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1.
A.B. Cadle B. Cairncross A.D.M. Christie D.L. Roberts 《International Journal of Coal Geology》1993,23(1-4)
The coal-bearing sediments and coal seams of the Karoo Basin, Southern Africa are described and discussed. The Karoo Basin is bounded on its southern margin by the Cape Fold Belt, onlaps onto the Kaapvaal Craton in the north and is classified as a foreland basin. Coal seams are present within the Early Permian Vryheid Formation and the Triassic Molteno Formation.The peats of the Vryheid Formation accumulated within swamps in a cool temperate climatic regime. Lower and upper delta plain, back-barrier and fluvial environments were associated with peat formation. Thick, laterally extensive coal seams have preferentially accumulated in fluvial environments. The coals are in general inertinite-rich and high in ash. However, increasing vitrinite and decreasing ash contents within seams occur from west to east across the coalfields. The Triassic Molteno coal seams accumulated with aerially restricted swamps in fluvial environments. These Molteno coals are thin, laterally impersistent, vitrinite-rich and shaly, and formed under a warm temperate climatic regime.Palaeoclimate, depositional systems, differential subsidence and basin tectonics influence to varying degrees, the maceral content, thickness and lateral extent of coal seams. However, the geographic position of peat-forming swamps within a foreland basin, coupled with basin tectonics and differential subsidence are envisaged as the primary controls on coal parameters. The Permian coals are situated in proximal positions on the passive margin of the foreland basin. Here, subsidence was limited which enhanced oxidation of organic matter and hence the formation of inertinitic coals. The coals in this tectonic setting are thick and laterally extensive. The Triassci coals are situated within the tectonically active foreland basin margin. Rapid subsidence and sedimentation rates occurred during peat formation which resulted in the preservation of thin, laterally impersistent, high ash, vitrinite-rich, shaly coals. 相似文献
2.
The No. 1 and No. 2 coal seams from the Permian Vryheid Formation in the east Witbank Coalfield, South Africa are described with respect to their distribution, thickness and quality. These two coal seams accumulated in a postglacial climatic environment and peat accumulation was closely associated with and influenced by deposition in a braided river system. The fluvial channels that were syndepositional with peat accumulation have resulted in thinning of coal below and above channel axes and pinch-out of coal adjacent to channel margins. Low-ash coal originated from peat which accumulated in areas away from the influence of clastic sedimentation. In contrast, higher-ash coals are situated adjacent and parallel to channel margins where interbedded channel sand and silt contaminated the peat.The lower No. 1 seam peat originated under near-optimum conditions in a lacustrine swamp which blanketed an underlying platform of glaciofluvial braided river sediment. This peat swamp was not subjected to syndepositional clastic contamination and as a result is of superior quality (lower ash/higher calorific value and volatile matter) than the overlying No. 2 coal seam. The No. 2 seam is split by a clastic parting produced by a braided fluvial channel which transected the swamp midway through peat accumulation. This fluvial clastic parting deleteriously affected coal thickness and quality.A comparison of the Gondwanan Permian peat-forming conditions with those from Carboniferous northern hemisphere counterparts suggests that the differences in coal characteristics between these two regions are probably related to different palaeoclimatic conditions and basin tectonics. Cool-temperate climatic conditions which prevailed over the Permian peat swamps resulted in less species diversification of vegetation at these high-latitude settings than the diverse floral assemblages of the Carboniferous swamps. A stable intracronic basin platform caused lateral dispersion of sedimentary facies rather than the stacking of vertical facies which occurred in rapidly subsiding depositories. Partial exposure of the Permian peat swamps during peat accumulation may account for the relatively higher inertinite content of the coals. 相似文献
3.
Factors controlling the vegetation distribution and coal‐forming environments in a strike‐slip basin. The Pennsylvanian Peñarroya‐Belmez‐Espiel Basin,southern Spain 
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下载免费PDF全文 Coal‐forming environments require humid to perhumid conditions. Tectonics governs the size, location and availability of coal seams developed in such environments. While large Pennsylvanian paralic basins generated thick and continuous coal seams, many other small coeval basins, which were tectonically active, developed a puzzling succession, with carbonaceous deposits that varied in size, thickness and the nature of the coal‐forming flora. This study, conducted in the Peñarroya‐Belmez‐Espiel coalfield, a Variscan strike‐slip basin in the south of Spain, provides insights into this subject. The coal seams analysed, generated in different depositional environments, have quantitatively different palynological assemblages. Lacustrine coals are dominated by lycopsids; distal alluvial plain/marginal lacustrine coals are dominated by sphenophytes and tree ferns, and middle alluvial fan coals are dominated by sphenophytes, tree ferns and lycopsids. This means that when conditions were favourable for peat accumulation, peat accumulated regardless of the nature of the available flora. 相似文献
4.
