“…The end of the Ordovician and the beginning of the Silurian was an important period in Earth history, − and it is marked by marine mass extinction, large-scale glaciation, sea-level change, extensive volcanism, ocean anoxic event, and extensive deposition of marine black shale. − Black marine shale, as a source rock for oil and gas, is widely accumulated in paleogeographic environments. − To this day, such a black shale has been widely developed as unconventional reservoirs in many countries, such as the United States, Canada, Australia, China, Germany, Russia, etc. − Thus, the study of the sedimentary environment and the mechanism of organic matter accumulation for the marine shales of the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation in the northern Sichuan Basin not only can provide important information about the climatic and paleoenvironmental change of the Ordovician–Silurian but also provides evidence for the prediction of favorable areas for oil and gas exploration.…”