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Timing the termination of the Doushantuo negative carbon isotope excursion: evidence from U-Pb ages from the Dengying and Liuchapo formations,South China

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Science Bulletin 2018年第21期63卷 1431-1438页

作者： Mingzhong Zhou Taiyi Luo Warren D.Huff Zhiqing Yang Guanghong Zhou Tian Gan Hua Yang Di Zhang School of Geographical and Environmental Sciences Guizhou Normal University State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of Sciences Department of Geology University of Cincinnati Beijing SHRIMP Center Chinese Academy of Geological Sciences School of Geography and Tourism Guizhou Education University College of Earth Sciences University of Chinese Academy of Sciences

The Doushantuo negative carbon isotope excursion(DOUNCE) is the largest known marine inorganic carbon isotope anomaly. The origin of this pronounced negative excursion is still an enigmatic issue that attracts geologists. Time constraints on the excursion are the critical information that would provide insight into its genesis. In previous decades, the timing of its termination has been constrained by the widely cited zircon U-Pb age of 550.5 ± 0.8 Ma for the tuff at the top of the Miaohe Member at the Jiuqunao section in the Yangtze Gorges area, South China. However, results of recent studies indicate that the reliability of this time constraint needs to be re-evaluated. Here, a geochronological study was carried out using two K-bentonites from Fanglong in South China. A K-bentonite in the lower Dengying Formation yielded a U-Pb age of 557 ± 3 Ma, while a K-bentonite in the basal Liuchapo Formation yielded an age of 550 ± 3 Ma. Based on regional correlations between the Ediacaran successions in South China,the age(557 ± 3 Ma) for the K-bentonite in the lower Dengying Formation may serve as a second critical timing constraint for the ending of the DOUNCE. Combined with available estimates of the DOUNCE duration, our new data indicate that the DOUNCE has a maximum onset age ～570 Ma.

关键词： Doushantuo formation Dengying formation Shuram carbon isotope excursion South China

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Shuram-Wonoka carbon isotope excursion:Ediacaran revolution in the world ocean's meridional overturning circulation

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Geoscience Frontiers 2018年第2期9卷 391-402页

作者： George E.Williams Phillip W.Schmidt Department of Earth Sciences University of Adelaide MagneticEarth

The late Ediacaran Shuram-Wonoka excursion, with δ^(13)C_(carb) values as low as-12‰(PDB) in marineshelf deposits and spanning up to 10 Myr, is the deepest and most protracted δ^(13)C_(carb) negative anomaly recognised in Earth history. The excursion formed on at least four continents in low(≤32°) palaeolatitudes, and in China is associated with a major phosphogenic event. Global and intrabasinal correlation, magnetostratigraphy, isotope conglomerate tests and further geochemical data are consistent with a primary or syn-depositional origin for the excursion. Continental-margin phosphorites are generated by oceanic upwelling driven by surface winds, and δ^(13)C_(carb) negative anomalies are explicable by oceanic upwelling of 13 C-depleted deep oceanic waters, arguing that a feature common to these exceptional Ediacaran events was unprecedented perturbation of the world ocean. These events occurred during the transition from an alien Proterozoic world marked by low-palaeolatitude glaciation near sea level and strong seasonality to the familiar Phanerozoic Earth with circum-polar glaciation and temperate climate, suggesting that the Shuram-Wonoka excursion is related to this profound change in Earth's climate system. Of various hypotheses for Proterozoic low-palaeolatitude glaciation, only the high obliquity(>54°) hypothesis, which posits secular decrease in obliquity to near the present-day value(23.5°) during the Ediacaran, predicts an unparalleled revolution in the Ediacaran world ocean. The obliquity controls the sense of the world ocean's meridional overturning circulation, which today is driven by the sinking of cold, dense water at the poles and upwelling driven by zonal surface *** the decreasing obliquity passed the critical value of 54° during the Ediacaran the meridional temperature gradient reversed, with the equator becoming warmer than the poles and Hadley lowlatitude(<30°-35°) atmospheric zonal circulation reversing. This reversal of the temperat

