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1.
吴明清 《矿物学报》1998,18(1):17-22
本文研究了贵州望谟乐康深水槽谷相二叠/三叠系界线剖面的有机碳同位素记录。研究结果表明,乐康剖面上二叠统δ13Corg值的变化幅度不大,越过第34层进入第35层以后,在WL-16号样品层位上,δ13Corg值突然从WL-15号样品的-25.419‰降低到-28.235‰,衰减幅度达到近3‰;其后δ13Corg值逐渐回升,并进入下三叠统。根据δ13Corg值的突然衰减正好发生在第34,35层的界线过渡层内这一事实,我们认为乐康剖面的P/T界线应划在第35层的WL-16号样品层位上。由于沉积有机物的碳同位素组成与海洋生物原始生产率(primaryproductivity)密切相关,因此,贵州乐康二叠/三叠系界线剖面的有机碳同位素变化曲线,不仅可以作为精确划分地层界线的一种新的有效手段,而且反映了海洋原始生产率的变化情况。  相似文献   

2.
早元古代碳同位素突变的发现   总被引:3,自引:0,他引:3       下载免费PDF全文
钟华  马永生 《地质学报》1995,69(2):185-191
本文较详细较系统地研究了早元古代碳酸盐岩的碳同位素组成。样品采自山西五台县滹沱群建安村组,大关洞组和槐荫村组。平均采样间距6。9m,分析样品总数209个,所分析的样品全部为泥晶白云岩。碳同位素分析结果,清楚地显示了建安村组一大关洞组界线处以及大关洞组一槐荫村组界线附近碳同位素突变的存在。这次在前寒武系中发现的碳同位素突变,与白垩系-第三系、二叠系-三叠系、寒武系-前寒武系等界线层碳同位素突变类似。  相似文献   

3.
王国庆  夏文臣 《现代地质》2003,17(4):378-386
湖北黄石二门二叠系/三叠系界线剖面出露完好,原始沉积连续,由乐平统龙潭组保安段灰黑色硅质岩、大隆组黑色硅质岩—硅质泥岩和下三叠统大冶组黑灰色泥岩以及泥岩夹灰岩组成,为介于典型浅水碳酸盐岩型与深海硅质岩型二叠系/三叠系界线剖面之间的半深海剖面。长兴阶可划分为Clarkinasubcarinata—Clarkinawangi及Clarkinachangxingensis两个牙形刺带。后者又可划分为3个亚带,自下而上依次为Clarkinachangxingensischangxingensis—Clarkinadeflecta亚带、Clarkinameishanensis亚带及Waning—Clarkina亚带,完全可以与二叠系/三叠系界线的全球层型剖面与点进行对比。另外,二叠纪末牙形刺的生态演化呈阶段性绝灭模式;有机碳同位素值在二叠纪/三叠系界线处出现明显的负偏移,指示了二叠纪/三叠纪之交生物绝灭后海水表层水原始产率的降低以及大气和海水中CO2含量的增加。  相似文献   

4.
中国煤山剖面二叠系/三叠系(P/T)事件界线地层以赋存白粘土和黑粘土著称。本文采用六氟化硫方法经质谱测定发现,白粘土中的自形晶石膏、白粘土中的全溶提取石膏和黑粘土中的全溶提取石膏,其s同位素均呈显著负值:δ^34Sv-CDT均值依次为一9.2‰、-10.7‰和~15.6‰;δ^33Sv-CDT均值依次为-4.6‰、-5.5‰和-8.2‰。P/T事件界线地层中硫酸盐(石膏)s同位素如此极端负异常在煤山剖面尚属首次发现;在其他P/T剖面乃至在与生物灭绝议题相关的全球其他重要地层界线剖面,迄今也未见类似报道。本文还测定出与白粘土密切相关并紧邻的似黄铁矿的铁硫化物(FeS),其S同位素的δ^34Sv-CDT均值为 1.3‰和δ^33Sv-CDT均值为 0.7‰,且研究中未见任何生物或有机成因黄铁矿痕迹。这在相当大的程度上排除了这里的极轻硫石膏的生物或有机次生来源的可能性。因此,本文揭示的显著负硫同位素石膏很可能在自然界中也是罕见的,值得进一步积累数据和深入研究。另一方面,煤山剖面P/T事件界线层原本富含石膏,其极轻硫同位素特征的发现很可能成为一个重要突破口,有利于从新的角度认识和探索P/T转折期的灾变与环境变化。  相似文献   

