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A Speculation: Avian Migration and the K-T Extinction
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作者 Laurence Stephenson 《Natural Resources》 2024年第5期125-129,共5页
One caveat to the dinosaur’s extinction is the conclusion that avian dinosaurs survived and became ancestors of birds. Their mobility enabled them to migrate great distances and find the nutrients needed to survive. ... One caveat to the dinosaur’s extinction is the conclusion that avian dinosaurs survived and became ancestors of birds. Their mobility enabled them to migrate great distances and find the nutrients needed to survive. Given this scenario, could the current observable migration of birds (the “dinosaurian offspring”) now be related? Migration is the regular seasonal movement undertaken by many species of birds, with the most common pattern, flying north in the Northern spring to breed in the temperate or Arctic summer and returning in the Northern autumn to wintering grounds in warmer regions of the south. The primary motivation for migration appears to be food. None of the major North-South migratory pathways fly over the Caribbean but three main fly ways, past to the west of the theorized K-T impact centre. Due to their ability to fly, the “avian Dinosaurs” adapted and survived very quickly in response to the disaster that marked the K-T boundary. It is an interesting speculation that the avian migration that we witness today is rooted in an event that occurred 66 million years ago! But it does explain why the migratory birds mostly fly from Polar summer to polar summer when they could just be as easily fly from Polar zone to the warmer equatorial region and back. In the recent article in Nature by Melanie During about identifying the late spring timing of the “Astro disaster”, it can be cited as consistent with my speculation. A late April early May Impact as suggested by During would have seen these migrations completely. The western migratory routes would have been found to be “luxurious” in vegetation in that first northern autumn after the “Astro-impact” while all eastern routes would have still been barren. 展开更多
关键词 Dinosaur Clades K-T mass extinction Avian Migration Migratory Pathways Avian Dinosaurs K-T Impact Centre
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Determination of aerosol extinction coefficient and mass extinction efficiency by DOAS with a flashlight source 被引量:3
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作者 司福祺 刘建国 +6 位作者 谢品华 张玉钧 刘文清 Hiroaki Kuze 刘诚 Nofel Lagrosas Nobuo Takeuchi 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第11期2360-2364,共5页
With the method of differential optical absorption spectroscopy (DOAS), average concentrations of aerosol particles along light path were measured with a flashlight source in Chiba area during the period of one mont... With the method of differential optical absorption spectroscopy (DOAS), average concentrations of aerosol particles along light path were measured with a flashlight source in Chiba area during the period of one month. The optical thickness at 550 nm is compared with the concentration of ground-measured suspended particulate matter (SPM). Good correlations are found between the DOAS and SPM data, leading to the determination of the aerosol mass extinction efficiency (MEE) to be possible in the lower troposphere. The average MEE value is about 7.6m^2.g^-1 , and the parameter exhibits a good correlation with the particle size as determined from the wavelength dependence of the DOAS signal intensity. 展开更多
关键词 aerosol extinction coefficient differential absorption optical spectroscopy mass extinction efficiency size distribution
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Volcanism at the Permian-Triassic Boundary in South China and Its Effects on Mass Extinction 被引量:21
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作者 Yin Hongfu, Huang Siji, Zhang Kexin, Yang Fengqing, Ding Meihua, Bi Xianmei and Zhang Suxin China University of Geosciences, Wuhan, Hubei 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1989年第4期417-431,450-451,共17页
