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Sand veins and MISS from the mesoproterozoic black shale (ca. 1.7 Ga) in North China:Implication for methane degassing from microbial mats

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Science China Earth Sciences 2008年第11期51卷 1525-1536页

作者： SHI XiaoYing JIANG GanQing ZHANG ChuanHeng GAO LinZhi LIU Juan School of Earth Science and Resources China University of GeosciciencesBeijing 100083China State Key Laboratory of Geological Process and Mineral Resources Beijing 100083China Department of Geoscience University of NevadaLas VegasNV 89154-4010USA Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

The mesoproterozoic Chuanlinggou Formation (ca. 1.7 Ga) consists mainly of dark-gray to black shales that are widespread in the North China Platform. Abundant centimeter-scale sand veins are present within the shale layers of this unit, particularly in the middle part. Sand veins display ptygmatic shapes, perpendicular or with a high angle to bedding planes. They penetrate the black shale layers but are often terminated by thin, lenticular sandstone beds, forming small-scale ‘tepee-like’ structures. On bedding planes, sand veins are expressed as small ridges with 1–3 mm positive relief. Lack of polygonal shapes and their occurrence in thinly laminated, relatively deep-water shales preclude an origin from sand-filled desiccation cracks. Instead, their close association with microbially induced sedimentary structures (MISS) such as micro-wrinkles and gas blisters, putative bacterial fossils (possibly coccoidal cyanobacteria) and framboidal pyrites, suggests that they were formed by degassing of methane from microbial mat decay. Methane gas disrupted overlying sedimentary layers, creating fractures open to seawater. Fine-grained quartz sands, which were transported into the depositional environment by strong winds, filled the fractures. Sand-filled fractures were shortened and folded during burial compaction, forming ptygmatic shapes. The presence of dispersed dolomite and siderite in these sand veins suggests authigenic carbonate precipitation from anaerobic oxidation of methane (AOM). Sand veins are intensely distributed within the Chuanlinggou Formation and are spatially widespread in the North China Platform. If their methane origin is confirmed, they may have important implications for the mesoproterozoic paleoclimate. With anoxic oceans and low seawater sulfate concentration during the mesoproterozoic, methane release from microbial mat decay and/or microbial methanogenesis during shallow burial may have been proportionally higher than that of the modern marine e

关键词： sand veins methane degassing microbial mats Chuanlinggou Formation mesoproterozoic North China Platform

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Origin of Molar-Tooth Structure Based on Sequence-Stratigraphic Position and Macroscopic Features: Example from mesoproterozoic Gaoyuzhuang Formation at Jixian Section, Tianjin, North China

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Journal of China University of Geosciences 2006年第3期17卷 201-208,271页

作者：梅冥相 Key Laboratory of Lithospheric Tectonics and Lithoprobing Technology Ministry of Education China University of Geosciences School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China

Both the macroscopic feature and the sequence-stratigraphic position of the molar-tooth structure developed in the third member of the Gaoyuzhuang （高于庄） Formation at the Jixian （蓟县） Section in Tianjin （天津） can provide some useful information about its origin and can reveal some problems to be further researched in the future. The mesoproterozoic Gaoyuzhuang Formation is a set of 1 600 m thick carbonate strata. This formation can be divided into four members. The first member is mainly made up of stromatolitic dolomites; the second is marked by a set of manganese dolomites; the third is mainly composed of lamina limestones with the development of molar-tooth strcutures; the fourth is a set of stromatolitic-lithoherm dolomites. According to lithofacies and its succession, several types of meter-scale cycles can be discerned in the Gaoyuzhuang Formation： the L-M type, the subtidal type and the peritidal type. There is a regularly vertical stacking pattern for meter-scale cycles in the third-order sequence. Therefore, the mesoproterozoic Gaoyuzhuang Formation can be divided into 13 third-order sequences （SQ1 to SQ13 ） and can further be grouped into 4 second-order sequences. The third member is marked by lamina limestones and can be grouped into three third-order sequences （SQ9 to SQ11 ）. The molar-tooth structure is developed in the middle part of the third sequence, i.e. SQH , in the third member. Several features of this kind of molar-tooth structure reflect some features of carbonate sedimentation in the Precambrian, such as the particular configuration, abundant organic matter, and easy silication. Stromatolites are chiefly formed in a shallow tidal-flat environment; lamina are mainly formed in the shallow ramp and molar-tooth structures are mainly generated in a relatively more deep-water environment from the middle to the deep ramp. Therefore, similar to stromatolite and lamina, the molartooth structure might also be a kind of bio-sedimentation structure. This s

关键词： molar-tooth structure sequence stratigraphy Gaoyuzhuang Formation mesoproterozoic Jixian Section in Tianjin.

