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The origin of the Jurassic low maturity natural gas in the Turpan‐Hami Basin has attracted scientists' attention for some time, and it is known that radiogenesis may have played a role. However, little has been done on the uranium‐rich background of the whole basin. Based on plentiful logging and geological data for the Jurassic strata in the Turpan‐Hami Basin, this research examined the features and factors controlling the distribution of rocks with high gamma reading. The results show that 70%‐100% of the rocks with high gamma readings correspond to mudstones in the prodelta subfacies rather than those in semideep‐deep lacustrine subfacies rich in mudstones. Therefore, we propose that the distribution of rocks with high gamma readings is mainly controlled by sedimentary facies rather than by lithology. Further analysis of the gamma spectrometry logging data shows that high gamma values are more strongly correlated with U content than with Th or K content. By comparing the U and Th contents of felsic rocks in peripheral provenances, we find that the Jueluotage Mountain and Harlik Mountain were the dominant uranium sources for the Jurassic Turpan‐Hami Basin. Radiolysis due to high‐level uranium in the prodelta subfacies can make the low maturity source rocks generate H2 and CH4, thus contributing to the production of low maturity natural gas in the Turpan‐Hami Basin. [ABSTRACT FROM AUTHOR]

Abstract: A series of branched alkylbenzene ranging from C15 to C19 with several isomers (2–5) at each carbon number were identified in sediments from the Dongsheng sedimentary uranium ore deposits, Ordos Basin, China. The distribution patterns of the branched alkylbenzenes show significant differences in the sample extracts. The branched alkylbenzenes from organic-rich argillites and coals range from C15 to C19 homologues, in which the C17 or C18 dominated. On the other hand, the C19 branched alkylbenzenes dominated in the sandstone/siltstone extracts. The obvious differences of the branched alkylbenzene distributions between the uranium-host sandstones/siltstones and the interbedded barren organic-rich mudstones/coals probably indicate their potential use as biological markers associated with particular depositional environments and/or maturity diagenetic processes. Possible origins for these branched alkylbenzenes include interaction of simple aromatic compounds with, or cyclization and aromatization reactions of, these linear lipid precursors such as fatty acids, methyl alkanoates, wax esters or alkanes/alkenes that occur naturally in carbonaceous sediments. The possible simple aromatic compounds may include substituted benzenes, functionalized compounds such as phenols that are bound to kerogen at the benzyl position, and phenols that are decomposition products derived from aquatic and terrestrial sources. The distributions of methyl alkanoates and n-alkanes were found to be different between organic-rich mudstone/coal and sandstone/siltstone. From this result, it can be concluded that such differences of the alkylbenzene distributions were mainly resulting from the differences of organic precursors, although maturity effect and radiolytic alteration cannot be completely excluded. [ABSTRACT FROM AUTHOR]