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ORIGINAL RESEARCH article

Front. Earth Sci.
Sec. Sedimentology, Stratigraphy and Diagenesis
Volume 12 - 2024 | doi: 10.3389/feart.2024.1429584

Sedimentary architecture of microbial mound-shoal complex: A case study of the Ediacaran Dengying Formation, Sichuan Basin, China

Provisionally accepted
Qinyu Xia Qinyu Xia 1*Zhenhua Guo Zhenhua Guo 1Fei Zhang Fei Zhang 2Lin Zhang Lin Zhang 1Rui Xu Rui Xu 2Xue Wang Xue Wang 1Wenzheng Li Wenzheng Li 1Shuyuan Shi Shuyuan Shi 1Haijun Yan Haijun Yan 1Yuyang Liu Yuyang Liu 1
  • 1 Research Institute of Petroleum Exploration and Development (RIPED), Beijing, China
  • 2 PetroChina Southwest Oil and Gasfield Company, Chengdu, Sichuan Province, China

The final, formatted version of the article will be published soon.

    The Ediacaran Dengying Formation in the Sichuan Basin exhibits well-developed microbial moundshoal complex (MMSC) sedimentation. Its abundant outcrops, core samples, and thin section data provide advantageous conditions for sedimentary architecture studies. Based on these data, this study elucidates typical lithofacies, identifies sedimentary architectural elements, summarizes MMSC stacking styles, describes sedimentary evolution characteristics, and explores the controlling factors of different stacking styles and the reservoir development conditions of architectural elements. Research indicates that MMSC primarily develops five lithofacies: thrombolitic dolomite, undulate stromatolitic dolomite, laminar stromatolitic dolomite, granular dolomite, and micritic dolomite. MMSCs sedimentary architecture is categorized into composite MMSCs, single MMSC, and lithofacies. Three stacking styles of MMSC are observed: superimposed MMSCs represent aggradational sedimentation, migratory MMSCs depict progradational sedimentation, and isolated MMSC denotes single parasequence depositional cycle. The stacking styles of MMSC are fundamentally controlled by the relationship between MMSC sedimentation rates and variations in accommodation space, with the latter predominantly influenced by fluctuations in sea level. Superimposed MMSCs sedimentation rates are comparable to accommodation space change rates, while migratory MMSCs sedimentation rates exceed accommodation space change rates, and isolated MMSC sedimentation rates are lower than accommodation space change rates. Various composite MMSCs are isolated from each other by sediments formed under low hydrodynamic conditions, constituting distinct connectivity units. Compared to isolated MMSC, superimposed and migratory MMSCs exhibit superior reservoir conditions. Within individual MMSC, different lithofacies lead to high-quality reservoirs in mound cores and flanks due to variations in physical properties, while mound bases, flats, and caps form non-reservoirs.

    Keywords: microbial mound-shoal complex, Sedimentary architecture, Ediacaran, Dengying Formation, Sichuan Basin

    Received: 08 May 2024; Accepted: 30 Dec 2024.

    Copyright: © 2024 Xia, Guo, Zhang, Zhang, Xu, Wang, Li, Shi, Yan and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Qinyu Xia, Research Institute of Petroleum Exploration and Development (RIPED), Beijing, China

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