华北晚古生代成煤环境与成煤模式多样性研究 总被引：23，自引：2，他引：23
华北晚古生代聚煤盆地存在活动体系成煤环境和废弃体系成煤环境。前者的海相成煤环境主要为泻湖泥炭坪,陆相成煤环境以三角洲平原沼泽意义最大。晚石炭世至晚二叠世,海相为主的成煤环境逐渐被陆相为主的成煤环境所取代,由盆缘到盆内成煤环境总体呈环带状展布。成煤环境差异性影响了成煤特点,这些成煤特点成为识别海、陆相煤层的显著相标志。华北晚古生代聚煤盆地在时间上和空间上存在成煤模式的多样性,以陆表海滨岸成煤模式、废弃碎屑体系成煤模式和浅水三角洲成煤模式为主。 相似文献
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6.
在吐哈盆地中、下侏罗统含煤岩系层序地层分析的基础上,对聚煤期古地理特征及其与聚煤作用的关系进行了研究。结果表明,吐哈盆地中、下侏罗统含煤岩系形成于河流-三角洲-湖泊沉积体系,其中共发育4个三级层序,分别对应于八道湾组、三工河组、西山窑组一、二段和三、四段。吐哈盆地从层序Ⅰ到层序Ⅳ,先后经历了沼泽（层序Ⅰ）-湖泊（层序Ⅱ）-沼泽（层序Ⅲ）-湖泊（层序Ⅳ）过程。在对应于最大湖泛面的湖侵体系域末期和高位体系域早期,较快的可容空间增加速率与泥炭堆积速率相平衡,从而有利于厚煤层的堆积。煤层厚度、碳质泥岩厚度与砂砾岩含量呈负相关关系,即砂砾岩含量越少,煤和碳质泥岩厚度越大;地层厚度300～500 m（层序Ⅰ）和400～550m之间（层序Ⅲ）时,煤层厚度最大,说明有利于煤和碳质泥岩聚集的环境是沉降速率中等、陆源碎屑供给相对较少的三角洲间湾、湖湾以及下三角洲平原环境,层序Ⅰ和层序Ⅲ的聚煤中心如艾维尔沟、柯尔碱、桃树园、七泉湖、柯柯亚、鄯善、艾丁湖、沙尔湖、大南湖和三道岭等均属于这类环境。 相似文献
7.
Previous investigations have not well defined the controls on the development of minable coals in fluvial environments. This study was undertaken to provide a clearer understanding of these controls, particularly in of the lower Tertiary coal-bearing deposits of the Raton and Powder River basins in the Rocky Mountain region of the United States. In this region, large amounts of coals accumulated in swamps formed in the flow-through fluvial systems that infilled these intermontane basins. Extrabasinal and intrabasinal tectonism partly controlled the stratigraphic and facies distributions of minable coal deposits. The regional accumulation of coals was favored by the rapid basin subsidence coupled with minimal uplift of the source area. During these events, coals developed in swamps associated with anastomosed and meandering fluvial systems and alluvial fans. The extensive and high rate of sediment input from these fluvial systems promoted the formation of ombrotrophic, raised swamps, which produced low ash and anomalously thick coals. The petrology and palynology of these coals, and the paleobotany of the associated sediments, suggest that ombrotrophic, raised swamps were common in the Powder River Basin, where the climate during the early Tertiary was paratropical. The paleoecology of these swamps is identical to that of the modern ombrotrophic, raised swamps of the Baram and Mahakam Rivers of Borneo. 相似文献
8.
准噶尔盆地侏罗系八道湾组聚煤作用控制因素分析 总被引：11，自引：2，他引：9
从煤层厚度及其在层序地层格架中的平面展布特征入手,并在分析煤层在层序格架中的发育和分布规律的基础上,探讨了沉积环境、沉积体系演化和湖平面变化对陆相盆地---准噶尔盆地侏罗系层序Ⅰ(八道湾组的主体)聚煤作用的影响。河流泛滥平原、三角洲平原、湖湾等沉积环境的可容空间变化速率和泥炭堆积速率常能保持有利于泥炭沉积的平衡关系,从而成为富煤环境。实质上,沉积环境是聚煤作用控制因素的外在表现形式,而其最根本的控制因素则是可容空间变化速率。在本研究区,主要体现为湖平面变化对煤层分布的控制作用。 相似文献
9.
