Recognition of geological age for acanthomorphic acritarchs from the Ruyang Group,southern margin of North China Craton and its implication for evolution of early eukaryotes
Peng Nan;Kuang Hong-Wei;Liu Yong-Qing;Geng Yuan-Sheng;Xia Xiao-Xu;Wang Yu-Chong;Chen Xiao-Shuai;Zheng Hang-Hai;Key Laboratory of Stratigraphy and Paleontology,Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences;China University of Geosciences (Beijing);
The geological age of eukaryotes represented by large acanthomorphic acritarchs from the Ruyang Group,southern margin of North China Craton,has been controversial. New zircon SHRIMP UPb age of tuff( ca. 1639±13 Ma) was obtained from the Luoyukou Formation of the Luoyu Group,Yangpo,Ruzhou,west Henan Province. This new age,combined with the ages from the Xiong'er and Ruyang Group,can well constraint the time of these eukaryotes with complex morphology from the Ruyang Group at 1. 75-1. 64 Ga,which belongs to early Mesoproterozoic. Moreover,it shows that some eukaryotes with relatively higher degree of evolution,which were previously thought to be preserved in the Neoproterozoic,may have appeared in the Early Mesoproterozoic. We further suspect that there might be more primitive microfossils preserved in the older strata( 1. 6 Ga) in the southern margin of the North China Craton,which provides an important window to explore the ancestor of the eukaryote. Thus,caution should be taken when applying these Mesoproterozoic eukaryotes for stratigraphic correlation.