Basic characteristics of key interfaces in Upper Ordovician Wufeng Formation - Lower Silurian Longmaxi Formation in Sichuan Basin and its periphery, SW China

WANG Yuman,WANG Hongyan,QIU Zhen,SHEN Junjun,ZHANG Qin,ZHANG Leifu,WANG Canhui,LI Xinjing

Fig. 2. Concretions of Longmaxi Formation in Sichuan Basin (the geological hammer is 33 cm long, and the arrows point to concretions). (a) Shuanghe section in Changning, discontinuous bedding concretions in upper Rhuddanian; (b) Thin-section photograph of concretions in upper Rhuddanian on Shuanghe section in Changning, calciferous siliceous shale, with TOC of 0.76%; the bright particles are quartz, radiolarian, sponge spicule and dolomite, single polarization; (c) Heizhugou section in Ebian, dispersed concretions in Aeronian; (d) Thin-section photograph of concretions on Heizhugou sectin in Ebian, crystal powder dolomite, with TOC of 1.85%; there are lamina under the microscope, with a large number of dolomites and radiolarians, single polarization.