5.
广西东攀P-T界线深水相剖面与煤山剖面地层学对比   总被引:1,自引:0,他引:1  
从放射虫生物地层学、黏土矿物事件地层学和有机碳同位素地层学方面对广西柳桥地区东攀二叠系-三叠系深水相剖面进行了研究,并与浙江煤山剖面(GSSP)同期地层进行了对比.结果表明,东攀剖面上二叠系-三叠系界线处与煤山剖面具有较好的可比性:①东攀剖面放射虫A.yaoi带可以与煤山剖面的Clarkina changxingensis-C.postwangi-C.postsubcarinata-C.deflecta组合带对比;②两剖面都具有性质相似、延伸稳定的界线黏土岩;③在两剖面界线黏土岩中,有机碳同位素组成都发生了巨减.  相似文献   

6.
本系统研究了扬子地台西缘宁蒗泸沽湖地区志留系沉积旋回及海相碳酸盐岩的锶、碳、氧同位素特征,并对同位素曲线演化规律与海平面变化和区域地壳运动的关系进行了探讨。研究结果表明,本区志留系除底部有少量细碎屑岩沉积外,主要为浅海潮坪相碳酸盐岩沉积,其锶、碳、氧同位素值变化范围分别是0.7093~0.7196、-1.28‰~2.74‰和-1.302‰~-10.721‰;平均值分别是0.7114、0.984‰和-7.810‰。由于受区域地壳隆升运动的影响,同位素组成和同位素演化规律与海平面变化的关系并不明显。  相似文献   

7.
广西中-上泥盆统界线附近的化学地层学特征   总被引:5,自引:1,他引:5  
中国广西是世界上泥盆系发育最好的地区之一 ,沉积相齐全、出露良好 ,是进行地层学及沉积相研究的理想地区。大乐剖面与马鞍山剖面直线距离约为 7km,根据生物地层学的研究 ,两剖面中 -上泥盆统 (D2 - D3 )界线附近发生了明显的穿时现象。化学地层学的研究表明在这两条剖面上的界线附近 disparilis带内碳同位素组成发生了明显的两次负向波动 ,波动幅度分别可达 1.1‰和 0 .8‰ (马鞍山军田剖面 )和 1.5‰和 1.3‰ (大乐剖面 ) ;两条剖面上该牙形石化石带内及上下地层中元素锶 (Sr)的含量波动趋势同样可以很好地对比 ,本研究结果显示了岩石地层学界线的穿时现象并纠正了以往用岩石地层学特征划定 D2 - D3 界线的错误  相似文献   

8.
扬子台区二叠-三叠系界线层综合地层学研究   总被引:6,自引:0,他引:6       下载免费PDF全文
华南二叠-三叠系界线研究一直在地学界备受瞩目.目前被广泛接受的界线标准化石为牙形石Hindeodusparvus,该化石的首现位置被定义为二叠-三叠系界线层型剖面点.然而在全球研究精度最高的4个候选层型剖面中,生物地层单位的对比问题尚存在分歧,从而影响了区域高精度地层对比框架的建立.在扬子台区丰富的资料及大量二叠-三叠系界线剖面进一步研究的基础上,发现许多剖面上二叠-三叠系界线处具有相似的岩石地层特征.其基本结构为粘土岩层、灰岩或泥灰岩层及粘土岩层沉积组合.从综合地层学角度的研究表明:该套沉积组合(界线层)在岩性特征、生物群总体面貌以及其他事件标志(如同位素年龄、磁性地层、地球化学特征等)上具有一定的对比意义.认为界线层应该是等时的地层单位,是扬子台区二叠-三叠系界线处重要的标志层组,并对这套地层进行了区域性对比.这套地层的发现大大提高了扬子台区二叠-三叠系界线处地层的对比精度.  相似文献   