This paper discusses the clayrocks widespread at the Permian-Triassic boundary, which are mostly of volcanic origin. Volcanogenetic textures, structures and minerals such as high-temperature quartz are found in clayro... This paper discusses the clayrocks widespread at the Permian-Triassic boundary, which are mostly of volcanic origin. Volcanogenetic textures, structures and minerals such as high-temperature quartz are found in clayrocks at the Permian-Triassic boundary in many places. Thousands of microspherules have been collected from the Boundary clayrocks, many of which exhibit the typical features of the process from melting to cooling and solidification. indicating that they were formed by volcanic eruption or extraterrestrial impact. Volcanic effects on the Permian-Triassic mass extinction may be reflected in conodonts, algae and ammonoids. The Boundary clayrocks are found in many Permian-Triassic sections along the coast of Tethys. Their orighin remains to be studied. 展开更多
关键词 Volcanism at the Permian-Triassic Boundary in South China and Its Effects on mass extinction mass
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Stratigraphical Time——Correlation and Mass Extinction Event Near Permian——Triassic Boundary in South China 被引量:2
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作者 Xu GuirongChina University of Geosciences , Wuhan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1991年第1期39-49,共11页
Shaw's method used to correlate 40 sections across the Permo-Triassic boundary in South China is applied in the paper. Two steps are adopted to get an Integral Composite Section (ICS) by synthesizing these data : ... Shaw's method used to correlate 40 sections across the Permo-Triassic boundary in South China is applied in the paper. Two steps are adopted to get an Integral Composite Section (ICS) by synthesizing these data : First , South China is divided into five areas and composite section developed for each area . Then the second step . the Changxing composite section is regarded as a composite standard (CSRS) while the ICS is produced by matching the CSRS with composite sections of the other areas. Three biozones in the Changxingian and two biozones in the Griesbachian can be discerned on the basis of computing Z values in the ICS. These biozones are marked by the Z values which quantitatively represent their time ranges ; therefore , they may increase accuracy of stratigraphic time correlation . The mass extinction at the end of the Permian is an abrupt event that is supported by the relative rate of extinction near the P/T boundary . About 90% of invertebrate species died out by the end of the Permian . The duration of the mass extinction is rather short ,approximately 0.018Ma . 展开更多
关键词 South China the Permian - Triassic boundary stratigraphic time - correlation biostratigraphic events biologic events mass extinction .
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Combination Features,Paleobiogeographic Affinity and Mass Extinction of the Latest Ordovician(Hirnantian) Rugosan Fauna from Northern Guizhou,China 被引量:1
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作者 HE Xinyi CHEN Jianqiang XIAO Jingyi 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2007年第1期23-41,共19页
The rugosan fauna from the Guanyinqiao Bed (latest Ordovician, Hirnantian) of northern Guizhou, China is known to belong to the cold or cool-water type corals. The components of the fauna are solitary corals only, a... The rugosan fauna from the Guanyinqiao Bed (latest Ordovician, Hirnantian) of northern Guizhou, China is known to belong to the cold or cool-water type corals. The components of the fauna are solitary corals only, and corallite septa are generally strongly dilated, especially the streptelasmatid corals are dominant comprising 98% of the whole fauna. The Guanyinqiao Bed is rich in rugosans of 18 genera, which are streptelasnmtid Streptelasma (=Helicelasma), Brachyelasma, Amplexobrachyelasma, Salvadorea, Grewingkia, Borelasma, CrassUasma, Leolasma, KenophyUum, UUernelasma, Paramplexoides, Siphonolasma, Pycnactoides, Dalmanophyllum, Bodophyllum, Axiphoria, Lambeophyllum and cystiphyllid Sinkiangolasma. Although this fauna was fairly abundant in a confined area (northern-northeastern Guizhou, southern Sichuan) during the Hirnantian age, the rugosan mass extinction (generic extinction rate 81%) happened at the end of the Hirnantian Stage. It is conduded that the mass extinction is related to the ending of maximum glaciation and ice cap melting in Gondwana in the southern hemisphere in the latest Hirnantian, resulting in rapid