Organic geochemical study of the Lower Miocene Kremna Basin, Serbia

摘要: The Kremna Basin is located in southwest Serbia, the Zlatibor area, which part of Internal Dinarides. This basin noteworthy because type bedrock drainage, it represents. It was formed on ultrabasic rocks and volcanic materials that influenced occurrence organic matter (OM) fill. objective study to determine geochemical characteristics sediments from central Basin. studied belong an intrabasinal facies, two sequences were distinguished. lower sequence occurs at depths 216–343 m, while upper found 13.5–216 m. At start development (265–343 m) sedimentation took place shallow alkaline water, rich Mg ions. Through time, a slight deepening occurred. followed by chemical deposition carbonates (216–265 m). most important change sedimentary environment occurred with formation marking transition between (at about 200 Sediments are characterized dominance dolomite magnesite. There indications activity, i.e. tuff layers presence searlesite. prevalence calcite dolomite. amounts MgO, Na 2 O B higher sequence, whereas CaO content sequence. contain different immature OM (late diagenesis). Biomarker analysis shows diverse precursors OM: methanogenic archaea, photosynthetic green sulfur bacteria ( Chlorobiaceae ), bacterivorous ciliates, various bacteria, both non-photosynthetic, unicellular microalga, Botryococcus braunii race A (exclusively sequence) terrestrial plants. contains amount OM, composed primarily kerogen II/III III types, indicating contribution allochtonous biomass land plants lake catchment, particularly part. enriched autochthonous aquatic comprises mostly I, I/II II types. one associated decrease pristane phytane ratio, gammacerane index C 28 steroids, absence or significantly squalane, 24 25 regular isoprenoids, 8-methyl-2-methyl-2-(4,8,12-trimethyltridecyl) chroman 30 hop-17(21)-ene. Pyrolytic experiments showed catagenetic stage could be source liquid hydrocarbons. values hopane, sterane phenanthrene maturation parameters indicate through pyrolysis 400°C samples investigated reached value vitrinite reflectance equivalent approximately 0.70%. estimated should 2300–2900 m order become active rocks. calculated minimum temperature, necessary for hydrocarbon generation, 103 107°C.