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Electron Probe Microanalysis of Monazite and Its Applications to U-Th-Pb Dating of Geological Samples

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Journal of Earth Science 2019年第5期30卷 952-963页

作者： Wenbin Ning Junpeng Wang Deng Xiao Fenfang Li Bo Huang Dong Fu State key laboratory of Geological Processes and Mineral Resources Hubei Key Laboratory of Critical Zone Evolution Center for Global Tectonics School of Earth Sciences China University of Geosciences

Electron probe microanalysis(EPMA) dating of monazite has been developed over decades. However, limited by the detectability and analytical sensitivity of dating-related elements(Th, Pb, U and Y), the EPMA dating has been restricted to geological research. In this study, various probe currents, beam diameters and counting times have been utilized on a JEOL JXA-8230 electron microprobe to determine the optimal experimental conditions for measuring Th, Pb, U and Y in monazite. The optimal conditions are:(1) accelerating voltage is 15 k V;(2) probe current is 100 n A;(3) beam diameter is 1 μm;(4) the peak and background counting time of U and Pb are 200 and 100 s;and(5) the peak and background counting time of Th and Y are 100 and 50 s. We apply this method to monazite from garnet-bearing biotite gneiss in the Zanhuang area of the Central Orogenic Belt of the North China Craton. The Pb O-Th O2* isochron age calculated by EPMA data is 1 812±17 Ma(MSWD=2.06), which is similar to the weighted mean 207 Pb/206 Pb age(1 805±12 Ma, MSWD=1.07) obtained by LA-ICP-MS. This study suggests that EPMA dating of monazite as a powerful dating technique can be widely used in geochronological study.

关键词： monazite EPMA dating garnet-bearing biotite gneiss Zanhuang area North China Craton geochemistry

Fluctuations of Water Table Level in a Subtropical Peatland,Central China

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Journal of Earth Science 2022年

作者： Guang Yang Yiming Zhang Xianyu Huang State key laboratory of Biogeology and Environmental Geology China University of Geosciences Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information Engineering China University of Geosciences

Water level is the overriding control on carbon cycles in peatlands, which are important for global carbon cycles and ecosystem services. To date, our knowledge of the pattern of water level fluctuations in peatlands and the influence of precipitation and air temperature on them in the subtropical remains poor. In this study, we conducted continuous high-resolution monitoring of water levels from 2014 to 2021 in the Dajiuhu peatland, a typically subtropical peatland in central China. Monitoring results showed that the water level had strong annual(370 days) and seasonal(130 days) oscillations in the Dajiuhu peatland. The annual oscillation is associated with both precipitation and temperature, while the seasonal oscillation is mainly controlled by precipitation. In addition, the depth of peat surface to the water table(DWT) has weak but significant correlations with precipitation and temperature on the daily and weekly scales(r = 0.1–0.21, P < 0.01). Once replacing DWT with water table fluctuation cumulation, the correlation coefficients increase apparently(r = 0.47–0.69, P < 0.01), especially on the monthly scale. These findings highlight a more important role of the fluctuation than the mean position of water level and have the potential to improve the interpretation of water-level related paleoenvironmental proxies and the understanding of the relationship between water level and biogeochemical processes.

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地质病毒学:地质历史时期的病毒及其作用

Science Bulletin 2023年第4期68卷 379-382,M0003页

作者：谢树成朱秀昌 Thomas Algeo 邱轩 State key laboratory of Biogeology and Environmental Geology Hubei Key Laboratory of Critical Zone EvolutionSchool of Earth SciencesChina University of GeosciencesWuhan 430074China State key laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China Department of Geology University of CincinnatiCincinnati OH 45221-0013USA

Viruses are the most diverse and abundant type of biological entity on Earth,infecting species from all of life’s domains and being found in almost all types of environments.They are gaining increasing attention from scientists,officials and the public due to recent major outbreaks with human health consequences(e.g.,AIDS,SARS,COVID-19)and a growing appreciation of the impact viruses have had on the long-term development of both the biosphere and geosphere.The ability to identify viruses in ancient times is of importance in promoting our understanding of viral evolution and the relationships of viruses to their hosts and to paleoclimate conditions,enabling predictions of present and future impacts of the virosphere on life and the climate system.

