Mississippian foraminifera from the Lueyang Formation in Guozhen area, South Qinling Orogen, China

Abstract

The Mianlue Suture Belt, located in the southern part of the Qinling Orogenic Belt, is a significant tectonic zone in China that formed by the collision of the South China Block with the North China Block during Triassic. The Lueyang Formation, distributed along the southern margin of the Mianlue Suture Belt, is one of the major components of the Late Paleozoic marine strata of the Mianlue Belt. Unfortunately, only a few published paleontological studies are available. This hinders the understanding of the age and sequence of this formation and the evolution of the Mianlue Ocean. Herein, we report, for the first time, at least 51 species and 25 genera of foraminifera from the Lueyang Formation at the Zhuyuanba section. The Zhuyuanba foraminiferal fauna is dominated by Eostaffella, Archaediscus, Paraarchaediscus, Omphalotis, Bradyina, Janischewskina, Endothyra and Mediocris, and possesses some stratigraphically important taxa such as Bradyina cribrostomata, Janischewskina spp. and Paraarchaediscus stilus. Two foraminiferal zones are recognized in the Lueyang Formation, ascendingly the Visean Paraarchaediscus stilus Zone and Serpukhovian Bradyina cribrostomata Zone. So, the age of the Lueyang Formation at the Zhuyuanba section is considered from Visean to Serpukhovian. This paper confirms for the first time that the Lueyang Formation contains the Visean and Serpukhovian strata, providing new paleontological evidence for understanding the evolution of the Mianlue Ocean during the Late Paleozoic.