川东北飞仙关组白云岩的主要类型、地球化学特征和白云化机制

四川盆地东北部蕴藏有丰富的烃类资源,三叠系飞仙关组的白云岩是最主要的储层和产层,这使得飞仙关组白云岩成为人们近年来高度关注的对象.按照结构,我们可以将飞仙关组白云岩分为三种端元类型:微晶白云岩、具原始结构的粒屑白云岩和结晶白云岩,在一个向上变浅的剖面旋回中,这三种白云岩分别位于旋回的顶部、上部和中下部.微晶白云岩和具原始结构的粒屑白云岩具有较高的锰含量和较低的包裹体均一化温度,白云化流体的δ~(18O) 值(从白云石的包裹体均一化温度和δ~(18O) 值反演,以下同)介于大气水和海水之间,反映这类白云岩形成于有大气水参与的相对开放的沉积-成岩环境中,蒸发泵作用(对于微晶白云岩)和混合水作用(对于具原始结构的粒屑白云岩)可能是其主要的形成机制;结晶白云岩(表现为好储层)具有很低的锰含量和较高的包裹体均一化温度,白云化流体的δ~(18O) 值显著高于早三叠世海水,表明这类白云岩形成于相对封闭的埋藏成岩环境,白云化流体具较高的温度和盐度,但到目前为止,还没有一个已有模式可以较好地解释这类白云岩的成因.     

四川盆地东北部三叠系飞仙关组碳酸盐岩成岩作用和白云岩成因的研究现状和存在问题

四川盆地东北部三叠系飞仙关组是我国重要的天然气储集层，优质储层形成机制直接与碳酸盐岩成岩作用、尤其是白云岩化作用相关，但飞仙关组碳酸盐岩在锰含量、锶含量、阴极发光性等特征上反映其成岩过程与经典成岩理论相悖；碳酸盐岩的锶同位素组成和锰、锶含量的关系也表明与大气水有关的成岩过程和作为重要储集岩的结晶白云岩的形成机制无关，传统的白云岩化机制难以解释结晶白云岩的成因。具有海源色彩的高锶、低锰成岩流体在很大程度上控制了飞仙关组碳酸盐的成岩作用，其来源与成因值得进一步关注，控制其运移、封存和发生水—岩反应的时空机制有待回答。整个海相三叠纪时间段盆地尺度碳酸盐岩和蒸发岩的沉积地球化学研究、尤其是不同结构组分碳酸盐的锶同位素组成、锶和锰含量研究（包括碳酸盐岩中不同结构组分的阴极发光性研究），可为四川盆地东北部飞仙关组碳酸盐岩成岩作用（尤其是白云岩化作用和作为重要储集岩的结晶白云岩的成因研究），天青石矿床成因研究和四川盆地三叠系深层富钾、锶、硼、溴卤水的成因研究提供重要的线索。     

川东三叠系飞仙关组碳酸盐岩的阴极发光特征与成岩作用

四川盆地东部三叠系飞仙关组是近年来我国发现的重要天然气储层, 高孔隙度、高渗透率的碳酸盐储层都分布于白云岩地层中, 因而碳酸盐的成岩作用, 尤其是白云岩化作用和白云岩的成因为石油地质学家和沉积学家高度关注.对四川盆地东部罗家寨构造三叠系飞仙关组42个碳酸盐岩样品进行了阴极发光分析, 结合与之有关的Mn、Fe、Mg元素分析和岩石学研究, 讨论了包括白云岩化作用在内的碳酸盐岩成岩过程中可能的成岩流体性质及来源.四川盆地东部三叠系飞仙关组碳酸盐岩普遍具有很弱的阴极发光性, 这与其很低的Mn、Fe含量有关, 说明沉积期后非海相流体对飞仙关组碳酸盐岩的影响非常有限, 海源流体在成岩过程中发挥了主导作用; 不同石灰岩类型和不同白云岩类型仍然具有不同的阴极发光性, 成岩组分含量越高的碳酸盐岩, 或者说与沉积期后流体(主要是孔隙流体) 关系越密切的碳酸盐岩的阴极发光强度越低, 说明随着埋藏成岩作用的进行, 四川盆地东部三叠系碳酸盐岩孔隙流体受海源流体的影响是逐渐增强的; 阴极发光分析结果表明, 作为四川盆地东部主要储集岩的结晶白云岩形成机制与埋藏过程中的深循环流体有关, 这种深循环流体没有或很少穿越铝硅酸盐地层, 但穿越了三叠系内部的某些海相地层, 这些海相地层可能是广泛存在于四川盆地三叠系的蒸发盐地层, 由蒸发盐成岩过程提供的海源流体参与了结晶白云岩的白云岩化作用.      

