Journal of Paleontology, 91(3), 2017, p. 369–392 Copyright © 2017, The Paleontological Society 0022-3360/15/0088-0906 doi: 10.1017/jpa.2016.163 Silicified microbiota from the Paleoproterozoic Dahongyu Formation, Tianjin, China Min Shi,1 Qing-Lai Feng,1 Maliha Zareen Khan,1 Stanley Awramik,2 and Shi-Xing Zhu3 1State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, 430074, China 〈
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[email protected]〉 2Department of Earth Sciences, Preston Cloud Research Laboratory, University of California, Santa Barbara, CA 93106, United States 〈
[email protected]〉 3State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China 〈
[email protected]〉 Abstract.—Cherts and silicified dolostones of the ca. 1600 Ma Dahongyu Formation (uppermost Changcheng Group) from North China contain well-preserved microfossils. Cyanobacteria filaments and coccoids dominate the studied Dahongyu microbiota in the Jixian section. These microfossils show the characteristics of endobenthic, epibenthic, and allochthonous microfossils, which illustrated well a vertical distributional view of an intertidal microbiota. Large num- bers and size of allochthonous microfossils are the distinguishing characteristics of this new microbiota. A few of these possess ornaments or odd morphology, which suggest their potential eukaryotic nature. Through regional comparisons, it is revealed that there was significant regional disparity within the Yanshan Basin of microbiotas during deposition of the Dahongyu Formation. The newly studied Dahongyu microbiota is similar to the microbiota from the underlying Changcheng Group, with only slight differences. The absence of typical eukaryotes and the emergence of unique micro- fossils (especially small fusiform microfossils) make the Dahongyu Formation and the subsequent strata of the Jixian Group distinct from contemporaneous eukaryote-bearing strata.