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A radical reinterpretation of the growth and form of the stromatolite Conophyton lituus(Maslov)from evidence of syngenetic biofilm mineralisation

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Journal of Palaeogeography 2022年第1期11卷 69-84页

作者： Robert V.Burne Research School of Earth Sciences The Australian National University CanberraACT 0200Australia School of Earth and Environmental Sciences The University of QueenslandBrisbaneQLD 4072Australia

Conophyton(Maslov)is a cylindroidal stromatolite form-genus characterized by nested conical ***-preserved Conophyton,up to 4 m tall and with basal diameters of up to 50 cm,are exposed in the Proterozoic Atar Formation of Mauritania,where many occur together,in growth position,as fields of individual columns spaced between 5 and 70 cm *** uniformity of these forms and their regular distribution suggest that they grew in quiet-water environments below wave *** for their penecontemporaneous organomineralization is indicated by nearby toppled examples of undeformed Conophyton forms alongside eroded lithified Conophyton fragments in carbonate *** characteristics of Conophyton have been used to classify the structures-the form of the lamination and the nature of its axial structure.A mathematical/physical model provides an explanation for the growth pattern of *** predicts that coniform structures with thickened axial zones form when upward organic growth of a biofilm moderately exceeds the rate of its *** varying characteristics of these features between different forms of Conophyton are thought to reflect biomineralization of the decaying biofilm rather than differences in the composition of microbial communities.A modern example of a syngenetic mineralization process capable of producing similar structures has been observed in the contemporary sediments of Lake Preston,Western Australia,where benthic microbial mats are being transformed into coniform lithified *** initial biomineralization of the coniform mat forms magnesium silicate that first coats and permineralizes web-like microbial extracellular polymeric substances(EPS)and then coalesces into a uniform mass that provides mechanical strength to the *** a later stage,massive carbonate crystal growth occurs that over-prints much of this texture,leaving only small,remnant areas of the magnesium silicate *** fossil Conophyton are composed o

关键词： Conophyton Morphogenesis Proterozoic stromatolite Microbialite Mineralisation Biofilm Lake Clifton Lake Preston Maslov

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stromatolite characteristics of Mesoproterozoic Shennongjia Group in the northern margin of Yangtze Block, China

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China Geology 2019年第3期2卷 364-381页

作者： Hong-wei Kuang Zheng-xiu Fan Yong-qing Liu Nan Peng Zhi-cai Zhu Zhen-rui Yang Zhi-xian Wang Hui-liang Yu Quan Zhong Institute of Geology Chinese Academy of Geological SciencesBeijing100037China College of Resources and Environment Yangtze UniversityWuhan430100China Administration of Shennongjia National Park ShengnongjiaHubei442421China

Mesoproterozoic Shennongjia Group in Shennongjia Area can be divided into three subgroups in ascender order. Of which the lower subgroup includes Yingwodong, Dayanping, Macaoyuan, Luanshigou, Dawokeng and Kuangshishan formations;the middle subgroup is formed by Yemahe, Wenshuihe and Shicaohe formations;the upper subgroup consists of Songziyuan and Wagangxi formations. stromatolites developed very well in the carbonate rocks of each subgroup in Shennongjia Group. Based on descriptions of stromatolites macrotypes and their characteristics, this paper studied the formation environments, discussed the relationship among types, sizes, abundance of stromatolites and sedimentary environment, and established the formation and development pattern of stromatolites. As a result, this research also reveals the paleoenvironment and paleoclimate during the period of the Shennongjia Group deposited, which is beneficial to the study of paleoenvironment, paleogeography and paleoclimate, stratigraphic succession and regional correlation of the northern edge of Yangtze block. stromatolites of Shennongjia Group are mainly conical, columnar, domal, wavy, stratiform and stromatolite reefs. The columnar and conical stromatolites are well developed. Conical stromatolites are mainly monomers, with a variety of pyramidal types, ranging in diameter from a few millimeters to several meters and formed in the high energy subtidal zone and tidal lagoon environment. Most of the columnar stromatolites are medium to small sizes implied a wide and gentle slope environment at that time. Stratiform (including wavy) stromatolites are larger scales and extends far away and distributed most widely in almost every horizon in the carbonate rocks. Stratiform stromatolites can be formed in low energy environments such as subtidal and intertidal zones and supratidal belts. Wavy stromatolites often developed in the hydrodynamic energy condition from weak energy intertidal zone gradually strengthened to the belo

