Influencia del tratamiento ácido sobre las medidas de la reflectancia de la vitrinita y la definición de la madurez termal de la materia orgánica dispersa

• Published in: Geologica colombiana Vol. 38; p. 137
• Main Authors: Ricardo Ruiz Monroy, Astrid Blandón Montes
• Format: Journal Article
• Language: Spanish
• Published: Bogota Universidad Nacional de Colombia 01.01.2013
• Subjects: Acids; Calcite; Cretaceous; Fluorescence; Hydrochloric acid; Low temperature; Organic carbon; Organic matter; Pyrolysis; Reflectance; Silicates; Colombia
• ISSN: 0072-0992; 2357-3767

The dispersed organic matter was concentrated by physical and chemical methods in some samples with different amounts of calcite, silicates and total organic carbon from marine Cretaceous Formations of the Upper Magdalena Valley of Colombia. Regarding to the organic fraction, the analysis involved the identification of macerals, reflectance measurements and pyrolysis Rock -Eval. In calcareous marine Cretaceous rocks as those found in Colombia, possible vitrinites found in organic matter concentrates normally are very liptinites rich, then they are not suitable for vitrinite reflectance measurements or they have lower values than expected and exhibit high fluorescence. On the other hand, marine organism fragments that have a very similar appearance to vitrinites are very common, therefore can be confused with real vitrinites. The difference is that these have defined shapes, have low reflectance (less than 0.4 %) and have not fluorescence. Values of vitrinite reflectance obtained in concentrate of organic matter, using hydrochloric acid are slightly higher than those measured on organic matter concentrate without using it. Even at low concentrations (<10%), short exposure times (<10 minutes) and at low temperature (<20°C), acid treatment (HCl), alter components, making it difficult to identify them and leads to uncertainty about surfaces in which carry out the measure of reflectance. The fluorescence of the organic matter was not qualitatively affected allowing its use as a complementary tool for identification of macerals; however quantitative analysis of this property was not carried out.