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Hydrothermal Mineralization on the mesoproterozoic Passive Continental Margins of China: A Case Study of the Langshan-Zha'ertaishan Belt,Inner Mongolia, China

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Acta Geologica Sinica(English Edition) 2004年第2期78卷 534-547页

作者： PENGRunmin ZHAIYusheng KeyLaboratoryofLithosphericTectonicsandLithoprobingTechnology ChinaUniversity

Most ore-forming characteristics of the Langshan-Zha'ertaishan hydrothermal exhalation belt, which consists of the Dongshengmiao, Huogeqi, Tanyaokou and Jiashengpan large-superlarge Zn-Pb-Cu-Fe sulfide deposits, are most similar to those of mesoproterozoic SEDEX-type provinces of the world. The characteristics include: (1) All deposits of this type in the belt occur in third-order fault-basins in the Langshan-Zha'ertaishan aulacogen along the northern margin of the North China Platform; (2) these deposits with all their orebodies hosted in the mesoproterozoic impure dolomite-marble and carbonaceous phyllite (or schists) have an apparent stratabound nature; ores display laminated and banded structures, showing clear depositional features; (3) there is some evidence of syn-sedimentary faulting, which to a certain extent accounts for the temporal and spatial distribution and the size of the orebodies in all deposits and the formation of intrabed conglomerates and breccias; (4) they show lateral and vertical zonation of sulfides; (5) The Cu/(Pb+Zn+Cu) ratio of the large and thick Pb+Zn+Cu orebodies gradually decreases from bottom to top; and (6) barite is interbedded with pyrites and sometimes with sphalerite. However, some characteristics such as the Co/Ni radio of the pyrites, the volcanism, for example, of the Langshan-Zha'ertaishan metallogenic belt, are different from those of the typical SEDEX deposits of the world. The meta-basic volcanic rock in Huogeqi, the sodic bimodal volcanic rocks in the Dongshengmiao and potassic bimodal-volcanic rocks with blastoporphyritic and blasto-glomeroporphyritic texture as well as blasto-amygdaloidal structure in the Tanyaokou deposits have been discovered in the only ore-bearing second formation of the Langshan Group in the past 10 years. The metallogeny of some deposits hosted in the Langshan Group is closely related to syn-sedimentary volcanism based on the following facts: most of the lead isotopes in sphalerite, galena, pyri

关键词： passive continental margin stratabound and rock-controlled character volcanism transitional SEDEX and VMS-type deposits mesoproterozoic northern margin of the North China Platform

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A Newly Discovered Oil-bearing mesoproterozoic Erathem within the Niu D1 Well, Liaoxi Depression, Yanliao Faulted Depression Zone, NE China

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Acta Geologica Sinica(English Edition) 2020年第1期94卷 202-203页

作者： SUN Qiushi GAO Xiaoyong ZONG Wenming SUN Shouliang ZHANG Tao XIAO Fei LI Yongfei SHI Lei Shenyang Center of Geological Survey China Geological Survey(CGS)/Northeast China Center for Geoscience InnovationShenyang 110034China

Objective The Yanshan Fold Belt is located within the northern margin of the North China platform and contains welldeveloped and widespread Neoproterozoic and mesoproterozoic sedimentary units with a total thickness of up to 9000 *** studies identified many oil seedlings as well as asphalt and ancient hydrocarbon reservoirs in Northern Hebei depression and western Liaoning *** research indicates that the mesoproterozoic and Neoproterozoic sedimentary units are ideally suited for the formation of significant oil and gas *** Niu D1 well was drilled by the China Geological Survey(CGS)in the Niuyingzi area and intercepted oil immersions and oil-and gas-bearing units within a limestone reservoir in the middle Proterozoic Gaoyuzhuang Formation(Fig.1).This study presents new biomarker compound and carbon isotope data that indicate that the oil within this formation was derived from hydrocarbon source rocks of the Hongshuizhuang Formation,part of the mesoproterozoic Jixian Series,and the reservoir type is overthrust fault fractured anticline hydrocarbon *** oil reservoir within the Gaoyuzhuang Formation limestone might represent the oldest oil reservoir discovered to date within the Yanliao faulted depression zone.

