Late Tremadocian-early Floian acritarchs from graptolitic shales of the Yinzhubu and Ningkuo formations of Yiyang, South China

► Three acritarch assemblage zones are distinguished from the graptolite shales. ► Detailed calibrations between acritarch-chitinozoan-graptolite are suggested. ► Precise regional and global correlations are possible based on acritarchs. ► This study provides some improvements in the paleogeographical reconstructions.