关键词： consequences system abundant

Habitat Influence on the Molecular, Carbon and Hydrogen Isotope Compositions of Leaf Wax n-Alkanes in a Subalpine Basin, Central China

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Journal of Earth Science 2020年第4期31卷 845-852页

作者： Chaoyang Yan Yiming Zhang Yanzhen Zhang Zhiqi Zhang Xianyu Huang State key laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430078China Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430078China

Epidermal leaf waxes of terrestrial higher plants have been widely utilized for the reconstructions of paleoenvironment and paleoclimate in peat deposits. In this study, specimens of four plant species growing in both peatland and non-peatland habitats were retrieved to compare their molecular, carbon(δ13 C) and hydrogen(δ2 H) isotopic compositions of leaf wax n-alkanes from a closed subalpine basin in Central China. Three of the four species show quite higher total concentrations of n-alkanes in the relatively dry non-peatland setting than in the peatland. In addition, the δ2 H values of long-chain n-alkanes are generally less depleted in the peatland and are comparable among different plant species, which is interpreted as the influence of inundation condition and the possible limited supply of photosynthetic products. This study reveals different patterns of plant wax molecular and isotopic compositions between peatland and the surrounding non-peatland conditions, and confirms the paleoenvironmental potential of leaf wax ratios on the peat sequences.

关键词： habitat n-alkane compound specific carbon isotope compound specific hydrogen isotope peat deposit

Different patterns of molecular,carbon and hydrogen isotope compositions of n-alkanes between heterotrophic plant and its hosts

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Frontiers of Earth Science 2020年第4期14卷 783-788页

作者： Xin Yang Xianyu Huang State key laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan430078China Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan430078China

This study investigates the molecular,carbon,and hydrogen isotope compositions of n-alkanes in eight pairs of a holoparasitic plant(Cuscuta chinensis)and its hosts.It is unexpected that C.chinensis has a higher concentration of n-alkanes than its hosts in seven of the eight pairs,and it is preferentially dominated by n-C_(29) alkane(representing>75%of the total n-alkanes).In addition,theδ^(13)C values of C_(29) alkane in C.chinensis are less negative(avg.1.8‰)than those in the hosts,while theδ^(2)H values of C_(29) alkane are more negative in C.chinensis(the difference averages 48‰).We propose that the ^(2)H-depletion of n-alkanes in the stem parasite C.chinensis may result from the utilization of stem water with less influence from evapotranspiration or the use of newly synthesized carbohydrates which is ^(2)H-depleted relative to stored sugars.These results highlight the importance of plant nutrient status on the molecular and isotopic compositions of leaf waxes,which shed light on the(paleo)ecological potential of leaf waxδ^(2)H values.

关键词： heterotrophic plant Cuscuta n-alkane carbon isotope hydrogen isotope

Detrital-Zircon Evidence for the Origin of the Late Quaternary Loess in Qingzhou,Shandong Province and Its Implications for the evolution of the Yellow River

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Journal of Earth Science 2022年第1期33卷 205-214页

作者： Yanfei Shen Meiyan Liang Jianxun Wu Shuzhen Peng Guoqiao Xiao Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China State key laboratory of Biogeology and Environmental Geology School of Earth SciencesChina University of GeosciencesWuhan 430074China School of Tourism Resources and EnvironmentTaishan UniversityTai'an 271021China

The loess depositions in Shandong Province are important parts of loess records in eastern China,but their origin and genetic linkage between the Yellow River and the Chinese Loess Plateau are still unclear.This paper presents the detrital-zircon evidence for the origin and provenance evolution of the Qingzhou loess in Shandong Province.The results show that:(1) the Qingzhou loess was sourced from the sandy lands within the North China Plain that were fed by the silty materials from the Chinese Loess Plateau,the mountainous region in central Shandong Province,and the Yanshan and Taihang Mountains;(2) the Qingzhou loess was mainly sourced from the loess materials transported by the Yellow River,and the basal age of the Qingzhou loess indicates the timing of intensified aridification of the North China Plain and integration of the Yellow River was not later than 0.5 Ma;and(3) the provenance and grain-size of the Qingzhou loess underwent a significant transition at ~0.22 Ma,which was related to the expansion of the sandy land within the North China Plain.Our results indicate that the origin of the loess on the North China Plain are obviously different from the loess on the Chinese Loess Plateau,and the increase of grain-size and accumulation rate in the loess records on the North China Plain at ~0.22 Ma was due to the environmental deterioration of the eastern China.

