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Origin of Tafoni in the Late Cretaceous Aeolian Sandstones,Danxiashan UNESCO Global Geopark,South China

Acta Geologica Sinica(English Edition) 2019年第2期93卷 451-463页

作者： CHEN Liuqin GUO Fusheng LIU Fujun XU Huan DING Ting LIU Xin State Key Laboratory of Nuclear Resources and environment East China University of Technology Shandong Provincial Key Laboratory of Depositional Mineralization & sedimentary Mineral Shandong University of Science and Technology School of Earth Sciences East China University of Technology

Tafoni occur generally in granular rocks around the world, but their origin remains controversial. In this study,the roles of lithology, micro–climate, and organism in tafoni development are investigated in the Danxiashan UNESCO Global Geopark of South China. The Jinshiyan Temple and Luyitang sites along the Jinjiang River are chosen to conduct tafoni morphometry, bedrock petrography, and micro–climate analyses. The research methods used in this study include field observations and measurements, Voronoi diagrams, polarizing microscopic and scanning electron microscopic(SEM)image analysis, and meteorological detection. The tafoni are mostly 2–10 cm in length and elliptical in shape. The Late Cretaceous Jinshiyan sandstones are characterized by a grain–to–grain contact fabric and moderate sorting with a high proportion of soluble grains and cements. The Voronoi diagrams developed through the Arc GIS software are largely consistent with the tafoni openings. Moreover, owing to exposure to solar insolation, the external temperature values are higher than the internal ones, while the external relative humidity values are lower than the internal ones. Therefore, the permeable Jinshiyan sandstones are fundamental for tafoni development, while the abundant moisture from the Jinjiang River and frequent rains is favorable for salt weathering in tandem with biological activities. At last, a five–stage development model is proposed for the tafoni progression in the study area.

关键词： tafoni aeolian sandstone salt weathering moisture Danxia landscape

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Discovery of ~409 Ma Amphibolite in the Zhikong-Songduo Subduction Complex,Southern Tibet

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Acta Geologica Sinica(English Edition) 2021年第2期95卷 699-701页

作者： XIE Long ZHU Lidong YANG Wenguang WANG Gang LU Zhiyou MAI Yuanjun ZHONG Yao ZHANG Hongliang Institute of sedimentary Geology Chengdu University of TechnologyChengdu 610059China College of Earth Science Chengdu University of TechnologyChengdu 610059China School of environment and Resource Southwest University of Science and TechnologyMianyangSichuan 621010China

Objective Discovery of Songduo eclogites exposed in southern Tibet has attracted wide attention from *** recently completed regional geological surveys show that a lithotectonic belt extends at least 100 km from Zhikong in the west to Songduo in the east and is mainly composed of oceanic fragments such as eclogites,blueschists,ophiolites and oceanic island assemblages,with their associated arc igneous and metasedimentary *** is referred to hereafter as the Zhikong-Songduo(ZS)subduction complex.

关键词： oceanic sedimentary island

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Stratigraphic framework and sedimentary evolution during the Cryogenian-Ediacaran transition in northeastern Sichuan Basin,South China

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Petroleum Science 2024年第2期21卷 823-835页

作者： Yi Zhang Hong-Wei Kuang Yong-Qing Liu Qiang Shi Dong-Ge Wang Ke-Ning Qi Yu-Chong Wang Da-Wei Qiao Xiao-Shuai Chen Li-Zhi Wu Meng Tian Long Chen Yi Wei Liao-Yuan Song Jian Li Zi-Gang Wu Yun-Qian Liu Xuan-Chun Liu An-Qing Chen Zhi-Wei Liao Institute of Geology Chinese Academy of Geological SciencesBeijing100037China State Key Laboratory of Coal Mine Disaster Dynamics and Control School of Resources and Safety EngineeringChongqing UniversityChongqing400044China No.205 Geological Team Chongqing Bureau of Geology and Minerals ExplorationChongqing401121China Chongqing Institute of Geological Survey Chongqing401122China Key Laboratory of Deep-time Geography and environment Reconstruction and Applications of Ministry of Natural Resources Chengdu University of TechnologyChengdu610059SichuanChina

