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煤系地层中高岭石的形态-成因类型 总被引：3，自引：0，他引：3
大量的透射电子显微镜(TEM)观察表明:煤系地层中的主要粘士矿物——高岭石有独特的形貌特征。这些特征反映物源、沉积环境以及成岩后生作用的特点。本文将矿物形态与成煤各阶段的地质环境相联系,把煤系地层中高岭石划分为碎屑状高岭石、胶凝状高岭石、玻屑状高岭石、鳞片状高岭石四种形态-成因类型。它们相应的成因类型为沉积成因、胶体成因、火山灰蚀变成因、成岩变质成因。认识和研究高岭石矿物的形态与成因,在煤田地质学领域中有理论和实用意义。 相似文献
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目前对于粘土层中伊蒙混层矿物的堆垛结构、单元层含量与岩浆母质及环境条件关系的了解等,仍然十分匮乏.一定沉积环境下火山灰层中粘土矿物组合、以及伊蒙混层堆垛方式精细结构特征,可能记录了沉积(包括成岩作用) 环境对火山物质蚀变产物的影响.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、元素地球化学分析、氧同位素分析方法等方法,对贵州新民深海相二叠系-三叠系(P-T) 界线附近蚀变火山灰层的地球化学特征、粘土矿物精细结构特征等进行了深入研究.结果表明,4个火山灰粘土层均含有2种具有R3结构、不同混层比的伊蒙混层矿物相,且均出现粘土矿物集合体取代原先的火山碎屑颗粒或在颗粒表面生长的现象,粘土矿物形成于沉积-成岩阶段因而其泥质结构被保留;样品XM-5-1和XM-5-2的Fe3+原子数分别为0.16和0.17个且具有明显Eu负异常和较低的K2O含量,而XM-5-3和XM-5-4的Fe3+原子数均为0.14个,说明相对于前2个粘土层,后2个的岩浆母质更加偏向酸性而表现为成岩蚀变程度更强.粘土矿物的氧同位素组成为17.3‰~18.1‰,与常温下蒙脱石与海水的平衡数值相近,表明粘土矿物化学组成与海底成岩蚀变环境有关,而不同火山灰层的粘土矿物学特征则主要取决于岩浆岩母质以及成岩蚀变强度. 相似文献
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岩溶型铝土矿中火山物质参与成矿的直接证据需要进一步明确。通过线路调查和剖面研究，在桂西大范围内的铝土矿及其早期的铝土质岩中观察到大量的火山灰，含量大于30%；火山灰种类有岩屑、晶屑、玻屑和火山尘，塑性—半塑性变形及刚性爆裂显著，自由降落为主，属原地—准原地沉积；火山灰易于分解为水铝石、高岭石、赤铁矿等微细矿物，屑状火山灰相对尘状火山灰更易于矿化，大量火山灰主要以直接铝土矿化作用成矿。元素地球化学特征显示铝土矿和铝土质岩具有亲岩浆性，不活动元素图解判别及铝土矿测年数据显示火山灰原岩浆以碱性玄武岩为主，与岛弧火山岩一致，主要来自于哀牢山—松马造山带的二叠纪岛弧，铝土矿层具有穿时性，部分火山灰可来源于峨眉山火成岩。铝土矿层中的火山灰丰富，跨度长，可能是瓜德鲁普统末生物灭绝的肇凶。 相似文献
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岩溶型铝土矿中火山物质参与成矿的直接证据需要进一步明确。通过线路调查和剖面研究，在桂西大范围内的铝土矿及其早期的铝土质岩中观察到大量的火山灰，含量大于30%；火山灰种类有岩屑、晶屑、玻屑和火山尘，塑性—半塑性变形及刚性爆裂显著，自由降落为主，属原地—准原地沉积；火山灰易于分解为水铝石、高岭石、赤铁矿等微细矿物，屑状火山灰相对尘状火山灰更易于矿化，大量火山灰主要以直接铝土矿化作用成矿。元素地球化学特征显示铝土矿和铝土质岩具有亲岩浆性，不活动元素图解判别及铝土矿测年数据显示火山灰原岩浆以碱性玄武岩为主，与岛弧火山岩一致，主要来自于哀牢山—松马造山带的二叠纪岛弧，铝土矿层具有穿时性，部分火山灰可来源于峨眉山火成岩。铝土矿层中的火山灰丰富，跨度长，可能是瓜德鲁普世末生物灭绝的肇凶。 相似文献
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黔西晚二叠世煤地球化学性质变异及特殊组构的火山灰成因 总被引：18，自引：2，他引：18
运用仪器中子活化分析(INAA)、电感耦合等离子体原子发射光谱(ICP—AES)、X射线衍射(XRD)、带能谱仪的扫描电镜(SEM—EDX)及光学显微镜等手段，对黔西晚二叠世煤地球化学性质变异及其特殊组构的火山灰成因进行了研究。结果表明，贵州西部织金矿区9煤层中异常高含量的Fe(4．24％)、Cu(369．90μg／g)、U(49．6μg／g)、Mo(63．10μg／g)、Zn(33．97μg／g)等是来源于同沉积基性火山灰降落到泥炭沼泽中所致；高含量的Fe、Cu并非以通常意义的煤中硫化物状态存在；除煤中有机质和陆源碎屑外，发现了由火山灰、有机质和陆源碎屑所形成的煤层中的特殊组构，暂定名为沉碳质火山胶凝物，它是一种有机—无机高度混合物质，根据沉碳质火山胶凝物的形态特征和物质组成，厘定出6种组构类型，分别是：网状组构、细屑组构、基质组构、孔腔组构、均质组构和碎屑组构。 相似文献
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《地学前缘》2016,(3):103-112
含煤地层中广泛分布的火山灰蚀变成因的高岭石黏土岩被称为Tonstein。少数情况下,煤系蚀变火山灰层的黏土矿物以蒙脱石和伊蒙混层矿物为主,则分别称为斑脱岩和钾质斑脱岩。尽管中外学者对煤系火山灰蚀变黏土岩已有大量研究,然而,迄今为止这几个术语在定义和使用上在国内外科学界仍然存在争议。煤中火山灰的淋滤作用会对煤的地球化学组成产生重要影响。含煤地层中这类岩石因为分布广泛可以被用作等时标志层,提供地层对比的依据,其中的原生矿物还可以提供绝对年龄信息。有的碱性火山灰层具有找矿指示意义。煤中火山灰蚀变黏土岩夹矸中化学性质相对稳定的元素可以用来推断原始火山灰的组成,提供原始岩浆的成分以及区域地质历史演化方面的信息。 相似文献
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华北石炭二叠纪煤系中I／S间层矿物的研究 总被引：1，自引：1，他引：1
华北石炭二叠煤系中的Ｉ／Ｓ间层粘土岩夹矸或粘土岩层，在太行山以东较为发育。Ｉ／Ｓ间层矿物的类型有累托石、ＩＳ有序间层矿物、Ｓ／Ｉ无序间层矿物，它们是在近岸泥岩沼泽或沼泽环境中由同期降落的火山灰蚀变而成，在酸性介质的影响下，形成ＩＳ有序间层矿物，在偏碱性的介质条件下，形成Ｓ／Ｉ无序间层矿物；高压异常区则形成累托石。 相似文献
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在晚石炭世—早二叠世,鄂尔多斯盆地泥炭沼泽环境下发育的富含火山尘填隙物砂岩是煤成气的主要储集层。研究表明,该类砂岩的原杂基主要由同沉积期初步水化作用的火山尘构成;在煤系地层水环境下,火山尘经过初步水化作用后并不能形成沸石族矿物,主要形成了铝硅酸盐和硅酸盐的微细混合物;在埋藏过程中,砂岩火山尘填隙物的水岩反应受到煤系地层水介质性质及其活动性影响,主要发生脱水收缩作用、溶解作用、蚀变作用、碳酸盐交代作用和重结晶作用;火山尘填隙物的成岩作用在局部范围内可改善天然气储层,但也增强了储层的非均质性。 相似文献
