DISCOVERY OF OLIGOCENE MINGGUANG FORMATION AROUND THE CITY OF MINGGUANG
A suite of clastic rocks outcropped to the north of the City of Mingguang and dicordantly overlapping the Dingyuan Formation was regarded as the Miocene deposit,called the Caowan Formation.Recently,a regional geological survey of 1:50000 scale mapping in the city indicated that the clastic rocks are of Oligocene deposit by ESR dating.So the Mingguang Formation is set up to ammend the viewpoint of the lack of Oligocene deposit in the area held by many geologists.