Application of combustion and DTA-TGA analysis to the study of metamorphic organic matter

Coalification of organic matter in the North Penninic Bundnerschiefer of eastern Switzerland has been studied using combustion analysis, thermal analysis and X-ray diffraction. Organic matter used for analysis was characterized by optical microscopy (maceral analysis). Combustion analysis was applied with most encouraging results to determine metamorphic grade. Results correlate well with the known metamorphic pattern and also additional information relevant to the tectono-metamorphic history. Two types of CO2 peaks are recognized: a sharp narrow (type-S) peak and a broad (type-B) peak. Distribution of these peak types is regular in samples taken along the metamorphic profile, from high diagenesis to lower amphibolite facies conditions. The combustion temperatures of organic matter increases essentially with increasing metamorphic grade. while the total weight loss decreases slightly. Combustion analysis and differential thermal - thermal gravimetric analysis have proven to be useful in characterizing metamorphic organic matter and in detecting heterogeneities therein.