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鄂尔多斯盆地周缘晚古生代火山活动对盆内砂岩储层的影响 总被引：14，自引：0，他引：14
鄂尔多斯盆地上古生界天然气储集体是一套以次生孔隙为主的低渗透砂岩。通过次生孔隙成因研究发现，各种溶蚀孔隙的形成与砂岩中火山物质和硅酸盐碎屑颗粒的溶蚀、蚀变关系密切。通过储层岩石学研究，对火山物质成分、结构构造、物态、次生变化等特征精细观察表明，这些火山物质具有同沉积的特点，即来源于盆地周缘同期的火山喷发。这些同沉积火山物质不仅改变了储层砂岩的物质成分，而且为储层次生孔隙的形成提供了溶蚀母质，形成了晶屑溶孔、岩屑溶孔、灰屑溶孔以及蚀变高岭石、绿泥石晶间孔，在原生孔隙基本消失的砂岩中形成了以次生孔隙为主的砂岩储层。同时，火山物质的残存、蚀变和溶蚀的差异使储层表现出强烈非均质性。 相似文献
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探讨了渤中坳陷石臼陀凸起东段CO2来源及CO2充注对储层粘土矿物的影响.研究表明,CO2中δ13C组成较重,R/Ra值较大,CO2为幔源成因;控盆的深大断裂是CO2的主要运移通道;CO2热流体晚期充注对砂岩储集层粘土矿物产生了明显的影响:CO2热流体侵位后形成的热波动效应加快了储集层中伊蒙混层粘土的演化,含CO2储集层中伊蒙混层中蒙脱石含量要比同深度的泥岩低15％ ～30％;CO2热流体晚期侵入加剧了长石的溶蚀作用,长石溶蚀促进了自生高岭石的大量形成;CO2热流体侵位后形成的偏酸性环境抑制伊利石生长,促进了其他粘土矿物向高岭石转化;含CO2储集层以少见的高自生高岭石、低伊利石为特征,这对储层物性改善起到了决定性的影响. 相似文献
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湘中下石炭统粘土矿物组合特征 总被引：1，自引：0，他引：1
湖南中部下石炭统是一套以碳酸盐岩为主夹碎屑岩含煤岩系的沉积,根据粘土矿物在下石岩统剖面分布规律,结合各组段岩性岩相特征,可推断出粘土矿物组合特征及其环境分布,从滨岸碎屑沉积到滨外泥质陆棚、滨外浅水碳酸盐陆棚,到深水碳酸盐陆棚和浅海盆地,即从滨岸向盆地方向,高岭石含量急剧减少,伊利石逐渐增加,伊利石/蒙脱石混层矿物和绿泥石则先是增加,然后又趋于减少,其最高含量分别在浅水碳酸盐陆棚和滨外泥质陆棚。测水组含煤岩系粘土矿物以高岭石为主,伊利石次之,并有一定量的绿泥石和伊利石/蒙脱石混层矿物,它们在垂向上的变化反映了沉积环境水介质酸碱度和盐度的变化规律。 相似文献
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Inorganic minerals in mudstone are composed of clay minerals,carbonate and detrital minerals.Detrital minerals(such as quartz and feldspar)are mainly original deposit.However,clay minerals(kaolinite,illite,and chlorite)and carbonate(calcite and dolomite)are mostly diagenetic minerals.Furthermore,conversion of the four kinds of clay minerals are common.The formation of clay minerals and carbonate is controlled by temperature,pressure,p H,Eh and type of cations during diagenesis.Therefore mineral assemblage can indicate the characteristics and change of diagenetic environment.In addition to inorganic minerals,there are also organic matter of different sources and chemical properties in mudstone.Traditionally,it is considered that evolution of organic matter is controlled by thermal effect.Now studies show that inorganic and organic matter can interact with each other and form clay-organic complexes.This suggest that attention should be paid to the influence of diagenetic mineral assemblage and diagenetic environment on the evolution of organic matter* Samples of mudstone from 1500-4500m of the Palaeogene in the Dongying Depression,China,were collected to investigate the changes of mudstone diagenetic environment.XRD,thin section and SEM were used to detect diagenetic minerals and assemblage characteristics.Results showed that content of detrital minerals,which are floating in mud matrix or preserved as silt laminae,is basically unchanged from shallow to deep strata.Clay minerals which are gathered as argillaceous matrix or preserved as argillaceous laminae have growth and decline relation to carbonate which mainly appear as micropoikilitic ferriferous calcite and ferriferous dolomite.All these characteristics indicate that detrital minerals are exogenetic,whereas