关键词： Ediacaran ShurameWonoka carbon isotope excursion Oceanic meridional circulation Atmospheric circulation Proterozoic paleoclimate Obliquity of the ecliptic

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Measurement　of　excursion　of　Finger　Flexor　Tendons　Produced　by　a　Continuous　Passive　Motion　Machine

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中华骨科杂志 1995年第2期15卷 76-83页

作者： Yoshida E Dent JA Rowley JI University of Dundee 苏格兰

ＭｅａｓｕｒｅｍｅｎｔｏｆＥｘｃｕｒｓｉｏｎｏｆＦｉｎｇｅｒＦｌｅｘｏｒＴｅｎｄｏｎｓＰｒｏｄｕｃｅｄｂｙａＣｏｎｔｉｎｕｏｕｓＰａｓｓｉｖｅＭｏｔｉｏｎＭａｃｈｉｎｅＹｏｓｈｉｄａＥ；ＤｅｎｔＪＡ；ＲｏｗｌｅｙＪＩ... 详细信息

ＭｅａｓｕｒｅｍｅｎｔｏｆＥｘｃｕｒｓｉｏｎｏｆＦｉｎｇｅｒＦｌｅｘｏｒＴｅｎｄｏｎｓＰｒｏｄｕｃｅｄｂｙａＣｏｎｔｉｎｕｏｕｓＰａｓｓｉｖｅＭｏｔｉｏｎＭａｃｈｉｎｅＹｏｓｈｉｄａＥ；ＤｅｎｔＪＡ；ＲｏｗｌｅｙＪＩＲｅｃｅｉｖｅｄ９Ａｕｇｔｔｓｔ１...

关键词：掌指关节指尖手指指间关节指关节 Continuous excursion Finger Flexor Machine Measurement Motion Passive Produced Tendons

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On the Possibility of Obtaining a High Resolution Relative Paleointensity Record of the Pringle Falls excursion at the Type Locality of Pringle Falls, Oregon, USA

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Natural Science 2016年第3期8卷 115-124页

作者： Emilio Herrero-Bervera Paleomagnetics and Petrofabrics Laboratory SOEST-Hawaii Institute of Geophysics and Planetology University of Hawaii at Manoa Hawaii USA

In order to further understand the full vector excursional details of the geomagnetic field, a paleomagnetic and rock magnetic study of four sites has been conducted at the type locality of Pringle Falls, Oregon where 827 samples were drilled and spaced along a distance of 5 km, for their detailed directional and relative paleointensity studies. The profiles have registered a high-reso- lution (>10 cm/kyr) paleomagnetic record of the excursion (ca. 211+/13 ka) as recorded by diatomaceous lacustrine sediments. Remanence as well as induced magnetization experiments to investigate the reproducibility of the signal throughout the profiles have been conducted. In addition, low-field susceptibility vs. temperature analysis was performed indicating that the main magnetic carrier is pure magnetite (Curie point 575 ℃). The magnetic grain size also has indicated Single Domain-Multi-Domain (SD-MD) magnetite. The demagnetization was done by alternating field (a.f.) experiments, and the mean directions were determined by principal component analyses. In addition, induced magnetic tests were done, such as magnetic susceptibility (x) analyses, saturation IRM, anhysteretic remanent magnetization (ARM70) as well as the normalization of J17.5 mT/ARM70 to attempt to obtain relative paleointensity records of these sediments in question. The results of the induced rock magnetic tests such as the normalization studies indicate a direct correlation between the decrease of the relative paleointensity variations (i.e. lows) with respect to the directional changes. The detailed behavior of the paleosignal is highly consistent, since they are rapidly deposited sediments providing a detailed representation of the paleofield. The dissected VGP paths in 3 different phases are highly internally consistent and are defined by clockwise and anticlockwise loops traveling from the high northern latitudes over eastern North America and the North Atlantic to South America and then to high southern latit

关键词： Pringle Falls excursion Lacustrine Sediments Geomagnetic Signature

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马氏链的excursion

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高校应用数学学报A辑(中文版) 1986年第2期 157-164页

