Sequence stratigraphic interpretation of a Pennsylvanian (Upper Carboniferous) coal from the central Appalachian Basin,USA

Peat mires retain a sensitive record of water‐table (base‐level) fluctuations throughout their accumulation. On this basis, coals provide one of the best opportunities to interpret high‐resolution base‐level change in ancient non‐marine deposits. The petrographic composition of 275 samples collected from 11 localities along a 100 km south‐west to north‐east transect across the regionally extensive (>37 000 km²) Pennsylvanian (Upper Carboniferous) Fire Clay coal of the Central Appalachian Basin, USA was analysed to determine its internal stratigraphy. The coal is positioned within the late lowstand/early transgressive systems tract of a fourth‐order depositional sequence. The results of the petrographic analyses reveal a cyclicity in the composition of the Fire Clay coal, which defines six units that are correlated over more than 100 km. Each coal cycle is characterized by a gradual upward transition from vitrinite‐dominated to inertinite‐dominated coal, which represents a ‘drying‐up’ succession. Increased concentrations of resistant peat components at the top of the drying‐up successions indicate reduced peat accumulation rates associated with slowing rate of water‐table rise, and may represent a residue of peat remaining from a phase of exposure and erosion resulting from a falling water table. These drying‐up successions are bound by surfaces that display an abrupt coal facies shift from inertinite‐rich to vitrinite‐rich coal, representing a rapid water‐table rise. Each cycle represents markedly different mire conditions with different aerial distributions, which supports the notion of temporal disconnection between each unit of coal, and suggests that considerable time may be ‘locked‐up’ in unit bounding exposure surfaces. Recognition that the rate of peat accumulation in a mire may vary considerably through time, has important implications for studies which assume that peat and coal successions provide continuous and time‐invariant records of base‐level fluctuations or palaeoecological change.     

沉积旋回叠置形式的波形分析及旋回层序划分方法

在陆源碎屑岩地层的沉积记录中,测井曲线上一个砂泥岩旋回可以采用正弦波进行描述,测井曲线幅度的高低反映旋回粒度大小的变化,旋回波长则是度量旋回厚度的标尺。本研究表明,测井曲线变化幅度与其平均值之差计算的累积残差曲线,是识别沉积体系、判别旋回层序界面的一个有效图解方法。根据数值模拟实验,证实对于任意一个级次的旋回复合波系,累积残差曲线的正半波和负半波曲线分别对应低频旋回的向上变细和向上变粗的沉积序列,正半波和负半波曲线的转换点位置对应旋回层序界面的深度。同时,引进测井曲线的频谱分析和滤波方法,可以划分沉积旋回的级别,进而研究沉积旋回变化形式的驱动机制。文中以柴达木盆地东部地区仙3井为例,根据测井数据计算的累积残差曲线,说明了划分低频和高频旋回层序的方法和流程,讨论了旋回幅度、波长变化与沉积环境和沉积速率的关系。     

Sedimentary environment dynamics and the formation of coal in the Pennsylvanian Variscan foreland in the Ruhr Basin (Germany, Western Europe)

During the Pennsylvanian, formation of coal was a phenomenon that was spread over many continents. It is the aim of this paper to illustrate factors that led to the formation of coal seams in paralic clastic sedimentary environments in the Ruhr Basin (German Variscan foreland) during the Pennsylvanian in terms of sequence stratigraphy and the structural evolution of the basin. Lithostratigraphic sections from exploration wells in the currently explored zone of the coal basin allowed the generation of volumetric lithofacies models, using geostastical methods. These models support the analysis of sedimentary facies and a sequence stratigraphic interpretation of the successions that are widely correlated throughout the basin. We then evaluate the relation of the sequence stratigraphic elements derived from the facies models with the abundance of coal seams.     