The northeastern Sichuan area in the northern Yangtze margin has unique Ediacaran geological records,especially the Doushantuo Formation(DST),and become a hot research area in recent ***,the Cryogenian-Ediacaran(C-E)boundary has not been precisely identified,which restricts the in-depth study of geological information during this crucial transitional period and is unfavorable for a systematic and complete understanding of the Yangtze Block and even the global paleogeographic *** study conducted stratigraphy,sedimentology,and chronostratigraphy to establish the stratigraphic framework and sedimentary evolution of the C-E transition strata in northeastern *** results showed that the Ediacaran sediments,without the cap dolomite,unconformably overlaid the Cryogenian sediments in the studied *** Member II of the DST,characterized by 50-160 m of red-green sandstone(approximately equivalent to the original Chengkou“Guanyinya Formation”),directly overlaid the Cryogenian sediments and displayed a 623±2.3 Ma maximum depositional age from the detrital zircon U-Pb *** stratigraphic correlations indicate that the C-E transition strata in northeastern Sichuan had a consistent lithological association and sedimentary sequence characteristics but differed from the Three ***,the upper Nantuo massive glacial diamictites transition to the icebergs rafted lonestone-bearing mudstones at the top,then change upward to DST barrier coast *** proposed DST of the northeastern Sichuan Basin was divided into three lithostratigraphic members without the regional Member I cap dolomite:(i)Member II purple-red,gray-green sandstone strata,(ii)MemberⅢblack mudstone strata,and(iii)Member IV P-Mn bearing *** the C-E transition,the study area experienced(i)the global deglaciation stage in the terminal Marinoan glaciation and(ii)the filling-leveling up stage with clastic rocks in the early ***,the early Ediacaran

关键词： Marinoan glaciation Doushantuo formation Cap dolomite Deglacial and coastal deposits Detrital zircon U-Pb dating

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Distribution characteristics and indicative significance of grain size and elemental content in surface-sediments of Qinghai Lake， Northeastern Tibetan Plateau

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Journal of Earth Science 2024年

作者： Yuqi Cheng Haicheng Wei Ronglei Duan Shun Wang Zhixiang Wang Hongyu Li Fangming Zeng Yilin Hou Hongpan Xue Key Laboratory of Green and High-end Utilization of Salt Lake Resources， Qinghai Institute of Salt Lakes， Chinese Academy of Sciences Qinghai Provincial Key Laboratory of Geology and environment of Salt Lakes Qinghai Institute of Salt Lakes， Chinese Academy of Sciences University of Chinese Academy of Sciences

Qinghai Lake in the northeastern Qinghai-Tibet Plateau (QTP)， being sensitive to paleoclimate change and anthropogenic activities， has attracted much attention from paleoenvironmental researchers. Grain size and elemental content in lake sediments are indispensable proxies for reconstructing paleoclimate and paleoenvironment. However， limited research on grain size and elemental content of surface-sediments in Qinghai Lake complicates decoding the information from lacustrine sedimentary strata. In this study， 55 surface-sediment samples were collected for grain size and elemental content analysis， combined with grain size end-member modeling algorithm (EMMA)， correlation (CA) and principal component (PCA) analysis to explore the controlling mechanisms and their environmental indications. Our results show that the hydrodynamic condition controls the distribution of surface-sediments in Qinghai Lake: exhibiting a belt-like pattern of sand-silt-clay， the clockwise circulation in the northwestern and southwestern lake transports sand to the two primary sedimentary centers. Three primary components representing different transport/depositional processes were separated: ‘lacustro-aeolian’， ‘fluvio-aeolian’ and river-transported bedload. Grain size controls the elemental content， particularly in terrestrial particles. Nitrogen (N) and phosphorus (P)， mainly derived from endogenous organic matter (OM)， tend to be absorbed by finer particles. The hydrodynamic conditions and anthropogenic activities also influence their spatial distribution. The chemical weathering index (CIA)， indicating a cold and dry climate， is highly related to grain size. This research provides crucial modern process references for accurately interpreting grain size and element records in sediment cores from Qinghai Lake.

