New Evidence of Eocene Ingression in Grabens of the Tan-Lu Fault System (East Asia): An Important Event Level

Abstract

New evidence of Eocene ingression in the area of the present-day Russian–Chinese border is provided. It was previously believed that Cenozoic grabens of the Tangcheng–Lujiang (Tan-Lu) Fault Zone, located in China and also traced in Russia, were filled predominantly by continental, rarely, lagoonal sediments. In 2015, drilling in the Huadian Basin (graben), which is part of the Tan-Lu system, recovered the Hydrobia zhuoxianensis gastropod in the black shales among the continental fauna. This finding indicates coastal marine conditions and therefore specifies the extent of the Eocene ingression. This gastropod can also be used in interregional stratigraphic correlation.