Paleoenvironmental Reconstruction and Organic Matter Accumulation of the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin, South China
Paleoenvironmental Reconstruction and Organic Matter Accumulation of the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin, South China
复制标题
四川盆地下寒武统筇竹寺组古环境重建与有机质成藏
DOI：
10.1021/acsearthspacechem.2c00224
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发表时间：
2022-09
影响因子：
3.4
通讯作者：
L. Bian;N. Schovsbo;A. Chappaz;A. Rudra;Jin Xu;Q. Luo;H. Sanei
中科院分区：
文献类型：
--
作者：
L. Bian;N. Schovsbo;A. Chappaz;A. Rudra;Jin Xu;Q. Luo;H. Sanei
四川盆地下寒武统琼竹寺组是扬子地台最富的油气源之一。然而，四川盆地下寒武统（琼竹寺）全盆地范围内的环境变化仍不清楚，这可能阻碍了有希望的有机质聚集区的解锁。本文首次对四川盆地下寒武统环境重建进行了详细的无机地球化学研究。主成分分析结果表明，下琼珠寺岩系（LQS）富集碳酸盐伴生元素和稀土元素（REE），而中上琼珠寺岩系（MQS-UQS）则富集铝硅酸盐伴生元素（如，Al和Ti）。保守的金属组合表明，沉积物的物源为中长英质火成岩，构造背景为大陆岛弧。Sr/Ba和S/TOC值的组合表明，它是在半咸水到正常的海洋条件下形成的。与中琼竹寺序列相比，上琼竹寺序列和下琼竹寺序列具有较高的生物生产力（增加Cu/Al）、较低的碎屑输入（降低Ti/Al）、较低的沉积速率（降低Th/U）和还原条件。这些属性可能导致更高的有机质生产力和保存。从时间上看，该盆地的北方部分有机质含量较高，沉积条件较还原，陆源物质沉积速率较低。
: The lower Cambrian Qiongzhusi Formation in the Sichuan Basin of the Yangtze Platform is one of the most proliferous petroleum sources. However, the basin-wide lower Cambrian (Qiongzhusi) environmental variation in the Sichuan Basin remains unclear, which could have impeded the unlocking of promising areas of organic matter accumulation. This paper presents the first detailed inorganic geochemical investigation of the lower Cambrian environmental reconstruction in the Sichuan Basin. The results of principal component analysis show that the lower Qiongzhusi succession (LQS) is enriched in carbonate-associated elements and rare earth elements (REE), whereas the middle − upper Qiongzhusi successions (MQS − UQS) are enriched in elements affiliated with aluminosilicates (e.g., Al and Ti). The conservative metal associations suggest that the provenance of the sediments was intermediate-felsic igneous rocks and the tectonic setting was a continental island arc. The combination of Sr/Ba and S/TOC values indicates that it was formed under brackish to normal marine conditions. In contrast to the middle Qiongzhusi succession, the lower and upper Qiongzhusi successions had elevated biological productivity (increased Cu/Al), low detrital inputs (decreased Ti/Al), low sedimentation rate (decreased Th/U), and reducing conditions. These attributes probably resulted in higher organic matter productivity and preservation. Temporally, the northern part of this basin had higher organic matter contents and was deposited under more reducing conditions, with a lower sedimentation rate of terrigenous materials.