تعيين درجه پختگي مواد آلي سازند سرچاهان با استفاده از انعكاس گراپتوليت

Thermal Maturity Determination of Sarchahan Formation (NE Bandar Abbas, South Iran) Using Graptolite Reflectance (GRo%)

In order to determine the maturity of the organic matter of Sarchahan Formation in northern Bandar Abbas, 15 outcrop samples were collected from Tang-e-Zakin, North Syahoo village, 70 km. from the city of Bandar Abbas. The Reflectance of Graptolites (%GRo) were measured by a reflected light microscope (MPV-SP) and histograms were plotted. The Mean Random Reflectance of these samples were 1.11% which indicate the cat- agenetic stage of maturity. These samples were also subjected to Rock- Eval Pyrolysis. The average Tmax for these samples is 455°C that indicates the end of oil generation window and early stage of gas generation. The Gahkum Formation (Silurian shales) as a whole was reported as overmature and its organic matter considered to have graphitic stage of maturity. Nevertheless Gahkum Fm. was divided into Syahoo Fm. (Ordovician) and Sarchahan Fm. (lower Silurian) on the basis of their biozones. On the other hand, this study geochemically investigated Sarchahan Formation separately with the help of Rock-Eval data, TAI, elemental analysis of kero- gen and measurements of graptolite reflectance (Gro%), and concluded that it is in the catagenetic stage of maturity and emphasis on the Silurian strata for future hydrocarbon exploration in Iran.