关键词： stromatolite Mesoproterozoic Shennongjia Group Shennongjia Area Northern Margin of Yangtze Craton Geological survey engineering China

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Discovery of the Jiawengmen stromatolite Assemblage in the Southern Belt of Eastern Kunlun, NW China and Its Significance

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Acta Geologica Sinica(English Edition) 2005年第4期79卷 471-480页

作者： BIAN Qiantao ZHU Shixing I. I. POSPELOV M. A. SEMIKHATOV SUN Shufen CHEN Daizhao NA Chunguang Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Tianjin Institute of Geology and Mineral Resources China Geological Survey Tianjin 300170 China Geological Institute Russian Academy of Sciences Moscow 119017 Russia

This paper reports a newly discovered Late Mesoproterozoic-Early Neoproterozoic stromatolite assemblage, named here the ＂Jiawengmen stromatolite assemblage＂, represented by a Conophyton-Baicalia association in the Jiawenmen area in the southern belt of the Eastern Kunlun. This stromatolite assemblage is dominated by large-scale conical stromatolites and related elements, i.e., Conophyton garganicus var. inkeni, C. cf. ressoti Menchikov, Jacutophyton cf., Conicodomenia f., which commonly co-exist with elements of the group of Baicalia. This assemblage can be correlated with that of the middle Jixian-middle Qingbaikou System in North and Northwest China, but is different from that in South China. Correlation can also be made with that in the upper horizon of the Middle Riphean-lower horizon of the Upper Riphean in the South Ural Mountains and Siberia of Russia, in North Africa, and in the Alaskan Peninsula of North America. These facts suggest that the Jiawengmen stromatolite assemblage probably colonized during 1300-850 Ma ago. Accordingly, the stromatolite-bearing carbonate rocks are then proposed to correspond to the middle Jixian System-middle Qingbaikou System or the upper Middle Riphean-lower Upper Riphean. Our stromatolite data further suggest that a Precambrian microblock, named the Xialawen microblock here, occurred in the southern belt of Eastern Kunlun, the western part of the Maqên microblock. Similar stromatolite assemblages in the Maqên microblock and those blocks that occurred in North China, Siberia and North Africa point to similar paleogeographic and paleoenvironmental conditions. These microblock and blocks were probably located at low latitudes and on the continental margins of the Rodinian supercontinent, where warm epicontinental seas were favorable to widespread colonization of stromatolites during the Late Mesoproterozoic-Eady Neoproterozoic. However, these stromatolite assemblages are quite different from those of the South China block, which

关键词： stromatolite Precambrian Rodinia supercontinent Eastern Kunlun Tibetan Plateau

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Proterozoic to Phanerozoic case studies of laser ablation microanalysis for microbial carbonate U–Pb geochronology

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Geoscience Frontiers 2024年第2期15卷 30-40页

作者： Yuxiang Jiang Simon V.Hohl Xiangtong Huang Shouye Yang State Key Laboratory of Marine Geology School of Ocean and Earth SciencesTongji UniversityShanghai 200092China

Some of the earliest bio-sedimentary records of life on Earth are represented by microbial carbonates,which are also critical geochemical archives of ancient seawater chemistry and the environmental circumstances in which they *** paleo-microbial environments on Earth and potentially other planets requires precise determination of the depositional ages of these ***(abiogenic)carbonate geochemistry communities can now use developments in in-situ laser ablation U-Pb dating using inductively coupled plasma mass spectrometry(LA-ICP-MS).Due to the effects of impurity mixing and diagenesis,microbial carbonates have received little geochronological study despite their broad relevance for understanding ancient seawater’s environmental conditions and geochemical *** study demonstrates using time-of-flight mass spectrometry(TOF-MS)to perform quick,quantitative elemental mapping before U-Pb spot dating to improve experiment success rates and data reliability and offers four practical application examples.

