Early Cambrian eodiscoid trilobites of the Yangtze Platform and their stratigraphic implications

Analysis of the taxonomy and stratigraphic distribution of the Early Cambrian eodiscoid trilobites of the Yangtze Platform indicates that species of Tsunyidiscus and Hupeidiscus can be used for biostratigraphic correlation. T. aclis occurs only in the lower Qiongzhusian, T. armatus occurs in the lower and middle Qiongzhusian, while T. niutitangensis and T. tingi occur mainly in the middle and upper Qiongzhusian, with only T. tingi extending upward into the lower Canglangpuian. H. orientalis first appears in the upper Qiongzhusian, reaching peak abundance in the lower Canglangpuian and becoming extinct above the Drepanuroides Zone. Biostratigraphic and lithostratigraphic correlations indicate that the limestone in the lower part of the Mingxinsi Formation, the Upper Member of Jiumenchong Formation, and the upper part of the Middle Member of the Huangbailing Formation, can be correlated with each other as Hupediscus, an index fossil of the lower Canglangpuian, is abundant in all these units. The lower part of the Niutitang and Jiumenchong formations in eastern Guizhou, which mainly represent Qiongzhusian strata, can be correlated with the Lower Member of the Huangbailing Formation. The basal part of the Niutitang Formation, which may be equivalent to the Upper Meishucunian Shiyantou Formation in eastern Yunnan, is very condensed. Well-preserved sponge faunas and non-mineralized fossils in the lower part of the Niutitang and Hetang formations are not older than Qiongzhusian in age.     

Phosphatized biotas from the Neoproterozoic Doushantuo Formation on the Yangtze Platform

The Doushantuo Formation in South China was deposited after the Nantuo glaciation but before the evolution of complex Ediacaran metazoans. It contains multiple taphonomic windows, in its cherts, carbonaceous shales, and phosphorites, onto the late Neoproterozoic biosphere. The phosphatic window is unusually clear; Doushantuo phosphorites at Weng'an (Guizhou Province) are known to exquisitely preserve a multitude of single-celled eukaryotes, multicellular algae, and microscopic animals. Our recent survey reveals that, in addition to the now famous Weng'an locality, Doushantuo phosphorites at Baokang (Hubei), Chadian (Shaanxi), and Shangrao (Jiangxi) also contain diverse eukaryotes preserved at the cellular level. All these phosphorites were deposited in shallow-water environments, typically above fair weather wave base and close to ancient islands. Along with Doushantuo cherts and shales, these phosphorites give us a clearer and more complete picture of late Neoproterozoic biological evolution: there is a remarkable diversification of multicellular eukaryotes shortly after several Neoproterozoic glaciation events.     

Plankton from Early Cambrian black shale series on the Yangtze Platform, and its influences on lithologies

Blackshalesandcherts ,containingnodularphosphoritesandorelayers[1] arecommonintheEar lyCambriandeeperwaterfaciesoftheYangtzePlat form[2 ] andoffera goodchanceformicropaleonto logicalresearchusingtechniquesofchemicaldissolu tion ,peelingandsectioning .Wetriedtoseparateandinvestigateoceanicplanktoncommunitiesfrombitu minous,“deeperwater”chert ,blackshale andphosphoritelithologies ,andtodocumenttheirpreser vationandinfluencesonthecompositionofthesedi ments .Thepresentpaperaimsatgivingareportof…     

Isotopic evolution of the terminal Neoproterozoic and early Cambrian carbon cycle on the northern Yangtze Platform, South China

Profound geotectonic, climatic and biological changes occur during the terminal Neoproterozoic and its transition into the early Cambrian. These are reflected in temporal variations of the chemical and isotopic composition of seawater. We are studying a sequence of sedimentary rocks at the Shatan section, northern Yangtze Platform, Sichuan Province of China. This succession comprises, in ascending stratigraphic order, predominantly calcareous sediments of the Sinian upper Dengying Formation and black shales of the lower Cambrian Guojiaba Formation (time equivalent of Niutitang Fm.). Paleoenvironmental setting represents shallow-water shelf deposits. The objective of our study is to provide temporal records for the isotopic compositions of organic and carbonate carbon throughout this time interval. Organic carbon isotope values display a range between -35.8‰ and -30.1‰ with clear stratigraphic variations. Carbonate carbon isotope data vary between -3.5‰ and +0.5‰. These secular variations are interpreted to reflect perturbations of the global carbon cycle, specifically changes in the fractional burial of organic carbon. However, local conditions have further affected the isotopic signals.     

