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tonian Tectonic-Strata Regions and their Geological Significance in China

Acta Geologica Sinica(English Edition) 2020年第4期94卷 914-941页

作者： XU Yadong ZHANG Kexin HE Weihong YU Yang KOU Xiaohu SONG Bowen LUO Mansheng WANG Lijun MA Zhongjie YANG Fengli Hubei Key Laboratory of Critical Zone Evolution School of Earth SciencesChina University of GeosciencesWuhan 430074China Central South China Innovation Center for Geosciences Wuhan Center of the Chinese Geological SurveyWuhan 430074China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China Center of Global Tectonic China University of GeosciencesWuhan 430074China Institute of Geological Survey China University of GeosciencesWuhan 430074China State Key Laboratory of Marine Geology School of Ocean and Earth ScienceTongji UniversityShanghai 200092China

The continent of China developed through the coalescence of three major cratons(North China, Tarim and Yangtze) and continental micro-blocks through the processes of oceanic crust disappearance and acceretionary-collision of continental crusts. The strata of the Chinese continental landmass are subdivided into 12 tectonic-strata regions. Based on the composition of geological features among the three main cratons, continental micro-blocks and other major global cratons, their affinities can be preliminarily deduced during the tonian period, using evidence from sedimentary successions, paleobiogeography, tectonic and magmatic events. The Yangtze and Tarim cratons show that they have close affinities during the assembly-dispersal milestone of the Rodinia Supercontinent. The sedimentary record and magmatic age populations in the blocks suggest that there was a widespread, intensive magmatic event that resulted from a subduction process during ~1000–820 Ma, related to continental rifting around the Yangtze and Tarim cratons. However, they differ greatly from the North China Craton. The continental micro-blocks in the Panthalassic Ocean could have some missing connection with the North China Craton that persisted until the Middle-Late Devonian. In contrast, the Alxa Block showed a strong affinity with the Tarim Craton. The revised tonian paleogeography of the Rodinia Supercontinent is a good demonstration of how to show the relationship between the main cratons and the continental micro-blocks.

关键词： Sedimentary paleogeography tonian craton micro-block

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Magnetic field hyperactivity during the early Neoproterozoic: A paleomagnetic and cyclostratigraphic study of the Katav Formation, southern Urals, Russia

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Geoscience Frontiers 2023年第4期14卷 42-56页

作者： Inessa V.Golovanova Konstantin N.Danukalov Raushaniia Yu.Salmanova Natalia M.Levashova Nikita P.Parfiriev Nina D.Sergeeva Joseph G.Meert Institute of Geology-Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences(IG UFRC RAS) Russia Geological Institute Russian Academy of SciencesMoscowRussia Department of Earth and Planetary Sciences Neil Opdyke Paleomagnetic LaboratoryUniversity of FloridaGainesvilleFL 32611United States

We present a detailed magnetostratigraphic and cyclostratigraphic profile through the Riphean(tonian)Katav Formation in the southern Urals.The study confirms the primary nature of the magnetization in these rocks.The cyclostratigraphic study identified several orbital periods including the 405 ka long eccentricity.This allows us to quantify the reversal frequency in the Katav and our estimates range of 7–12 reversals per million years.Based on our study,we identify an interval of magnetic field reversal hyperactivity in the Neoproterozoic interval.Age estimates for the Katav are contentious and range somewhere between 800 Ma and 900 Ma based on carbonate Pb-Pb ages and stable isotope correlations.The paleomagnetic poles obtained in this study of the Katav(and overlying Inzer)Formation do not fit anywhere on the Baltica apparent polar wander path between 1100 Ma and 900 Ma.Furthermore,they lie 90away from the 900 Ma segment of the path.We tentatively estimate their age to be closer to 800 Ma and perhaps confirm a previously hypothesized pulse of rapid true polar wander between 825 Ma and 790 Ma.

