Sedimentary environment and petrological features of organic-rich fine sediments in shallow water overlapping deposits: A case study of Cambrian Yuertus Formation in northwestern Tarim Basin, NW China

JIN Zhimin,TAN Xiucheng,TANG Hao,SHEN Anjiang,QIAO Zhanfeng,ZHENG Jianfeng,LI Fei,ZHANG Shixuan,CHEN Lei,ZHOU Chenggang

Fig. 3. Macroscopic and microscopic characteristics of thin organic-rich shale and siliceous rock interbeds. (a) Macroscopic photo of thin shale and siliceous rock interbeds, Shiairike section; (b) Micrograph of siliceous rock with metasomatic residual granular structure, plane-polarized light; (c) Counterpart of Fig. 3b under orthogonally polarized light (G: silicified particle structure, A: algal particles, C: siliceous cement); (d) Micrograph showing siliceous rock with metasomatic residual laminated structure, Shiairike section, plane-polarized light; (e) Counterpart of Fig. 3d under orthogonally polarized light (A: algae particles, C: siliceous cements and fillings in along-layer cavities, with generational features); (f) Sharp contact between black shale and gray-green shale, Sugaite section.