层序地层学是近20年来发展起来的一门新的方法学科,并在聚煤作用分析中得到广泛应用。作者就近海型含煤岩系沉积学研究历史以及煤系层序地层学研究方法及有关问题进行探讨,认为近海环境的聚煤作用实际上是海平面(基准面)上升过程中发生的,同时提出煤层厚度受泥炭堆积速率与可容空间增加速率的控制：靠陆一侧冲积平原和三角洲平原沉积环境中,厚煤层主要出现在最大海泛面位置;而靠海一侧障壁-潟湖或碳酸盐岩台地沉积环境中,厚煤层主要出现在初始海泛面的位置;但就整个三级复合层序来说,层序中厚度最大、分布最广的煤层主要分布于可容空间增加速率最大的最大海泛面附近的位置。对于中国晚古生代近海型煤系中常见的“根土岩-煤-石灰岩”序列,聚煤作用发生于海相石灰岩“滞后时段”,即在海侵之后、海相石灰岩层真正沉积下来之前的时段,这一时段可容空间增加速率与泥炭堆积速率平衡,有利于聚煤作用发生。 相似文献
10.
Microfacies and depositional environment of Tertiary Tanjung Enim low rank coal, South Sumatra Basin, Indonesia 总被引：2，自引：2，他引：2
The South Sumatra basin is among the most important coal producing basins in Indonesia. Results of an organic petrography study on coals from Tanjung Enim, South Sumatra Basin are reported. The studied low rank coals have a mean random huminite reflectance between 0.35% and 0.46% and are dominated by huminite (34.6–94.6 vol.%). Less abundant are liptinite (4.0–61.4 vol.%) and inertinite (0.2–43.9 vol.%). Minerals are found only in small amounts (0–2 vol.%); mostly as iron sulfide.Based on maceral assemblages, the coals can be grouped into five classes: (1) humotelinite-rich group, (2) humodetrinite-rich group, (3) humocollinite-rich group, (4) inertinite-rich group and (5) humodetrinite–liptinite-rich group. Comparing the distribution of maceral assemblages to the maceral or pre-maceral assemblages in modern tropical domed peat in Indonesia reveals many similarities. The basal section of the studied coal seams is represented typically by the humodetrinite–liptinite-rich group. This section might be derived from sapric or fine hemic peat often occurring at the base of modern peats. The middle section of the seams is characterized by humotelinite-rich and humocollinite-rich groups. The precursors of these groups were hemic and fine hemic peats. The top section of the coal seams is typically represented by the humodetrinite-rich or inertinite-rich group. These groups are the counterparts of fibric peat at the top of the modern peats. The sequence of maceral assemblages thus represents the change of topogenous to ombrogenous peat and the development of a raised peat bog.A comparison between the result of detailed maceral assemblage analysis and the paleodepositional environment as established from coal maceral ratio calculation indicates that the use of coal maceral ratio diagrams developed for other coal deposits fails to deduce paleo-peat development for these young tropical coals. In particular, mineral distribution and composition should not be neglected in coal facies interpretations. 相似文献
11.
The coal deposits of Meghalaya occur in the Lakadong Sandstone (25–250 m thick) of Eocene age. The coal-bearing formations are understood to have been deposited over platform areas in estuarine and lagoonal environments and subjected to recurrent marine transgressions and regressions during the Eocene period. There are three major groups of coalfields in Meghalaya, viz. Garo Hills (West Daranggiri and Siju Coalfields), Khasi Hills (Langrin and Mawlong–Shella Coalfields) and minor coalfields (Laitryngew, Cherrapunji and Bapung Coalfields). Pillar coal samples have been collected from 10 seams at 15 locations and have been subjected to a detailed petrographic examination for their characterization. An effort has been made to trace the path of their evolution based on coal petrography-based models. The quantitative petrographic analysis shows that these coals are vitrinite rich (45.0–92.9%, mean 73.4% mmf basis) with low concentration of inertinite (0.0–13.8%, mean 3.0% mmf basis), whereas the liptinite occurs in appreciable concentration (5.5–53.1%, mean 22.5% mmf basis). Further, these coals are rich in vitrite (51.6–100%, mean 78.3% mmf basis). The volatile matter (from 38.5% to 70.0%, d.a.f.) and vitrinite reflectance (Rom from 0.37% to 0.68%) characterize these coals, as per German (DIN) and North American classification, approximately as sub-bituminous ‘C' to high volatile ‘C' bituminous. The occurrence of teleutospore (single, double and triple celled) suggests that these coals have originated from a characteristic Tertiary flora. The maceral and microlithotype composition in the coal petrography-based depositional models suggest that the coals of Garo Hills were formed in reed to open water swamps in telmatic to limnic conditions. The coals of Khasi Hills were dominated by forest swamps and telmatic to limno-telmatic conditions. In addition, the occurrence of large-size resins suggests prolific growth of conifers in the swamps. 相似文献
12.