carbonate is diagenetic minerals.Based on the SEM analysis of the clay minerals,it was found that smectite present honeycomb and reticulate structure,while illite present filiform and schistose structure and there are growth and decline relationship between them.Nevertheless,hexagonal tabular and stratified kaolinite has the highest content from 2400m to3300m.Rosette and stratified chlorite shows increase trend when the burial depth is deeper than 3300m.These characteristics indicated that clay minerals are diagenetic minerals and there are conversions among the four types.Therefore form shallow to deep,three diagenetic mineral assemblage zones can be divided based on the characteristics of carbonate and clay minerals in mudstone.Namely,smectite+illite/smectite zone in the depth of 2000-2500m;kaolinite+illite/smectite zone in the depth of 2500-3300m and illite+chlorite+carbonate zone below 3300m.Previous studies showed that kaolinite is stable under acidic conditions,while other clay minerals and carbonate are stable under alkaline conditions.Hence according to mineral assemblages feature,it was inferred that diagenetic environment of mudstonehasundergonethechangeof alkaline-acid-alkaline.For the organic matter with different chemical properties in mudstone,the hydrocarbon generation will be different in the acidic and alkaline diagenetic environment even if the conditions of temperature and pressure are the same.Therefore,for hydrocarbon generation we should not only focus on thermal effect,but also pay more attention to the differences of diagenetic environment which have great significance for the understanding of hydrocarbon generation,hydrocarbon expulsion and reservoir formation in mudstone. 相似文献
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腾冲地热区出露有众多热泉泉群,地热活动频繁,岩石发生强烈蚀变,形成的主要蚀变矿物包括高岭石、绢云母、蒙脱石、I/M间层矿物、石英和蛋白石。主要蚀变矿物的种类和含量受蚀变母岩性质的控制,花岗质砂砾岩和花岗岩形成高岭石,玄武岩形成伊利石和蒙托石,安山岩中发育硅化作用。泥化作用增强的趋势是安山岩→花岗岩→玄武岩→花岗质砂砾岩。由于花岗质砂砾岩在热区内广泛分布,通过蚀变作用形成了有经济价值的高岭土矿床。 相似文献
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海陆过渡相煤系泥页岩广泛分布,具有良好的天然气资源潜力。以淮南煤田煤系泥页岩为研究对象,运用X射线衍射、扫描电镜等分析手段,对淮南煤田煤系地层泥页岩的矿物学、岩相、储层特征等方面进行相关测试,并探讨了泥岩岩相对页岩气储集空间的控制作用。研究表明:淮南煤田煤系泥页岩矿物成分中黏土矿物含量多、自生非黏土矿物相对较少,致使岩石脆性降低并对压裂裂缝产生具有负效应,但部分菱铁矿的存在可能起改善作用;存在花斑状高岭石泥岩、浅灰色高岭石泥岩、鲕状泥岩、暗色泥岩、粉砂质泥岩等5种岩相。泥页岩储层裂缝包括层面剪切缝、有机质演化异常压力缝、层间页理缝、构造裂缝等宏观类型和与石英和高岭石有关的微裂缝类型;泥页岩孔隙包括化石孔、粒间孔、粒内孔和晶间孔及可能的有机质孔等类型,为页岩气赋存提供了储集空间。不同沉积环境下的泥岩岩相不同,进而决定了矿物成分特征与有机质相对含量,对泥页岩储集空间起主要控制作用。 相似文献
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Raphael A. J. Wüst Colin R. Ward R. Marc Bustin Michelle I. Hawke 《International Journal of Coal Geology》2002,49(4)
Since the Carboniferous, tropical latitudes have been the site of formation of many economic coal deposits, most of which have a restricted range of mineralogical composition as a result of their depositional environment, climatic conditions, and diagenesis. Mineralogical and microscopic investigations of tropical peats from Tasek Bera, Peninsular Malaysia, were performed in order to better understand some of these factors controlling the nature, distribution and