9.
季长军  吴珍汉  伊海生  夏囯清  赵珍  王霆 《地质学报》2018,92(10):2018-2027
华南海相二叠系-三叠系界线(PTB)剖面研究相当成熟,且滇东黔西和天山地区的陆相PTB剖面也取得了重大突破,但西藏特提斯域该领域研究相对薄弱。在前人建立完整二叠系-三叠系牙形刺生物地层剖面的基础上开展碳氧同位素分析,研究表明西藏文布当桑PTB剖面附近碳同位素明显负偏,但偏移样式与华南煤山剖面突变模式具有明显差异,表现为随时间推移逐渐变小,且变化连续,类似南阿尔卑斯地区PTB剖面变化样式,通过与中下扬子地区代表碳酸盐岩台地相到下斜坡相沉积环境的典型海相PTB地层剖面对比发现,西藏文布当桑剖面与江苏西山浅水碳酸盐岩台地相剖面碳同位素变化曲线高度一致。此外,西藏文布当桑PTB剖面伴随碳同位素负偏,出现了两次明显的氧同位素波动,氧同位素两次负偏对应着海水温度的增加和盐度的降低。  相似文献   

10.
严正  侯鸿飞 《地质科学》1993,28(2):135-144
本文对广西香田晚泥盆世弗拉斯-法门阶界线剖面进行了系统的碳、氧稳定同位素研究。发现随着弗拉斯-法门期之交的生物大量死亡和绝灭,在弗拉斯-法门阶界线层中,碳、氧稳定同位素组成出现了明显的异常。这和白垩—第三系界线灾变事件中出现的异常颇为相似。碳同位素异常达-6.6‰左右,氧同位素出现正异常达2‰。此外,在界线层中出现铱异常为230×10-12g/g。这些表明,上述同位素地球化学异常是地球历史中生物绝灭灾变事件的重要标志。  相似文献   

11.
Most sulfide-rich magmatic Ni-Cu-(PGE) deposits form in dynamic magmatic systems by partial melting S-bearing wall rocks with variable degrees of assimilation of miscible silicate and volatile components, and generation of barren to weakly-mineralized immiscible Fe sulfide xenomelts into which Ni-Cu-Co-PGE partition from the magma. Some exceptionally-thick magmatic Cr deposits may form by partial melting oxide-bearing wall rocks with variable degrees of assimilation of the miscible silicate and volatile components, and generation of barren Fe ± Ti oxide xenocrysts into which Cr-Mg-V ± Ti partition from the magma. The products of these processes are variably preserved as skarns, residues, xenoliths, xenocrysts, xenomelts, and xenovolatiles, which play important to critical roles in ore genesis, transport, localization, and/or modification. Incorporation of barren xenoliths/autoliths may induce small amounts of sulfide/chromite to segregate, but incorporation of sulfide xenomelts or oxide xenocrysts with dynamic upgrading of metal tenors (PGE > Cu > Ni > Co and Cr > V > Ti, respectively) is required to make significant ore deposits. Silicate xenomelts are only rarely preserved, but will be variably depleted in chalcophile and ferrous metals. Less dense felsic xenoliths may aid upward sulfide transport by increasing the effective viscosity and decreasing the bulk density of the magma. Denser mafic or metamorphosed xenoliths may also increase the effective viscosity of the magma, but may aid downward sulfide transport by increasing the bulk density of the magma. Sulfide wets olivine, so olivine xenocrysts may act as filter beds to collect advected finely dispersed sulfide droplets, but other silicates and xenoliths may not be wetted by sulfides. Xenovolatiles may retard settling of – or in some cases float – dense sulfide droplets. Reactions of sulfide melts with felsic country rocks may generate Fe-rich skarns that may allow sulfide melts to fractionate to more extreme Cu-Ni-rich compositions. Xenoliths, xenocrysts, xenomelts, and xenovolatiles are more likely to be preserved in cooler basaltic magmas than in hotter komatiitic magmas, and are more likely to be preserved in less dynamic (less turbulent) systems/domain/phases than in more dynamic (more turbulent) systems/domains/phases. Massive to semi-massive Ni-Cu-PGE and Cr mineralization and xenoliths are often localized within footwall embayments, dilations/jogs in dikes, throats of magma conduits, and the horizontal segments of dike-chonolith and dike-sill complexes, which represent fluid dynamic traps for both ascending and descending sulfides/oxides. If skarns, residues, xenoliths, xenocrysts, xenomelts, and/or xenovolatiles are present, they provide important constraints on ore genesis and they are valuable exploration indicators, but they must be included in elemental and isotopic mass balance calculations.  相似文献   