关键词： NE China A Newly Discovered Oil-bearing mesoproterozoic Erathem within the Niu D1 Well Yanliao Faulted Depression Zone Liaoxi Depression

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Chemical and Sr-Nd compositions and ^(40)Ar/^(39)Ar ages of NW-trending dolerite dikes of Burkina Faso: Evidence for a mesoproterozoic magmatism in the West African Craton

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Geoscience Frontiers 2018年第6期9卷 1957-1980页

作者： Boukare Tapsoba Ching-Hua Lo Urbain Wenmenga Yoshiyuki Iizuka Sun-Lin Chung Gregory Shellnutt Department of Geosciences National Taiwan University UFR-SVT Département de Géologie Université Pr.Joseph Ki-Zerbo de Ouagadougou Institute of Earth Sciences Academia Sinica Department of Earth Sciences National Taiwan Normal University

The Paleoproterozoic basement of the northeastern part of the Leo-Man craton is intruded by generally NW-trending dikes. These regional scale dikes extend over 1000 km in Burkina Faso, Mali and Niger. We present chemical and Sr-Nd isotope compositions, as well as 40 Ar/39 Ar ages of these dikes with the following strikes N98°-N112°, and N114°-N124° in NE Burkina Faso. Field relationships show that the dikes are posterior to all other rock types dated between 2.26 Ga and 2.0 Ga. Chemical data indicate that the dikes are continental flood basalts and composed of low-Ti(TiO2 ≤ 2 wt.%) sub-alkaline basalts and andesites. They exhibit a minor negative Europium anomaly(0.86-0.99) and slightly fractionated REE patterns((La/Yb)_N= 2.5-9.1; Yb_N = 9.5-19.9). The ratios of Th/Ta(1.3-11.4) and Ce/Pb(5.2-58.5)suggest a varying crustal assimilation of the dike magmas during ascent in the continental crust for all studied samples. Calculated P-T conditions indicate that the magma reached temperatures of 1285 ℃(calculated from olivine compositions) and pressures of 6.9 kbar(calculated for pyroxene minerals).Calculated initial 87 Sr/86 Sr(0.70040-0.70260) and ε_(Nd)(t)=+2.1 to-3.5 at 1575 Ma,also point to a crustal contamination with the most primitive samples showing T_(DM) values of 1946 Ma and 2154 Ma. The low values of La/Ba(mesoproterozoic magmatism between 1.6 Ga and 1.2 Ga, and were affected by a thermal event causing the argon systematics resetting, best constrained by the date of sample KK1(123

关键词： Mafic dike swarm Depleted mantle mesoproterozoic Continental tholeiites Nuna West African Craton

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Trace and rare earth elemental geochemistry of carbonate succession in the Middle Gaoyuzhuang Formation,Pingquan Section:Implications for Early mesoproterozoic ocean redox conditions

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Journal of Palaeogeography 2013年第2期2卷 209-221页

作者： Guo Hua Du Yuansheng Zhou Lian Yang Jianghai Huang Hu State Key Laboratory of Biogeology and Environmentary Geology China University of Geosciences(Wuhan) State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences(Wuhan)

The concentrations of redox-sensitive trace elements,such as uranium(U),vanadium(V),molybdenum(Mo),cobalt(Co),chromium(Cr) and rare earth elements(REE+Y) were determined in a given carbonate succession in the Gaoyuzhuang Formation(～1.56 Ga),which spans depths from outer shelf to intertidal,to explore the Early mesoproterozoic ocean redox *** values of the Zr-normalized redox-sensitive trace element concentrations and some relevant ratios show obvious changes from bottom to top in the *** from the outer shelf setting(M1 interval) demonstrate significantly enhanced values in Zr-normalized redox-sensitive trace element concentrations and relevant ratios(the peaks of Mo/U,V/Cr and Ni/Co ratios larger than 8,4.25,and 7,respectively).Authigenic framboidal pyrites were also found within oncolite-like carbonate concretions and surrounding host rocks in this *** all indicate a euxinic state in the outer shelf *** enrichment of Zr-normalized redox-sensitive elemental abundances and a mild decrease in the values of geochemical ratios were present in the inner shelf environment(M2 interval)(the V/Cr and Ni/Co ratios fall into a range of 2.5 4.25 and 4 5,respectively),suggesting dysoxic conditions dominant in the inner shelf *** from the shallower subtidal and intertidal settings(M3 and M4 intervals) are mostly invariable with much lower values of Zr-normalized redox-sensitive elements and relevant ratios,with the V/Cr and Ni/Co ratios typically near or less than 2 and 5 respectively,indicative of oxic conditions in the high energy subtidal/intertidal zones.A remarkable negative Ce anomaly exhibited in the shale-normalized REE+Y diagram in the M4 interval may provide evidence in support of the *** together,our results suggest a relatively shallow chemocline in the Early mesoproterozoic ocean:the transitions between euxinic,dysoxic and oxic may occur in quiet-water outer shelf and highenergy subtidal zone,