川东北地区长兴组白云岩储层的成因研究

以岩石结构与白云石Mg/Ca比值和有序度分析为基础,结合Sr,Fe,Mn微量元素和C,O,Sr同位素地球化学特征,对川东北地区上二叠统长兴组白云岩成因进行研究,结果表明长兴组白云岩有准同生白云岩和埋藏白云岩两种成因类型,储层只是埋藏白云岩化作用的产物,其形成过程可划分为早、中、晚3个成岩阶段,各成岩阶段埋藏白云岩化流体都来自于上覆地层飞仙关组的高盐度海源地层水,证据包括如下几个方面:①埋藏白云岩的岩石学特征明显地有别于准同生白云岩;②长兴组各类白云岩的Sr,Fe,Mn微量元素特征表明埋藏白云岩作用发生在无大气水影响的封闭体系中;③白云岩的C,O同位素组成特征符合埋藏白云岩的δ13C和δ18O分布区间;④长兴组与飞仙关组埋藏白云岩的Sr,Fe,Mn微量元素和Sr同位素地球化学特征基本一致。     

川东北地区三叠系飞仙关组白云化流体的Ca/Mg比定量估算

作为川东北地区三叠系飞仙关组天然气气藏最重要储集岩的粒屑白云岩和结晶白云岩的成因始终是沉积和石油地质学家高度关注的研究热点之一.在总结川东北地区三叠系飞仙关组不同类型白云岩形成温度的基础上,通过已有的白云化流体Ca/Mg值和温度之间关系式获得了川东北地区三叠系飞仙关组白云化流体的Ca/Mg值的主要分布范围.结果表明:不同类型白云岩对应的白云化流体具有不同的Ca/Mg值,同时证实了三叠纪海水或与之有关的海源流体、三叠纪海水与大气淡水混合流体的Ca/Mg值都符合在40～130℃区间、甚至更高温度下白云化(白云石沉淀)作用的要求,微晶白云岩和具原始结构的粒屑白云岩可能与地表—近地表的低温、小Ca/Mg值混合流体中相对快速的白云石沉淀作用有关,并形成了相对细的他形白云石;结晶白云岩(包括结构类似的过渡岩石类型、白云石胶结物)可能与埋藏的高温、大Ca/Mg值三叠纪海水或与之有关的海源流体中相对缓慢的白云石沉淀作用有关,并形成了相对粗的自形白云石.白云化流体的Ca/Mg值估算,可望为川东北地区三叠系飞仙关组优质储层白云岩的成因研究提供一些有价值的基础资料.     

四川盆地三叠系飞仙关组气藏储层成岩作用研究拾零

近年来在四川盆地三叠系飞仙关组鲕粒白云岩储层中发现的高含硫天然气三级储量已近1×1012 m3。鲕粒白云岩储层集中分布在含蒸发岩的层序中,储层中有残余石膏、硬石膏及它们的模孔、方解石铸模（假象）等,表明白云石化流体与蒸发海水有关。白云石化由层间古暴露面向下增强的成岩层序说明这种白云石化是成岩早期发生的,并可能有大气降水与蒸发海水混合的影响。白云岩样品各结构组分氧、碳同位素微区测试数据差别显著,这说明采用岩石混合样做研究白云石化成因的地球化学分析可能导致误解。飞仙关组的白云岩中多数保存了原岩结构幻影、结构残余或原岩的全部结构说明白云石化过程是等体积交代。白云岩储层中的孔隙是各种溶蚀孔而非白云石化等摩尔交代的体积收缩孔。飞仙关组高含硫气藏储层中沥青和溶蚀孔的关系表明深埋晚期溶蚀孔最发育。在溶液中碳酸的电离常数大大高于氢硫酸,飞仙关组高含硫气藏天然气组分中的CO2相对于H2S的质量亏损和储层中有富轻碳的高温方解石充填晚期溶孔、裂缝表明储层中的晚期溶解作用是由硫酸盐热还原过程（TSR）中生成的CO2引起的。     