12.
Between 1985 and 1991, two new mountain protected areas (MTNPA) covering more than 35,000 km2 and based on participatory management models — the Makalu-Barun National Park and Conservation Area, Nepal, and Qomolangma Nature Preserve, Tibet Autonomous Region — were successfully established through the collaborative efforts of Woodlands Mountain Institute and conservationists in China and Nepal. Characteristics common to both projects include the importance of establishing (1) effective rationales, (2) local support constituencies, (3) a senior advisory group, (4) a task force, (5) linkages between conservation and development, and (6) fund raising mechanisms. The lessons derived from the experiences of Woodlands Mountain Institute are of significant value to others in preserving MTNPA. Increased collaboration and communication between all interested in conservation, however, will remain a critical component for expanding mountain protected area coverage to throughout the world.  相似文献   

13.
This article advances critical geographies of youth through examining the spatiality implicit in the imagined futures of young women in rural India. Geographers and other scholars of youth have begun to pay more attention to the interplay between young people’s past, present, and imagined futures. Within this emerging body of scholarship the role of the family and peer group in influencing young people’s orientations toward the future remain underexamined. Drawing on eleven months of ethnographic fieldwork, my research focuses on a first generation of college-going young women from socioeconomically marginalized backgrounds in India’s westernmost state of Gujarat. I draw on the “possible selves” theoretical construct in order to deploy a flexible conceptual framework that links imagined post-educational trajectories with motivation to act in the present. In tracing the physical movement of these young women as they navigate and complete college, my analysis highlights the ways in which particular kinds of spaces and spatial arrangements facilitate and limit intra- and inter-generational contact, and the extent to which this affects young women’s conceptions of the future. I conclude by considering the wider implications of my research for ongoing debates surrounding youth transitions, relational geographies of age, and education in the Global South.  相似文献   

14.
The contents of As, Cd, Cu, Cr, Mg, Mn, Ni, Pb and Zn have been determined in sediment and water samples from Valle de las Garzas estuary and Port Manzanillo (Colima, Mexico) using ICP-AES. The concentrations of these elements were used for a comparative study to determine the distribution of heavy metals and to evaluate which elements reflect natural or anthropogenic backgrounds. For this purpose, seven sampling points were selected: Four of them correspond to the lagoon, and three were situated in the port. Statistical analysis of the mineral content was assessed. Initially, data comparison was assessed by statistical tests for each variable. Principal component analysis was then applied considering the influence of all variables at the same time by obtaining the distribution of samples according to their scores in the principal component space. In this way, four studies were carried out: (1) study of sediments collected during the dry season; (2) study of sediments collected during the rainy season; (3) comparative study between sediments from rainy and dry season; and (4) study of water composition collected during rainy season. From the results of the performed analyses, it can be concluded that metals distribution pattern reflected natural and anthropogenic backgrounds (e.g., sediments from the lagoon, situated at the beginning of the rain channel, presented high contents of Zn and Cu, perhaps related to anthropogenic activities or the influence of igneous sediments).  相似文献   

15.
Partition coefficients of Hf,Zr, and REE between zircon,apatite, and liquid   总被引:25,自引:2,他引:25  
Concentration ratios of Hf, Zr, and REE between zircon, apatite, and liquid were determined for three igneous compositions: two andesites and a diorite. The concentration ratios of these elements between zircon and corresponding liquid can approximate the partition coefficient. Although the concentration ratios between apatite and andesite groundmass can be considered as partition coefficients, those for the apatite in the diorite may deviate from the partition coefficients. The HREE partition coefficients between zircon and liquid are very large (100 for Er to 500 for Lu), and the Hf partition coefficient is even larger. The REE partition coefficients between apatite and liquid are convex upward, and large (D=10–100), whereas the Hf and Zr partition coefficients are less than 1. The large differences between partition coefficients of Lu and Hf for zircon-liquid and for apatite-liquid are confirmed. These partition coefficients are useful for petrogenetic models involving zircon and apatite.  相似文献   