Relationship of geological and geothermal field properties: Midcontinent area, USA, an example

Quantitative approaches to data analysis in the last decade have become important in basin modeling and mineral-resource estimation. The interrelation of geological, geophysical, geochemical, and geohydrological variables is important in adjusting a model to a real-world situation. Revealing the interdependences of variables can contribute in understanding the processes interacting in sedimentary basins. It is reasonably simple to compare spatial data of the same type but more difficult if different properties are involved. Statistical techniques, such as cluster analysis or principal components analysis, or some algebraic approaches can be used to ascertain the relations of standardized spatial data. In this example, structural configuration on five different stratigraphic horizons, one total sediment thickness map, and four maps of geothermal data were copared. As expected, the structural maps are highly related because all had undergone about the same deformation with differing degrees of intensity. The temperature gradients derived (1) from shallow borehole logging measurements under equilibrium conditions with the surrounding rock, and (2) from non-equilibrium bottom-hole temperatures (BHT) from deeper depths are mainly independent of each other. This was expected and confirmed also for the two temperature maps at 1000 ft which were constructed using both types of gradient values. Thus, it is evident that the use of a 2-point (BHT and surface temperature) straightline calculation of a mean temperature gradient gives different information about the geothermal regime than using gradients from temperatures logged under equilibrium conditions. Nevertheless, it is useful to determine to what a degree the larger dataset of nonequilibrium temperatures could reflect quantitative relationships to geologic conditions. Comparing all maps of geothermal information vs. the structural and the sediment thickness maps, it was determined that all correlations are moderately negative or slightly positive. These results are clearly shown by the cluster analysis and the principal components. Considering a close relationship between temperature and thermal conductivity of the sediments as observed for most of the Midcontinent area and relatively homogeneous heat-flow density conditions for the study area these results support the following assumptions: (1) undifferentiated geothermal gradients, computed from temperatures of different depth intervals and differing sediment properties, cannot contribute to an improved understanding of the temperature structure and its controls within the sedimentary cover, and (2) the quantitative approach of revealing such relations needs refined datasets of temperature information valid for the different depth levels or stratigraphic units.     

Cyclic characteristics of sediments in the Moon Island Beach Subgroup, Newcastle Coal Measures, New South Wales

Cyclic characteristics of a sequence of Permian coal-measure sediments have been studied using Markov chain analysis on borehole data. Fining-upwards and oscillating sequences can be distinguished, and depositional regimes are proposed to explain the observed sequences. However, there is no clearly defined relationship of sequence type to tectonosedimentary environment. The relationship of the number of coal-defined and fining-upwards cycles to total thickness and mean cycle thickness is examined using linear regression. The relationships for coal-defined and fining-upwards cycles are essentially the same. Significant positive correlations are present between the number of cycles and total thickness and significant inverse relationships are present for the number of cycles and the mean cycle thickness.     

辽河清水洼陷东营组高分辨率层序格架下沉积演化特征及有利区带预测

根据地层基准面原理,通过对岩心、测井、地震资料的综合分析,将辽河清水洼陷东营组划分为4个3级地层旋回（层序）:东三下、东三上、东二和东一层序;识别出3种类型的沉积体系:较深水湖—水下扇、浅湖—三角洲以及河流—泛滥平原体系;并在层序格架内分析了各旋回的沉积体系构成和储层砂体的发育情况。综合分析生、储、盖条件后认为,在纵向上,东三下和东三上旋回为研究区最有利的储集层段;在平面上,研究区的油气勘探应主要寻找洼陷中部的水下扇砂体和洼陷北部、西部与构造及断层相配合的辫状三角洲或扇三角洲前缘砂体,主要储层砂体类型为前缘水下分支河道砂体、河口坝和席状砂。     

Palynology, petrography and geochemistry of the Sewickley coal bed (Monongahela Group, Late Pennsylvanian), Northern Appalachian Basin, USA

