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Peter Chadwick 《Tectonophysics》1976,30(1-2)
By considering the ways (symmetric, asymmetric and antisymmetric) in which layer interfaces can mutually deflect (see Fig.2.), and the relative curvatures which occur in waves of each of the interfaces (Fig.1), it is possible to generate a classification of structures which covers a wide range of buckle fold shapes, load casts and interface buckles, some types of boudins and asymmetric folds, in one three-dimensional plot. 相似文献
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Ilmenite is one of the common kimberlitic indicator minerals recovered during diamond exploration, and its distinction from non-kimberlitic rock types is important. This is particularly true for regions where these minerals are present in relatively low abundance, and they are the dominant kimberlitic indicator mineral recovered. Difficulty in visually differentiating kimberlitic from non-kimberlitic ilmenite in exploration concentrates is also an issue, and distinguishing kimberlitic ilmenite from those derive from other similar rocks, such as ultramafic lamprophyres, is practically impossible. Ilmenite is also the indicator mineral whose compositional variety has the most potential to resolve provenance issues related to mineral dispersions with contributions from multiple kimberlite sources.
Various published data sets from selected kimberlitic (including kimberlites, lamproites, and various ultramafic lamprophyres) and non-kimberlitic rock types have been compiled and evaluated in terms of their major element compositions. Compositional fields and bounding reference lines for ilmenites derived from kimberlites (sensu stricto), ultramafic lamprophyres, and other non-kimberlitic rock types have been defined primarily on MgO–TiO2 graphs as well as MgO–Cr2O3 relationships. 相似文献
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Variously shaped discrete bodies with reflectance higher than the associated vitrinite occur in Permian coals in India, Australia and Africa and the Carboniferous coals of the United States, Canada and Europe. These bodies have been variously named by different authors. In the present paper they are described as ‘resino-inertinites’ as suggested by Lyons et al. (1982).Based on available information and our observations on Carboniferous and Permian coals, it is presumed that resino-inertinites were formed mainly from the resinous (resinite) and to some extent from the phlobaphinitic or corpocollinitic substances. Various morphological patterns developed on resino-inertinites have been interpreted to be governed by the chemical composition of their precursors and the degree of oxidation or fusinization during coalification. Influences of other vvariables viz., paleoenvironmental, paleodepositional, tectonic set up etc. on resino-inertinites are not clearly recognizable probably because all the previous effects were masked by subsequent fusinization.Different morphological features of resino-inertinites associated with early diagenetic and secondary mineralization have caused much confusion in their proper identification and classification. In order to resolve this problem, an attempt has been made to ascertain the source of resins in Indian Permian coals and their subsequent mode of transformation into resino-inertinites during coalification.Further, by critically evaluating morphological features of resino-inertinites and keeping the chemical nature of their precursors in view, a classification scheme has been proposed categorizing them into 3 types. The classification proposed may prove as a useful means for coal-seam correlation. 相似文献
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微生物碳酸盐岩分类体系的修订:对灰岩成因结构分类体系的补充 总被引：18，自引：0，他引：18
微生物沉积作用在前寒武纪地层中普遍发育,在显生宙的一些地层中也较为发育。在碳酸盐岩地层之中,以叠层石为代表的微生物岩尤为引人注目。经过长期研究,2000年Riding曾经将微生物碳酸盐岩分为叠层石、凝块石、树形石和均一石4大类型。实际上,核形石以其较为广泛的发育和特殊的微组构也应该作为一种典型的微生物碳酸盐岩类型而纳入微生物碳酸盐岩的分类体系之中,而不能简单地作为球状叠层石。而那些纹理石灰岩,较厚的纹理和较深的产出沉积环境与叠层石形成明显的区别,也应该作为一种微生物碳酸盐岩的类型。生物沉积作用所形成的碳酸盐岩,以生物礁岩最为典型,在20世纪70年代曾经被Embry和Kloven归为骨架岩、障积岩、粘结岩三大类型,后来又增加了胶结岩,这是对20世纪50年代Folk、Dunham关于灰岩成因结构分类体系的良好补充。这些生物礁岩石以其高能量形成环境而有时又几乎见不到颗粒而与"颗粒含量越高沉积环境的能量越高"的基本理念不相符,所以Wright在1992年将它们归为生物作用类岩石,从而将灰岩划分为沉积作用、生物作用、成岩作用三大类。根据该分类,Folk和Dunham所描述的分类则属于沉积作用类灰岩,而Embry和Kloven所描述的生物礁岩石则归为生物作用类灰岩。微生物碳酸盐岩,总体上构成生物作用类碳酸盐岩中的粘结岩类,以其明显的微生物作用特点而具有自己的分类体系;它不但作为生物礁岩石的主要类型,而且也常常以生物礁、生物层和生物丘三种形式发育在地层之中。因此,上述概念和认识的进步,在强调微生物沉积作用的重要性的同时,有必要将微生物碳酸盐岩重新分为6大类:叠层石、凝块石、核形石、树形石、纹理石和均一石。 相似文献
