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<p>The evolutionary history of the Deyang–Anyue depression (DAD) during the Sinian and Cambrian periods in the Sichuan Basin (SB) remains unclear, and the lithofacies palaeogeography during key stages is poorly understood. To address these gaps, this study integrates data from core samples, thin sections, well logs, seismic records, and previous research. The analysis focuses on the tectonic–sedimentary background shaped by the evolution of the DAD in the SB. Using 2D and 3D continuous seismic data, the study reconstructs the evolutionary process of the DAD, reconstructs lithofacies palaeogeography for critical periods, analyses the temporal and spatial distribution patterns of reservoir variations within the context of DAD evolution, and identifies the reservoir development zones of the Dengying Formation (DY). The research reveals that the inherited geomorphic pattern of the DY during its depositional and karst exposure stages—characterized by lower elevations in the west and north and higher elevations in the east and south—controlled the deposition and filling patterns of the DY across different periods. Consequently, the formation is thicker in the west and north and thinner in the east and south. The scale and morphology of the DAD were shaped by the combined effects of negative geomorphology, regional extensional forces, and sea-level fluctuations prior to DY deposition. The DAD underwent four major evolutionary stages: initial embryonic formation, progressive development, structural stabilization, and eventual infill and demise. Controlled by the tectonic and sedimentary evolution of the DAD, the DY platform evolved from a ramp platform depositional system to a rimmed-platform depositional system. Constrained by seismic facies, the mound–shoal complexes of each stage display a sequential evolutionary pattern, characterized by both inherited construction and a consistent ring-shaped distribution around structural highs. The DAD governs the differential reservoir-forming processes of the DY and the development of high-quality source rocks. The Intraplatform karst-reworked slope reservoir zone of the fourth member of the Dengying Formation (D4) represents a key future exploration target, owing to its favorable reservoir development potential and excellent hydrocarbon source configuration.</p>

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Tectonic–sedimentary evolution of the Sinian-Cambrian Deyang–Anyue depression in the Sichuan Basin and its hydrocarbon geological significance

  • 期刊论文

  • 发表日期：

    2026年3月12日

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  • Lei Tan,
  • Weihao Zhao,
  • Gang Zhou,
  • Feng Liang,
  • Lin Qiao,
  • Hong Liu,
  • Minxing Li,
  • Kun Zhang,
  • Mengxiang Yang

摘要

The evolutionary history of the Deyang–Anyue depression (DAD) during the Sinian and Cambrian periods in the Sichuan Basin (SB) remains unclear, and the lithofacies palaeogeography during key stages is poorly understood. To address these gaps, this study integrates data from core samples, thin sections, well logs, seismic records, and previous research. The analysis focuses on the tectonic–sedimentary background shaped by the evolution of the DAD in the SB. Using 2D and 3D continuous seismic data, the study reconstructs the evolutionary process of the DAD, reconstructs lithofacies palaeogeography for critical periods, analyses the temporal and spatial distribution patterns of reservoir variations within the context of DAD evolution, and identifies the reservoir development zones of the Dengying Formation (DY). The research reveals that the inherited geomorphic pattern of the DY during its depositional and karst exposure stages—characterized by lower elevations in the west and north and higher elevations in the east and south—controlled the deposition and filling patterns of the DY across different periods. Consequently, the formation is thicker in the west and north and thinner in the east and south. The scale and morphology of the DAD were shaped by the combined effects of negative geomorphology, regional extensional forces, and sea-level fluctuations prior to DY deposition. The DAD underwent four major evolutionary stages: initial embryonic formation, progressive development, structural stabilization, and eventual infill and demise. Controlled by the tectonic and sedimentary evolution of the DAD, the DY platform evolved from a ramp platform depositional system to a rimmed-platform depositional system. Constrained by seismic facies, the mound–shoal complexes of each stage display a sequential evolutionary pattern, characterized by both inherited construction and a consistent ring-shaped distribution around structural highs. The DAD governs the differential reservoir-forming processes of the DY and the development of high-quality source rocks. The Intraplatform karst-reworked slope reservoir zone of the fourth member of the Dengying Formation (D4) represents a key future exploration target, owing to its favorable reservoir development potential and excellent hydrocarbon source configuration.