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The comment by Yin (2024) referred to the systematic morphology and identification of the newly recovered in situ ammonite assemblage Tiltoniceras sp. and Hildoceratidae sp. from the Bilong Co section in the Qiangtang Basin. Yin (2024) suggests that Tiltoniceras sp. should be assigned to Oxycerites aspidoides. Upon re-examination of our paper and the reply to the released comment, it is demonstrated that the morphologic characteristics of the recovered ammonites are more consistent with Tiltoniceras rather than Oxycerites aspidoides. These ammonites, along with in situ calcite U–Pb age (ca. 181 Ma), carbon isotope stratigraphy, and age-diagnostic palynomorphs, constrain the age of the Bilong Co oil shale to the Lower Jurassic (Toarcian) with plausible credentials. [ABSTRACT FROM AUTHOR]

[Objective] The current focus of non-conventional petroleum theories is the accumulation mechanism of organic matter. One of the most commonly debated issues regards the main influences on organic matter enrichment previous studies lack analysis of the depositional process, which is the likely reason for the debate. [Methods] This study combines sedimentological and geochemical methods to conduct detailed sequence stratigraphy, and facies and elemental analyses, aiming to address the accumulation mechanism of sedimentary organic matter. [Results] The Late Permian Wuchiaping Formation and Dalong Formation in the northern Sichuan Basin and the West Hubei Basin are subdivided in ascending order into the First, Second and Third members of the Wuchiaping Formation, and the First and Second members of the Dalong Formation. The Late Permian is subdivided into five third-order stratigraphy sequences, SQ1 to SQ5. Analysis of the sequence stratigraphy revealed the four-stage developmental history of the rift basin in the northern Sichuan Basin and the West Hubei Basin: the initial stage followed by rapid rifting, rifting climax and a shrinking stage. The initial stage mainly coincided with the deposition of SQ2, and consists of dark cherty limestones of slope facies. The rapid rifting stage mainly occurred during SQ3, and comprises calcareous shales of deepwater shelf facies. The rifting climax stage mainly took place during SQ4, consisting of black bedded cherts of basin facies. The shrinking stage mainly occurred during SQ5, and consists of medium- or thin-bedded limestones. The sweet-spot interval developed mainly between the highstand system tract (HST) of SQ3 and the transgressive system tract (TST) of SQ5, during which the nutrient elements Fe, Cu, Ni, Zn and redox-sensitive elements Mo, V, Fe/Al and S were highly enriched. This sweet-spot interval is also associated with highly active hydrothermal activity indicated by Al/ (Al+Fe+Mn) ratios < 0.6 and the Al-Fe-Mn diagram. [Conclusions] The development of high primary productivity occurred prior to the strongly reducing conditions during the deposition of the sweet-spot interval. This suggests that the reducing conditions in the bottom water resulted from high consumption of oxygen during the decomposition of organic matter, and that organic matter enrichment was mainly the result of primary productivity. The nutrient material input was related to hydrothermal activity and volcanism during the formation of the rifting basins. Episodic tectonic activity brought abundant nutrient elements to the rifting sea, enhancing the primary productivity level; the primary productivity level was the onset and basic condition for the extraordinarily high organic matter accumulation in the sweet-spot interval, and the strongly reducing conditions in the bottom water was the key factor for organic matter preservation and burial. [ABSTRACT FROM AUTHOR]

[Objective] The Lower Cambrian Shuijingtuo Formation black shale is an important source rock and shale gas exploration target in the Sichuan Basin. However, the enrichment mechanism of organic matter in this series of black shale is still unclear. [Methods] Here, we reported total organic carbon (TOC) contents, sedimentary microfacies, major and trace elements, and pyritic framboid size distributions in the lower part of Shuijingtuo Formation in the Chengkou area, northeastern Sichuan Basin on the Upper Yangtze Platform, providing new evidence for reconstructing the paleogeography, paleoenvironment, and main controlling factors of organic matter enrichment. The results show that the black shale succession in the Shuijingtuo Formation developed five sedimentary microfacies which related to the deep-water shelf slope environment. Productivity index (BaXS, P/Ti) and continental input index Ti, Al indicate that the sedimentary environment of black shale in the Shuijingtuo Formation is at a low level of paleoproductivity, and the continental input is relatively stable and has no obvious correlation with TOC. Therefore, paleoproductivity and continental input are not the main controlling factors of organic matter enrichment in the black shale of the Shuijingtuo Formation. The redox-sensitive element index (U/Th, UEF, MoEF ) and pyrite framboid size distributions show that the organic matter content is positively correlated with the redox index, indicating that the organic matter enrichment in Shuijingtuo Formation is mainly controlled by the change of redox conditions of the water column. [Conclusions] Based on the above understanding, it can be inferred that the organic matter enrichment of the black shale of the Shuijingtuo Formation was controlled by the fluctuation of redox conditions of the bottom water caused by the large-scale transgression event during the stage 2 to stage 3 Cambrian (529-514 Ma), and the organic matter enrichment model was proposed here. [ABSTRACT FROM AUTHOR]

[Objective] The organic-enriched black bedded cherts in the Kuhfeng Formation were deposited in the Lower Yangtze during the Middle Permian. The hydrothermal cherts may be the key part for the relationship analysis between chert deposits and the extra-ordinarily high organic matter enrichment. This would be the basic theories for the shale gas exploration in this area. [Methods] This work uses major, minor, and rare-earth elements, combined with the petrology, to analyze the origin of chert and their tectonic setting for the Kuhfeng Formation in the Yeshan of Tongling and Pingdingshan of Chaohu, Anhui province. [Results] The black bedded cherts in the Chaohu area contain abundant siliceous sponge spicules and radiolarians. The cinerous cherts in the Kuhfeng Formation in the Tongling area contain extremely rare siliceous fossils and consist of micro-quartz. Hydrothermal proxies, such as Al/(Al+Fe+Mn), Eu/Eu*, Al-Fe-Mn diagram, and LuN/LaN, indicate a hydrothermal and biotic origin for the chert in the Kuhfeng Formation in the Tongling and Chaohu areas, respectively. The La-Th-Sc diagram and crossplot between La/Sc and Ti/Zr indicate oceanic island arc and active continental margin origins for the Tongling and Chaohu areas. [Conclusions] The chert in the Kuhfeng Formation in the Tongling area was primary deposited by hydrothermal activity. The silicic acid was brought by a hydrothermal vent near the slope environments. The black bedded cherts in the Lower Yangtze area are biotic in origin, but the source of silicon was related to the hydrothermal activity. The organic matter enrichment in the Kuhfeng Formation in the Lower Yangtze area may be related to the phytoplankton flourishment induced by the nutrient element input from hydrothermal activity. [ABSTRACT FROM AUTHOR]