global sea-level rise in the earliest Silurian. In the Upper Yangtze Basin, the sea bottom environments were replaced by anoxic and warmer water during that time, so that the cool-water type rugosan became extinct. The present paper attempts to revise some already described rugose coral genera and species (He, 1978, 1985) and to supplement a few new forms from the Guanyinqiao Bed. Fourteen species of 12 genera are re-described and illustrated, of which one species- Grewingkia latifossulata is new. As a whole, the rugosan fauna of the Guanyinqiao Bed may be correlated with those contemporaneous of North Europe, Estonia and North America, indicating a dose biogeographic affinity to North Europe. 展开更多
关键词 RUGOSA cool-water type corals paleobiogeographic affinity mass extinction latest Ordovician northern Guizhou
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A New View of the Mass Extinctions and the Worldwide Floods 被引量:2
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作者 Alexander N. Safronov 《International Journal of Geosciences》 2020年第4期251-287,共37页
In this study, the reasons for mass extinction in Jurassic were investigated. It was shown that galactic compression led to the activation of terrestrial nuclear reactors, which in turn led to the changes in tectonic ... In this study, the reasons for mass extinction in Jurassic were investigated. It was shown that galactic compression led to the activation of terrestrial nuclear reactors, which in turn led to the changes in tectonic activity, volcano eruptions, LIPs, MORBs, paleoclimate change, drift of continents, narrowing of the Earth, worldwide floods, tsunami, changes in mantle and core structures, in magnetic fields and in sedimentary isotopes. It was shown that the mass extinctions occurred during worldwide floods, caused by the narrowing of the Earth at the time of galactic gravitational compression. It was shown that the average statistical altitude distribution of dinosaurs has a bimodal distribution and corresponds to permanent migrations between the plains and the hills. It has been suggested that the skeletons of dinosaurs are well preserved as a result of covering the bodies of dinosaurs with mud flows of coastal sediments and the soil layers at worldwide tsunami. It was formulated the requirement to paleontology, consisting in the obligatory registration of altitudes of the actual place of the fossils found. The simple explanation of the presence of boundaries in the structure of the Earth is given: the 40K nuclear layer corresponds to the boundary between upper and lower mantle;the 137Cs layer located on the boundary between the lower mantle and the outer core;the Th-U nuclear layer is a border between outer and inner core. The previously abstract theories of subduction and continents drift have a clear and obvious physical sense. It was shown that the standard geological table is a registration book of galactic events during Paleozoic. It is proposed to restore the structure of the galactic arms by the geological deposits on the Earth. It was suggested to create the stations on elevated hills for rescue and regeneration of biological forms in the future. 展开更多
关键词 PLANET Size Milky Way Galaxy Natural Nuclear Reactor mass extinction Sea Level WORLDWIDE FLOOD JURASSIC FOSSILS
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Terrestrial End-Triassic Mass Extinction and the Triassic/Jurassic Boundary of the Junggar Basin,NW China:A Brief Review
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作者 SHA Jingeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2019年第S01期138-139,共2页
1 Introduction The end-Triassic mass extinction event is one of the five global mass extinctions,and destroyed both the marine and terrestrial biological worlds.Though years the marine endTriassic mass extinction(ETE)... 1 Introduction The end-Triassic mass extinction event is one of the five global mass extinctions,and destroyed both the marine and terrestrial biological worlds.Though years the marine endTriassic mass extinction(ETE)event has been widely studied and discussed,and the standard marine Triassic/Jurassic boundary(TJB)(base-Jurassic)has also been determined.However. 展开更多
关键词 TERRESTRIAL end-Triassic mass extinction event climate variability orbital CYCLICITY JUNGGAR Basin
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Late Ordovician mass extinction caused by global warming or cooling?
