petroleum and that can also sometimes be created by microbial alteration of sediment organic matter. The presence of a UCM in sediment is generally considered to be diagnostic of petroleum hydrocarbons. 

The effects of laboratory thermal alteration experiments (low water-rock ratio) on the organic matter of composited Cretaceous black shale samples from DSDP Hole 368 are evident in the following parameters (1) for the hydrocarbons—total yield, formation of PAH and thio-PAH compounds, and increase of Pr/Ph and (2) for kerogen—atomic H/C, HI, 6 C, and vitrinite reflectance (cf. Tables 1 and 2). 

Perregaard j. and Schiener E. J. (1979) Thermal alteration of sedimentary organic matter by a basalt intrusive (Kimmeridgian Shales, Milne Land, East Greenland). Chem. Geol. 26, 331-343. 

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