The Middle Permian Collinsville Coal Measures of the northern Bowen Basin illustrate a range of cold to cold-temperate, coal-forming environments. Cold climate is indicated by Glossopteris flora in the coal measures, and by restricted marine fauna dominated by brachiopods and bryozoa in correlative marine sequences of the Back Creek Group which contains also abundant lonestones (dropstones). Sedimentation was characterised by an overall transgression, interrupted by local fluvial and coastal progradation in a shallow, epicontinental sea during a relatively quiescent tectonic period.Six sedimentary environments are represented: fluvial, fluvio-paralic, barrier-strandplain, back-barrier, tidal flat and open marine. The basal coal formed from peat of swamps of abandoned areas of gravelly braided streams, and is massive, dull, and with high ash (20%), low sulphur (1%) contents. Overlying coals developed from peats formed in fluvio-paralic and paralic environments, and thicker seams are generally brighter, with low to moderate ash (8–17%) and moderate to high total sulphur (1–6%) contents. Seams associated with fluvial influence show splits and high ash yield, while seams associated with coastal deposits show high sulphur levels (up to 21%).In contrast to reported models of coal-forming environments, no clearly defined deltaic or inter-distributary bay-fill sequences were identified in the area studied. Rather, vast freshwater wetlands backed low-gradient, progradational coasts locally having bars and barriers. The barriers were not prerequisites for substantial peat accumulation, although may have locally assisted peatland development by raising the profile of coastal equilibrium. 相似文献
13.
通过对蔚县煤田下花园组煤中植物残体——分散角质层、半丝炭化木材等研究,结合非煤层中植物化石和孢粉组合特征分析,认为泥炭沼泽植物群落主要由松柏类、银杏类、苏铁类和蕨类组成,它们都是本区成煤的重要物质来源。这种森林体系代表了一种温暖潮湿、雨量充沛的古气候条件。煤中丝炭及半丝炭化组分含量丰富是泥炭堆积速度快于盆地基底沉降速度,并最终导致泥炭沼泽覆水浅,泥炭层多处于相对干燥、氧化环境的表现。不同煤层中丝炭及半丝炭化组分含量的差异,为煤层对比提供了新的依据。 相似文献
14.
Weihua Ao Wenhui Huang Chengmin Weng Xiuling Xiao Dameng Liu Xiuyi Tang Ping Chen Zhigen Zhao Huan Wan Robert B. Finkelman 《地学前缘(英文版)》2012,3(1):85-95
Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin,northwestern China.The huge reserves of this high quality coal have a high commercial value.We studied the coal’s petrologic characteristics and its maceral distribution to determine the maceral’s contribution to generation of oil and gas.The results show that the Jurassic coals in the Ordos Basin have special penological features because of the Basin’s unique depositional environment which was mainly a series of high-stand swamps in the upper fluvial system.These petrographic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers.After burial,the peat continued to undergo oxidizing conditions,this process generated extensive higher inertinile contents in the coals and the vitrinite components were altered to semi-vitrinite.The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal,dull coal,semilustrous and lustrous coal.The proportions of semi-dull coal and dull coal are higher in the basin margins,especially in the area near the northern margin.The numbers of semilustrous and lustrous coals increase southwards and towards the central basin.This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components.Another observation is that in the Ordos" coal sequences,especially in the lower part,some sandstone beds are thick,up to 20 m with a coarse grain size.The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure.The fusinite structure is clear and well preserved.After burial,the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology.The sand bodies in the roof and floor exhibit good physical conditions so that pore water can maintain a long-term state of oxidation,circulation and connection to the coal.So coal components remain in an oxidation environment for a long time.Conversely,in the basin center,lacustrine facies developed and peat was rapidly covered by mudstone after burial and subsequent coal beds rapidly entered a reducing environment.As a result,abundant gelatification occurred and the vitrinite content increased.Exinite often accumulated in a specific position in the coal bed.Although the average exinite content is not high on the whole,it does significantly contribute to the total hydrocarbon generation. The exinite content has been underestimated,especially the amorphous bituminous fluid and its importance is emphasized here.The reason is that the fluid flows easily into fusinite which has strong rigidity,or flows into some fissures,where it is commonly neglected. 相似文献
15.