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作者 Renqiang Liao Weidong Sun 《Acta Geochimica》 EI CAS CSCD 2020年第5期595-598,共4页
The Late Ordovician mass extinction(LOME)was the first global extinction with the destruction of 85%of marine species.However,the cause of LOME is still controversial.Most studies attribute it to large-scale volcanism... The Late Ordovician mass extinction(LOME)was the first global extinction with the destruction of 85%of marine species.However,the cause of LOME is still controversial.Most studies attribute it to large-scale volcanism caused by global cooling or warming.Through analyzing the driving difference between global cooling and warming on large-scale magmatism,the perspective is intended to evoke a hot discussion on the cause of LOME.Did global cooling or warming trigger the LOME? 展开更多
关键词 Late Ordovician mass extinction VOLCANISM GLACIATION
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Biostratigraphy and Mass Extinction Pattern across the Cretaceous/Paleogene Boundary, Northern Alborz, Iran
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作者 Masoud Asgharian Rostami Mohammad Vahidinia +1 位作者 Ebrahim Ghasemi-Nejad Abbas Sadeghi 《Open Journal of Geology》 2013年第1期33-38,共6页
High resolution sampling across the Cretaceous/Paleogene boundary (K/Pg) at the Galanderud section in northern Iran provides the most expanded and continuous section for us to consider biostratigraphy and the mass ext... High resolution sampling across the Cretaceous/Paleogene boundary (K/Pg) at the Galanderud section in northern Iran provides the most expanded and continuous section for us to consider biostratigraphy and the mass extinction pattern of Cretaceous planktic foraminifera. Based on planktic foraminifera, four biozones and five sub-biozones have been identified across the K/Pg boundary. These biozones include the Abathomphalus mayaroensis Biozone (Plummerita hantkeninoides subbiozone), the Guembelitria cretacea Biozone (including two sub-biozones: the Hedbergella holmdelensis and the Parvularugoglobigerina longiapertura), the Parvularugoglobigerina eugubina Biozone (including two subbiozones: the Parvularugoglobigerina Sabina and the Eoglobigerina simplicissima) and finely the Parasubbotina pseudobulloides Biozone. Planktic foraminiferal extinction occurred over a brief period, with 3% of the species disappearing in the late Maastrichtian, and 72% of the species becaming extinct at the K/Pg boundary. About 25% of the species survived into the early Danian. Extinction of 73% of the species at the K/Pg boundary is very compatible with the effect of a large asteroid impact. 展开更多
关键词 BIOSTRATIGRAPHY mass extinction Pattern Cretaceous/Paleogene BOUNDARY NORTHERN ALBORZ Iran
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Law of Physics 20<sup>th</sup>-Century Scientists Overlooked (Part 4): Mass Extinction by Aether Deprivation
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作者 Conrad Ranzan 《Journal of High Energy Physics, Gravitation and Cosmology》 2021年第1期191-209,共19页
Extreme gravitational collapse is explored by utilizing two fundamental properties and one reasonable assumption, which together lead logically to an end-state gravitating structure. This structure, called a Terminal ... Extreme gravitational collapse is explored by utilizing two fundamental properties and one reasonable assumption, which together lead logically to an end-state gravitating structure. This structure, called a Terminal state neutron star, manifests nature’s ultimate density of mass and possesses the ultimate electromagnetic barrier. It is then shown how this structure is central to the remarkable mechanism whereby the density is prevented from going higher. A simple process assures that such density is not exceeded—regardless of the quantity of additional mass. As an example, the discourse focuses on the expected progression and outcome when a compact star of <img src="Edit_2c290d68-3330-4724-9e68-e7f1c9d3df1a.png" width="25" height="15" alt="" />—far more mass than can be accommodated by the basic Terminal state structure—undergoes total gravitational collapse. An examination of what happens to the considerable excess mass leads the discussion to the <i>principle of mass extinction by the process of aether deprivation</i> and its profound implications for black-hole physics and the current revolution in cosmology. 展开更多
