Article
Geosciences, Multidisciplinary
Yongjie Hu, Chunfang Cai, Peng Sun, Hong Zhang, Zixuan Liu, Ying Li, Qiang Wang, Youjun Tang, Adrian Immenhauser
Summary: By analyzing samples from two regions in southern China, the deposition and alteration history of cap carbonates, as well as the formation process of fibrous dolomite cement, were revealed. These data are significant for studying the paleoenvironment and dolomitization process of Marinoan cap dolostones.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geochemistry & Geophysics
Chunfang Cai, Dawei Liu, Yongjie Hu, Taiyu Huang, Ziwen Jiang, Chenlu Xu
Summary: The strongly 13C-depleted calcite in the Doushantuo cap dolostones (-635 Ma) of South China is formed via thermochemical or biological oxidation of methane by sulfate. The coeval seawater sulfate levels were low (-1 to 3 mM), initially consumed by sulfate reducing microorganisms. Mn-driven anaerobic oxidation of methane (AOM) by sulfate occurred in pore water to produce H2S, which was then oxidized by Mn oxides back to sulfate. This previously unrecognized biogeochemical cycling serves as the mechanism for major methane sink during the Proterozoic and Archean with low sulfate concentrations in the oceans.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2023)
Article
Geosciences, Multidisciplinary
Mingzhong Zhou, Bin Wan, Li Zhou, Enlin Yang, Liansheng Yang, Taiyi Luo
Summary: This study on the K-bentonites in the Doushantuo cap dolostones on the Yangtze Platform in South China reveals the different nature of the primary magmas and trace element contents in volcanic zircons of K-bentonites from different sections, suggesting source volcanoes possibly located in the extensional setting on the northern margin of the Yangtze Block. The findings from this systematic geochemical analysis provide insights into the origin and tectonic settings of the source volcanoes of the studied K-bentonites.
PRECAMBRIAN RESEARCH
(2021)
Article
Geosciences, Multidisciplinary
Freya K. Morris, John P. Grotzinger
Summary: This field study investigates the termination of the Marinoan Snowball Earth glaciation by characterizing the basal-Ediacaran cap carbonate succession in the Naukluft Mountains of Namibia. Sedimentologic and stratigraphic field observations, supplemented by chemostratigraphic analyses, reveal the stratigraphic stacking patterns and facies changes during this climate transition. The study suggests a retreat of the shoreline and multiple base-level fluctuations in the depositional patterns of the Tsabisis Formation cap carbonate.
PRECAMBRIAN RESEARCH
(2023)
Article
Geology
Xiaoshuai Chen, Hongwei Kuang, Yongqing Liu, Daniel Paul Le Heron, Yuchong Wang, Huaqing Bai, Nan Peng
Summary: This study focuses on barite-bearing cap dolostones in northern Three Gorges, South China, providing insights into their sedimentary characteristics, depositional environment, and formation mechanisms. The cap dolostone was predominantly formed in a shallow-water ramp environment, with barites showing a primary (syngenetic) origin linked to ongoing glacier melting and water density stratification.
Article
Geosciences, Multidisciplinary
Renan F. dos Santos, Afonso C. R. Nogueira, Juliane B. da Costa, Leandro F. Sepeda, Juliana Okubo, Isabele S. Barros, Argel A. N. Sodre, Pedro G. A. Oliveira, Ivan A. R. Barrera, Pierre Sansjofre
Summary: The post-snowball Earth world is favorable for the development of hydrocarbon source rocks and potential petroleum exploration. In the Southern Amazon Craton, there is a remarkable example of post-Marinoan rocks which act as unconventional petroleum reservoirs. This study aims to understand the paragenesis sequence and control factors of these reservoir rocks dominated by microbialites. The findings enhance our knowledge of syndepositional diagenesis in microbial-induced reservoirs and provide a guide for future petroleum exploration.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Ruiyang Sun, Jun Shen, Stephen E. Grasby, Jiawei Zhang, Jianshu Chen, Chuang Yang, Runsheng Yin
Summary: The specific causes of ocean/climate changes that led to Marinoan deglaciation and the genesis of Ediacaran cap carbonates are still unknown. This study examines the Hg records in Ediacaran cap carbonates from South China and suggests that background volcanic activity, rather than a short-term large igneous province event, drove Marinoan deglaciation. The study also reveals a binary mixing of seawater- and terrestrial-derived Hg in early Ediacaran Ocean, which could be due to ongoing volcanic emissions of CO2 and global warming. These findings are important for understanding climate changes in Earth's history.