扬子板块西北缘早志留世层序地层分析

本文简述了层序地层学的意义及经典层序地层学理论的由来,并以层序地层学理论为指导,结合扬子板块西北缘早志留世法表海级坡环境的特.点,研究了本区层序地层的特殊性,进而指出经典层序地层理论在法表海缓坡环晚沉积组合中并昨完全适合,必须加以补充和修正.本文还讨论了凝缩层在本区的生油意义。     

Late Neoproterozoic to early Cambrian sulphur cycle-An isotopic investigation of sedimentary rocks from the Yangtze Platform

The sulphur cycle responds to changes in seawater chemistry, biological evolution and tectonic activity. We follow an isotopic approach in order to constrain the state of the ocean/atmosphere system during late Neoproterozoic and early Cambrian. For this purpose, a sedimentary succession deposited on the Yangtze Platform, South China, was analysed for its sulphur isotopic composition in different S-bearing phases. Redox changes were defined by the degree of pyritization (DOP) values in order to show variations in the oxygenation of the depositional environment. The sulphur isotopic composition of late Neoproterozoic to early Cambrian seawater sulphate ranges from +30‰ to +35‰ as evident from trace sulphate in unaltered carbonates and phosphorites. The isotopic composition for pyrite and organic sulphur varies between -16‰ and +23‰. The apparent sulphur isotopic fractionation between seawater sulphate and pyrite as well as organically bound sulphur varies between 7‰ and 50‰. This large fractionation, as well as its variability suggests a biological origin for pyrite and organically bound sulphur. The temporal evolution of different geochemical proxy signals is comparable for different successions across the Yangtze Platform.     

Stratigraphic implications of Sinian-Early Cambrian volcanic ash beds on the Yangtze Platform

Volcanic ash beds from shallow- to deep-water facies strata of the Sinian-Early Cambrian (Meishucunian) on the Yangtze Platform consist of bentonites and tuffites which are readily recognized in the field by their physical features and confirmed by geochemical analyses.Geochemistry suggests that the volcanic ash beds in Meishucunian time are rhyolite and rhyodacite while those in the Qiongzhusian and Sinian are andesite and trachyandesite.The ash beds in the time-equivalent strata, even in different areas display rather similar geochemical features, whereas the ash beds in different strata even in the same areas show large chemical difference.The results suggest that these ash beds can be used for intra- and extra-basinal correlations of the Sinian-Early Cambrian interval on the Yangtze Platform.Additionally, these ash beds suggest high potentials for further U-Pb dating strategies.     

Petrogenesis of the Neoproterozoic bimodal volcanic rocks along the western margin of the Yangtze Block： New constraints from Hf isotopes and Fe/Mn ratios

High-precision major element and Hf isotope data are reported for the Neoproterozoic Suxiong volcanic rocks along the western margin of the Yangtze Block. These volcanic rocks have variable εHf（T） values and Fe/Mn ratios. The relatively primitive basalts have high Fe/Mn ratios and high Hf-Nd isotopic compositions, indicating that they were generated by partial melting of garnet clinopyroxene in mantle plume at high pressure. Thus, the Suxiong basalts are genetically related to the proposed Neoproterozoic superplume. On the contrary, a few differentiated basalts have low Fe/Mn ratios and low Hf-Nd isotopic compositions. They are likely to experience assimilation-fractional crystallization process. The Suxiong rhyolites have consistent Hf and Nd model ages of 1.3-1.4 Ga. They are likely generated by shallow dehydration melting of pre-existing young arc igneous rocks associated with the basaltic underplating/intrusion in a continental rift.     

