Magnetic susceptibility variations of the Edicaran cap carbonates in the Yangtze platform and their implications for paleoclimate

Magnetic susceptibility(MS)data were obtained from 11 sections of the Doushantuo(Edicaran)cap carbonate that directly overlies the Nantuo glacial diamictite in the southeastern margin of the Yangtze plat-form.The MS data revealed two regionally correlatable peaks at the bottom and top of the cap carbonate,sepa-rated by an interval of low values.The lower MS peak coincides with high percentage of insoluble siliciclastic residues that are compositionally identical to the matrix of the underlying diamictite,suggesting its origin con-trolled mainly by detrital components during the first phase of cap carbonate deposition at the end of the glacia-tion.The upper MS peak is associated with high clay content and iron sulfides,and can be interpreted as either derived from enhanced greenhouse weathering that could have brought more terrigenous components into the ocean,or the result of ocean anoxia at the late stage of cap carbonate deposition that could led to formation of abundant iron sulfides.The regionally consistent MS curves from the cap carbonates provided the first geo-physical record for the rapid climate change from icehouse to greenhouse conditions in the aftermath of the Neoproterozoic“snowball Earth”event.

Sedimentary and Geochemical Characteristics of Sinian Cap Carbonates in the Upper Yangtze Region

A global\|scale glaciation occurred at about 600 Ma ago. As a result, the Earth became the "Snowball Earth". The glaciation came to the end abruptly when atmospheric carbon dioxide increased to such an extent as to be about 350 times the modern level because of subaerial volcanic degassing. The rapid termination of glaciation would have led to warming of the Snowball Earth and extreme greenhouse conditions would have been created. The transfer of atmospheric carbon dioxide to oceans would give rise to the rapid precipitation of calcium carbonate in warm surface seawaters, thus forming the cap carbonate rocks as observed worldwide today.\; Regionally persisting, thin layers of carbonate rocks directly and ubiquitously overlie Proterozoic glacial deposits almost on every continent, and are commonly referred to as cap carbonates. Their unusual litho\| fabrics, stratigraphically abrupt basal and upper\|level contacts and strongly negative carbonate isotopic signatures (\{δ\{\}\+\{13\}C\-\{carb.\}\} values range from -7.0‰-0‰) suggest a chemical oceanographic origin, the details of which remain unknown. It is proposed that these enigmatic deposits are related to the destabilization of gaseous hydrate in terrestrial permafrost following rapid postglacial warming and flooding of widely exposed continental shelves and internal basins.\; The authors carried out studies on the geochemistry, sedimentology and palaeontology of the Sinian cap carbonates in Guizhou and Hunan provinces, including the occurrence of cap carbonates of unusual fabrics, strongly negative carbon isotopic signatures, and a lot of bitumen nodules. From the results it is suggested that the cap carbonates were formed from solid methane seepage, and it is in agreement with Kennedy’s viewpoint (2001) that the cap carbonates resulted from the rapid precipitation of calcium carbonate in response to solid methane seepage.

Chemostratigraphy and lithological characters of Neoproterozoic cap carbonates from the Kuruktag Mountain, Xinjiang, western China