关键词 mass extinction Aether Deprivation Process Gravitational Collapse Black Hole Physics Aether Energy Layer Ultimate Density End-State Neutron Star Terminal star DSSU Theory
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Vertical profile of aerosol extinction based on the measurement of O4 of multi-elevation angles with MAX-DOAS 被引量:4
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作者 Fusheng Mou Jing Luo +2 位作者 Suwen Li Wei Shan Lisha Hu 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第8期195-200,共6页
A method for aerosol extinction profile retrieval using ground-based multi-axis differential optical absorption spectroscopy(MAX-DOAS)is studied,which is based on a look-up table algorithm.The algorithm uses parametri... A method for aerosol extinction profile retrieval using ground-based multi-axis differential optical absorption spectroscopy(MAX-DOAS)is studied,which is based on a look-up table algorithm.The algorithm uses parametric method to represent aerosol extinction profiles and simulate different atmospheric aerosol states through atmospheric radiation transfer model.Based on the method,aerosol extinction profile was obtained during six cloud-free days.The O4 differential air mass factor(dAMF)measured by MAX-DOAS is compared with the corresponding model results under different atmospheric conditions(R^2=0.78).The aerosol optical thickness,aerosol weight factor in boundary layer,and the height of the boundary layer are obtained after the process of minimization and look-up table method.The retrieved aerosol extinction in boundary layer is compared with PM2.5 data measured by ground point instrument.The diurnal variation trends of the two methods are in good agreement.The correlation coefficients of the two methods are 0.71 when the aerosol optical thickness is smaller than 0.5.The results show that the look-up table method can obtain the aerosol state of the troposphere and provide validation for other instrument data. 展开更多
关键词 vertical profile of AEROSOL extinction look-up TABLE O4 DIFFERENTIAL air mass factor MULTI-AXIS DIFFERENTIAL optical ABSORPTION spectroscopy
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Dependence of Mixed Aerosol Light Scattering Extinction on Relative Humidity in Beijing and Hong Kong 被引量:4
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作者 LI Cheng-Cai HE Xiu +2 位作者 DENG Zhao-Ze Alexis Kai-Hon LAU LI Ying 《Atmospheric and Oceanic Science Letters》 CSCD 2013年第2期117-121,共5页
The hygroscopic properties of mixed aerosol particles are crucial for the application of remote sensing products of aerosol optical parameters in the study of air quality and climate at multiple scales. In this study,... The hygroscopic properties of mixed aerosol particles are crucial for the application of remote sensing products of aerosol optical parameters in the study of air quality and climate at multiple scales. In this study, the authors investigated aerosol optical properties as a func tion of relative humidity (RH) for two representative me tropolises: Beijing and Hong Kong. In addition to the RH data, mass concentrations of PM10 (particulate matter up to 10 utm in diameter) and aerosol scattering extinction coefficient (aext) data were used. The relationship between the mass scattering extinction efficiency (MEE, defined as O'ext/PMl0) and RH can be expressed by regression func tions asf= 1.52x + 0.29 (re= 0.77),f= 1.42x + 1.53 (re= 0.58),f= 1.19x + 0.65 (re= 0.59), andf= 1.58x + 1.30 (re = 0.61) for spring, summer, autumn, and winter, respec tively, in Beijing. Here, f represents MEE, x represents I/(1-RH), and the coefficients of determination are pre sented in parentheses. Conversely, in Hong Kong, the corresponding functions are f= 1.98x- 1.40 (r^2= 0.55),f = 1.32x - 0.36 (r^2 = 0.26),f= 1.87x - 0.65 (r^2 = 0.64), and f= 2.39x - 1.47 (r^2 = 0.72), respectively. The MEE values for Hong Kong at high RHs (RH 〉 70%) are higher than those for Beijing, except in summer; this suggests that aerosols in Hong Kong are more hygroscopic than those in Beijing for the other three seasons, but the aerosol hy groscopicity is similarly high in summer over both cities. This study describes the effects of moisture on aerosol scattering extinction coefficients and provides a potential method of studying atmospheric visibility and ground level air quality using some of the optical remote sensing products of satellites. 展开更多
