Organic geochemistry of freshwater and alkaline lacustrine sediments in the Green River Formation of the Washakie Basin, Wyoming, U.S.A.

Upper Permian Junggar and Upper Triassic Ordos lacustrine source rocks in Northwest and Central China: Organic geochemistry, petroleum potential and predicted organofacies

“…The same phenomenon has been reported from the Laney Shale (Green River Formation, Washakie Basin) by Horsfield et al (1994), and has been interpreted as resulting from the origination via the cracking of a highly structured macromolecular precursor at sterically favoured position rather than from a random thermal cracking. The Open-system pyrolysis GC-FID typing of molecular kerogen structure for Junggar and Ordos shales using a ternary diagram modified from Eglinton et al (1990). paradox here is that, according to Horsfield et al (1994), this feature was usually detected in those sediments deposited immediately after prolonged desiccation, but no evidence of subaerial exposure is there in Chang 7-1 shale has favoured to this hypothesis. Therefore, consecutive work needs to be conducted to further study this kind of feature.…”

Methylhopanoids: Molecular indicators of ancient bacteria and a petroleum correlation tool

“…This characteristic is reminiscent of the dominance of 3␤-methylBHPs in sediments of two of the modern alkaline lakes. Indeed, some phases of deposition of the Green River Shale occurred under alkaline conditions (e.g., Horsfield et al, 1994), and abundant 3␤-methylhopanes have been reported previously, having very light carbon isotopic compositions indicative of an origin from methanotrophic bacteria (Collister et al, 1992;Ruble et al, 1994). Furthermore, the Observatory Hill Formation of Australia, which was deposited in a Cambrian continental alkaline playa lake, is also characterized by abundant 3-methylhopanes (Logan et al, 1997).…”

Predicted bulk composition of petroleum generated by Lower Cretaceous Wealden black shales, Lower Saxony Basin, Germany

“…The frequency factor of the more heterogeneous sample 1 (3.84E + 14 s −1 ) is also lower than those of samples 2-4 (1.12E + 15 to 5.30E + 15 s −1 ) indicating a lower thermal stability. With respect to the broader E a distribution of sample 1, it should be noted that heterogeneous (broad E a distributions) as well as homogeneous (single E a ) type I kerogens are found in lacustrine settings, as reported, for example, in the Laney Shale and Luman Tongue of the Green River Shale (Horsfield et al 1994) or in the ES4 member of the Shahejie Formation in the Western Depression of the Liaohe Basin, NE China (Fuhrmann et al 2004). It is clear that kinetic parameters vary appreciably, even within lacustrine settings, and therefore, evaluations should be conducted on a case-by-case basis.…”

“…from wells Brotherson 1-23B4 and Government 33-4) from Uinta Basin (Braun et al 1991) and Pematang samples [Indonesian Brown Shale, (Tegelaar and Noble 1994)] exhibit maximum generation potentials (T max ) ranging between 147 and 165 °C. Horsfield et al (1994) reported geological T max values of 150-170 °C for the Laney Shale member and T max values of 170-175 °C for the Luman Tounge member of the Green River Formation (Washakie Basin). In the case of an Australian Torbanite composed of the remains of B. braunii, an even higher maximum petroleum generation rate temperature of 180 °C was reached (Tegelaar and Noble 1994).…”