The Neoproterozoic Era includes some of the most largest ice ages in the geological history. The exact number of glaciations is unknown, though there were at least two events of global glaciation. Neoproterozoic glacial deposits in the Kuruktag Mountain, Xinjiang, western China have proven that there had occurred three discrete Neoproterozoic glaciations. Diamictite units occurred in the Bayisi, Tereeken, and Hankalchough formations, carbonate units were recognized among the diamictites and immediately overlied the Bayisi, Tereeken and Hankalchough diamictites. Carbonates at the top of the Bayisi Formation are characterized by the dolo-sility stones with negative δ13C values ranging from -4.10‰ to -8.17‰ (PDB), comparable to the Sturtian cap carbonates that overlie the Sturtian glacial deposits from other Neoproterozoic sequences. Carbonates overlying the Tereeken Formation are characterized by the pinkish cap dolostones (ca. 10 m thick) with negative δ13C values ranging from -2.58‰ to -4.77‰ (PDB), comparable to the Marinoan cap carbonates. The cap is also characterized by tepee-like structures, barite precipitates and pseudomorphous aragonite crystal fan limestones. Carbonates at the top of the Hankalchough Formation are characterized by subaerial exposure crust (vadose pisolite structure, calcareous crust structure) dolostones with negative δ13C values ranging from -4.56‰ to -11.45‰ (PDB) and the calcareous crust dolostones, implying that the Hankalchough cap carbonates differ from either the Sturtian or Marinoan cap carbonates in sedimentary environment and carbon isotopic composition. In addition, it is suggested the Hankalchough glaciation belongs to a terrestrial glaciation and it is the third largest glaciation during the Neoproterozoic period on the Tarim platform.

New Computerized Method for the Geochemical Classification of Precambrian Carbonate Rocks: Case of a Set of African Cap Carbonates

Post-sedimentary transformations have masked or completely obliterated the structures and textures of Precambrian carbonate rocks. Therefore, methods of classification of the carbonate rocks founded on the observation of primary structures or textural characteristics are ill-adapted. Consequently, only certain geochemical classification methods allow us to distinguish the various rock-types in the case of Neoproterozoic carbonates. After presenting the most suitable geochemical classifications, we propose a new classification into 14 groups based on a regular ternary diagram with computerized data input. For each sample of carbonate rock, analysis of calcium and magnesium contents allows us to calculate the input data for our diagram i.e. the percentages of Calcite, Dolomite and Insoluble Residue. To automate the application of this diagram, input parameters are created in a descriptive file “Roches.ternaires.txt” using an option called “Ternaires” in the “Diagrammes” software developed by Roland Simler. Thirty cap carbonates of Africa are used to validate this new method.

A high-resolution chemostratigraphy of post-Marinoan Cap Carbonate using drill core samples in the Three Gorges area, South China

Cap Carbonates overlie the Marinoan Snowball Earth-related glacial diamictite, and possibly record the drastic surface environmental change and biological evolution after the Snowball Earth. We conducted on-land drilling from the Liantuo Formation, through the Nantuo, to the lower Doushantuo Formation in the Three Gorges area of South China to collect fresh, continuous samples in the Three Gorges area. We obtained high-resolution chemostratigraphies of ~13C and 6180 values of carbonates from the topmost part of the Nantuo Formation to the Cap Carbonate, in order to decode the detailed surface environmental change in the shallow marine setting. The δ3C chemostratigraphy possesses some unique characteristics： （1） stable δ13C values as a whole, but ubiquitous low δ13C anomalies through the Cap Carbonate, （2） increase of the δ13C values from -3 to ＋5‰ across the C2/C3 boundary, （3） no δ13C anomaly between the CI and C2 boundary, and （4） presence of an anomalous high δ13C value （＋2.3%0） and a faint positive correlation between δ13C and δ18O values in the C1 unit. Evidence of quite low δ13C anomalies （with a nadir of -41‰）, ubiquitous negative δ13C anomalies through the Cap Carbonate, and a high 613C anomaly accompanied with a faint positive correlation between δ13C and δ18O values in the C1 unit supports decomposition and formation of methane hydrate during Cap Carbonate formation. The drastic increase of δ13C values from the upper C2 to C3 units in- dicates enhancement of primary productivity and organic carbon burial, possibly due to high continental fluxes after the Snowball Earth event, evidenced by high Sr isotope values. The increase is restricted to the proximal side of the inner shelf in South China, and the timing of the increase of δ13C values of carbonates is earlier at Three Gorges area than any other area, suggesting that the enhancement of primary productivity started in the proximal environment because of higher continental influxes. The increase in oxygen contents of seawater due to the enhanced primary productivity possibly resulted in the emergence of multicellular animals soon after Cap Carbonate deposition.