16.
17.
《Chemical Geology》2007,236(1-2):13-26
We examined the coprecipitation behavior of Ti, Mo, Sn and Sb in Ca–Al–Mg fluorides under two different fluoride forming conditions: at < 70 °C in an ultrasonic bath (denoted as the ultrasonic method) and at 245 °C using a Teflon bomb (denoted as the bomb method). In the ultrasonic method, small amounts of Ti, Mo and Sn coprecipitation were observed with 100% Ca and 100% Mg fluorides. No coprecipitation of Ti, Mo, Sn and Sb in Ca–Al–Mg fluorides occurred when the sample was decomposed by the bomb method except for 100% Ca fluoride. Based on our coprecipitation observations, we have developed a simultaneous determination method for B, Ti, Zr, Nb, Mo, Sn, Sb, Hf and Ta by Q-pole type ICP-MS (ICP-QMS) and sector field type ICP-MS (ICP-SFMS). 9–50 mg of samples with Zr–Mo–Sn–Sb–Hf spikes were decomposed by HF using the bomb method and the ultrasonic method with B spike. The sample was then evaporated and re-dissolved into 0.5 mol l 1 HF, followed by the removal of fluorides by centrifuging. B, Zr, Mo, Sn, Sb and Hf were measured by ID method. Nb and Ta were measured by the ID-internal standardization method, based on Nb/Mo and Ta/Mo ratios using ICP-QMS, for which pseudo-FI was developed and applied. When 100% recovery yields of Zr and Hf are expected, Nb/Zr and Ta/Hf ratios may also be used. Ti was determined by the ID-internal standardization method, based on the Ti/Nb ratio from ICP-SFMS. Only 0.053 ml sample solution was required for measurement of all 9 elements. Dilution factors of ≤ 340 were aspirated without matrix effects. To demonstrate the applicability of our method, 4 carbonaceous chondrites (Ivuna, Orgueil, Cold Bokkeveld and Allende) as well as GSJ and USGS silicate reference materials of basalts, andesites and peridotites were analyzed. Our analytical results are consistent with previous studies, and the mean reproducibility of each element is 1.0–4.6% for basalts and andesites, and 6.7–11% for peridotites except for TiO2.  相似文献   

18.
Models have become so fashionable that many scientists and engineers cannot imagine working without them. The predominant use of computer codes to execute model calculations has blurred the distinction between code and model. The recent controversy regarding model validation has brought into question what we mean by a ‘model’ and by ‘validation.’ It has become apparent that the usual meaning of validation may be common in engineering practice and seems useful in legal practice but it is contrary to scientific practice and brings into question our understanding of science and how it can best be applied to such problems as hazardous waste characterization, remediation, and aqueous geochemistry in general. This review summarizes arguments against using the phrase model validation and examines efforts to validate models for high-level radioactive waste management and for permitting and monitoring open-pit mines. Part of the controversy comes from a misunderstanding of ‘prediction’ and the need to distinguish logical from temporal prediction. Another problem stems from the difference in the engineering approach contrasted with the scientific approach. The reductionist influence on the way we approach environmental investigations also limits our ability to model the interconnected nature of reality. Guidelines are proposed to improve our perceptions and proper utilization of models. Use of the word ‘validation’ is strongly discouraged when discussing model reliability.  相似文献   