关键词 mass extinction efficiency hygroscopicityJBeijing Hong Kong /
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改进和优化黑果枸杞及其制品中花青素测定的pH示差法 被引量:1
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作者 谭亮 杲秀珍 +2 位作者 王环 赵静 李玉林 《食品与发酵工业》 CAS CSCD 北大核心 2024年第4期267-278,共12页
建立一种基于美国官方分析化学师协会(Association of Official Analytical Chemists,AOAC)方法检测黑果枸杞及其制品中花青素含量的改进pH示差法。考察了黑果枸杞及其制品中花青素的最佳提取和检测条件,通过液相色谱-三重四级杆串联质... 建立一种基于美国官方分析化学师协会(Association of Official Analytical Chemists,AOAC)方法检测黑果枸杞及其制品中花青素含量的改进pH示差法。考察了黑果枸杞及其制品中花青素的最佳提取和检测条件,通过液相色谱-三重四级杆串联质谱法鉴别出黑果枸杞中花青素的具体化学结构,并计算出混合花青素的平均摩尔质量。通过分光光度法测得混合花青素的平均摩尔消光系数,对改进后的pH示差法进行方法学验证和花青素的含量测定。结果显示,最佳提取和检测条件如下:黑果枸杞花青素提取溶剂为盐酸-80%(体积分数)乙醇(3∶97,体积比),料液比为1∶100(g∶mL),提取温度为50℃,提取时间为30 min,缓冲溶液稀释5倍后静置平衡20 min。液相色谱-三重四级杆串联质谱法鉴别黑果枸杞中主要以矮牵牛素类花青素为主(占97.96%),黑果枸杞特有的混合花青素平均摩尔质量为912.7 g/mol,平均摩尔消光系数为29591 L/(mol·cm)。pH示差法改进后能够满足方法学验证要求,固体样品和液体样品最低检出限分别为28.2 mg/100 g、0.282 mg/100 mL。方法改进后花青素提取增长率均大于20%,静置平衡20 min后单次检测结果精密度小于0.3%。以矮牵牛素类花青素代替矢车菊素-3-O-葡萄糖苷计算花青素含量平均提高了2.41倍,能真实地反映黑果枸杞及其制品中花青素的含量。 展开更多
关键词 黑果枸杞及其制品 花青素 AOAC法 pH示差法改进 提取和检测条件优化 液相色谱-三重四级杆串联质谱法鉴别 平均摩尔质量和平均摩尔消光系数优化
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Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition:Enlightening from carbon isotopes and molecular fossils 被引量:14
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作者 GONG Yiming1,2, XU Ran1, TANG Zhongdao1, SI Yuanlan3 & LI Baohua4 1. Faculty of Earth Science and State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China 2. Institute of Resources & Environments, Henan Polytechnic University, Jiaozuo 454003, China +1 位作者 3. Department of Computer Science, South-Central University for Nationalities, Wuhan 430074, China 4. Laboratory of Marine Geology, Tongji University, Shanghai 200092, China 《Science China Earth Sciences》 SCIE EI CAS 2005年第10期1656-1665,共10页
Studies show positive shifts of inorganic and organic carbon isotope values (δ 13Ccarb and δ 13Ckerogen) from +0.43 (‰ V-PDB) to +3.54 (‰ V-PDB) and from ?29.38 (‰ V-PDB) to ?24.14 (‰ V-PDB), respectively, B* (B... Studies show positive shifts of inorganic and organic carbon isotope values (δ 13Ccarb and δ 13Ckerogen) from +0.43 (‰ V-PDB) to +3.54 (‰ V-PDB) and from ?29.38 (‰ V-PDB) to ?24.14 (‰ V-PDB), respectively, B* (Ba* = Ba/ (Al2O3 X 15%)) values from 0.015 to 0.144, TOC values from 0.02% to 0.21%, V/Cr values from 0.3 to 2.0, Sr/Ba values from 3.20 to 49.50 in the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone of the Yangdi sec-tion deposited in carbonate slope facies of Guilin, Guangxi, South China, which indicates that biomass, productivity, organic carbon burial and salinity increase and that oxygenation near the boundary between sediments and waters decreases from the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone. Abundance of molecular fossils increases and normal alkanes, isoprenoid hydrocarbon, terpanes and steranes are dominated from the Late Devonian Frasnian to the bottom of Famennian, which shows that the predecessors of molecular fossils of the Frasnian-Famennian (F-F) transition are dominated by marine phytoplankton, zooplankton and benthic bacteria with no photosynthesis. Therefore, it is considered that the F-F transitional mass extinction with a multistage, selection and global synchronizing was caused by bacte-rial-algal proliferating, continuing deterioration of the shallow marine ecoenvironment of the mid-dle-lower latitudes. A simple cause and effect chain can be expressed as: appearance of seed plants and multi-storied forests → enhanced chemical and biochemical weathering and pe-dogenesis → wide development of soils → increasing riverine nutrient fluxes in epicontinental sea → from superoligotrophic to eutrophic in epicontinental sea → proliferating of marine phyto-plankton and zooplankton → frequent red tide and anoxia → mass extinction of shallow marine organisms in the middle-lower latitudes. It is worth notice that the factor drawdown of atmos-pheric Pco2, climatic cooling and sea level falling caused by eutrophication, anoxia and organic carbon burial increasing may be important for the mass extinction. 展开更多
关键词 mass extinction bacteria-algae carbon isotopes molecular fossils biodiversity Late Devonian Guangxi South China.