我国长江垃圾倾倒防范机制的不足及完善策略——以“长江口倾倒垃圾案”为视角

频繁出现的垃圾倾倒事件已成为建设和谐长江、健康长江、清洁长江、优美长江、安全长江等目标的重要障碍,长江垃圾倾倒防范机制的构建尚存在法律依据不足、责任约束性不够、协同监管机制欠缺等制度障碍,以及地方垃圾处理能力普遍欠缺的现实障碍。我们应秉承"创新、协调、绿色、开放、共享"发展理念,探讨相应的对策,以扭转长江资源环境约束趋紧的状况,促进长江经济带尽快走上生态优先、绿色发展之路。     

Detrital zircon U-Pb ages of Late Cenozoic sediments from the Yangtze delta: Implication for the evolution of the Yangtze River

Detrital zircon grains of Late Cenozoic sediments dated back to ca.3.6 Ma from core DY03 in the Yangtze delta were dated by LA-ICP-MS,in order to investigate the sedimentary provenance and to find some clue for the evolution of the Yangtze River.Most of the detrital zircon U-Pb ages are distributed at 100 300 Ma,350 550 Ma,600 1000 Ma,1400 2000 Ma and 2200 2800 Ma,which correspond well with the main tectonic and magmatic events in the Yangtze drainage.The detrital zircon age patterns show distinct differenc...     

面向区域发展的区域创新服务平台构建研究——以浙江省绍兴县区域创新服务平台为例

首先界定了区域创新服务平台的概念,然后论述了它在提升区域创新能力中的作用,并对其运行机制进行了初步的探讨,最后以浙江省绍兴县区域创新服务平台为案例进行了实证研究。     

能源价格变动对长江经济带宏观经济的影响——基于可计算一般均衡(CGE)模型分析

构建长江经济带开放静态的可计算一般均衡(CGE)模型,通过在标准CGE模型中加入碳排放和能源强度等式,模拟了煤炭、石油及天然气、电力等能源在价格变动情况下,对于区域宏观经济波动、产业部门能源消耗强度和碳排放水平的影响.提出将能源价格作为区域发展战略之一纳入长江经济带发展规划,改善能源结构,稳定宏观经济等建议.     

Zircon U-Pb age and Hf isotope of Quanyishang A-type granite in Yichang: signification for the Yangtze continental cratonization in Paleoproterozoic

Zircon U-Pb age and Hf isotope, and major and trace element compositions were reported for granite at Quanyishang, which intruded into the Kongling complex in Yichang, Hubei Province. The results show that the Quanyishang granite is rich in silicon and alkalis but poor in calcium and magnesium, and displays enrichment in Ga, Y, Zr, Nb but depletion in Sr and Ba, exhibiting the post-orogenic A-type affinity. 90% zircons from the granite are concordant, and give a middle Paleoproterozoic magmatic crystallization age (mean 1854 Ma). Initial Hf isotope ratios (176Hf/177Hf)i of the middle Paleoproterozoic zircons range from 0.280863 to 0.281134 and they have negative eHf(t) values with a minimum of -26.3. These zircons give the depleted mantle model ages (TDM) of 2.9―3.3 Ga (mean 3.0 Ga), and the average crustal model ages (Tcrust) of 3.6―4.2 Ga (mean 3.8 Ga). A Mesoarchean grain with 207Pb/206Pb age of 2859 Ma has a slightly high TDM (3.4 Ga) but similar Tcrust (3.8 Ga) to the Paleoproterozoic zircons. All these data suggest that the source materials of the Quanyishang A-type granite are unusually old, at least ≥2.9 Ga (even Eoarchean). The event of crustal remelting, which resulted in the formation of the Quanyishang granite in the middle Paleoproterozoic, recorded the cratonization of the Yangtze conti-nent. The process may have relation to the extension and collapse of the deep crust with Archean ages, in response to the transition stage of the assembly and breakup of the Columbia supercontinent.     