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In this paper we propose an exploratory methodology, devoted to classify the pixels of a Digital Elevation Model (DEM), to be used as a morphometric basis for studies in other frameworks. The aim is to classify the terrain units according to eight topographical local gradients, computed as differences between each pixel and the eight surrounding ones. A partition of the pixels into homogeneous classes is carried out, emphasizing different details of the terrain units characteristics. Each class is described by a complete set of statistics of terrain attributes, including elevation, slope, and aspect, and graphical tools are used to ease the understanding of the partition. In addition, appropriate colours are attributed to each class, in order to build a thematic map that may simulate a three-dimensional effect. They are defined by computing their hue and saturation according to each class mean slope and aspect, respectively. Applications to Mount Soratte (Italy) and Cephalonia island (Greece) show how the results may be successfully used to describe in different ways the morphometric structure of the terrain under study and provide appropriate graphical representations. 相似文献
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Multi‐scale classification of fluvial architecture: An example from the Palaeocene–Eocene Bighorn Basin,Wyoming 
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下载免费PDF全文 Amanda Owen Alena Ebinghaus Adrian J. Hartley Maurício G. M. Santos Gary S. Weissmann 《Sedimentology》2017,64(6):1572-1596
Fluvial channel geometry classification schemes are commonly restricted in relation to the scale at which the study took place, often due to outcrop limitations or the need to conduct small‐scale detailed studies. A number of classification schemes are present in the literature; however, there is often limited consistency between them, making application difficult. The aim of this study is to address this key problem by describing channel body geometries across a depositional basin to ensure that a wide range of architectures are documented. This was achieved by studying 28 locations over 4000 m of vertical succession in Palaeocene‐aged and Early Eocene‐aged deposits within the Bighorn Basin, Wyoming, USA. Five different channel body geometries have been defined based on the external geometric form, and internal arrangement and nature of storey contacts. These include the massive channel body geometry, semi‐amalgamated channel body geometry, internally amalgamated channel body geometry and offset stacked channel body geometry, which are considered to be subdivisions of the sheet geometry of many other classifications. An isolated channel body geometry has also been recognized alongside splay channel and sheet sandstone geometries in the floodplain facies associations. Field evidence, including the stacking style of storey surfaces, suggests that the different geometries form a continuum. The nature and degree of amalgamation at the storey scale are important in producing the different geometries and are related to the degree of channel migration. It is speculated that this is the result of differences in sediment supply and available accommodation. In contrast to previous schemes, the classification scheme presented here recognizes the importance of transitional geometries. This geometrical range has been recognized because of the basin‐scale nature of the study. 相似文献
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根据变质作用分类研究的历史回顾和最新进展,本文介绍了一个试行的、较系统的变质作用分类方案,可分为局部性的变质作用和区域性的变质作用两个大类9个类型.局部性的变质作用包括以下5个类型:(1)接触变质作用,包括热变质作用、接触交代变质作用和高热变质作用3个亚类;(2)低-中-高温动力变质作用,包括低-中-高温韧性剪切带变质作用和温压递进逆冲断层变质作用2个亚类;(3)冲击变质作用;(4)水热变质作用;(5)燃烧变质作用.区域性的变质作用可分为以下4个类型:(6)早前寒武纪克拉通基底变质作用-低中压-中高温区域变质作用,可分为5个亚类,分别是低-中压角闪岩相变质作用、低-中压麻粒岩相变质作用、低-中压角闪岩相-麻粒岩相变质作用、低-中压绿片岩相-角闪岩相递增的变质作用和区域超高温麻粒岩相变质作用;(7)造山带变质作用,可分为3个亚类,分别是低温-低压区域动力变质作用、碰撞造山变质作用和深俯冲高压-超高压区域变质作用;(8)埋深变质作用;(9)洋底变质作用. 相似文献
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Phyto-geomorphic classification of the landscape 总被引：1，自引：0，他引：1