封闭系统中的白云石化作用过程及其油气地质意义——以南羌塘拗陷中侏罗统布曲组白云岩为例

南羌塘拗陷中侏罗统布曲组结晶白云岩作为盆地最优质的储层是通过埋藏成岩过程中封闭条件下的白云石化作用形成的,岩石所具有的高孔隙度与封闭系统中白云石化反应有关。根据对羌资11井和羌资12井布曲组的岩石结构分类、碳氧同位素组成及温度计算、流体包裹体均一温度等分析结果,可以认为：结晶白云岩碳同位素值分布区间较窄（2. 86‰~4. 27‰）,氧同位素值随着白云石晶体变粗（自形程度变差）逐渐偏负（-3. 27‰~-8. 17‰）,显著低于保留原始组构的白云岩,表明结晶白云岩碳源来自于先驱灰岩中的碳,其白云石化作用应是在远离大气水的封闭成岩环境中进行;结晶白云岩流体包裹体均一温度主峰值区间为90~140 ℃,且随着白云石晶粒变粗（自形程度变差）,均一温度呈升高的趋势,与氧同位素计算温度变化趋势一致,表明白云石化作用过程是在封闭的条件下进行,白云石随地热增温而生长,并非受外来流体的影响。开放系统中的白云石化作用对油气储集空间的形成没有实际意义,而埋藏成岩过程中封闭系统的白云石化是形成南羌塘拗陷优质储层最为重要的成岩机制。     

川东北地区飞仙关组白云岩成岩作用与系统划分

通过对川东北地区下三叠统飞仙关组白云岩的结构-成因分类、成岩作用方式、成岩演化序列和铁、锰、锶微量元素,碳、氧、锶稳定同位素地球化学特征的综合研究,从盆地大尺度的成岩作用组合特征出发,按“水文体制”将飞仙关组白云岩划分为4个成岩系统:(1)准同生阶段孔隙卤水成岩系统;(2)早-中成岩阶段地层压实热卤水成岩系统;(3)晚成岩阶段混合热卤水成岩系统;(4)构造隆升阶段油田热卤水成岩系统.各阶段成岩系统白云化流体性质和来源具有一定的亲缘性和继承性发展演化特点,但水－岩相互作用过程、成岩方式、产物和组合特征各不相同,与储层发育密切相关的成岩方式主要是各成岩系统中的多期次埋藏白云化和溶蚀作用.根据各成岩系统中成岩作用与储层在时间-空间上的耦合与匹配关系,可将优质白云岩储层和油气藏控制因素归结为3点:(1)早-中成岩阶段埋藏白云化为储层发育基础;(2)晚成岩阶段埋藏白云化扩大,提高了储层分布范围与质量;(3)构造隆升阶段破裂、TSR和溶蚀作用是形成飞仙关组高效气藏的关键.      