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Construction of a fluvial facies knowledge graph and its application in sedimentary facies identification

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Geoscience Frontiers 2023年第2期14卷 268-281页

作者： Lei Zhang Mingcai Hou Anqing Chen Hanting Zhong James G.Ogg Dongyu Zheng Key Laboratory of Deep-time Geography and environment Reconstruction and Applications MNR&Institute of Sedimentary GeologyChengdu University of TechnologyChengdu 610059China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology) Chengdu 610059China

Lithofacies paleogeography is a data-intensive discipline that involves the interpretation and compilation of sedimentary *** sedimentary facies analysis is a labor-intensive task with the added complexity of using unstructured knowledge and unstandardized ***,it is very difficult for beginners or non-geology scholars who lack a systematic knowledge and experience in sedimentary facies *** hurdles could be partly alleviated by having a standardized,structured,and systematic knowledge base coupled with an efficient automatic machine-assisted sedimentary facies identification *** this end,this study constructed a knowledge system for fluvial facies and carried out knowledge *** include a domain knowledge graph for types of fluvial facies(meandering,braided and other fluvial depositional environments)and their characteristic features(bedforms,grain size distribution,etc.)with visualization,a method for query and retrieval on a graph database platform,a hierarchical knowledge tree-structure,a data-mining clustering algorithm for machineanalysis of publication texts,and an algorithm model for this area of sedimentary facies *** underlying sedimentary facies identification and knowledge reasoning system is based on expert experience and synthesis of *** testing,17 sets literature publications data that included details of sedimentary facies data(bedforms,grain sizes,etc.)were submitted to the artificial intelligence model,then compared and *** testing set of automated reasoning results yielded an interpretation accuracy of about 90%relative to the published interpretations in those ***,the model and algorithm provide an efficient and automated reasoning technology,which provides a new approach and route for the rapid and intelligent identification of other types of sedimentary facies from literature data or direct use in the field.

关键词： Fluvial facies Knowledge graph Domain ontology sedimentary facies identification Machine-assisted interpretation

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Major element,trace element,and Sr,Nd and Pb iso-tope studies of Cenozoic basalts from the South China Sea

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Science China Earth Sciences 2008年第4期51卷 550-566页

作者： YAN QuanShu SHI XueFa WANG KunShan BU WenRui XIAO Long Key Lab of Marine sedimentary and environment Geology The First Institute of OceanographyState Oceanic AdministrationQingdao 266061China Institute of Oceanology Chinese Academy of SciencesQingdao 26607China Faculty of Earth Sciences China University of GeosciencesWuhan 430074China

The whole rock K-Ar ages of basalts from the South China Sea basin vary from 3.8 to 7.9 Ma, which suggest that intra-plate volcanism after the cessation of spreading of the South China Sea (SCS) is comparable to that in adjacent regions around the SCS, i.e., Leiqiong Peninsula, northern margin of the SCS, Indochina block, and so on. Based on detailed petrographic studies, we selected many fresh ba-saltic rocks and measured their major element, trace element, and Sr-Nd-Pb isotope compositions. Geochemical characteristics of major element and trace element show that these basaltic rocks belong to alkali basalt magma series, and are similar to OIB-type basalt. The extent of partial melting of mantle rock in source region is very low, and magma may experience crystallization differentiation and cu-mulation during the ascent to or storing in the high-level magma chamber. Sr-Nd-Pb isotopic data of these basaltic rocks imply an inhomogeneous mantle below the South China Sea. The nature of magma origin has a two end-member mixing model, one is EM2 (Enriched Mantle 2) which may be originated from mantle plume, the other is DMM (Depleted MORB Mantle). Pb isotopic characteristics show the Dupal anomaly in the South China Sea, and combined with newly found Dupal anomaly at Gakkel ridge in Arctic Ocean, this implies that Dupal anomaly is not only limited to South Hemisphere. In variation diagrams among Sr, Nd and Pb, the origin nature of mantle below the SCS is similar to those below Leiqiong peninsula, northern margin of the SCS and Indochina peninsula, and is different from those below north and northeast China. This study provides geochemical constraints on Hainan mantle plume.

关键词： Cenozoic alkali basalt Dupal anomaly Hainan mantle plume the South China Sea geochemistry.