Forty-two bench samples of the Sewickley coal bed were collected from seven localities in the northern Appalachian Basin and analyzed palynologically, petrographically, and geochemically. The Sewickley coal bed occurs in the middle of the Pittsburgh Formation (Monongahela Group) and is of Late Pennsylvanian age. Palynologically, it is dominated by spores of tree ferns. Tree fern spore taxa in the Sewickley include Punctatisporites minutus, Punctatosporites minutus, Laevigatosporites minimus, Spinosporites exiguus, Apiculatasporites saetiger, and Thymospora spp. In fact, Punctatisporites minutus was so abundant that it had to be removed from the standard counts and recorded separately (average 73.2%). Even when Punctatisporites minutus is removed from the counts, tree fern spores still dominate a majority of the assemblages, averaging 64.4%. Among the tree fern spores identified in the Sewickley coal, Thymospora exhibits temporal and spatial abundance variation. Thymospora usually increases in abundance from the base to the top of the bed. Thymospora is also more abundant in columns that are thick (>100 cm) and low in ash yield (<12.0%, dry basis). Calamite spores (e.g. Calamospora spp., Laevigatosporites minor, and L. vulgaris) are the next most abundant plant group represented in the Sewickley coal, averaging 20%. Contributions from all other plant groups are minor in comparison.Petrographically, the Sewickley coal contains high percentages of vitrinite (average 82.3%, mineral matter-free (mmf)), with structured forms being more common than unstructured forms. In contrast, liptinite and inertinite macerals both occur in low percentages (average 7.7% and 10.0%, respectively). Geochemically, the Sewickley coal has a moderate ash yield (average 12.4%) and high total sulfur content (average 3.4%).Four localities contained a high ash or carbonaceous shale bench. These benches, which may be coeval, are strongly dominated by tree fern spores. Unlike the lower ash benches, they contain low percentages of vitrinite, which mainly occurs as unstructured vitrinite, and higher liptinite and inertinite contents.The accumulated data suggest that the Sewickley paleomire was probably a rheotrophic, planar mire that had a consistent water cover. This is supported by the high vitrinite contents, moderate ash yields, and high total sulfur contents. The high ash and carbonaceous shale benches probably represent either periods of dryness and substrate exposure, or flooding of the mire surface, the duration of which is unknown.     

On smoothing techniques for the removal of periodic noise of known period

This paper is concerned with the analysis of the linear modely(n)=X(n)+S(n)+(n) for the data sequencey(n) (n=1, 2, ..., N) whereX={x _IJ} is a knownJ × M matrix of full rankM. Here, the(n) are unknown vectors, which we wish to estimate for eachn; S(n) (n=1, 2, ..., N) is a periodic component (which we wish to estimate or remove) superimposed on the linear structureX(n); and(n) is an error vector which is specified as having zero expectation (with possible further properties). Such models commonly occur in geophysical data analysis.Modified from Technical Report No. 33, Computer Centre, The Australian National University.     

Evaluation of coalbed gas potential of the Seelyville Coal Member, Indiana, USA

The Seelyville Coal Member of the Linton Formation in Indiana potentially contains 0.03 trillion m³ (1.1 TCF) of coalbed gas. The gas content determined by canister desorption technique ranges from 0.5 to 5.7 cm³/g on dry ash free basis (15.4 to 182.2 scf/ton). The controls on gas content distribution are complex, and cannot be explained by the coal rank alone. Ash content and the lithology of the overlying strata, among other factors, may influence this distribution.     

美国印第安纳州宾夕法尼亚系含煤地层和煤层简介

美国中部伊利诺伊煤田(跨伊利诺伊、印第安纳、肯塔基等三个州)的含煤地层为上石炭统宾夕法尼亚系。美国印第安纳地质研究所2006年编制的印第安纳州基岩综合地层柱状图建立了宾夕法尼亚系含煤地层的岩相层序,现将此岩相层序介绍到国内,对我们了解美国晚古生代煤田地质及阅读国外文献资料颇有帮助。     

Sedimentary facies of a glacially influenced continental succession in the Pennsylvanian Jericho Formation, Galilee Basin, Australia