基准面旋回对储层宏观非均质性的控制——以胡状集油田沙三中6—8油层组为例

储层层间非均质性与沉积微相和砂体发育规律关系密切,明显受控于基准面升降造成的可容空间变化和沉积物通量大小.通过对胡状集油田沙三中6—8油层组基准面旋回的识别、划分与对比,建立了该区高分辨率层序地层格架,采用砂岩分层系数、分布密度和隔层密度、频率等参数描述了各中期旋回储层层间非均质性变化,认为储层宏观非均质性受控于基准面的旋回变化,长期基准面上升的早期和下降的晚期形成的中期旋回,储层非均质性弱,长期基准面旋回由上升到下降的转换时期储层非均质性强.     

“引江济太”工程背景下河网稀释净污需水计算及其应用

在分析河网水体稀释容量和自净容量的基础上，以太湖流域“引江济太”工程为契机，探讨河网水系污染物稀释扩散和截留净化规律，建立河网稀释净污需水量的计算模式，给出引水总量和流量确定的方法．以张家港市引长江水改善市区河网水环境工程为例，研究引长江水改善水环境的总体方案和实施的可行性，运用河网一维水量水质模型，分析计算各种引水方案，并进行引水效果预测评估，确定了张家港市区河网的引水量和引水方案，为“引江济太”工程的实施提供理论依据和技术支持．     

疫情应对中政务短视频传播策略研究以哔哩哔哩平台为例

本研究对哔哩哔哩平台与疫情相关的、播放量最高的政务短视频进行了考察,并且对每个视频按照热度选取一级评论来分析视频的网络情绪。研究发现,疫情应对中政务短视频传播效果较好,网络情绪正向为主。研究认为,需要进一步发挥政务短视频在疫情应对中的作用,打造优质的视频内容,采取积极的营销措施,并利用新技术促进政务短视频传播。     

Studies on the osteology of the bagrid catfishes from the Jialing River（IV）：an approach to the phyloge－neti

ＳｔｕｄｉｅｓｏｎｔｈｅｏｓｔｅｏｌｏｇｙｏｆｔｈｅｂａｇｒｉｄｃａｔｆｉｓｈｅｓｆｒｏｍｔｈｅＪｉａｌｉｎｇＲｉｖｅｒ（ＩＶ）：ａｎａｐｐｒｏａｃｈｔｏｔｈｅｐｈｙｌｏｇｅ－ｎｅｔｉｃｒｅｌａｔｉｏｎｓｈｉｐＺｈａｎｇＹａｏｇｕａｎｇ；ＷａｎｇＤｅ...     

A new approach to the generation of initial perturbations for ensemble prediction: Conditional nonlinear optimal perturbation

Conditional nonlinear optimal perturbation （CNOP）, which is a natural extension of singular vector （SV） into the nonlinear regime, is applied to ensemble prediction study by using a quasi-geostrophic model under the perfect model assumption. SVs and CNOPs have been utilized to generate the initial perturbations for ensemble prediction experiments. The results are compared for forecast lengths of up to 14 d. It is found that the forecast skill of samples, in which the first SV is replaced by CNOP, is comparatively higher than that of samples composed of only SVs in the medium range （day 6-day 14）. This conclusion is valid under the condition that analysis error is a kind of fast-growing ones regardless of its magnitude, whose nonlinear growth is faster than that of SV in the later part of the forecast. Furthermore, similarity Index and empirical orthogonal function （EOF） analysis are performed to explain the above numerical results.     

构建最新科研成果大众化传播的有效机制——中国科协科技期刊与新闻媒体见面会实施情况评述

介绍了中国科协科技期刊与新闻媒体见面会制度的缘起,以及近两年来的实施情况和实施效果,认为见面会制度构建了学术期刊发表的最新科研成果大众化传播的有效机制,实现了学术期刊、论文作者、新闻媒体和社会公众多方共赢,同时指出了见面会制度目前存在的不足;简要介绍了国外科研成果发布的"限时禁发"制度以及相应的惩戒措施;提出了改进和完善见面会制度的具体建议.