19.
Pools,riffles, and channelization   总被引:2,自引:0,他引:2  
The addition of regularly spaced deeps (pools) and shallows (riffles) that provide a variety of flow conditions, areal sorting of stream-bed material, cover for wildlife, and a positive aesthetic experience, may be desirable in many channel projects. Such designs will reduce adverse environmental impacts of stream channel modifications. Analysis of variance for pool-to-pool spacing data suggests that there is no significant difference with respect to channel width between pools that form in natural streams and those in streams affected by a variety of human uses. Short of channelization, which changes the channel width, pools and riffles, within limits, are not particularly sensitive to environmental stress. Experiments in Gum Branch near Charlotte, North Carolina, support the hypothesis that channel form and process evolve in harmony and that manipulation of cross-channel morphology can influence the development of desired channel processes. Planned manipulation of its channel form induced Gum Branch to develop as desired. Morphologic stability consisting of incipient point bars, pools, and riffles was maintained over a period of high magnitude flood events, only to be degraded later by a wave of sediment derived from upstream construction and stream-bank failures. Thus, environmentally desirable channel morphology in urban streams cannot remain stable if changes in the sediment load or storm-water runoff exceed the limits of the stream's ability to make internal adjustments while maintaining morphologic stability.  相似文献   

20.
Materials and energy are the interdependent feedstocks of economic systems, and thermodynamics is their moderator. It costs energy to transform the dispersed minerals of Earth's crust into ordered materials and structures. And it costs materials to collect and focus the energy to perform work — be it from solar, fossil fuel, nuclear, or other sources. The greater the dispersal of minerals sought, the more energy is required to collect them into ordered states.But available energy can be used once only. And the ordered materials of industrial economies become disordered with time. They may be partially reordered and recycled, but only at further costs in energy. Available energy everywhere degrades to bound states and order to disorder — for though entropy may be juggled it always increases. Yet industry is utterly dependent on low entropy states of matter and energy, while decreasing grades of ore require ever higher inputs of energy to convert them to metals, with ever increasing growth both of entropy and environmental hazard.Except as we may prize a thing for its intrinsic qualities — beauty, leisure, love, or gold — low-entropy is the only thing of real value. It is worth whatever the market will bear, and it becomes more valuable as entropy increases. It would be foolish of suppliers to sell it more cheaply or in larger amounts than their own enjoyment of life requires, whatever form it may take. For this reason, and because of physical constraints on the availability of all low-entropy states, the recent energy crises is only the first of a sequence of crises to be expected in energy and materials as long as current trends continue.The apportioning of low-entropy states in a modern industrial society is achieved more or less according to the theory of competitive markets. But the rational powers of this theory suffer as the world grows increasingly polarized into rich, over-industrialized nations with diminishing resource bases and poor, supplier nations with little industry. The theory also discounts posterity, the more so as population density and percapita rates of consumption continue to grow. A new social, economic, and ecologic norm that leads to population control, conservation, and an apportionment of low-entropy states across the generations is needed to assure to posterity the options that properly belong to it as an important but voiceless constituency of the collectivity we call mankind.
Zusammenfassung Rohstoffe und Energie sind die Grundlagen unseres ökonomischen Systems, das von den Gesetzen der Thermodynamik bestimmt wird. Es kostet Energie, um die auf der Erde verteilten Rohstoffe diesem System zuzuführen. Andererseits braucht man Rohstoffe, um die Energie nutzbar zu machen.Die verfügbare Energie kann nur einmal genutzt werden und das Material verbraucht sich. Verbrauchtes Material kann teilweise zur weiteren Nutzung zurückgeführt werden, das kostet wiederum Energie. Die verfügbare Energie nimmt überall ab, und einmal geschaffene Ordnung gerät wieder in Unordnung — das heißt, die Entropie des Systems nimmt ständig zu. Die Industrie ist jedoch abhängig von einem niedrigen Entropiezustand sowohl der Materie als auch der Energie.Je ärmer die Erze sind, um so höher wird die Energie sein, um sie in Metalle umzuwandeln, wobei die Entropie und die Belastung der Umwelt ständig zunimmt.Außer den Dingen, die wir wegen höherer ideeller Werte schätzen, ist eine niedrige Entropie der einzige realistische Wertmaßstab, und der wirkliche Wertzuwachs ist nur an einer höheren Entropie zu messen. Es ist unverantwortlich, Dinge, die eine höhere Entropie bedingen, billiger zu verkaufen oder in größerer Menge zu erzeugen, als unbedingt notwendig ist. Da wir dies heute in unserem Handeln nicht berücksichtigen, ist die derzeitige Energiekrise nur der Anfang einer Folge von Krisen, die Energie und Rohstoffe betreffen, solange wir nicht umdenken.Die Verteilung von niedriger Entropie in einer modernen Industriegesellschaft wird mehr oder weniger nach dem Prinzip der konkurrierenden Märkte erreicht. Das selbstregulierende System gerät jedoch mit zunehmender Polarisierung in reiche Industrienationen mit abnehmenden Ressourcen und armen Nationen mit geringer Industrialisierung in Unordnung. Dieses Prinzip berücksichtigt auch nicht die Nachwelt, vor allem wenn die Bevölkerungsdichte stetig zunimmt und die Konsumbedürfnisse anwachsen. Es sind neue soziale, ökonomische und ökologische Normen notwendig, die zur Populationskontrolle, zur Erhaltung der Umwelt und zu einem Zustand niedriger Entropie für zukünftige Generationen führen. Die nach uns kommenden Menschen haben ein Anrecht darauf.