Mineralogical and Geochemical Characteristics of Caprock Formations Used for Storage and Sequestration of Carbon Dioxide

The main objective of the present study is to characterize cap rock formation used for geological storage of carbon dioxide (CO2). The petrophysical properties of several rocks were studied before CO2 injection. This step is necessary for an understanding of CO2-brine-rock interactions. The mineralogical composition of several clay samples collected from real storage sites located in the south of Tunisia was determined by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) coupled to a probe EDS, infrared spectroscopy, thermal analysis and fluorescence spectra. The obtained experimental results reveal that illite, calcite and quartz are the dominant clay minerals. Dolomite and albite are also present. Besides, SEM analysis shows laminated structure for these samples which suggests low crystallinity. This sample contains a higher content of Fe, Cl, Ca and O. The clay cover may also be useful in storage process by immobilizing the migration of CO2 outer of the geological site and activating the process of mineral sequestration.

双重资金约束下考虑碳配额交易的供应链融资决策

构建由生产和减排双重资金约束的制造商和零售商组成的低碳供应链系统,针对银行借贷和提前支付两种融资模式,探究碳配额交易下制造商的融资决策问题,并分析了碳减排成本系数和碳交易价格对融资决策和供应链成员利润的影响.研究发现:当提前支付利率等于银行借贷利率时,无论是否考虑碳配额交易,提前支付融资总会给制造商带来较大利润,因此,提前支付是制造商的最优融资选择.当融资利率不等时,制造商融资方式会受到碳配额交易和碳减排成本系数的影响.碳减排成本系数增大时,融资规模、供应链成员利润均降低,而碳交易价格提高时,融资规模、制造商利润均增加.另外,碳配额交易会增加制造商利润,但会损害零售商利润.

风险规避下考虑碳期货的工程机械再制造企业生产决策研究

在碳限额与交易政策下,研究碳期货对风险规避型工程机械再制造企业生产决策的影响。分别构建无碳期货情形和考虑碳期货情形下风险规避型再制造企业的生产决策模型;利用Kuhn-Tucker条件对模型求解,比较两种情形下的最优解;通过算例分析碳期货和风险规避系数对产量、企业效用、消费者剩余和碳排放总量的影响。研究表明,在企业风险规避程度较高情形下,引入碳期货总是会增加新品产量和总产量,而再制品产量,在完全再制造策略下随之增加,部分再制造策略下随之减少。此外,企业风险规避程度较高时,考虑碳期货情形下的企业效用、消费者剩余和碳排放总量均高于不考虑碳期货情形。

碳中和背景下国家碳预算的理论同构与立法路径

国家碳预算制度兼具碳排放总量控制与统计核算工具的双重功能,碳达峰目标的迫近及碳中和目标下国家降碳任务的紧迫性,使得如何将碳预算融入“双碳”目标的实践过程,实现制度和理论的双向促进成为重要问题。一方面,通过梳理碳预算制度产生的背景、碳预算概念的演变,事实印证了应对气候变化立法,是把承载全球碳排放环境容量的国际碳预算,转移至各国碳预算本土化的可靠实现方式。另一方面,域外国家应对气候变化立法的碳预算制度经验发现,其对我国碳预算目标设置、机制协同、资金渠道等方面具有重要启示。将碳预算纳入我国“双碳”目标实现的法治保障体系,可以结合已有预算法程序化规定,通过建立专门性机构、权责配置、预算调整机制、专项资金供给等制度,建构起“双碳”目标下符合我国需要的碳预算制度体系。

碳限额及碳交易机制下低碳供应链合作促销与减排研究

构建Stackelberg博弈模型,在碳限额及碳交易机制下,考虑由单一制造商和零售商组成的两级供应链,通过制造商和供应链成员之间的合作,来探讨减排与促销策略问题。分析了零售商制造商独自承担各自费用、合作促销和合作减排等情形下供应链成员最优决策。并通过算例分析研究发现:合作促销与合作减排成本分担比例在满足一定条件时都优于独自促销和减排,因此,碳排放依赖较大的行业可以选取合作减排模式,依赖销售努力较大的行业可以选取合作促销模式。

