High-frequency sequences and their control on reef-shoal complexes: a case study of the Changxing formation at the southern margin of the Kaijiang-Liangping trough, NE Sichuan Basin

Le résumé fourni par la source

The Upper Permian Changxing Formation at the southern margin of the Kaijiang-Liangping Trough (NE Sichuan Basin) is characterized by small-scale, thin, and scattered reef-shoal complexes, resulting in strong stratigraphic heterogeneity. Conventional qualitative methods struggle to achieve accurate high-frequency sequence division due to limited core data. To address this, we integrate INPEFA (Integrated Prediction Error Filter Analysis) with wavelet transform techniques using drilling and logging data to establish a high-resolution sequence stratigraphic framework for the Changxing Formation. The formation is subdivided into two third-order sequences and six fifth-order sequences (PSS1–PSS6). Results demonstrate a strong sequence control on reef-shoal development: reefs and bioclastic shoals are preferentially developed at the tops of fifth-order highstand systems tracts (HST). This integrated approach significantly improves sequence division accuracy in complex carbonate successions and provides a methodological reference for high-resolution sequence stratigraphic analysis in similar stratigraphically complex settings globally.

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