Résumé Matériaux et énergie sont les sources des systèmes économiques et sont régis par les lois de la thermodynamique. Il faut de l'énergie pour transformer les ressources minérales dispersées dans la croûte terrestre en matériaux et structures ordonnancées. Et il faut des matériaux pour receuillir et concentrer l'énergie, qu'elle soit solaire ou atomique, ou provienne de combustibles fossiles ou d'autres sources. Plus les minéraux recherchés sont dispersés et plus est côuteuse l'énergie pour leur donner une ordonnance.Or l'énergie disponsible ne peut être utilisée qu'une seule fois. Et les matériaux ordonnancés des économies industrielles se dégradent avec le temps. Ils peuvent être remis partiellement en état et recyclés, mais pour cela il faut de nouveau de l'énergie. Partout l'énergie disponible se dégrade et l'ordre devient désordre; -malgré toutes les jongleries possibles l'entropie augmente toujours.L'industrie dépend clairement d'états de basse entropie tant en ce qui concerne les matériaux que l'énergie, tandis que plus pauvres sont les minerais, plus; élevée est l'énergie à mettre en jeu pour en extraire les métaux, avec toujours augmentation à la fois de l'entropie et de la degradation des milieux.A l'exception de ce que nous apprécions pour leur valeur intrinsèque — la beauté, le loisir, l'amour ou l'or — la basse entropie est la seule chose de réelle valeur. Son prix est réglé par le marché, et sa valeur augmente au fur et à mesure que l'entropie s'accroît. Ceux qui en disposent seraient insensés de la vendre à bas prix ou en quantité supérieure à ce qu'exige leur propre niveau de vie. Pour cette raison, et à cause des contraintes physiques liées à la disponibilité en états de basse entropie, la récente crise d'énergie n'est, en ce qui concerne les matières premières et l'énergie, que la première d'une série de crises auxquelles il faut s'attendre aussi longtemps que se poursoit la marche actuelle des étènements.Dans les sociétés industrielles modernes, les approvisionnement en basse entropie s'effectuent plus ou moins conformément à la théorie de la concurrence des marchés. Cependant la rationalité de cette théorie se ressent de l'accentuation croissante de la polarisation, à l'échelle du monde, en nations riches, surindustrialisées, à ressources de base décroissantes, et en nations pauvres, sous-industrialisées, mais fournisseurs de resources-naturelles. De plus cette théorie ne tient pas compte de notre postérité, et ce, en face d'une densité de population et d'un taux de la consommation par tête d'habitant en augmentation continue.Nous avons donc besoin de nouvelles normes sociales, économiques et écologiques qui conduisent au contrôle de la population, à la conservation et à la répartition des états de basse entropie à travers les générations pour assurer à notre postérité les options qui leur riviennent de droit comme une constituante importante, mais encore muette, de la collectivité que nous appelons l'Humanité.

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Dedicated with appreciation to Nicholas Georgescu-Roegen, distinguished economist, realist among cornucopians  相似文献   

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