PRECAMBRIAN RESEARCH
(2022)
Article
Geology
J. Javier Alvaro, Kjell Billstrom, Christiand Hallmann, Yosuke Hoshino, Alberto Jorge
Summary: The study focuses on the carbonates in the Kaarta Mountains of Mali and their formation under episodic non-oxidising conditions. The presence of methane oxidation by microbes and the input of barium-rich fluids were observed, challenging previous understanding of carbonates formation. This research provides valuable insights into the variability and distribution of methane seeps and microbial activity in the aftermath of glaciation.
SEDIMENTARY GEOLOGY
(2023)
Review
Geosciences, Multidisciplinary
Meng Ning, Fan Yang, Haoran Ma, Xianguo Lang, Bing Shen
Summary: The rapid diversification of eukaryotes after the Marinoan Snowball Earth glaciation suggests a possible link between the extreme icehouse climate and biological evolution. The delayed cap carbonate precipitation post melting of the Marinoan Snowball Earth glaciation indicates suboxic postglacial seawater enriched in Mn2+. Likely due to continuous hydrothermal Mn2+ flux for about 15 million years, the postglacial ocean was enriched in Mn, with potential remobilization of MnO2 from glacial sediments.
EARTH-SCIENCE REVIEWS
(2021)
Article
Geography, Physical
Lichao Wang, Guang Hu, Dongfang Zhao, Xiucheng Tan, Hongyuan Wang
Summary: The study investigated dolomitic microbialites in the late Ediacaran of the Upper Yangtze Platform in China, revealing unique microbial structures and the composition of dolomite cements. By studying different features, it is inferred that these microbialites were deposited in a subtidal to intertidal setting.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2022)
Article
Geography, Physical
Wenchao Yu, Thomas J. Algeo, Qi Zhou, Wei Wei, Mingyu Yang, Fei Li, Yuansheng Du, Wen Pan, Ping Wang
Summary: By analyzing three sites in the Nanhua Basin of China, we have revealed the mechanisms of cap carbonate formation under different environmental conditions, providing insights into Sturtian and Marinoan cap carbonate deposits on other cratons.
GLOBAL AND PLANETARY CHANGE
(2022)
Article
Geochemistry & Geophysics
Jiuyuan Wang, Andrew D. Jacobson, Bradley B. Sageman, Matthew T. Hurtgen
Summary: Several studies have used stable calcium and strontium isotopes in marine carbonate rocks to investigate ancient carbon cycle dynamics and seawater geochemistry. However, these proxies have rarely been used together. The δ44/40Ca- δ88/86Sr multi-proxy can distinguish between different processes affecting the isotope compositions and provides additional constraints on mixing. This multi-proxy was applied to two Marinoan cap carbonate sequences from Namibia, revealing primary environmental signals deriving from seawater-glacial meltwater mixing and kinetic isotope effects.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2023)
Article
Geography, Physical
Ruimin Wang, Chaochao Xing, Bin Wen, Xubin Wang, Kunwei Liu, Tianzheng Huang, Chuanming Zhou, Bing Shen
Summary: Cap carbonate is a unique component of a Snowball Earth glaciation, but its occurrence in Ediacaran glacial successions challenges the traditional model of cap carbonate precipitation. The Ediacaran glacial cap carbonate differs from the Snowball Earth cap carbonate in various aspects. The enigmatic cap carbonate precipitation after the Ediacaran glaciations implies a unique climatic condition different from both Snowball Earth glaciation and Phanerozoic ice age.
GLOBAL AND PLANETARY CHANGE
(2023)
Article
Geosciences, Multidisciplinary
Tian Gan, Guanghong Zhou, Taiyi Luo, Ke Pang, Mingzhong Zhou, Weijun Luo, Shijie Wang, Shuhai Xiao
Summary: This study reports the widespread distribution of miniature paleo-speleothems from the Doushantuo cap dolostone in South China, approximately 635 million years ago, providing insights into the rapid recovery of terrestrial life after the Cryogenian snowball Earth glaciations.
PRECAMBRIAN RESEARCH
(2022)
Article
Geosciences, Multidisciplinary
Hongwei Kuang, Yongqing Liu, Nan Peng, Thomas M. Vandyk, Daniel Paul Le Heron, Zhicai Zhu, Huaqing Bai, Yuchong Wang, Zhixian Wang, Quan Zhong, Jinxin Chen, Huiliang Yu, Xiaoshuai Chen, Changgui Song, Kening Qi
Summary: The cap dolomites in Shennongjia exhibit unique sedimentary features, suggesting deposition in restricted shallow-water tidal environments. The variations in thickness and distribution of the cap dolomites can be explained by a sedimentary facies model for a ramp environment.
PRECAMBRIAN RESEARCH
(2022)