The subdivision of landscape into phyto-geomorphic units forms a useful basis for land resource surveys and for providing a holistic approach to potential biological productivity. This paper explains the natural basis for such units, justifies their subdivision into a hierarchy and gives definitive criteria for each categoric level. The main levels are the land zone, land division, land province, land region, land system, land catena and land facet, of which the province, system and facet are the more important. Most bear some analogy with categories recognized in pedology and plant ecology. Vegetation varies in importance in relation to landforms in land unit definition both regionally and categorically, being most important in forested areas and for certain other land categories. Sample areas in the United Kingdom, Australia and Jordan illustrate complete hierarchies of land units for different climatic zones. A simple procedure based on critical path analysis and using remotely sensed imagery, maps and other data can give a landscape analysis suitable for planning at a variety of scales. 相似文献
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李奎 《沉积与特提斯地质》1998,18(2):39-47
文章对蜥脚类恐龙的分类进行了探讨,提出了新的分类方案,即将蜥脚类划分为２个超科、７个科。它们分别为勺齿蜥龙超科Ｂｏｔｈｒｏｓａｕｒｏｐｏｄｏｉｄｅａ,包含火山齿龙科Ｖｕｌｃａｎｏｄｏｎ－ｔｉｄａｅ,鲸龙科Ｃｅｔｉｏｓａｕｒｉｄａｅ,腕龙科Ｂｒａｃｈｉｏｓａｕｒｉｄａｅ,圆顶龙科Ｃａｍａｒａｓａｕｒｉｄａｅ和马门溪龙科Ｍａｍｅｎｃｈｉｓａｕｒｉｄａｅ;圆齿蜥龙超科Ｈｏｍａｌｏｓａｕｒｏｐｏｄｏｉｄｅａ,包含梁龙科Ｄｉｐｌｏｄｏｃｉｄａｅ和巨龙科Ｔｉ－ｔａｎｏｓａｕｒｉｄａｅ。 相似文献
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《International Journal of Coal Geology》1987,8(3):233-246
Proposals for the new international classification systems of bituminous coals, at present being prepared by the respective U.N. ECE group of experts, presuppose applying the micropetrographic parametes — vitrinite reflectance, as a measure of rank, and inertinite content. These parameters, the utilizability of which is indisputable from the scientific point of view, are not sufficient for a complete characterization of the coal mass properties in thermo-chemical transformations, particularly in the coking process. These proposals, therefore, assume the use of further parameters, specially the swelling index and volatile matter, to eliminate the limitation of the micropetrographic parameters.On the basis of an extensive sampling base of bituminous coals produced in the Ostrava-Karviná coal district (OKR coals), an evaluation was carried out of different parameters characterizing the most important properties of the coal mass and respective classifications were proposed. Selected classification parameters were: vitrinite reflectance, as a measure of rank, associated with the properties of the ordered part of vitrinite macromolecules, the H/Oat ratio, reflecting the properties of their disordered part, inertinite content and coking property, expressed by the swelling index (SI). The scientific character of this classification consists in the fact that it reflects significant physical and chemical properties which can be measured by means of the instrumental techniques available at present and, moreover, that it is associated with coal mass genesis.In order to evaluate coal reserves in seams, this classification has been modified to a less complicated variant, using three parameters, which is applicable to evaluating coal blends for coke production on the basis of expressing the coal-blend composition according to rank. 相似文献
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《International Geology Review》2012,54(3):518-525
Commercial uranium deposits and those likely to become commercial in the near future are genetically classified as magmatic, hydrothermal, exogenous, metasedimentary, and deposits of questionable origin. A brief discussion of each type is included. — C.E. Sears. 相似文献
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《地学前缘(英文版)》2018,9(6):1903-1909
In order to adopt the best safety procedures, man-made earthquakes should be differentiated as a function of their origin. At least four different types of settings can be recognized in which anthropogenic activities may generate seismicity: (I) fluid removal from a stratigraphic reservoir in the underground can trigger the compaction of the voids and the collapse of the overlying volume, i.e., graviquakes; the deeper the reservoir, the bigger the volume and the earthquake magnitude; (II) wastewater or gas reinjection provides the reduction of friction in volumes and along fault planes, allowing creep or sudden activation of tectonic discontinuities, i.e., reinjection quakes; (III) fluid injection at supra-lithostatic pressure generates hydrofracturing and micro-seismicity, i.e., hydrofracturing quakes; (IV) fluid extraction or fluid injection, filling or unfilling of artificial lakes modifies the lithostatic load, which is the maximum principal stress in extensional tectonic settings, the minimum principal stress in contractional tectonic settings, and the intermediate principal stress in strike-slip settings, i.e., load quakes; over given pressure values, the increase of the lithostatic load may favour the activation of normal faults, whereas its decrease may favour thrust faults. For example, the filling of an artificial lake may generate normal fault-related seismicity. Therefore, each setting has its peculiarities and the knowledge of the different mechanisms may contribute to the adoption of the appropriate precautions in the various industrial activities. 相似文献