关键词： stromatolite Microbial carbonate Carbonate geochronology In-situ LA-ICP-MS ICP-Time Of Flight-MS Trace element mapping

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stromatolites Discovered in Nihewan Formation and Their Paleoenvironment

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Science China Chemistry 1994年第5期37卷 634-640页

作者：夏正楷张昀杨德军陈铁梅杨全胡艳秋 Department of Geography Peking University Beijing 100871 PRC Department of Geology Peking University Beijing 100871 PRC Chronological Laboratory Peking University Beijing 100871 PRC

Columnar stromatolites have been discovered in two beds of the upper part of the Nihewan Formation, a series of lacustrine deposits. The structure of the stromatolites is characterized by alternation of light, intergranular pore-rich laminae and dark, organic substance-rich laminae. Abundant filamentous algal remains have been discovered in stromatolite laminae, some of them are similar to the species present on the shore of the Caribbean Sea that are living in warmer climate than in the Nihewan area now. With the ESR and U-series age methods, it has been determined that the ages of the lower and upper stromatolite beds are about 130,000 and 93,000 a B. P. , respectively. Compared with many other geologic events taking place during the period in Northern China, we conclude that the two stromatolite beds were formed during the two warmer stages of the Last Interglacial.

关键词： Nihewan Fm. stromatolite filamentous algal.

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Rare earth element signatures of Paleoproterozoic Sallopat phosphorites of Aravalli Basin,India:implications for diagenetic effects and depositional environment

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Acta Geochimica 2023年第4期42卷 726-738页

作者： Samsuddin Khan Shamim A.Dar K.F.Khan Mohd Shuaib Department of Geology Aligarh Muslim UniversityAligarhUttar Pradesh 202002India Department of Geology Centre of Advanced StudyInstitute of ScienceBanaras Hindu UniversityVaranasi 221005India

As a repository of REE,the Paleoproterozoic phosphorite of the Aravalli Basin in India is explored time to *** phosphorite deposits of the Sallopat sub-basin Banswara district of the Aravalli Supergroup show moderate REE concentrations much lower than that of average marine *** ratios and PAAS-normalized REE distribution patterns reflect MREE enrichment over LREE and HREE in these *** enrichment confirmed by(Sm/Yb)Nversus(Sm/Pr)Nrelationship and attributed to the selective uptake by cyanobacteria and mixing of riverine inputs.Y/Ho,La/Ce and Er/Nd ratios confirm that the REE in Sallopat phosphorites might have been affected by the argillaceous terrigenous and plagioclase-rich sediments probably derived from Banded Gneissic *** modeling indicates that REE were concentrated during early diagenetic processes with limited weathering *** negative to low Ce anomaly depicts oxic to sub-oxic conditions of seawater due to oxidation of Ce^(3+)to Ce^(4+)whereas Eu^(3+)reduced to Eu^(2+)indicating positive Euanomaly and reducing conditions as well during the *** anomalies may be due to the stratified restricted marine environment of upwelling and mingling of organic-rich anoxic deep water with oxic upper seawater prior to the formation of phosphorite deposits in the *** of REE in Sallopat phosphorite relies on various physico-chemical *** phosphorites may have been formed in restricted marine water which was influenced by extra clastic sediment input carried out by fluvial systems.