作者：吴荣杨振明南开大学南开大学

本文将生灭过程的Excursi一文的结果推广到一般马尔可夫链的情形。

关键词：马氏链 excursion 生灭过程概率空间转移矩阵绝对连续状态空间下半连续最小链宁才

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Carbon isotopic record from Upper Devonian carbonates at Dongcun in Guilin, southern China, supporting the world- wide pattern of carbon isotope excursions during Frasnian-Famennian transition

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Chinese Science Bulletin 2003年第2期48卷 1259-1264页

作者： XU Bing GU Zhaoyan LIU Qiang WANG Chengyuan LI Zhenliang Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Nanjing Institute of Geology and Palaeontology Chinese Academy of SciencesNanjing 210008China Guangxi Institute of Regional Geology Survey Guilin 541003China

Two positive d 13C excursions are presented in records from the Frasnian-Famennian (F-F) marine carbon-ate sediments in Europe, America, Africa, and Australia, having been considered as a worldwide pattern, and attrib-uted to enhanced organic carbon burial during the F-F biological mass extinction. However, this worldwide pattern has not been revealed from the well-deposited Late Devonian sequences in southern China. In this paper, a detailed inves-tigation has been made on the Late Devonian section at Dongcun, Guilin, southern China to constrain perturbations in d 13C of carbonates in the F-F deposited sequence. The result from this section also indicates two positive d 13C ex-cursions during the F-F transition. The first excursion with an amplitude of 1.5 occurred at the bottom of linguiformis Zone, later than the early excursion existing in the Late rhe-nana Zone of the Late Devonian profiles in other continents, especially, in central Europe. This difference has been ex-pected to be a result as conodont Palmatolepis linguiformis occurred earlier in southern China than other sites. The second excursion with an amplitude of 2.1 is located at the F-F boundary, same as the records from other continents. This result strongly supports the view that two carbon iso-tope positive excursions during the F-F transition are com-mon in carbonate sediments, resulting from worldwide in-creases of organic carbon burial intensity.

关键词： F-F event d 13C positive excursion mass extinction.

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埃迪卡拉纪Shuram碳同位素负偏事件有机碳氧化假说的定量模型评估

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中国科学：地球科学 2017年第12期47卷 1436-1446页

作者：石炜李超 Thomas J.ALGEO 中国地质大学(武汉)生物地质与环境地质国家重点实验室武汉430074 中国地质大学(武汉)地质过程与矿产资源国家重点实验室武汉430074 Department of Geology University of Cincinnati

埃迪卡拉纪(635~541Ma)记录了地质历史上最大的全球碳循环扰动事件(即"Shuram excursion"事件,简称SE事件).在约25~50个百万年的时间里,全球海水无机碳同位素组成持续负偏,最大负偏至–12‰.这一碳同位素负偏被认为是当时古海洋中存在... 详细信息

埃迪卡拉纪(635~541Ma)记录了地质历史上最大的全球碳循环扰动事件(即"Shuram excursion"事件,简称SE事件).在约25~50个百万年的时间里,全球海水无机碳同位素组成持续负偏,最大负偏至–12‰.这一碳同位素负偏被认为是当时古海洋中存在的超大型溶解有机碳库被完全氧化或空间差异性氧化的结果,同时也被认为是古海洋微型生物碳泵强烈储碳而形成超大型溶解有机碳库的关键证据.随着研究的深入,这一认识受到了挑战,新假说认为陆源沉积老碳的氧化或古海洋海底释放的富烃流体的氧化同样可以导致这一碳循环扰动事件.为解决这一争论,本文基于碳循环质量平衡原理对上述各种假说进行了数值模拟与评估,结果表明:(1)在给定的埃迪卡拉纪大气氧水平下(≤40%目前大气氧水平),全球规模的陆源有机碳氧化假说和溶解有机碳完全氧化假说受限于氧化剂,大气氧将分别在4Myr和6Myr内消耗殆尽,难以在长时间尺度上形成全球规模的–12‰碳同位素负偏信号;(2)全球范围内的富烃流体氧化假说由于对参加反应的流体烃类的需求量过大也面临挑战;(3)全球海洋溶解有机碳库的空间差异性氧化(部分氧化)假说所要求的DOC库部分氧化(<50%)所需的氧化剂和DOC总量都具有可行性.

