<p>Early Cambrian organic-rich shales in the Yangtze Plate are key shale gas exploration targets in China, but their sedimentary environments are not well understood. This lack of knowledge complicates the evaluation of these targets and associated risks. Assessing shale depositional environments is also challenging due to the fine-grained nature of the sediments and subtle compositional variations. Herein, marine black shales of the Lower Cambrian Shiyantou (SYT) Formation (Fm) and Yu’anshan (YAS) Fm are investigated through a series of experiment, including thin sections, scanning electron microscopy, and major and trace elements analysis. Results show that five lithofacies can be identified in the SYT and YAS shales: (1) calcareous mudstone; (2) wavy-laminated sand, silt, and clay bearing mudstone; (3) laminated and massive mudstone; (4) planar-laminated pyritic mudstone, and (5) thin bedded sand and siltstone. Average content of major elements SiO₂, Al₂O₃, MgO, Fe₂O₃, K₂O, CaO, Na₂O, TiO₂, P₂O₅, and MnO of SYT Fm are 57.03%, 12.74%, 4.20%, 3.97%, 3.93%, 3.35%, 1.09%, 0.68%, 0.28%, and 0.05%, respectively. Average content of major elements SiO₂, Al₂O₃, MgO, Fe₂O₃, K₂O, CaO, Na₂O, TiO₂, P₂O₅, and MnO of Yu’anshan Fm are 54.93%, 14.52%, 5.26%, 6.00%, 3.77%, 3.88%, 0.15%, 0.63%, 0.19%, and 0.10%, respectively. Samples from SYT Fm are enriched in Li, V, Cr, Co, Zr, Cs, and U relative to Upper Continental Crust (UCC) and most of shale samples from YAS Fm are enriched in Li, V, Co, and U relative to UCC. The marine black shales are deposited in dynamic anoxic to oxic environment in upper Yangtze Plate, which indicated the seabed had already oxidized in the Cambrian Stages 2 and 3. The Chemical Index of Alteration (CIA) values ranged 51.84–79.46 indicate a warm and humid climate in the 2 stages. These findings are consistent with the region’s paleogeography and previous studies. They hold significance for sedimentologists, paleontologists, and other researchers involved in petroleum geology.</p>