四川盆地及其周缘下寒武统麦地坪组-筇竹寺组层序充填和演化模式

Sequence filling and evolutionary model of the Lower Cambrian Maidiping-Qiongzhusi formations in Sichuan Basin and on its periphery

吴冬 邓虎成 熊亮 曹凯旋 董晓霞 赵勇 魏力民 王同 马若龙

Dong WU Hucheng DENG Liang XIONG Kaixuan CAO Xiaoxia DONG Yong ZHAO Limin WEI Tong WANG Ruolong MA

四川盆地及其周缘下寒武统筇竹寺组页岩气资源丰富，是重要的页岩气产气层段之一。由于该套地层埋藏深、资料少且地质条件复杂，对其开展的层序地层研究较为薄弱，这严重制约了后续研究和生产。首先对四川盆地及其周缘早寒武世构造-沉积背景开展研究，在此基础上结合岩性、颜色、测井曲线、微量元素、古生物和地震反射同相轴等特征，对麦地坪组-筇竹寺组层序地层开展研究，提出层序划分思路，将麦地坪组-筇竹寺组从下往上依次划分为4个Ⅲ级层序。进而厘清层序地层空间分布规律，建立受全球板块张性活动控制的四川盆地及其周缘麦地坪组-筇竹寺组“早期窄盆差异沉积，后期广盆稳定分布”的层序演化模式。该演化模式对深化认识四川盆地寒武纪构造-沉积格局、推动沉积成藏等地质研究及促进深部页岩气勘探开发具有一定意义。

The Lower Cambrian Qiongzhusi Formation in the Sichuan Basin and on its periphery is rich in shale gas resources and has been proven to be one of the important shale gas pay zones in the basin. Due to the deep burial depth， few data and complex geological conditions， the research on its sequence stratigraphy has been relatively weak， having seriously restricted the follow-up research and development. The study on the Early Cambrian tectono-sedimentary setting of the Sichuan Basin and on its periphery， coupled with lithology， rock color， logging curve， trace elements， paleontology， seismic reflection event and other characteristics， is carried out to further explore the sequence stratigraphy of the Maidiping-Qiongzhusi formations， with the idea for the sequence division proposed. As a result， the Maidiping-Qiongzhusi formations are divided into four third-order sequences from bottom to top. By revealing the spatial distribution pattern of the sequence stratigraphy， we establish a sequence evolutionary model of “differential sedimentation in early narrow basin， and stable sedimentation in later wide basin” for the Maidiping-Qiongzhusi formations in the Sichuan Basin and on its periphery under the control of global plate extensional activity. The sequence evolutionary model will be of help to deepening understanding of the Cambrian tectono-sedimentary setting in the Sichuan Basin， promoting geological research on sedimentary reservoirs， and serving the exploration and development of deep shale gas.

10.11743/ogg20230318