关键词： stromatolite Lower Aravalli Group Apatite-(CaF) Alkaline environment Diagenesis

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Study on the Main Controlling Factors of the Early Ordovician stromatolites Development in Liujiachang Area of Songzi City

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Open Journal of Yangtze Oil and Gas 2019年第3期4卷 157-173页

作者： Lanjun Wu Chuantao Xiao Zhongzhen Cheng Yichen Bao Li Huang Kanglin Chen School of Geosciences Yangtze UniversityWuhanChina

The Early Ordovician stromatolites in the study area are mainly exposed at the bottom and middle and lower parts of the Second Member of Nanjinguan Formation,the top of the Fourth Member of Nanjinguan Formation,the middle of the Second Member of Fenxiang Formation and the bottom of the First Member of Honghuayuan *** order to find out the controlling factors of Lower Ordovician stromatolites development in the study area,the analysis data of carbon,oxygen isotope samples,macro element samples as well as their variation characteristics are studied and then combined them with previous research results,which is eventually beneficial for reaching the conclusion:sea level change is one of the main factors controlling the formation of *** are five sea level change cycles in the Early Ordovician *** analysis of sea level change and accommodation space variation characteristics show that when the growth rate of the accommodation space is approximately equal to that of carbonate,the circulation of seawater is well,and the amount of light and oxygen is sufficient,so that the cyanobacteria organism can be multiplied in large *** growth and development provide favorable conditions,and favorable conditions are provided for the growth and development of stromatolites;The peak changes in CaO content and CaO/MgO ratio indicate that the formation period of stromatolites is arid climate environment with high water temperature and large *** reproduction is suitable for the environments with high seawater *** the amount of land-based debris injected into the sea increases,the turbidity of water will lead to a large number of deaths of algae microorganisms that form stromatolites,and the stromatolitic microbial mats cannot be *** addition,the growth and predation of macro-organisms play a restrictive role in the development of stromatolite-forming micro-organisms blue-green *** to the actual

关键词： stromatolite Main Controlling Factor Formation The Early Ordovician

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Microfabric features of microbial carbonates:experimental and natural evidence of mold holes and crusts

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Journal of Palaeogeography 2021年第3期10卷 321-333页

作者： Ya-Sheng Wu Hong-Xia Jiang Ying Li Gong-Liang Yu Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Institute of Paleontology Hebei GEO UniversityShijiazhuang 050031Hebei ProvinceChina Institute of Hydrobiology Chinese Academy of SciencesWuhan 430072Hubei ProvinceChina

Results of our study based on examination of induced precipitation of carbonate by a cyanobacterium, Lyngbya in the laboratory, and the analyses of microphotographs of both modern and ancient microbial carbonates,demonstrated the importance of recognition of mold holes and carbonate crusts in understanding microbial carbonates. In the experiment, only cyanobacteria Lyngbya can induce precipitation of carbonate, forming scattered grains on the surface of Lyngbya filaments. Carbonate crusts enclosing the old parts of the filaments were formed through aggregation of these scatter grains while mold holes were formed after decay of the filaments. Mainly based on the experiment, six different ways of microbial carbonate formation were recognized:(1) trapping without mold holes,(2) trapping with mold holes,(3) particle-forming induced-precipitation of carbonate,(4) discrete crustforming induced-precipitation of carbonate,(5) induced precipitation, forming tangled crusts that build a porous construction, and(6) induced precipitation, forming a dense construction. And mold holes and crusts can form in ways(4),(5), and(6). Examination of both modern microbial carbonates from the Shark Bay of Australia, Highborne Cay of Bahamas and the atoll of Kiritimati and the microbialites from the Cambrian dolostone sequence in Tarim,Xinjiang, China all demonstrated the limitation of recognizing only mesofabric features and importance of examining microfabric features for understanding of the genesis of the microbial carbonates and their proper classification. The shape, size and arrangement of the mold holes, crusts, and the features of the minerals filling in pores between the crusts, which are referred as the microfabric features here, are keys to better understand the formation and environments of both modern and ancient microbial carbonates.