Recent work on the Late Palaeozoic Ice Age in eastern Australia has shown the Joe Joe Group in the eastern Galilee Basin, Queensland, to be of critical importance as it is one of few records of Pennsylvanian glacial activity outside South America. This paper presents detailed sedimentological data, from which the Late Palaeozoic environment of the region is reconstructed and which, consequently, allows for robust comment on the broader Gondwanan glaciation. The Jericho Formation, in the lower Joe Joe Group, was deposited in an active extensional basin in lacustrine to fluvial environments, during the mid‐Namurian to early Stephanian. The region experienced a cool climate during this time, and polythermal mountain or valley‐type glaciers periodically advanced into the area from highlands to the north‐east. The Jericho Formation preserves a suite of proglacial to terminal glacial facies that is characterized by massive and stratified diamictites deposited from debris flows, massive and horizontally laminated conglomerates and sandstones deposited from hyperconcentrated density flows, laminated siltstones with outsized clasts and interlaminated siltstone/conglomerate deposited through ice‐rafting into lakes, and sedimentary dykes and breccias deposited through overpressurization of groundwater beneath permafrost. Non‐glacial facies are dominated by fluvial sandstones and lacustrine/overbank siltstones. The glacigenic rocks of the Jericho Formation are confined to discrete packages, recording three separate glacial advances during the latest Namurian to late Westphalian. This arrangement is consistent with the temporal distribution of glacigenic rocks from around the remainder of Australia and Gondwana, which supports the theory that glacial deposits occurred in discrete intervals. The Joe Joe Group is a key succession in the world in this context as, at this time, eastern Australia provides the only unequivocal evidence of a Namurian/Westphalian glaciation outside South America. The continuous record of sedimentation through the Pennsylvanian and Early Permian is indicative of significant warming between glacial intervals, which is difficult to reconcile with the development of long‐lived, cold‐based ice sheets across the supercontinent.     

Preliminary paleomagnetic dating of the metalliferous (Zn–Pb rich), Stark black shale, Kansas City region, U.S.A.

The Stark metalliferous black shale is a member of the Dennis Formation, which is a cyclothemic limestone and shale unit in the Missourian (Upper Pennsylvanian) Kansas City Group. Paleomagnetic analysis of 96 specimens from 7 sites indicates that the characteristic remanent magnetization of the Stark Shale yields a Late Mississippian to Early Pennsylvanian age. This age is close to, but slightly older than, the Middle Pennsylvanian host rock age and implies that the metalliferous content of the shale is syngenetic in origin.     

歧口凹陷滩海区下第三系层序地层分析及沉积体系研究

利用地震、测井、岩心等资料,通过对该区进行层序地层学的分析和研究,把歧口凹陷滩海区下第三系划分出一个二级层序,六个三级层序,并对每个层序的主控成因进行了详细的研究,总结出构造层序和气候层序的不同特点。同时对每个层序内部的沉积特点和沉积体系进行了分析,指出了层序发育对岩石储集性的控制作用。研究过程中,还发现陆相盆地的单断特点控制了该区层序发育的总体特征;而断陷湖盆内部三级断层对层序内砂体的位置则有明显的控制作用。     

鄂尔多斯盆地陇东地区延长组沉积相特征与层序地层分析

晚三叠世鄂尔多斯盆地是一个东缓西陡的不对称坳陷盆地。通过岩心、录井、测井等资料综合研究,识别出陇东地区延长组发育河流、三角洲、浊积扇和湖泊等4种沉积相类型,其中河流沉积和浊积扇发育在湖盆的西缘陡坡带,三角洲则在西缘和东部缘坡均有发育。根据层序地层学原理,将延长组划分出5个三级层序;延长组地层经历过5次大的湖泛,在层序演化上具有早期形成、中期鼎盛、晚期衰退的特点。利用恢复后的原始地层厚度,绘制的陇东地区延长组地层的F ischer图解,与本区5次显著的湖平面上升-下降旋回之间有很好的对应关系,这不仅证实了上述层序地层分析的正确性,同时揭示了F ischer图解在划分地层层序方面的潜在意义。     

准噶尔盆地北三台地区三叠系克拉玛依组沉积相

根据岩心观察,结合地震、测井资料,将准噶尔盆地北三台地区三叠系克拉玛依组作为一个三级层序进行研究,并划分了体系域。在等时格架内,以体系域为单位进行了沉积相研究,定量编制克拉玛依组沉积体系平面分布图。查明有利砂体的展布位置,为准噶尔盆地北三台地区进一步油气勘探提供依据。     

