The Mao-1 Member of the Middle Permian Maokou Formation in the Yongchuan area contains distinctive eyelid–eyeball limestones developed in an outer-ramp to intraplatform-basin transitional setting. The two components alternate as mud-rich laminae and carbonate-rich nodules or layers. Eyelid limestone contains 10–45% micritic carbonate mud and a mean total-grain content of 69.11%, whereas eyeball limestone contains