关键词： Thrombolite stromatolite Induced calcification Trapping Laminite Proclot

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Oxygenation in carbonate microbialites and associated facies after the end-Permian mass extinction:Problems and potential solutions

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Journal of Palaeogeography 2018年第1期7卷 32-47页

作者： Stephen Kershaw Hao Tang Yue Li Li Guo Department of Life Sciences Kingston Lane Brunel University State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University CAS Key Laboratory of Economic Stratigraphy and Palaeogeography Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences CASP Department of Earth Sciences University of Cambridge

Carbonate sediments deposited in normally-oxygenated shallow ocean waters of the latest Permian period, immediately prior to the end-Permian mass extinction, contain well-developed diverse shelly faunas. After the extinction of these skeletal metazoans, the sediments commonly comprise microbialites(regarded by most authors as benthic) and associated facies bearing evidence interpreted by many authors to indicate reduced oxygenation of the shallow ocean waters. However, the evidence of oxygenation state is inconsistent and the sequences have gaps, indicated in the following 5 points:1) Shelly fossils occur commonly in post-extinction shallow marine limestones, and likely to have been aerated in contact with the atmosphere. Nevertheless, although the largest mass extinction in Earth history may have caused reduced body size in shelly organisms, such reduction is arguably due to environmental stress of lowered oxygenation. Discriminating between these controls remains a challenge.2) Abundant pyrite framboids in many post-extinction limestones are interpreted by several authors as indicating dysoxic contemporaneous waters, so the organisms that lived there, now shelly fossils, were dysaerobic. However, verification is problematic because pyrite framboids scattered amongst shelly fossils cannot have formed amongst living organisms, which need at least some oxygen; synsedimentary framboid formation requires anoxic conditions in the redox boundary where sulphate-reducing processes work. Thus, framboids and shelly fossils found together means taphonomic mixing of sediments, destroying original depositional relationships so that it is not possible to determine whether the shells were aerobic or dysaerobic prior to sediment mixing. Furthermore, diagenetic growth of framboids is possible, as is import of previously-formed framboids from deeper water during upwelling. Thus, there is no proof of an environmental link between framboid size and occurrence, and contemporaneous oxyg

关键词： stromatolite Thrombolite Microbialite Permian-Triassic boundary Pyrite Anoxia

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The sedimentological characteristics of microbialites of the Cambrian in the vicinity of Beijing,China

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Journal of Palaeogeography 2017年第2期6卷 117-131页

作者： Yin- Ye Wu Tian-Shu Zhang Jia-Lei Lü Yan Liu Department of Petroleum Geology Research Institute of Petroleum Exploration and DevelopmentPetroChinaBeijing 100083China School of Earth Sciences Zhejiang UniversityHangzhou 310027Zhejiang ProvinceChina

With oil and gas exploration transferring to deeper and more ancient marine strata,more researches have been conducted about the Meso—Neoproterozoic and Cambrian microbial carbonate rocks by petroleum *** Cambrian deposits experienced the first transgression of the Paleozoic,with shallow marine facies depositing in most areas,which are favorable for different kinds of biological *** Lower Cambrian in Beijing area is lithologically dominated by purple red shales interbedded with limestones,the Middle Cambrian is mainly composed of thick oolitic limestones,and the Upper Cambrian consists of thin limestones and flat-pebble *** beds of microbial carbonate rocks were discovered in the Cambrian outcrops in the vicinity of *** is from the Zhangxia Formation of Middle Cambrian,and the other is from the Gushan Formation of Upper *** microbialites are characterized by combination of multiple stromatolites forming different *** bioherms are mostly in oval shape and with different sizes,which are 3-4 m long,and 1-3 m *** surrounding strata beneath the bioherms are oolitic limestones.A central core of flat-pebble conglomerates occurred within each *** or columnar stromatolites grow on the basis of flat-pebble conglomerates,with dentate erosional *** bioherm carbonate rocks are interpreted as products from a deep ramp sedimentary environment where potential oil and gas reservoirs can be *** analysis of sedimentological characteristics of bioherm carbonate rocks and its lithofacies palaeogeography has significant implication for petroleum *** on geological record of microbialites is beneficial to investigating the Earth evolution,biodiversity,palaeoenvironment and palaeoclimate change,as well as biological extinction event during geological *** also gives warning to human beings of modern biological crisis.

关键词： Cambrian stromatolite Bioherm Microbialite Oil and gas reservoir Marine sedimentary environment Beijing

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