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Hydrothermal activities and seawater acidification in the Late Devonian F-F transition:Evidence from geochemistry of rare earth elements

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Science China Earth Sciences 2011年第4期54卷 540-549页

作者： ZENG JianWei XU Ran GONG YiMing Key Laboratory of Biogeology and environmental Geology of Ministry of Education & State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan 430074 China Institute of Resources and environment Key Laboratory of Biogenic Traces & Sedimentary Minerals of Henan Province Henan Polytechnic University Jiaozuo 454003 China

Rare-earth dements （REE） in limestones were measured by ICP-MS from the Yangdi section across the Frasnian-Famennian （F-F） transition in Guilin, Guangxi of South China. The average EREE contents of measured samples are 33.32 ppm. The average LREE/HREE ratio is 6.35. Data show LREE-enriched REE distribution pattern in the Yangdi section. Most of samples are characterized by positive Eu anomaly with average of 1.13, and there are two maxima of Eu anomaly just below the F-F boundary. Almost all analytical samples show obvious tetrad effects. Remarkable M-shaped tetrad effects are observed in these samples with positive Eu anomaly. The characters of REE and some relative elements （Fe, Mn, Al, etc.） indicate that hydro- thermal activities occurred and resulted in seawater acidification in Upper and Lower Kellwasser horizons of the Late Devonian. The changes of marine environment caused by hydrothermal activities, such as seawater acidification, heavy metal pollution, and eutrophication, would destroy the neritic ecosystem and finally result in the F-F mass extinction.

关键词： Devonian mass extinction REE hydrothermal activities tetrad effects seawater acidification

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Endolithic fungi:A possible killer for the mass extinction of Cretaceous dinosaurs

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Science China Earth Sciences 2008年第6期51卷 801-807页

作者： GONG YiMing1,2, XU Ran1 & HU Bi2 1 Key Laboratory of Biogeology and environmental Geology of Ministry of Education, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China 2 Institute of Resources and environment Key Laboratory of Biogenic Traces & sedimentary Minerals of Henan Province, Henan Polytechnic University, Jiaozuo 454003, China Key Laboratory of Biogeology and environmental Geology of Ministry of Education State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan China Institute of Resources and environment Key Laboratory of Biogenic Traces & sedimentary Minerals of Henan Province Henan Polytechnic University Jiaozuo China

Mycelium-like structures found under ESEM within radial sections of fragmental dinosaur eggshells would be the endolithic fungi coexistent with dinosaur eggs in the upper part of the Late Cretaceous Hugang Formation from the Wenjiaping section of Wenxian, Danjiangkou, northwestern Hubei, Central China. The endolithic fungi selectively occurred in the bad biomineral zone within the columnar layer of the eggshells, where the crowded endolithic fungi penetrated the columnar layer at near-vertical or near-horizontal angles. The endolithic fungi are needle-like, ribbon-like and silk-like, and 5–18 μm long, 0.3–0.5 μm wide at their base, with pointed tip, and are unbranched. The hyphae are mainly composed of oxygen, carbon and calcium, and are with minor sodium, potassium, chlorine and sulfur. The endolithic fungi and host have the same characters in lithification, fracture and main chemical composition. We suggested that the episode endolithic fungi invading dinosaur eggs may have taken place in the interval between after formation of dinosaur eggshells and before their petrification and that dinosaur eggs invaded by endolithic fungi would not be normally incubated or would only be incubated into venerable and pathologic baby dinosaurs to be easily to aborted and contributed to the mass extinction of the dinosaurs at the end of Cretaceous.

关键词： endolithic fungi dinosaur eggs mass extinction Cretaceous

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Constraints of palaeoenvironment on organic matter of Benxi Formation shale and discussion on enrichment mechanism under different facies

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Frontiers of Earth Science 2024年第1期18卷 148-171页

作者： Qianyang HE Delu LI Qiang SUN Jianwen GAO Haibin LI Xinhu LI Xiaochen ZHAO Shaofei WANG Gaozhe JI College of Geology and environment Xi’an University of Science and TechnologyXi’an 710054China Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation Xi’an University of Science and TechnologyXi’an 710054China Geological Research Institute for Coal Green Mining Xi’an University of Science and TechnologyXi’an 710054China Research Institute of Exploration and Development PetroChina Changqing Oilfield CompanyXi’an 710018China School of Civil Engineering and Architecture Shaanxi University of TechnologyHanzhong 723001China

