摘要：Macroscopic observations, microscopic studies and literature data revealed that Middle Jurassic wood fromCzęstochowa area has a different state of preservation, and various types and degrees of mineralization and oxidation. Obtainedresults of organic matter fractionation illustrate a clear domination of polar fraction in the obtained extracts revealinglow thermal maturity stage. Total organic carbon (TOC) values for analysed samples are in a wide range from 1.06% to68.50%. The highest amount of TOC were measured in not or poorly mineralized wood samples but most of them are mineralizedwood fragments, showing the TOC values in the range of 2% - 10%. Percentage content of carbonate in fossil woodconstitute in a wide range from less than 1% CaCO3 to above 85% CaCO3. The resulting percentage of the total sulfur contentis very varied and do not show convergence with other data such as TOC, carbonate content, etc and is most probableconnected with pyritisation range. Unlike the Middle Jurassic clay samples, where long-chain and short-chain n-alkanes occurin similar concentrations, in wood samples always short-chain n-alkanes dominated, in the range from 15 to 23 carbonatoms in molecule. The values of the CPI are generally higher than 1 which indicates the contribution of organic matter derivedfrom higher plant waxes, which are characteristic of e.g. needles from gymnosperm plants. Under the influence of post -diagenetic oxidation in mineralized wood samples distribution of n-alkanes is changing. Diaster-13(17)-enes with 28 and 29carbon atoms in molecule are present in the wood samples, while those with 29 atoms strongly prevail.
