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Significance Igneous rocks are well-developed in the southern Pinghu slope zone, Xihu Sag, East China Sea Shelf Basin. In this zone, the increased local geotemperature caused by magmatic activity produced significant impacts on the thermal evolution of source rocks and the formation of secondary pores in sandstone reservoirs and also serves as a significant indicator of regional tectonic movements, thus holding great significance for understanding the regional geological history. Objective and Methods This study aims to determine the formation stages and distribution patterns of igneous rocks as the cap rocks in the southern Pinghu slope zone. Using previous study results and the data of adjacent areas, as well as 3D seismic data and related attributes, and data from drilling and logs, this study analyzed the types, corresponding strata, and distribution ranges of volcanic rocks in the southern Pinghu slope zone. Furthermore, the formation stages of igneous rocks in the slope zone were explored based on the stratigraphic chronology, the morphologies of volcanic edifices, and the contact relationship between volcanic edifices and surrounding rocks. Results and Conclusions The results indicate that the seismic facies of igneous rocks in the Pingnan area can be divided into volcanic vent facies, along with explosive, overflow, and intrusive facies, with mounded and shield volcanic edifices proving the most developed. The magmatic activity in the Xihu Sag can be divided into three stages. Specifically, magmatic activity during the regional Longjing Movement, occurring in the late Miocene, exhibits the highest intensity and widest influence range. Besides, local small-scale tectonic movements occurred in the late depositional stage of the Yuquan Formation and the early depositional stage of the Santan Formation, corresponding to weak magmatic activity with minimal impacts. The Pingnan area contains five lithologic, low-amplitude drape anticline/fault combination traps associated with magmatic activity. The results of this study will provide a reference for future hydrocarbon exploration and production in the southern Pinghu slope zone of the Xihu Sag.

Frequent tectonic activity in rift basins has led to complex fault zones, which have led to extensive hydrocarbon distributions and tremendous resource potential. This study investigated the hydrocarbon potential in the southern Pinghu structural belt, focusing on fault traps in complex fault zones. Through fault sealing analysis and gas detection attenuation methods, this study aims to improve exploration success rates. The application outcomes demonstrate that the Shale Gouge Ratio (SGR) threshold for achieving the lateral sealing of faults in the southern Pinghu structural belt is 34%, with a critical fault throw of 100 m. Regions where the fault’s lateral sealing zone corresponds with areas exhibiting anomalous gas responses are deemed promising for hydrocarbon accumulation. Additional analysis indicates that favorable fault trap development occurs along the foot walls of significant faults, particularly in the eastern sector of the study area. The findings are corroborated by actual drilling data, affirming the efficacy of these methods in pinpointing hydrocarbon traps within complex fault zones and offering valuable insights for their broader global application.

The structure and function of intestinal microorganisms are closely related to host metabolism, development, physiology, and health. The red swamp crayfish, Procambarus clarkii, is an important farmed aquatic species in China, which is grown in aquaculture ponds and rice paddy fields. Since these are two distinct cultivation environments with important differences in nutrient input and ecological community composition, we hypothesized that they may have different effects on the gut microbiota of the crayfish. Here, we sought to examine this hypothesis. To that aim, metagenomics analyses were applied to unveil the taxonomic composition and functional diversity of the microbiota in the intestines of red swamp crayfish grown in aquaculture ponds and rice-crayfish cultivation environments. The results showed that Firmicutes and Proteobacteria were the two most abundant microbial components. In addition, the relative abundance of bacterial and archaeal communities, but not that of fungal and viral communities, significantly differed between the two environments. The abundance of genes involved in pathways related to genetic information processing and human diseases was lower in the guts of red swamp crayfish grown in rice-crayfish cultivation environments. In particular, the abundance of two gene sets, K13730 and K08303, which are related to epithelial cell invasion by Listeria monocytogenes and Helicobacter pylori, respectively, decreased in this culture environment. In addition, the samples from rice-crayfish cultivation environments tended to have lower relative abundance of glycosyltransferases (GTs), which were the most abundant carbohydrate-active enzymes in the samples from both groups, higher abundance of glycoside hydrolases, and lower abundance of GT2.