S.I. Arbuzov L.P. Rikhvanov S.G. Maslov V.S. Arhipov A.M. Belyaeva 《International Journal of Coal Geology》2006,68(3-4):127-134
One hundred twenty-two samples of Jurassic and Paleogene brown coals and 1254 peat samples from the south-eastern region of the Western-Siberian platform were analyzed for gold by the neutron-activation method. Mean content of Au in Jurassic coals is 30 ± 8 ppb, in Paleogene coals is 10.6 ± 4.8 ppb, and in peat is 6 ± 1.4 ppb. Concentrations of gold as high as 4.4 ppm were found in coal ash and 0.48 ppm in the peat ash. Coal beds with anomalous gold contents were found at Western-Siberian platform for the first time.Negative correlation between gold and ash yield in coals and peat and highest gold concentrations were found in low-ash and ultra-low-ash coals and peat. Primarily this is due to gold's association with organic matter.For the investigation of mode of occurrence of Au in peat the bitumen, water-soluble and high-hydrolyzed substances, humic acids, cellulose and lignin were extracted from it. It was determined that in peat about 95% of gold is combined with organic matter. Forty to sixty percent of Au is contained in humic acids and the same content is in lignin. Bitumens, water-soluble and high-hydrolyzed substances contain no more than 1% of general gold quantity in peat.The conditions of accumulation of high gold concentrations were considered. The authors suggest that Au accumulation in peat and brown coals and the connection between anomalous gold concentrations and organic matter in low-ash coals and peat can explain a biogenic–sorption mechanism of Au accumulation. The sources of formation of Au high concentration were various Au–Sb, Au–Ag Au–As–Sb deposits that are abundant in the Southern and South-Eastern peripheries of the coal basin. 相似文献
16.
研究鄂尔多斯盆地延安组的煤层发育特征,首先建立延安组等时的层序地层格架,进而分析可容空间变化对煤层形成的控制作用。通过分析野外露头、钻孔、测井等资料,识别延安组中发育的关键层序地层界面,将延安组划分为3个三级层序;层序由低位正常湖退、湖侵、高位正常湖退和强迫湖退4个体系域组成,并建立了全盆地范围等时的层序地层格架。研究发现:在等时层序地层格架中,煤层主要发育在层序I、层序Ⅱ湖侵和高位正常湖退体系域的中、晚期和层序Ⅲ的湖侵体系域的晚期;在区域上,盆地北部地势较为平坦,发育中等厚度、区域稳定性较好的煤层,盆地南部发育稳定性较差的厚-巨厚煤层;从滨湖平原到三角洲平原再到河流泛滥平原,厚煤层从位于四级基准面上升半旋回的底部逐渐过渡到中上部。综上可知,不同沉积区可容空间增加速率与泥炭堆积速率达到平衡的位置不同,厚煤层主要发育在二者近似处于平衡状态的位置,并且发育随着沉积相带变化有规律地迁移。 相似文献
17.
Improved regional and interregional stratigraphic correlations of Pennsylvanian strata permit comparisons of vegetational changes in Euramerican coal swamps. The coal-swamp vegetation is known directly from in situ coal-ball peat deposits from more than 65 coals in the United States and Europe. Interpretations of coal-swamp floras on the basis of coal-ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology. Objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation. Morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps.Changes in composition of Pennsylvanian coal-swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate. Paleobotany and paleogeography of the Euramerican province indicate a moist tropical paleoclimate. Rainfall, runoff and evapotranspiration were the variable climatic controls in the distribution of coal-swamp vegetation, peat accumulation and coal resources. In relative terms of climatic wetness the Pennsylvanian Period is divisible into five intervals, which include two relatively drier intervals that developed during the Lower-Middle and Middle-Upper Pennsylvanian transitions. The climate during Early Pennsylvanian time was moderately wet and the median in moisture availability. Early Middle Pennsylvanian was drier, probably seasonally dry-wet; late Middle Pennsylvanian was the wettest in the Midcontinent; early Late Pennsylvanian was the driest; and late Late Pennsylvanian was probably the wettest in the Dunkard Basin. The five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation. Regional differences in basinal geology and climate were significant variables, but the synchronous control of paleoclimate was of primary importance. 相似文献
18.