关键词： North China Plain loess Pleistocene zircon detrital-zircon Yellow River

Sedimentary and Heavy Mineral Records for the Oligocene–Miocene Exhumation of the Easternmost Tianshan

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Journal of Earth Science 2023年

作者： Yan Ding Tianyi Shen Guocan Wang Junliang Ji Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information Engineering China University of Geosciences State key laboratory of Geological Processes and Mineral Resources China University of Geosciences School of Earth Sciences Center for Global Tectonics China University of GeosciencesWuhan

The topography of the Harlik Mountain has a strong impact on the formation of current arid climate in the Turpan-Hami Basin. However, it is still controversial if Harlik Mountain experienced significant exhumation during the Middle to Late Cenozoic according to the previous thermochronology studies. The features of the Oligocene to Miocene sediments in the foreland basin could provide productive information for resolving the debates. The peak ages of detrital apatite fission track analysis of the Oligocene–Miocene sandstone in the Turpan-Hami Basin are well comparable with the cooling age records of the Harlik Mountain rocks, indicating that the Oligocene–Miocene Taoshuyuanzi Formation in the basin was mostly derived from the Harlik Mountain. The stratigraphic sequence exhibits coarsening upward, reflecting that the source area was in a tectonically active period during the deposition process. Heavy mineral assemblages also suggest that the unstable minerals in the sediment increased significantly at the end of the deposition. Moreover, the proportion of apatite increased upsection, while the garnet content decreased significantly, indicating that the Carboniferous metamorphic rocks have been gradually eroded out and more intrusive rocks have been exposed to the surface.These observations suggest that the Harlik Mountain experienced exhumation during the Oligocene to Miocene, and the denudation depth afterward was probably less than 2.5 km according to the previously apatite(U-Th)/He data. The Oligocene-Miocene exhumation probably acted as one of the triggers for the heavy drought of the Turpan-Hami Basin during the Middle–Late Neogene.

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Early Warning of Heavy Metal Pollution after Tailing Pond Failure Accident

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Journal of Earth Science 2022年第4期33卷 1047-1055页

作者： Yonggui Wang Yinqun Yang Qiang Li Yaxin Zhang Xiaolong Chen Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China Changjiang Water Resources Protection Institute Wuhan 430051China Beijing Tsinghua Holdings Human Settlements Environment Institute Beijing 100083China

Heavy metal pollution is a major issue after tailing pond failure accident.It is important to predict pollution trends for limited data of pollution sources.A simple phase separation heavy metal model was built for early warning simulation of heavy metal pollution accidents.Based on this,a new simulation framework has been developed to predict the pollution trends of the downstream according to the measured data at upstream sections.By setting the upstream monitoring date as the inflow boundary condition,the changing processes of heavy metal manganese(Mn) with different phases in the downstream can be accurately simulated and forecasted.Results showed that the concentration of the suspended phase in the downstream was larger than that in the aqueous phase and sediment phase.With this,the early warning of pollution trends after accidents could be made a few days ahead.It indicates that the impact of sediment on heavy metal should not be ignored in the early warning of tailing pond failure accidents.

关键词： heavy metal pollution early warning tailing pond failure accident phase separation model

Spatiotemporal Distribution of Microbial Tetraether Lipids in a Lake and Its Inflowing River:Implications for the Identification of Flooding Events

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Journal of Earth Science 2022年第6期33卷 1601-1613页

作者： Xiuchang Zhu Yongbo Wang Xinyue Dang Huan Yang Shucheng Xie State key laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan430078China School of Earth Sciences China University of GeosciencesWuhan430074China School of Finance and Business Shanghai Normal UniversityShanghai200234China Hubei Key Laboratory of Critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan430078China

Microbial glycerol dialkyl glycerol tetraethers(GDGTs)in lacustrine sediments are widely used to reconstruct terrestrial paleoenvironments.However,lipids of diverse origin in lakes make it difficult to decipher environmental information,appealing for the necessity to evaluate the impact of terrigenous input on the distribution of GDGTs through long-term monitoring.In this study,we conducted two-year monitoring of GDGTs along the river,estuary,near shore,to the center of Lake Liangzi in central China.By comparing the spatiotemporal changes of GDGT distribution in suspended particulate matter(SPM)and surface sediments,we found that the archaeal isoprenoid GDGTs(isoGDGTs)were mainly produced in situ in the river-lake systems,and not affected by the soil input.In contrast,the bacterial branched GDGTs(brGDGTs)were affected,to some extent,by soil input,depending on the distance to the lakeshore.The soil input of brGDGTs was enhanced during an episode of abnormal rainfall(flood).Moreover,the large variation of isoGDGTs indicates the in situ production under the anoxic condition in lake water.The paired increase in the GDGT-0/Cren ratio and GDGT concentration might be diagnostic of flooding events in ancient times.

关键词： GDGTs Lake Liangzi terrigenous input monitoring environmental geology