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《Tectonophysics》1999,301(1-2):159-171
A new classification scheme based on the degree of fluctuation in the geometry of different layers of a multilayered fold is suggested. The classification scheme uses the degree of fluctuation in geometry in terms of the standard deviation (σn) of the thickness parameters tα′ (orthogonal thickness parameter) and Tα′ (axial plane parallel thickness parameter) for n number of layers, and dip angle α. The degree of fluctuation in the geometry of a multilayered fold can be represented by σn(tα′) or σn(Tα′) versus α plots on a Cartesian plane. In the proposed classification scheme, multilayered folds have been divided into two broad categories, namely `isodeviatoric' and `anisodeviatoric'. Isodeviatoric folds have a constant fluctuation in the geometry of different layers recorded in terms of σn(tα′) or σn(Tα′) for α>10°. A special type of isodeviatoric fold is recognised as `analogous fold' in which each layer exhibits identical geometry [σn(tα′) or σn(Tα′)=0]. Plots of isodeviatoric folds lie parallel to the abscissa (α) and those of analogous folds lie along the abscissa in the σn(tα′) or σn(Tα′) (ordinate) versus α (abscissa) diagram. Analogous folds have been divided into ten varieties (1A1, 1A2, 1A3, 1B, 1C, 2, 3A, 3B, 3C and composite-analogous types). The anisodeviatoric folds do not exhibit constant fluctuation (deviation) in the geometry of different constitutive layers. Such folds have been subdivided into `peri-analogous', `sub-analogous', `sub-non-analogous', `non-analogous' and `strongly non-analogous' types. This classification scheme is applied to folds developed in low-grade metasedimentary rocks of the Mahakoshal Group and low- to medium-grade rocks of the Chhotanagpur Granite Gneiss Complex in central India. 相似文献
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Proposed engineering of gypsiferous soil classification is given. This classification depends on soil texture, mineralogy, geochemistry and engineering properties. Study areas are located within the Mesopotamian plain and include four locations, namely, Najaf, Karbala, Falluja and Samarra which are located between latitudes 32° and 35° and longitudes 43° and 44° 30??. The study performed includes analyses of soil samples for their mineralogy and physical and engineering properties as well as the chemical analyses of soil water extracts. The results suggest that these soils consist of different percentages of sand, silt, clay and some gravel. Analysis also detected secondary gypsum, quartz, calcite, feldspar, different types of rock fragments and different types of heavy minerals in trace amount. Clay minerals are dominated by palygorskite. Hydrochemical analysis results of soil water extracts show that the calcium and sulphate ions are most common, followed by sodium, bicarbonate, chloride, magnesium and potassium. Bicarbonate and chloride show increased values in Karbala and Najaf areas. The highest gypsum content reached 67.5% in the Samarra area, while the lowest is in Karbala, which reached 28.9%.The physical and engineering properties of the studied soils were determined. Samples which were allowed to soak in water show a sudden drop in unconfined compressive strength, compression and shear values immediately after soaking and then decreased gradually. This classification of gypsiferous soils is composed of two classes: gypsiferous soil and highly gypsiferous soil, according to their gypsum content and initial void ratio, coefficient of curvature, coefficient of uniformity, the collapse potential, the compressive strength, cohesion, plasticity index, content of fines and the total dissolve solids of the soil water extracts. It is believed that this newly proposed classification for gypsiferous soils can be applied to other locations and therefore will be useful for other soil scientists and engineers as well because this classification depends on soil texture, mineralogy, geochemistry and engineering properties, while the other existing classifications deal with only one of these variables. 相似文献
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