关键词： Magnetostratigraphy Cyclostratigraphy Hyperactive reversal True polar wander tonian

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Nitrogen Isotopes from the Neoproterozoic Liulaobei Formation,North China:Implications for Nitrogen Cycling and Eukaryotic Evolution

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Journal of Earth Science 2022年第5期33卷 1309-1319页

作者： Ting Yang Xinqiang Wang Dongtao Xu Xiaoying Shi Yongbo Peng School of Earth Science and Resources China University of GeosciencesBeijing100083China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing100083China International Center for Isotope Effect Research Nanjing UniversityNanjing210023China School of Earth Sciences and Engineering Nanjing UniversityNanjing210023China

The nitrogen isotope compositions(δ^(15)N )of sedimentary rocks can provide information about the nutrient N cycling and redox conditions that may have played important roles in biological evolution in Earth’s history.Although considerableδ^(15)N data for the Precambrian have been published,there is a large gap during the Early Neoproterozoic that restrains our understanding of the linkages among N cycling,ocean redox changes and biological evolution during this key period.Here,we report bulkδ^(15)N and organic carbon isotope(^(δ)13C_(org))compositions as well as the total nitrogen(TN)and total organic carbon(TOC)contents from the tonian fossiliferous Liulaobei Formation in the southern part of the North China Platform.Theδ^(15)N in the study section is dominated by very stable values centering around+4.3‰,which is moderately lower than that in modern sediments(~+6‰).These positiveδ^(15)N values were attributed to partial denitrification under low primary productivity(scenario 1)and/or denitrification coupled with dissimilatory nitrate reduction to ammonium(DNRA)(scenario 2).In either case,the availability of fixed nitrogen may have provided the nutrient N required to facilitate facilitated eukaryotic growth.Our study highlights the pivotal role of nutrient N in the evolution of eukaryotes.

关键词： Neoproterozoic tonian Liulaobei Formation nitrogen isotopes eukaryotic evolution nutrient limitation geochemistry

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Provenance and tectonic setting transition as recorded in the Neoproterozoic strata, western Jiangnan Orogen:Implications for South China within Rodinia

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Geoscience Frontiers 2019年第5期10卷 1823-1839页

作者： Jiawei Zhang Taiping Ye Yaran Dai Jianshu Chen Hui Zhang Chuangu Dai Guohua Yuan Kaiyuan Jiang Guizhou Geological Survey Bureau of Geology and Mineral Exploration and Development of Guizhou ProvinceGuiyang 550081China Chinese Academy of Land and Resources Economics Beijing 101149China Key Laboratory of Carrying Capacity Assessment for Resources and Environment Ministry of Land and ResourcesBeijing 101149China Guizhou Central Laboratory of Geology and Mineral Resources Bureau of Geology and Mineral Exploration and Development of Guizhou ProvinceGuiyang 550018China

The Neoproterozoic tonian strata (ca.870-725 Ma) in the western Jiangnan Orogen archive the records of sedimentary provenance and tectonic setting which can be used to understand the geological evolution of the South China Continent.These strata are separated into the basement and cover sequences by a regional angular unconformity.The basement sequence can be subdivided into the lower and the upper parts by the widespread interbedded ca.840 Ma basalt with pillow structure.In the present work,234 concordant detrital zircon analyses are obtained from three tonian sandstone samples in the Fanjingshan district,Guizhou Province.Combined with previous results,a total of 1736 analyses of detrital zircon U-Pb ages derived from 12 formations of tonian strata in the western Jiangnan Orogen are used to decipher the integrated sedimentary and tectonic histories.The zircons from the lowermost part of the basement sequence (the Yujiagou Formation) show oval morphology and display two Paleoproterozoic age peaks at 2325 Ma and 1845 Ma which are similar with the detrital zircon age peaks from the Late Paleoproterozoic to Early Mesoproterozoic Dongchuan/Dahongshan/Hekou groups,suggesting a passive margin basin in which the sediments were mainly sourced from the southwestern Yangtze Block.However,the zircon age population of the lower part of the basement sequence (the Xiaojiahe,Huixiangping formations and their equivalents) indicates the sedimentary derivation from bidirectional sources (the ca.870 Ma arc materials in the south and the old detritus from the southwestern Yangtze Block) which is consistent with a back arc setting for the deposition of the sediments.Zircons from the upper part of the basement sequence (the Duyantang Formation and its equivalent) show euhedral and subangular morphology and display a unimodal age peak at ca.835 Ma.This sequence was possibly deposited in a convergent setting and the detritus were came from the locally distributed syn-collisional igneous rocks.The lower part of the cover sequence (the Xi

关键词： Detrital zircon Fanjingshan Sibao Back arc basin Precambrian tonian

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