The lower Cambrian Yurtus Formation (Є₁y) in the Tarim Basin, characterized by its high organic matter content, serves as a critical source rock for oil and gas exploration in the platform basin. This study presents a high-resolution geochemical analysis of a geological section located near the Aksu Cement Plant in the northwest margin of the Tarim Basin. The focus is on elucidating the sedimentary environment, mechanisms of organic matter enrichment, and the depositional history of the Є₁y source rock. The Є₁y exhibits distinctive geochemical signatures, including elevated concentrations of Mo, Ba, and U, with an average rare earth element (REE) content of 155.75 μg/g. The formation shows significant light REE enrichment (LREE/HREE = 1.74–5.57), a moderate Ce negative anomaly (δCe = 0.4–0.71), and a notable Eu positive anomaly (δEu = 0.94–2.14), indicative of a unique depositional environment influenced by hydrothermal processes. Geochemical evidence suggests that the Є₁y siliceous shales were deposited in a highly reducing, anoxic, and sulfide-rich environment, promoting organic matter preservation and enhancing sedimentary productivity. The presence of hydrothermal trace elements, likely introduced by hydrothermal fluids from volcanic activity along fractures and faults, played a critical role in enriching the sedimentary system, preserving organic matter, and boosting paleoproductivity. The model of organic matter enrichment proposed in this study underscores the dynamic interplay between hydrothermal influences and high primary productivity. These findings provide important insights into the formation of high-quality source rocks and have significant implications for the exploration of deep and ultra-deep oil and gas reserves in the Tarim Basin.

The uplift–depression framework controls the source–reservoir assemblage. However, the exploration breakthrough is restricted by an insufficient understanding of the uplift–depression differentiation framework in the Early Cambrian Keping–Wensu area. In this paper, based on field outcrops evaluations, thin section analysis, logging data, drilling data, and 3D seismic data, Wensu low paleo-uplift was discovered in the northern Tarim Basin, and the planar distribution was demonstrated in detail, generally shown as a SW–NE trending nose structure, extending roughly 114 km in length to the southwest, about 35 km in width to the northeast, and with the overall characteristic of being high in the west and low in the east. During the Early Cambrian, the Tabei paleo-uplift evolved into the Wensu low paleo-uplift and largely died out by the Middle Cambrian, with the development of ramps and rimmed carbonate platforms. The tectonic-sedimentary evolution of the uplift–depression framework controlled the development of a set of main source rocks and two sets of large-scale effective reservoir rocks in the Lower Cambrian, constituting two sets of effective hydrocarbon accumulation in the upper and lower stratigraphic parts of the basin. Among them, the upper assemblage holds more potential for hydrocarbon exploration, and is expected to be a next strategic target area for hydrocarbon exploration of Cambrian subsalt in the Keping–Wensu area.

Multi-trace amplitude variation with angle inversion (MAVAI) is a vital tool for estimating the physical parameters of subsurface media, and it plays an important role in oil and gas exploration. However, the existing MAVAI method relies on the Kronecker product to construct an extremely large-scale inverse problem, and its computational inefficiency limits its widespread application. Furthermore, regarding regularization constraints, the existing MAVAI method only considers the smoothness of the inversion parameters, which leads to ambiguous formation boundaries and hinders accurate identification for complex reservoirs. To address these issues, a compressed MAVAI method with elastic half-norm regularization is proposed. Specifically, we first developed a compressed MAVAI (CMAVAI) framework that uses compressed measurements of seismic data and reference models in a sparse domain to construct the CMAVAI objective function, thereby reducing the scale of the inversion problem and improving inversion efficiency. Subsequently, the elastic half-norm is introduced into the CMAVAI framework as a regularization constraint for reservoir parameter estimation. Since the elastic half-norm can simultaneously characterize both the smoothness and blocky features of the subsurface medium, it effectively improves inversion accuracy compared to the MAVAI method. Finally, the performance of the proposed method is evaluated using a theoretical model and field data. The results demonstrate that, compared with the traditional MAVAI algorithm, the CMAVAI framework can effectively improve inversion efficiency while maintaining inversion accuracy. Moreover, the CMAVAI method regularized by the elastic half-norm can improve the accuracy of inversion parameters while retaining the high prediction efficiency of the CMAVAI framework.