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硫对地球早期演化和重大地质事件的制约
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作者 李继磊 《矿物岩石地球化学通报》 CAS CSCD 北大核心 2023年第6期1211-1220,I0001,共11页
硫是地球上的关键元素,是重要的氧化剂、示踪剂和挥发分元素,在约束地球演化和诸多地质过程方面起着至关重要的作用。硫是地核中最主要的轻元素之一,在核幔分异过程中,大量硫进入地核;整体硅酸盐地球与球粒陨石的δ^(34)S差异暗示核幔... 硫是地球上的关键元素,是重要的氧化剂、示踪剂和挥发分元素,在约束地球演化和诸多地质过程方面起着至关重要的作用。硫是地核中最主要的轻元素之一,在核幔分异过程中,大量硫进入地核;整体硅酸盐地球与球粒陨石的δ^(34)S差异暗示核幔分异过程中可能存在硫同位素分馏或地球早期存在显著的H_(2)S逃逸。硫同位素非质量分馏(S-MIF)是限定大氧化事件发生、起始时间以及增氧过程最重要的手段,陆壳出露海面造成火山喷气硫种型的变化可能是大氧化事件形成机制之一;海相硫酸盐与沉积硫化物的δ^(34)S差异是反演地史上海水硫酸盐含量进而限定大气氧含量的有效工具。此外,古老克拉通地体金刚石中S-MIF信号揭示了板块构造的启动时间,特殊地层中S-MIF异常指示了超级火山喷发与生物大灭绝的成因联系,海水δ^(34)S突变可能记录了大火成岩省及其诱发的环境剧变事件。本文对硫在地球早期演化和重大地质事件方面所扮演的角色进行了较为系统的综述和总结。 展开更多
关键词 核幔分异 大氧化事件 板块构造 新元古代氧化事件 大火成岩省 生物大灭绝
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古海洋氧化还原条件的遗迹化石定量表征特征:以华南二叠纪末生物大灭绝事件为例 被引量:2
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作者 丁奕 张立军 《古地理学报》 CAS CSCD 北大核心 2023年第2期405-418,共14页
地质历史时期的重大生物—环境事件往往伴随着古海洋海水氧化还原条件的改变,而遗迹化石作为原位保存的生物成因沉积构造,对于解读古海洋氧化还原条件具有显著的优势。通过对前人常用的遗迹学参数进行分析总结,发现遗迹化石多样性、生... 地质历史时期的重大生物—环境事件往往伴随着古海洋海水氧化还原条件的改变,而遗迹化石作为原位保存的生物成因沉积构造,对于解读古海洋氧化还原条件具有显著的优势。通过对前人常用的遗迹学参数进行分析总结,发现遗迹化石多样性、生物扰动强度、潜穴直径、特征遗迹化石组合这4项定量参数可以表征古海洋氧化还原条件的变化。文中以华南二叠系乐平统遗迹化石及生物扰动构造作为研究对象,系统分析了二叠纪末生物大灭绝事件前后遗迹化石参数表征的古海洋氧化还原条件变化特征:自吴家坪期晚期华南古海洋开始出现缺氧,然而该缺氧状态在长兴期不具有持续性,而是呈现出周期性缺氧/贫氧→富氧/有氧的波动特征;在二叠纪末生物大灭绝之前,煤山剖面高精度的定量遗迹学参数指示长兴组24e层顶部存在缺氧事件,并与大灭绝事件有着良好的对应关系。这一实例具体展示了遗迹学参数在古海洋水体氧化还原条件重建中应用前景广阔。 展开更多
关键词 古海洋 氧化还原条件 遗迹化石 生物扰动 二叠纪末生物大灭绝
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三叠纪末期全球生物大灭绝事件研究综述 被引量:2
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作者 侯海海 张华杰 +2 位作者 邵龙义 高莲凤 刘书君 《地质论评》 CAS CSCD 北大核心 2023年第4期1434-1448,共15页
三叠纪末期生物大灭绝是全球地质历史时期5大生物灭绝事件之一,它致使海洋生态系统中约53%的属和80%的种灭绝。显著灭绝的生物包括菊石亚纲、牙形类、放射虫目和陆地四足动物,发生部分灭绝的生物包括腕足动物门、介形亚纲、双壳纲和珊... 三叠纪末期生物大灭绝是全球地质历史时期5大生物灭绝事件之一,它致使海洋生态系统中约53%的属和80%的种灭绝。显著灭绝的生物包括菊石亚纲、牙形类、放射虫目和陆地四足动物,发生部分灭绝的生物包括腕足动物门、介形亚纲、双壳纲和珊瑚纲等。中大西洋火成岩省(CAMP)的爆发与三叠纪末期生物大灭绝在时间上具有较高的一致性,其火山的高强度和大面积喷发被认为是导致此次灭绝事件发生的主要原因。CAMP爆发释放出大量的CO_(2)、SO_(2)和CH_(4)等气体,一方面温室效应促使海平面升高,物种栖息地面积减少、海洋酸化和海洋缺氧等事件直接威胁着海洋和陆地生物的生存环境;另一方面温室效应亦会引发全球性森林火灾,造成陆地植物减少,大量植物碳屑注入海洋使其发生富营养化,又因伴随海洋酸化作用(碳酸化和硫酸化),海洋古生产率发生崩溃。不同地质时期生物大灭绝的发生往往伴随着剧烈的环境变化,在三叠纪末生物大灭绝期,这些变化多表现为古大气成分和古气温动荡、古火灾频繁、海洋酸化、海平面升高和海水缺氧等,它们之间的综合作用最终导致三叠纪末期全球生态系统失稳。在全球多个三叠纪—侏罗纪之交(TJB)剖面均可以识别出3次明显的碳同位素负偏移,最显著的1次发生于瑞替期末,早于TJB。上述情况说明,三叠纪末期生物大灭绝虽然是全球性事件,但并不是1次发生的,具有分阶段性、非同步性、区域性和有选择性等特点。 展开更多
关键词 生物大灭绝 晚三叠世 早侏罗世 火山喷发 环境演化
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Permian–Triassic Conodonts from Dajiang(Guizhou, South China) and Their Implication for the Age of Microbialite Deposition in the Aftermath of the End-Permian Mass Extinction 被引量:23
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作者 Haishui Jiang Xulong Lai +3 位作者 Yadong Sun Paul B Wignall Jianbo Liu Chunbo Yan 《Journal of Earth Science》 SCIE CAS CSCD 2014年第3期413-430,共18页
The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its afterm... The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its aftermath. However, the age of the microbialite event remains controversial. New conodont collection across the Permian–Triassic(P–T) transition from Dajiang(Guizhou Province, South China) in this study enable us to discriminate four conodont zones, in ascending order, they are: Hindeodus parvus zone, Isarcicella lobata zone, Isarcicella isarcica zone and Hindeodus sosioensis zone. The age