First lithological and organic geochemical characterization of organic rich mudstones from Shavar Formation, southeast Bulgaria

ABSTRACT

The paper reports the first results of the organic geochemical characterization of mudstones from the Shavar Fm (eastern Rhodope Mt., Bulgaria). The rock matrix is unevenly impregnated by amorphous organic matter at the onset of the oil generation (T_max ~ 445ºC; PI – 0.1–0.2). High total organic carbon contents (avg. TOC – 5.9 wt. %) and HI (~720 mg HC/g TOC) argue for oil-prone source-rocks with very good hydrocarbon potential. The n-alkane distributions with maxima in the range n-C_20-25 are consistent with organic matter origin from submerged plants. Additionally, sterane distributions dominated by C_28-30 4-methyl steranes, indicate dinoflagellate contribution. High pristane/phytane ratio (Pr/Ph = 2–4) argue for deposition under oxic conditions.

KEYWORDS:

• Shavar Formation
• SE Bulgaria
• mudstones
• biomarkers
• hydrocarbon potential

Acknowledgments

Publishing allowance from Dundee Precious Metals Inc. – branch Krumovgrad is greatly appreciated.

Additional information

Notes on contributors

Alexander Zdravkov

Alexander Zdravkov is an Associated Professor at the Department of Geology and Prospection of Mineral Resources, University of Mining and Geology “St. Ivan Rilski„, Sofia, Bulgaria.  His research interests include coal petrology, mineralogy and geochemistry, sedimentology, source rock characterization.

George Ajdanlijsky

George Ajdanlijsky is an Associated Professor at the Department of Geology and Geoinformatics, University of Mining and Geology “St. Ivan Rilski„, Sofia, Bulgaria.  His research interests include sedimentology, litho-, chrono- and sequence stratigraphic characterization of Mezozoic and Tertiary rock units.

Maya Stefanova

Maya Stefanovaa is Full Professor and Senior researcher at the Institute of Organic chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria. Her main research interests include organic geochemical characterization of fossil fuels.

Doris Groß

Doris Groß is an Associated Professor at the Department of Angewandte Geowissenschaften und Geophysik, Montanuniversität Leoben, Austria with research interests in geology, petrology, geochemistry and hydrogeology of fossil fuel deposits and source rocks.

Yaroslav Dintchev

Yaroslav Dintchev is a Senior geologist at “Dundee Precious Metals - branch Krumovgrad„ EAD, Krumovgrad, Bulgaria. He is responsible for the geological prospection and exploration of the Ada Tepe ore deposit, SE Bulgaria.