Hydrocarbon biomarkers from Ordovician sediments and the fossil alga Gloeocapsomorpha prisca Zalessky 1917

Organic geochemical characteristics of black shales across the Ordovician–Silurian boundary in the Holy Cross Mountains, central Poland

“…3) with a low OEP (Table 2) in the samples, particularly n-C 15 , n-C 17 , and n-C 19 in the Ordovician samples, and existence of trace amounts of n-alkylcyclochexanes with a slight odd-over-even predominance around C 17 alkylcyclohexane (Douglas et al, 1991;Fowler, 1992;Fowler et al, 1986) are characteristic features of organic matter derived from Gloeocapsomorpha prisca algae (Hoffmann et al, 1987;Peters et al, 2005;Reed et al, 1986). Bacteriohopanepolyols, which are bacterial membrane lipids, have been considered as the precursor of hopanoid biomarkers (Ourisson and Albrecht, 1992;Ourisson et al, 1979;Ourisson and Rohmer, 1992), consistent with the high relative abundance of homohopanes (C 31 -C 34 ) in all samples (Fig.…”

Identification of the Kukersite-type source rocks in the Ordovician Stratigraphy from the Tarim Basin, NW China

“…In general, the factor that distinguishes the crude oil generated by Kukersite-type source rocks from others generated by organic matter is the odd-even predominance of low carbon number N-alkane. In the meantime, the content of high carbon number N-alkane is relatively low [1][2][3][4][5][6][7][8][9][10][11][12][13]. However, this feature has yet been found in the crude oil of the Lower Paleozoic petroleum system in the Tarim Basin [19].…”

“…The third type of source rocks shows a feature of hydrogen enrichment due to the increase of phytoplangkton input. Although there are controversial opinions, most researchers tend to believe that the G. prisca is a photoheterotrophic cyanobacteria [7,28,[37][38][39]. After a thorough investigation of the G. priscaenriched development environment of Ordovician sediments in Estonia, Foster and his colleagues (1989,1990) believed that the G. prisca was mainly developed in intertidal zone [6,40].…”

“…The crude oil contributed by G. prisca usually has distinctive molecular geochemical fingerprint. In another word, there is odd-carbon number predominance such as n-C 15 , n-C 17 and n-C 19 in N-alkanes with low carbon numbers; meanwhile the relevant content of N-alkanes with high carbon numbers is very less [1][2][3][4][5][6][7][8][9][10][11][12][13]. According to the statistics, Kukersite-type source rocks are the primary contributor of petroleum resources of the Lower Paleozoic marine petroleum field that is discovered in north American platform, including the G. prisca-enriched and G. prisca-diluted types [11].…”

Detection of mono- and bicyclic alkanes and their characteristics in Neogene sediments of the Shinjo basin, Japan.

“…The increase in composition continued downward. Hoffmann et al, 1987;Kissin, 1990), or decarboxylation of ω-cyclohexyl carboxylic acids in thermoacidophilic bacterial products (De Rosa et al, 1972;Oshima and Ariga, 1975;Suzuki et al, 1981). n-Alkylcyclohexanes in the upper part of the sequence could have been derived mainly from n-carboxylic acids by cyclization because of the predominance of n-alkylcyclohexanes from C 15 to C 18 and that of n-carboxylic acids with C 16 and C 18 in these sediments (Ishiwatari and Shioya, 1986).…”