As a hydrocarbon-rich sedimentary basin in China,the Ordos Basin has enormous potential for shale gas *** shale of the Upper Carboniferous Benxi Formation is rich in organic matter,however,its palaeoenvironment and organic matter enrichment mode are yet to be *** this study,the geochemical characteristics of the shale of the Benxi Formation in the east-central part of the Ordos Basin were analyzed to investigate its *** the same time,the organic matter enrichment modes in different sedimentary facies were compared and *** results indicate that:1)the shale of the Benxi Formation was mainly deposited on the continental margin and strong terrestrial clastic input;2)the deposition period of the Benxi Formation shale had a hot and humid climate with high palaeoproductivity and local volcanic hydrothermal fluid,and a high sedimentation rate with the strong stagnant *** bottom water was in dysoxic conditions and a semi-saline deposition environment;3)multiple factors,such as palaeoproductivity,volcanic hydrothermal,redox conditions,and palaeosalinity interact to influence the enrichment of shale organic matter in Benxi Formation;4)the organic matter enrichment modes of continental,marine-continental transitional,and marine shales can be classified into three types:“production mode”,“hybrid mode of preservation and production”,and“preservation mode”,*** study provides a reference for the organic matter enrichment mode,shale gas formation conditions,and core area evaluation in these marine-continental transitional shales,and also offers new guidance for exploration ideas for shale gas in different sedimentary facies.

关键词： Benxi Formation shale palaeoenvironment organic matter enrichment facies

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Characterization of the Microbial Dolomite of the Upper Sinian Dengying Formation in the Hanyuan Area of Sichuan Province,China

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Acta Geologica Sinica(English Edition) 2017年第3期91卷 806-821页

作者： LIN Xiaoxian PENG Jun DU Lingchun YAN Jianping HOU Zhongjian Post-doctoral Research Center Southwest Petroleum University Key Laboratory of sedimentary Basin and Oil and Gas Resources Ministry of Land and Resources College of Geosciences and Technology Southwest Petroleum University Institute of sedimentary Geology Chengdu Univerisity of Technology College of Earth Sciences Chengdu Univerisity of Technology

The algal dolostone of the Upper Sinian Dengying Formation （corresponding to the Ediacaran system） in the Upper Yangtze Platform of China possesses a rich diversity of microorganisms and is an ideal site for the study of ancient microbial dolomite. We focused on algal dolostone and its microbial dolomite in the Hanyuan area of Sichuan Province, China. The macroscopic petrological features, microscopic morphology, texture characteristics of the fossil microorganisms and microbial dolomite, and geochemical characteristics were investigated. We found rich fossil microorganisms and microbial dolomites in the laminated, stromatolithic, uniform and clotted （algal） dolostones. The microorganisms present were mainly body fossils of cyanobacteria （including Renalcis, Girvanella, Nanococcus, and Epiphyton） and their trace fossils （including microbial mats （biofilms）, algal traces, and spots）. In addition, there was evidence of sulfate-reducing bacteria （SRB）, moderately halophilic aerobic bacteria, and red algae. The microbial dolomites presented cryptocrystalline textures under polarizing microscope and nanometer-sized granular （including spherulitic and pene-cubical granular） and （sub） micron-sized sheet-like, irregular, spherical and ovoidal morphologies under scanning electron microscope （SEM）. The microbial dolomites were formed by microbialiy induced mineralization in the intertidal zone and lagoon environments during the depositional and syngenetic stages and microbially influenced mineralization in the supratidal zone environment during the penecontemporaneous stage. The microbial metabolic activities and extracellular polymeric substances （EPS） determined the morphology and element composition of microbial dolomite. During the depositional and syngenetic stages, the metabolic activities of cyanobacteria and SRB were active and EPS, biofilms and microbial mats were well-developed. EPS provided a large number of nucleation sites. Accordingly, many nanometer-sized pene-

关键词： microbial dolomite microbial biomineralization morphological evolution of dolomite,algal dolostone Dengying Formation

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