塔里木盆地西北缘中奥陶统、下志留统的空间分布特征及其相变的遥感分析

根据塔里木盆地西北缘中奥陶统和下志留统各组岩石的光谱特征分析，选择了ＴＭ３/１（Ｙ）２/３（Ｍ）７/５（Ｃ）减色比值合成影像对研究区岩石地层层序进行划分和对比，划分出Ｏ1₂、Ｏ2₂、Ｏ3₂、Ｓ1₁和Ｓ2₁等５个影像岩石地层单元，它们与研究区的岩性组一致，但其精度高于研究区１:２０万地质图。通过影像岩石地层的对比研究发现，研究区西部皮羌断裂以西在中奥陶世几乎未接受沉积，皮羌断裂以东出现了坎岭组，再往东至研究区东部，中奥陶统沉积较全；早志留世早期研究区西部沉积了海相红层，往研究区东部则相变为海相绿色地层。尤其是通过ＴＭ比值图像的分析，发现前人认为分布很局限，但具有很大生油潜力的印干组在研究区分布范围较广，并推断其沉积中心位于与研究区相邻的塔北隆起和北部坳陷一带。这为塔里木盆地油气评价和勘探提供了新的资料，并表明ＴＭ遥感数据的应用是沉积盆地油气勘探研究中的一种很有潜力技术方法。     

Groundwater recharge and sustainability in the High Plains aquifer in Kansas, USA

Sustainable use of groundwater must ensure not only that the future resource is not threatened by overuse, but also that natural environments that depend on the resource, such as stream baseflows, riparian vegetation, aquatic ecosystems, and wetlands are protected. To properly manage groundwater resources, accurate information about the inputs (recharge) and outputs (pumpage and natural discharge) within each groundwater basin is needed so that the long-term behavior of the aquifer and its sustainable yield can be estimated or reassessed. As a first step towards this effort, this work highlights some key groundwater recharge studies in the Kansas High Plains at different scales, such as regional soil-water budget and groundwater modeling studies, county-scale groundwater recharge studies, as well as field-experimental local studies, including some original new findings, with an emphasis on assumptions and limitations as well as on environmental factors affecting recharge processes. The general impact of irrigation and cultivation on recharge is to appreciably increase the amount of recharge, and in many cases to exceed precipitation as the predominant source of recharge. The imbalance between the water input (recharge) to the High Plains aquifer and the output (pumpage and stream baseflows primarily) is shown to be severe, and responses to stabilize the system by reducing water use, increasing irrigation efficiency, adopting water-saving land-use practices, and other measures are outlined. Finally, the basic steps necessary to move towards sustainable use of groundwater in the High Plains are delineated, such as improving the knowledge base, reporting and providing access to information, furthering public education, as well as promoting better understanding of the publics attitudinal motivations; adopting the ecosystem and adaptive management approaches to managing groundwater; further improving water efficiency; exploiting the full potential of dryland and biosaline agriculture; and adopting a goal of long-term sustainable use.

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Resumen El uso sostenible de aguas subterráneas debe garantizar tanto que el recurso futuro no esté amenazado por sobreutilización como que los ambientes naturales dependientes del recurso sean protegidos (ie el flujo base de los arroyos, la vegetación ripariana, los ecosistemas acuáticos y los pantanos). El manejo adecuado de los recursos de aguas subterráneas requiere información precisa con respecto a los influjos (recarga) y descargas (bombeo y descarga natural) en cada cuenca de aguas subterráneas de tal manera que se pueda estimar o reevaluar el comportamiento de largo plazo del acuífero y su tasa de sotenibilidad. En un primer paso hacia esta meta, este trabajo destaca algunos estudios claves de recarga de aguas subterráneas en las llanuras altas de Kansas. Dichos estudios se concentran en diferentes escalas: estudios regionales del presupuesto para aguas del suelo y modelos de aguas subterráneas, estudios de recarga de aguas subterráneas a nivel provincial y estudios locales experimentales de terrenos que incluyen algunos interesantes descubrimientos nuevos. Estas investigaciones comparten el énfasis en los presupuestos de partida y las limitaciones así como en los factores ambientales que afectan los procesos de recarga. El impacto general de las irrigaciones y cultivos sobre la recarga es un obvio incremento en el monto de recarga y en muchos casos excede a la precipitación como la fuente principal de recarga. Se puede observar que el desequilibrio entre el influjo de agua (recarga) del acuífero de las llanuras altas y la descarga (bombeo y flujos base de los arroyos principalmente) es severo. Asimismo, se describen las respuestas para estabilizar el sistema a través de la reducción del uso de agua por medio del incremento de la eficiencia de las irrigaciones y de la adopción de las prácticas de ahorro de agua y del uso de tierras así como otras medidas adicionales. Finalmente se describen los pasos básicos necesarios para evolucionar hacia el uso sostenible de las aguas subterráneas en las llanuras altas de Kansas. Estos pasos están constituidos por una mejora del conocimiento base, comunicar y proporcionar fácil acceso a la información, mejorar el conocimiento público general así como promover un mejor entendimiento de las motivaciones para las actitudes de la comunidad, adoptar los enfoques administrativos de ecosistemas y administración adaptable en el manejo de las aguas subterráneas, continuar las mejoras del uso eficiente del agua, explotar el potencial de la agricultura de terrenos áridos y biosalina y adoptar como meta el uso sostenible a largo plazo.