关键词：碳同位素 Shuram excursion 溶解有机碳大气氧海洋氧化

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A simple model for reconstructing geomagnetic field intensity with (10)~Be production rate and its application in Loess studies

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Science China Earth Sciences 2008年第6期51卷 855-861页

作者： J. Warren BECK NSF-AMS Laboratory University of Arizona

A simple model for reconstructing the paleomagnetic field intensity with (10)~Be production rate was used for the first time in Loess (10)~Be studies of Luochuan profile. Using the LGM (Last Glacial Maxmium) method, the climatic effects and geomagnetic modulation effects on loess (10)~Be was separated and in turn the 80 ka geomagnetic excursion sequence reconstructed, of which the globally remarkable geomagnetic excursion events such as the Laschamp (42 ka), Mono Lake (32 ka) during the Last Glacial period were revealed and the paleo-geomagnetic intensity curve from Loess (10)~Be over the past 80 ka was quantitatively reconstructed. The reconstructed paleo-intensity fits well with the paleo-intensity curves (SINT200 and NAPIS75), which indicates the significance of global criterion of the (10)~Be paleo- intensity curve and the future direction of loess (10)~Be tracing studies. Results show the irregular vari-ability of the East Asian monsoon precipitation in Loess Plateau is the main cause that has resulted in the ambiguity of the geomagnetic modulation of the (10)~Be record in the loess, and the intrinsic source component of the loess (10)~Be and inherited fraction of magnetic susceptibility (SUS) are characterized by the 'quasi-homogeneous distribution' manner.

关键词： (10)~Be LGM geomagnetic excursion paleointensity quasi-homogeneous distribution

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The Mysterious Mid-Carnian “Wet Intermezzo” Global Event

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Journal of Earth Science 2015年第2期26卷 181-191页

作者： James G.Ogg Department of Earth Atmospheric and Planetary Sciences Purdue University Key Laboratory of Biogeology and Environmental Geology of Ministry of Education China University of Geosciences

Approximately 230 million years ago in the middle of the Carnian stage of the Upper Triassic, the sedimentary records in different regional basins display dramatic changes. Tropical carbonate platforms abruptly ended, and engorged river systems left widespread sand-rich layers across inland basins and coastal regions. This pulse lasted less than a million years in some basins, but constituted a permanent shift in others. Following this event, the Late Carnian has the earliest record of significant dinosaurs on land and the emergence of the calcareous nannoplankton in the oceans that now govern Earth＇s carbon cycle. This ＂most distinctive climate change within the Tri- assic＂ has been interpreted by some geoscientists as a global disruption of the Earth＇s land-ocean-biological system. The eruption of the Wrangellia large igneous province may have been the trigger for a sudden carbon-dioxide-induced warming and associated increased rainfall in some of these regions. Indeed, some workers have proposed that this ＂wet intermezzo＂ warming event is a useful analog to aid in predicting the effects of our future greenhouse on land ecosystems and ocean chemistry. However, the understanding of the onset, duration, global impacts and relatively rapid termination of this postulated warming pulse has been hindered by lack of a global dataset with inter-calibrated terrestrial and marine biostratigraphy, precise radio-isotopic ages, stable isotope records of temperature and the carbon system, and cycle-calibrated rates of regional and global change.

关键词： Triassic Carnian climate pluvial Wrangellia carbon isotope excursion dolomite China LIP Yangtze Platform Wet Intermezzo large igneous province.

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非时齐跳跃Markov过程序列到扩散过程的弱收敛

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江苏师范大学学报（自然科学版） 1992年第3期22卷 1-6页

作者：谢颖超徐州师范学院数学系

本文给出了非时齐跳跃Markov过程序列弱收敛于非时齐扩散过程的一般性定理。利用这一定理,证明了非负非时齐跳跃Markov过程序列弱收敛于Brownian excursion和经验分布过程弱收敛于Bown桥。

关键词：非时齐跳Markov过程弱收敛 Brownian excursion Brown桥半鞅

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