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. 6. Typical characteristics of exposed karsts in the Yuertus Formation. (a) Iron crust, Xiaoerbulake section; (b) Iron crust and near-surface breccia, Xiaoerbulake section; (c) Micrograph of iron crusts and weathered crust breccias, Shiairike section, plane-polarized light; (d) Characteristics of overlapping shale, Xiaoerbulake section; (e) Reticulated karrens filled with purple dolomitic mud, Xiaoerbulake section; (f) Sac-like cave filled with breccia and carbonate sand, Wushi section; (g) Sac-like cave filled with breccia and carbonate sands, Shiairike section;(h) Fine-grained dolomite, dissolved fractures filled with insoluble residues, Sugaite section, plane-polarized light; (i) Fine-grained dolomite with karrens and vadose matter, a zoomed-in part of Fig. 6h, plane-polarized light.