Production of charcoal has accompanied human life from the beginning. We aimed at evaluating the degree to which the chemical signatures of charcoal may serve as a fingerprint for burning conditions. After a compilation of fire literature we differentiated three typical fire regimes [grass and forest ground (285 ± 143°C), shrub (503 ± 211°C) and domestic fires (797 ± 165°C)] and three main factors impacting on charcoal formation: charring duration, temperature and fuel. For fingerprint calibration and validation, typical fuels of prehistoric burning events (wood and grass) were charred under laboratory conditions (300-700°C; varying duration) and compared with residues from natural fires in SE Europe. Analysis comprised assessment of benzene polycarboxylic acids (BPCAs), organic carbon (Corg) content, nitrogen content, oxygen index (OI: CO2/Corg) and hydrogen index (HI: HC/Corg), temperature of maximum heating (Tmax) and mid-infrared spectroscopy (MIRS). All parameters including mass loss increased with increasing combustion temperature, but were unaffected by charring duration. Grass charcoal had consistently lower Corg content and HI than wood, but values showed a bias towards the natural charcoals, probably because the latter contained higher amounts of mineral matter or were combusted under greater O2 supply. Nevertheless, natural charcoals could be differentiated into forest ground fires (B5CA/B6CA 1.3-1.9; OI >20; intense CH2 stretching, Tmax <488°C) and grass fires (B5CA/B6CA 0.8-1.4; OI >20; weak CH2 stretching, Tmax <425°C), whereas domestic fires revealed B5CA/B6CA values <0.8, OI values <20 and little MIRS absorbance. In summary, it appears possible to reconstruct fire regimes from the temperature sensitivity of BPCA patterns, Tmax, OI and aromatic and aliphatic MIRS signals, whereas assignment of fuel source was less reliable. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Investigating generation, expulsion and primary migration usually suffers from inadequate methodologies, failing in the provision of natural conditions, prevailing during the genesis of oil and gas. Destructive sample preparation, inappropriate pressure regimes and pyrolysis in closed mode and/or in the absence of water caused results not representative for natural processes. To overcome these limitations, a newly designed apparatus was developed and built, capable to perform pyrolysis experiments with intact rock samples under pressure regimes, prevailing during catagenesis. In detail, lithostatic (or overburden-) pressures and hydrostatic (or pore-) pressures, corresponding to 3000 m depth and beyond, can be simulated by this apparatus, the "Expulsinator" device. Additionally, the experiments are conducted as hydrous, semi-open pyrolysis, allowing the time-based sampling of the expelled products. Thus, generation/expulsion profiles are generated for each investigated source-rock. Comparison of generation and expulsion efficiency of the Expulsinator with established pyrolysis methodologies (MSSV, HyPy, Rock Eval and closed small vessel pyrolysis (CSVP)) reveals striking differences: Expulsinator experiments yielded more bitumen and released lower gas amounts than classic pyrolysis. This is caused by secondary alteration of products in case of classic pyrolysis, e.g. oil to gas cracking at higher temperatures and polymerization to pyrobitumen. The open setup of the Expulsinator experiments prevents successfully secondary alteration, increasing the liquid product yields and lowering the gas formation. This is mirrored in TOC conversion rates as well: Expulsinator conversion exceeds 81 %, whereas those of hydrous CSVP remains at 65 %. Further, interactions between kerogen, bitumen, pyrobitumen and pyrite are reduced in case of Expulsinator experiments. In contrast, CSVP experiments residues show enrichment of nitrogen and oxygen and depletion of sulphur, indicating intense interaction between the mentioned components. Investigating the impact of catagenesis onto the yields and composition of expelled products was carried out by a stepwise experimental setup, simulating burial depths of ~2000 m, ~2500 m and 3000 m, implementing overburden pressures from 600 bar to 900 bar and hydrostatic pressures from 200 bar to 300 bar. Each experiment step shows a distinct expulsion maximum of liquid hydrocarbons, reaching the total maximum at 3000 m. Confrontation of Expulsinator results with comparative CSVP and MSSV experiments reveal expulsion and primary migration effects onto the n-alkane distribution in dependence of maturation and subsidence. An n-alkane increase towards larger molecular size with ongoing expulsion is associated with molecular size controlled retention effects. The expulsion progress is mirrored in trends of isoprenoid-ratios (pristane vs. phytane) and isoprenoidn-alkaneratios (pristane vs. n-C17), caused mainly by generation controlled effects. However, both ratios qualify as expulsion indicator, taking ...