川东北普光气田下三叠统飞仙关组白云岩成因——来自岩石结构与Sr同位素和Sr含量的证据

研究了川东北普光气田下三叠统飞仙关组白云岩储层的岩石结构Sr的含量和Sr同位素组成,讨论了它的成因,飞仙关组优质储层为成岩期埋藏交代白云化作用的产物,来自岩石结构和Sr同位素和Sr含量的证据包括如下几个方面:(1)与准同生白云岩比较,埋藏白云岩的岩石结构和Sr同位素和Sr含量地球化学特征与前者有显著差别;(2)飞仙关组所有各类碳酸盐岩(或矿物)具有早三叠世海水Sr同位素组成特征,~(87)Sr/~(86)Sr比值变化范围为0.706588～0.708187,覆盖了全球早三叠世海水Sr同位素的变化范围(0.7076～0.7078),平均值0.707656与全球早三叠世平均值(0.707743)基本一致;(3)埋藏白云岩~(87)Sr/86Sr比值变化范围为0.707122～0.707419,平均值0.707421,都略低于全球早三叠世海水Sr同位素变化范围和平均值,但与已报道的川东北早三叠世飞仙关期海水Sr同位素变化范围(0.707330～0.707383)和平均值(0.707350)都非常接近,说明白云石化流体具有强烈的川东北地区早三叠世飞仙关期海水Sr同位素组成特征;(4)综合岩石结构、Sr同位素和Sr含量地球化学特征,证明飞仙关组白云岩储层为成岩期埋藏交代作用产物,白云石化流体来自地层中高Sr和高盐度的海源地层水.     

川东三叠系飞仙关组白云岩锶含量、锶同位素组成与白云石化流体

川东飞仙关组白云岩包括微晶白云岩、具原始结构的粒屑白云岩和结晶白云岩等3种主要的结构类型,其中结晶白云岩是重要的天然气储集岩。根据白云岩的锶舍量和锶同位素组成,结合相关岩石学和地球化学资料,本文研究了白云石化过程中锶的迁移和相应的同位素变化。三种类型白云岩具有类似的锶含量,但其(87)~Sr/(86)~Sr 比值均不同程度地高于同期海水值,锶在白云石和方解石(或文石)中分配系数的差别是影响白云石化过程中白云石锶含量最为重要的因素。不同流体中锶的混合方程计算表明:如果白云石化流体是大气淡水和海水的混合流体,则结晶白云岩的白云石化流体相当于94%的大气淡水和6%的海水混合,具原始结构的粒屑白云岩的白云石化流体相当于81%的大气淡水和19%的海水混合,微晶白云岩的白云石化流体相当于92%的大气淡水和8%的海水混合。但极低的锰含量、相对较高的锶含量和包裹体均一化温度等资料均不支持有94%的大气淡水参与了结晶白云岩的白云石化作用,其白云石化流体应是埋藏成岩过程中囚禁的近同期、但是非同期的海源流体,其来源可能与埋藏成岩过程中该时间段蒸发盐的溶解有关。锰含量、锶含量、(87)~Sr/(86)~Sr 比值都表明具原始结构的粒屑白云岩和微晶白云岩的白云石化过程都存在大气淡水的介入,微晶白云岩的白云石化可能与潮坪环境的蒸发泵机理有关;具原始结构的粒屑白云岩的白云石化可能与混合水白云石化作用有关,这类白云岩分布于向上浅滩化旋回滩体的顶部,这是埋藏前或浅埋藏阶段大气淡水与海水混合白云石化作用最容易发生地带。     

Mountains,nations, parks,and conservation

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.     

Roles of xenomelts,xenoliths, xenocrysts,xenovolatiles, residues,and skarns in the genesis,transport, and localization of magmatic Fe-Ni-Cu-PGE sulfides and chromite

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.     

Parents,permission, and possibility: Young women,college, and imagined futures in Gujarat,India

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.     

Comparative study of As,Cd, Cu,Cr, Mg,Mn, Ni,Pb and Zn concentrations between sediment and water from estuary and port

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).     

Partition coefficients of Hf,Zr, and REE between zircon,apatite, and liquid

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.     

Coprecipitation of Ti,Mo, Sn and Sb with fluorides and application to determination of B,Ti, Zr,Nb, Mo,Sn, Sb,Hf and Ta by ICP-MS

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.     

Entropy,materials, and posterity

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.

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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.

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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     

Models,validation, and applied geochemistry: Issues in science,communication, and philosophy

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.     

Pools,riffles, and channelization

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.