Shuai Wang Longyi Shao Dongdong Wang Jason Hilton Biao Guo Jing Lu 《Sedimentology》2020,67(2):991-1013
Coal seams preserve high-resolution records of ancient terrestrial water table (base level) fluctuations in ancient peat accumulations, but little is known about base level change in anomalously thick coal seams. Using the Early Cretaceous 91 m anomalously thick No. 6 coal (lignite) seam in the Erlian Basin (north-east China) as a case study, the origin and evolution of peat accumulation in a continental faulted basin is revealed by sedimentological, sequence stratigraphic and coal petrological analyses. The lignite is dominated by huminite, indicating oxygen-deficient and waterlogged conditions in the precursor mire. Four types of key sequence stratigraphic surfaces are recognized, including paludification, terrestrialization, accommodation-reversal and give-up transgressive surfaces. Vertically, the No. 6 coal seam consists of fourteen superimposed wetting-up and drying-up cycles separated by key sequence stratigraphic surfaces, with each of these cycles having a mean duration of about 156 to 173 kyr. In a high accommodation peat swamp system, the wetting-up cycles are generally characterized by an upward increase in mineral matter and inertodetrinite and an upward decrease in huminite with the paludification surface as their base and the give-up transgressive surface or accommodation-reversal surface as their top, representing a trend of upward-increasing accommodation. In contrast, the drying-up cycles are generally characterized by an upward decrease in mineral matter and inertodetrinite and an upward increase in huminite, with the terrestrialization surface as their base and the accommodation-reversal surface as their top, representing a trend of upward-decreasing accommodation. A multi-phase mire stacking model for accumulation of the coal seam is proposed based on high-frequency accommodation cycles and the stratigraphic relationships between coal and clastic sediments. High-frequency accommodation cycles in the coal are closely related to water table fluctuations in the precursor mires and are driven by high-frequency climate via changes in the intensity and seasonality of precipitation in a relatively stable subsidence regime. Recognition that the No. 6 coal seam is composed of multiple stacked mires has implications for studies addressing palaeoclimatic inferences and genesis of anomalously thick coals seams. 相似文献
19.
《Russian Geology and Geophysics》2014,55(11):1306-1315
We present new original data on the geochemistry of scandium in the coals of Asian Russia, Mongolia, and Kazakhstan. In general, the studied coals are enriched in Sc as compared with the average coals worldwide. Coal deposits with abnormally high, up to commercial, Sc contents were detected in different parts of the study area. The factors for the accumulation of Sc in coals have been identified. The Sc contents of the coals depend on the petrologic composition of coal basins (composition of rocks in their framing) and the facies conditions of coal accumulation. We have established the redistribution and partial removal of Sc from a coal seam during coal metamorphism. The distribution of Sc in deposits and coal seams indicates the predominantly hydrogenic mechanism of its anomalous concentration in coals and peats. The accumulation of Sc in the coals and peats is attributed to its leaching out of the coal-bearing rocks and redeposition in a coal (peat) layer with groundwater and underground water enriched in organic acids. The enrichment of coals with Sc requires conditions for the formation of Sc-enriched coal-bearing rocks and conditions for its leaching and transport to the coal seam. Such conditions can be found in the present-day peatland systems of West Siberia and, probably, in ancient basins of peat (coal) accumulation. 相似文献
20.
法国蒙索盆地的断裂活动与泥炭（煤）堆积的关系 总被引：2，自引：0，他引：2
通过对法国斯蒂芬期（Ｃ３）的蒙索煤盆地巴哈露天矿１号厚煤层的沉积构成及其同沉积断裂活动对其堆积的控制作用分析，建立了内陆、山间断陷盆地物源近、构造活动强烈、水动力条件变化大、快速充填的沉积─构造背景下的断块成煤模式。早期构造活动性质、方式的改变、沉积充填碎屑岩体类型的变化与成煤期区域构造背景的变化息息相关。 相似文献