碳限额管制、零售商利他偏好与制造企业的绿色决策研究

随着制造业的快速发展和大众低碳意识的增强,绿色供应链得到了快速发展。以政府主导,一个制造商和一个零售商组成的两阶段绿色供应链为研究对象,设定了制造商购买碳信用额的同时进行绿色技术创新或完全购买碳信用额,零售商有利他偏好或无利他偏好共计4种情境的博弈模型。运用Stackelberg博弈分析了存在碳市场交易情境下的政府碳限额管制、零售商的零售价格、制造商的减碳努力和市场产量。研究表明:政府在零售商无利他偏好时会为制造商制定更宽松的碳排上限;当制造商做出减碳决策后,社会福利、市场需求、产品价格和绿色度并不受零售商有无利他偏好的影响;虽然零售商的利他偏好不利于自己的利润,但它可以帮助增加制造商的利润,从而有利于供应链的稳定;当市场碳价格较低时,鼓励制造商进行绿色技术创新会给社会带来更高的社会福利,反之不进行绿色技术创新能带给社会更高的社会福利。

不确定条件下考虑碳交易与绿色证书交易的区域发电结构优化研究

区域发电结构的优化对实现“双碳”目标具有重要意义。该文探讨同时考虑碳限额交易机制与可再生能源配额制下的区域发电结构优化问题,以中国广东省长期的发电规划为例进行研究。考虑能源政策和相关经济参数等多种不确定因素对规划模型的影响,将区间规划和模糊规划结合到优化模型中去,构建不确定因素下考虑碳交易和绿色证书交易的区域发电结构优化模型。结果表明,不确定优化模型应用到区域电力生产的长期规划中,产生有效的规划结果,可为区域电力绿色低碳转型提供有效的参考意见。

金属离子诱导富含缺陷的二维碳基材料的构筑及其电催化制双氧水性能研究

二维碳基材料具有特殊的电荷传输通道和高效传质界面,是气-液-固三相电催化系统中优异的反应界面。提出了一种新颖的、可方便有效地实现二维碳材料构建的钠离子封端策略,在此基础上通过缺陷羰基化方法将丰富的不饱和含氧基团接枝到二维碳表面。结果表明,最终的产物在H型电解池中表现出高达90%的过氧化氢电催化选择性和270 mmol/(g_(catalyst)·h)的实际过氧化氢生产速率。该研究不仅为二维碳基结构的设计提供了一个新的方法,而且为富含不饱和含氧基团的二维碳在要求快速反应扩散和高密度活性位的气液固三相电催化系统中的应用提供了策略。

碳同位素录井技术在二氧化碳封存中的应用

为监测二氧化碳地质封存状态、评估封存效果,在钻井过程中对各个地层烃类和二氧化碳含量及碳同位素进行测量。检测结果表明,钻井液气碳同位素的纵向变化与油气藏储盖组合的划分具有一定的相关性,可为二氧化碳封存圈闭密封性评价提供依据,二氧化碳封存后可对盖层的封闭性评价及二氧化碳封存状态进行监测。

碳配额交易政策下闭环供应链谎报决策与协调研究

本文以单制造商和单零售商组成的闭环供应链为研究对象,考虑碳配额交易政策下制造商回收努力难度和新产品单位碳排放量信息不对称,探讨不同权力结构下制造商的谎报行为及其对供应链绩效的影响。研究发现:制造商主导供应链时,制造商不会谎报其私有信息;零售商主导供应链时,制造商会低报回收努力难度同时高报新产品单位碳排放量;制造商与零售商权力均等时,制造商仅高报新产品单位碳排放量。制造商的谎报行为始终会损害零售商及供应链总体利润。针对制造商的谎报行为,本文采用两部定价契约进行协调,并验证了该契约能有效激励制造商反馈真实信息,并使供应链绩效达到最优。