关键词： trace elements rare earth elements mesoproterozoic redox Gaoyuzhuang Formation Pingquan

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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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Deformed stromatolites in marbles of the mesoproterozoic Wumishan Formation as evidence for synsedimentary seismic activity

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Journal of Palaeogeography 2013年第4期2卷 390-401页

作者： A.J.(Tom) van Loon Su Dechen Geological Institute Adam Mickiewicz University Institute of Geology Chinese Academy of Geological Sciences State Key Laboratory of Continental Tectonics and Dynamics

The mesoproterozoic Wumishan Formation consists mainly of dolomites that represent diagenetically transformed limestones deposited in a shallow peritidal *** the environment was tectonically stable,the study area in the Changping District(north of the Beijing area) was affected by synsedimentary ***,the dolomites in the study area were intruded by a *** resulted in contact metamorphism of the dolomites,changing them in a halo around the intrusion into *** marble,which is exposed near Taoyukou Village,shows some levels with well-developed *** stromatolites contain structures that point at deformation when the stromatolites had not yet been lithified,and thus represent soft-sediment deformation *** stromatolites apparently built up during a time-span when repeated deformational processes affected the still unlithified sediment,from the sedimentary surface down to maximally a few *** deformed stromatolites thus represent seismites,which feature is exceptionally rarely recognizable in marble.

关键词： soft-sediment deformation stromatolites seismites Wumishan Formation mesoproterozoic Changping District Beijing

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Typical earthquake-induced soft-sediment deformation structures in the mesoproterozoic Wumishan Formation, Yongding River Valley, Beijing, China and interpreted earthquake frequency

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Journal of Palaeogeography 2012年第1期1卷 71-89页

作者： Su Dechen Sun Aiping Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China State Key Laboratory of Continental Tectonics and Dynamics Beijing 100037 China

The mesoproterozoic Wumishan Formation, composed of dolomite is a widely distributed stratigraphic unit in the Beijing area. It was formed over a long period of time in the Yan-Liao aulacogen, a stable peritidal environment that was ideal for recording earthquakes in the form of soft-sediment deformation structures (SSDS). Numerous examples occur in the upper part of the Wumishan Formation, along the Yongding River Valley. In addition, brittle structures include intrastratal fault and seismically cracked breccias. The soft-sediment deformation structures include liquefied features (diapirs, clastic dykes, convolute bedding), compressional deformation features (accordion folds, plate-spine breccias, mound-and-sag structures), and extensional plastic features (loop-bedding). Based on the regional geological setting and previous research, movements along the main axial fault of the Yan-Liao aulacogen are considered as the triggers for earthquakes since the Early mesoproterozoic. The number and distribution of the SSDS suggest the major earthquake frequency in the Wumishan Formation of 20 to 32 thousand years.

关键词： soft-sediment deformation structures mesoproterozoic Wumishan Formation Yongding River valley China, earthquake frequency

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Megaripples from the mesoproterozoic of the Kimberley region,northwestern Australia and its geological implications

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Journal of Palaeogeography 2012年第1期1卷 15-25页

作者： Lan Zhongwu 1,2,3,,Zhong-Qiang Chen 2,4,1.State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China 2.School of Earth and Environment,The University of Western Australia,Australia 3.Key Lab of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China 4.State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences (Wuhan),Wuhan 430074,China State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China School of Earth and Environment The University of Western Australia Australia Key Lab of Petroleum Resources Research Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences (Wuhan) Wuhan 430074 China

Large ripples are described from the mesoproterozoic Hilfordy Formation in the Kimberley region,northwestern *** ripple index (RI) and ripple symmetry index (RSI) suggest the Kimberley ripples were likely generated by storm *** wave height is up to 15 23 cm and wave length is up to 70 90 *** features,incorporated with other morphological characteristics such as symmetry,steepness,ripple spacing,and compositions,agree well with the megaripples previously reported from the intertidal-nearshore settings of modern seas and the geological *** mesoproterozoic ripples were likely generated by the storm-induced *** survey of the global record of megaripples reveals that such structures have occurred through the geological past from the Archean to present *** were particularly common in the Neoproterozoic and had the largest ripple length and ripple height among the modern and geological *** is probably because extreme storms prevailed at that *** frequent occurrence in present day beach is probably due to the prevalence of extreme storms caused by the monsoon or tsunami/earthquake influenced climatic regimes.

关键词： megaripples palaeohydrodynamics extreme storms mesoproterozoic Hilfordy Formation Kimberley northwestern Australia

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