MISSISSIPPIAN FORAMINIFERS FROM SOUTH CHINA

Foraminifers are significantly useful in high-precision biostratigraphic correlations for Mississippian strata. In this geological period, South China was located at a subequatorial-equatorial position in the east Paleotethys, with relatively continuous sedimentary sequences and abundant marine fossils. This study concentrates on analysis of foraminiferal succession of the Visean/Serpukhovian boundary interval in South China, and establishment of a refined Mississippian zonal scheme of foraminifers from South China.

Samples were collected from six sections located at different depositional subprovinces and in different environment. Five interval zones are identified from the Tournaisian to Serpukhovian at the Malanbian section. Four interval zones are identified from the Serpukhovian Stage at the Fenghuangshan section. Two, one, one, four interval zones are respectively identified from the Visean to Serpukhovian at the Naqing, Narao, Luokun, and Dianzishang sections.

The appearances of Plectomillerella tortula, Janischewskina delicate, Asteroarchaediscus postrugosus, and Eolasiodiscus donbassicus are valuable auxiliary indices to the base of the Serpukhovian which is defined by the FAD of L. ziegleri. Four index species could be all found in South China. At the GSSP candidate section-the Naqing section, Janischewskina delicata occurred nearly above the FAD of L. ziegleri.

A refined Mississippian zonal scheme of foraminifers from South China is preliminarily established. New zones named for cosmopolitan species allow better international correlations, and show the evolution of important groups such as the Archaediscacean foraminifers. There are 12 foraminiferal zones in ascending order: (1) Plectogyra komi - Granuliferella complanata Zone; (2) Dainella gumbeica Zone; (3) Eoparastaffella ex gr. ovalis Zone; (4) Eoparastaffella ex gr. simplex Zone; (5) Viseidiscus monstratus Zone; (6) Paraarchaediscus koktjubensis Zone; (7) Archaediscus krestovnikovi Zone; (8) Asteroarchaediscus baschkiricus Zone; (9) Janischewskina delicata / Plectomillerella tortula Zone; (10) Eostaffellina paraprotvae Zone; (11) Bradyina cribrostomata Zone; (12) Monotaxinoides transitorius Zone.