Middle Triassic Radiolaria from turbidites in Ziyun, Guizhou, South China

摘要

In the lower part of the widespread Middle Triassic turbidite succession in southern Guizhou and northern Guangxi (South China), a bed of radiolarian-bearing muddy chert intercalated with the dominant mudstone and thin-layered sandstone suite has yielded a Triassocampe deweveri-Pseudostylosphaera compacta radiolarian assemblage at Ziyun, Guizhou. Twelve genera and twenty-five species of Nassellaria and seven genera and ten species of Spumellaria are recognized in this radiolarian assemblage, two species of which are new. This radiolarian assemblage can be compared with the Triassocampe deweveri assemblage, the Pseudostylosphaera compacta and Emiluvia (?) cochleata assemblage, and the Eptingium manfredi(?) assemblage of Japan. This discovery confirms the assignment of the turbidite succession to the Anisian-Ladinian, and also indicates that an open, deep-sea environment was present during the Middle Triassic in South China.