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Résumé Lutilisation durable de leau souterraine doit permettre non seulement que la pérennité de leau ne soit pas menacée, mais aussi que les environnements naturels qui dépendent de cette ressource, tels que la végétation riveraine, les écosystemes aquatiques et les milieux humides, soient protégés. Afin dassurer une gestion appropriée des ressources en eau souterraine, une information précise concernant les entrées (recharge) et les sorties (décharge naturelle et pompage) deau dans chacun des bassins est nécessaire afin que le comportement à long terme de laquifère et le taux de pompage durable puissent être estimés. En guise dinitiative, ce travail illustre certaines études clé concernant la recharge de leau souterraine à plusieurs échelles dans les hautes plaines du Kansas. Ces études comprennent le bilan sol-eau et la modélisation numérique à léchelle régionale, létude de la recharge des nappes souterraines à léchelle du comté, des études expérimentales à petite échelle et certaines découvertes originales. Lors de la présentation de ces études, lemphase est portée sur les hypothèses et limitations ainsi que sur les facteurs environmentaux qui affectent les processus de recharge. En général, les effets de lirrigation et de lagriculture sur la recharge sont daugmenter considérablement le taux de recharge, et dans plusieurs cas, dexcéder les précipitations comme principale source de recharge. Le déséquilibre entre les intrants deau (recharge) et entrants (pompage et écoulement de base dans les rivières) dans laquifère des hautes plaines est très important. Les résultats des efforts de stabilisation du système aquifère en diminuant lutilisation deau, en améliorant lefficacité des techniques dirrigation, en adoptant des pratiques dutilisation du territoire qui réduisent lutilisation deau et en adoptant certaines autres mesures sont présentés. Enfin, les étapes de base nécessaires afin datteindre une utilisation durable de leau souterraine dans les hautes plaines sontexposées. Elles comprennent lamélioration des connaissance de base, lapromotion dune meilleure compréhension de la motivation et de lattitudedu public, ladoption dune approche de gestion de leau souterraineadaptable et basée sur les écosystèmes, lamélioration de lefficacitédutilisation de leau, lexploitation du plein potentiel de lagriculturebiosaline et en milieu aride, et ladoption dun objectif pourlutilisation durable à long terme.

     

Geology and utilization of underground space in metropolitan Kansas City area, USA

 Kansas City is the international leader in the commercial development of mined-out areas for warehousing, manufacturing, offices, business, and service-related activities. Over 3000 people work underground at about two dozen sites with a combined floor space of almost 2 sq km. Most of the space was created after mining a 6-m-thick bed of limestone that underlies the city and its environs. The most common usage of the space is for storage. The mined-out area can be converted to warehouse storage at a fraction of the cost of a comparable surface facility. Received: 2 October 1995 · Accepted: 6 November 1995     

B-splines for smoothing and differentiating data sequences

Sequence convolution formulae, based on the B-splines of I. J. Schoenberg provide simple and effective methods for smoothing and differentiating data sequences. Their time and frequency domain properties allow calculation of the degree of smoothing and noise rejection, and their z-transforms lead to the rapid calculation of formulae from a simple sequence of polynomials. As an example of their use, numerical differentiation is used to produce smooth velocity—depth profiles and to delineate major velocity discontinuities from time—depth data logged at a well.     

时间序列分析在灾变预测中的应用

本文介绍了利用时间序列分析原理预测灾变的方法，现以预测某地区降雨为例子，介绍了方法的原理与步骤，实践表明，本文提出的方法具有明显的优点。