I’m pleased to announce the online publication of a new paper from a Chinese-American geological team (Zhang et al., 2022). I’m the sole American! My role was minor, being mostly useful for literature review and writing. The senior author is my friend Yong-Li Zhang from Northeastern University, Shenyang. He was my host on my adventurous (and painful) trip to China in 2014. We’ve been colleagues ever since and have authored additional papers together.
This paper is a description of well-preserved stromatolites (sedimentary structures formed by microbial mats in supratidal and intertidal environments) in the Ganjingzi Formation (southern Liaoning Province), which was deposited about 930 Ma during the Tonian Period of the early Neoproterozoic Era. The Neoproterozoic is a fascinating time interval spanning the transition from single-celled to multicellular life. The lower stromatolite mounds formed in a transgression, while the stromatolite columns in the more complex upper biostrome changed vertically from dispersed to clumped growth. Biostratigraphic analysis shows that the stromatolites in the Ganjingzi Formation are similar to those from coeval strata in the Xuzhou-Huainan Region and in southern Jilin. Comparisons of the morphotype genera of stromatolites and the sedimentary setting between different areas imply that sea-level was fluctuating in the east of the North China Craton (NCC) during the Ganjingzi interval and that the transgressions were beneficial to stromatolite growth, as indicated by the increased number of stromatolites in the study area. Ultimately this work adds another piece to the puzzle of Neoproterozoic environments and life in northeastern China.
The image at the top of this post is figure 7 from the paper: Morphological characteristics in the lower stromatolite mound of the Ganjingzi Formation and stromatolites at three stages: I = supratidal; II = shallow intertidal; III = medium intertidal.
Fig. 1. Geology of the study area. (A) Paleogeographic location of the North China Craton in the early Neoproterozoic about 900 Ma (after Li et al., 2008). (B) Location of the study area in NCC. (C) Geological map showing the location of the measured section from a (121°36′22.96″E, 39°29′33.43″N) to b (121°36′54.37″E, 39°29′14.15″N). (D) Satellite view of stromatolite distribution and the measured section on Google Earth. [History-minded readers will note this site is near Port Arthur of the Russo-Japanese War.]
Stratigraphic column for this study (Fig. 2).
Distribution of stromatolite morphotypes in the Ganjingzi Formation and the water depths (Fig. 11).
Reference:
Li, Z.X., Bogdanova, S., Collins, A.S., Davidson, A., De Waele, B., Ernst, R.E., Fitzsimons, I.C.W., Fuck [his real name!], R.A., Gladkochub, D.P., Jacobs, J. and Karlstrom, K.E. 2008. Assembly, configuration, and break-up history of Rodinia: a synthesis. Precambrian Research 160: 179-210.
Zhang, Y-L., Lai, G-M, Gong, E-P., Wilson, M.A., Huang, W-T., Guan, C-Q. and Yuan, D-C. 2022. Early Neoproterozoic well-preserved stromatolites from south Liaoning Province, North China: characteristics and paleogeographic implications. Palaeoworld (in press as a pre-proof pdf).
Mark, I’d like to know how the stromatolites were dated (along with the accompanying rocks). Is there good biostratigraphy from Precambrian microfossils? I am quite familiar with some older stromatolitic dolomites in the UP of MI (e.g., the Kona Dolomite, a massive carbonate unit), but like many of the Proterozoic sediments and metasediments, there is little information available to constrain their ages. Even some of the sandstones, from the UP (e.g., the Jacobsville), which are mapped as “basal Cambrian,” have been acknowledged to have age error estimates in the hundreds of millions of years (often, the only thing constraining their age is an unconformable contact with Archaean basement, or whimsical supposition, since some are fossil-free)!!! What does this do to paleogeographic analysis of these areas?
I know practically zippo about East Asian geology, but perhaps you could fill us in? I am very curious, and have never investigated the work that supports the stratigraphy in some of these very old rocks, and the structural complexity of some of these areas make the analysis even more difficult (e.g., the Kona often has massive shear zone contacts with older rocks). Can researchers really delineate the biostratigraphy of stromatolites, microscopically, especially those that are that old?
Hello Bill. Good questions. The paper we relied upon for the stratigraphy of these Tonian rocks is: Pang, K., Tang, Q., Wan, B., Li, G.J., Chen, L., Yuan, X.L., Zhou, C.M., 2021. Integrated Meso-Neoproterozoic stratigraphy in the Jiao-Liao-Xu-Huai area of North China Craton: A review. Journal of Stratigraphy 45, 467–492 (in Chinese, with English abstract). From the abstract: “In recent years, more and more lithostratigraphic, biostratigraphic, chemostratigraphic, and especially radiometric geochronological data show that the Huainan and Feishui groups in the Huainan area, the Huaibei Group in the Huaibei area, the Tumen Group in the Luxi area, the Penglai Group in the Jiaodong area, the Yongning Formation and the Xihe, Wuhangshan, and Jinxian groups in the Liaonan area, as well as the Baifangzi Formation and the Xihe and Hunjiang groups in the Jinan area are of late Mesoproterozoic to early Neoproterozoic (Tonian) in age.”
This paper has English figure captions and shows remarkably detailed strat columns with lots and lots of data as noted above. Radiometric data is most important, but the abundance and diversity of microfossils is astounding.
I’m going to attach a massive link to the paper on ResearchGate. The link may not work so you may need to simply google the title to find it.
https://www.researchgate.net/profile/Ke-Pang-pangke-2/publication/356732501_Integrated_Meso-Neoproterozoic_stratigraphy_in_the_Jiao-Liao-Xu-Huai_area_of_North_China_Craton_A_review_Journal_of_Stratigraphy/links/61addaffaade5b1bf50b462c/Integrated-Meso-Neoproterozoic-stratigraphy-in-the-Jiao-Liao-Xu-Huai-area-of-North-China-Craton-A-review-Journal-of-Stratigraphy.pdf?_sg%5B0%5D=UKoXf4kg96to2tQYXAt-omeaooFfu8vPFdwPp8GYDLnjvK5Z5OgGyEVf2J8QlkXO38fkcxZu5M8NWXoWQ3acgA.Vsw392Quq9CRULbp9UAOsUe5Sg3WFbODvkcQ9Vndm-ipd5FxSJIdhvnMDfDwL92gkG08Y3EuAg89S4BalACBKg&_sg%5B1%5D=l2zEU_69HUkY6BXXEfWaagE4tn-EOdpstVWcdeWjC_tm3KkibY87e_1P6BfIEHwvLmFm8KNvPZh0zXLTsAj75TT60X5WB180Xq2Z64v4ipdN.Vsw392Quq9CRULbp9UAOsUe5Sg3WFbODvkcQ9Vndm-ipd5FxSJIdhvnMDfDwL92gkG08Y3EuAg89S4BalACBKg&_iepl=