of microbialite in the P–T transition at the Dajiang Section is considered to be within the Hindeodus parvus zone and thus to clearly post-date the main extinction crisis. Reviewing the age of onset of microbialites throughout the Tethyan regions reveals two different ages: a Hindeodus changxingensis zone age is dominant in south-western and westernmost Tethys, whilst most other regions show microbialite deposition began in the Hindeodus parvus zone. Our investigation also indicates that two conodont changes occur at this time: an increase of hindeodid species immediately following a sequence boundary and the mass extinction, and a phase of extinction losses in the earliest Triassic Isarcicella isarcica zone during highstand development. 展开更多
关键词 Permian–Triassic CONODONT Dajiang MICROBIALITE mass extinction.
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Late Devonian red tide and mass extinction 被引量:14
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作者 GONG Yiming LI Baohua +1 位作者 SI Yuanlan WU Yi 《Chinese Science Bulletin》 SCIE EI CAS 2002年第13期1138-1144,共7页
Molecular stratigraphical, carbonate carbon isotopic, stratigraphical and paleontological data show that algal booming, eutrophication, anoxia, hypersalinity, positive δ13C excursion and biomass decreasing occurred i... Molecular stratigraphical, carbonate carbon isotopic, stratigraphical and paleontological data show that algal booming, eutrophication, anoxia, hypersalinity, positive δ13C excursion and biomass decreasing occurred in the offshore carbonate environments of the Frasnian-Famennian (F-F) transition, which hints that red tide might frequently take place in the F-F transition of Guangxi, South China. We suggest that the mass extinction of the reef ecosystems and the shallow-water marine organisms in the F-F transition of the lower-middle latitudes may be related to the frequent occurrence of red tide in that time. 展开更多
关键词 RED TIDE EUTROPHICATION mass extinction DEVONIAN SOUTH China.
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Chief sources of brachiopod recovery from the end Ordovician mass extinction with special references to progenitors 被引量:10
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作者 戎嘉余 詹仁斌 《Science China Earth Sciences》 SCIE EI CAS 1999年第5期553-560,共8页
Survivor, Lazarus and progenitor taxa are sources of biotic recovery following mass extinction. Investigations of the benthic brachiopods through the latest Ordovician mass extinction shows that progenitors developed ... Survivor, Lazarus and progenitor taxa are sources of biotic recovery following mass extinction. Investigations of the benthic brachiopods through the latest Ordovician mass extinction shows that progenitors developed many evolutionary novelties and successful surviving mechanisms. They are superior to survivors and Lazarus taxa in their ability to adapt to environmental changes. They are the primary source of macroevolution and the ancestors of a number of new taxa. Three kinds of progenitors are recognized based on the Ordovician-Silurian brachiopods from South China: survivor-progenitors, crisis-progenitors and Lazarus-progenitors; the last has the strongest ability to resist adverse environments, and is the most diverse and abundant. 展开更多
关键词 mass extinction biotic RECOVERY progenitors South China Ordovician-Silurian.
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