碳配额交易背景下双渠道供应链减排决策研究

在碳配额交易政策实施与电子商务快速发展背景下,本研究考虑碳配额约束、碳交易价格、消费者低碳偏好和渠道偏好,构建了单一线下渠道减排、双渠道不减排和双渠道减排决策模型。本研究进一步以企业利润最大化为目标,分别求解得到渠道定价、减排努力程度和渠道选择最优决策。研究发现,双渠道供应链中,消费者低碳偏好对减排决策及供应链各主体利润有正向影响;碳配额对碳减排率有线性正向影响;碳配额交易价格对碳减排率影响与单位产品初始碳配额大小有关,随着碳交易价格增加碳减排率先增加后降低;零售商利润不受碳配额交易政策影响;当渠道偏好程度和低碳偏好程度在某一范围时,制造商开辟线上渠道或进行碳减排投资能够获得更多利润。

碳限额及交易下同时考虑制造商和零售商的中小企业低碳供应链补贴策略

零售商的低碳营销有利于扩大低碳产品市场规模,进而激励制造商低碳生产,但目前政府碳补贴多只针对制造商,缺乏对不同补贴策略的对比分析,且缺乏对中小企业所在供应链的补贴研究。为此,在考虑碳限额及交易的背景下,分别构建无政府补贴、补贴制造商、补贴零售商和分别补贴制造商与零售商的4种补贴博弈模型,并通过数值仿真分析,探讨不同补贴模式下低碳供应链上下游企业低碳努力决策、消费者低碳产品需求量以及社会总福利的差异,为政府制定补贴策略提供参考。研究发现:政府采取碳补贴策略能够有效激励制造商降低碳排放和零售商进行低碳营销,进而扩大低碳产品市场规模;采取补贴制造商策略的减排率最高;采取分别补贴策略时可以获得最优社会福利,但当存在补贴额度限制即补贴力度较小时,采用补贴零售商策略在同补贴额下能获得更高的社会福利;无论政府是否采取补贴策略,消费者低碳偏好、补贴率对减排率、低碳营销努力水平、低碳产品需求量有正向激励作用,而碳价与低碳营销努力水平和产品需求量呈负向变化关系。由此可以得到启示,政府应当加大对中小型制造企业的减排补贴力度,注重培养消费者环境保护意识和低碳意识,同时对碳价进行合理调控,激励企业低碳转型。

碳限额下考虑风险规避的低碳供应链联合减排决策研究

在一个制造商和一个零售商组成的二级供应链中,探讨碳限额和供应链成员风险规避行为对系统成员决策的影响,最后通过数值算例进行验证。研究结果表明:碳限额交易政策下拥有主导权企业获利更多,调整碳交易价格可以有效协调供应链成员的利润;系统成员风险规避特性不利于制造商和零售商的联合碳减排,且对系统成员自身效用具有负效应;零售商分担减排成本行为能减弱制造商风险规避特性对其自身效用的负效应,却加重了自身风险规避特性对效用的损害;集中决策下的联合减排效果最佳,分散决策下供应链效益更优。

考虑碳交易与产品损失率的农产品供应链优化配置

农业是碳排放的重要来源,为了减少农产品供应链的碳排放,文章研究了考虑碳排放限额与交易(即碳交易)及农产品损失率的多级农产品供应链优化配置问题,建立了非线性规划模型,并以某企业的农产品(苹果)供应链为例,利用基于PSO和GA的混合算法对模型进行求解,比较优化工具Lingo的求解结果,验证了混合算法的有效性;最后,为了研究碳排放限额,碳交易价格和农产品损失率对优化配置结果的影响,分别对其做了一系列敏感性分析,获得一些重要管理学启示。