Variation of maturity indicators (optical and Rock-Eval) with respect to organic matter type and matrix lithology: an example from Melville Island, Canadian Arctic Archipelago

The variation of maturity indicators with respect to mineral matrix and organic matter types was examined from the Mesozoic succession of Melville Island, Arctic Canada. The T max values of non-marine deltaic samples show a much greater degree of scattering with respect to vitrinite reflectance, whereas the marine samples show a narrow distribution. This behaviour is most likely to be a consequence of the differences in the chemical properties of terrestrial versus marine organic matter, which is a function of the organic matter type and of the depositional environment. The non-marine deltaic samples also show higher T max values than their marine counterparts, an indication either of the higher degree of oxidation of the non-marine deltaic samples or of the fact that type III organic matter has intrinsically higher T max values than types I and II organic matter at the same maturity level. Based on the relationship between hydrogen index (HI) and vitrinite reflectance (%Ro), it appears that marine organic matter is more sensitive (high negative correlation) to thermal maturity changes than non-marine deltaic organic matter. No clear correlation between S 2 (hydrocarbon yield) and %Ro (maturity) could be seen in the suite of samples. Both fluorescence parameters ( λ max and R G quotient) increase with maturity but the trends have different slopes for the various macerals, a function of their marine or non-marine origin.