association of inorganic matter in peat-forming environments. Distribution and nature of the inorganic fraction of peat deposits give insight into the weathering conditions and detrital input into the mire system. Because the inorganic composition of peat deposits is determined by plant communities, height of water table, and climate, the results of the quantitative and qualitative analysis can be used to reconstruct palaeoclimatic conditions.Tasek Bera is a peat-accumulating basin in humid tropical Malaysia with organic deposits of low- to high-ash yield and thus representative of many ancient peat-forming environments. Clay minerals dominate the mineralogical composition of the peat and organic-rich sediments, while quartz and clays dominate the underlying siliciclastic deposits. Kaolinite is the most abundant clay mineral in the organic deposits with minor amounts of illite and vermiculite. Particle size analyses indicate that >50% of the inorganic detrital fraction is <2 μm. Most detrital quartz grains range in size from fine silt to fine sand. The fine sand fraction accounts for a maximum of 5 wt.% of the inorganic constituents. In addition, abundant biogenic and non-biogenic, Al- and Si-rich amorphous matter occur. In the ombrotrophic (low-nutrient) environment, biogenic inorganic material contributes up to >75% of the ash constituents. As a consequence, the vegetational communities make an important contribution to the inorganic and overall ash composition of peats and coals. The ash content of the often inundated peat consists on average of 10% opaline silica from diatoms and sponge spicules, while the ash of the top deposits may have up to 50% biogenic silica. Hence, Al- and Si-hydroxides and the opaline silica from diatoms and sponges represent a large repository of Al and Si, which may form the basis of mineral transformation, neoformation and alteration processes during coalification of the peat deposits. As a result, most coal deposits from paleotropical environments are anticipated to have little to no biogenic inorganic material but high amounts of secondary clays, such as kaolinite (detrital kaolinite, resilisified kaolinite, or desilisified gibbsite) or illite, and various amounts of detrital and authigenetic quartz. 相似文献
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Burial Metamorphism of the Ordos Basin in Northern Shaanxi 总被引：1，自引：0，他引：1
Zhang Lifei 《《地质学报》英文版》1993,67(2):181-193
Burial metamorphism has been found in the Ordos basin of northern Shaanxi. On the basis of a rather intensive study of burial metamorphism of sandstone, it has been shown that the evolution from diagenesis to metamorphism involves four stages: cementation of clay minerals, regrowth of pressolved quartz and feldspar, cementation of carbonates and formation of laumontite. On that basis it has been put forward that the laumontite is formed by burial metamorphism of clay and carbonate minerals. According to the thermodynamic data of minerals, the conditions under which laumontite is formed are T<250℃ and X_(CO_2)<0.17. High-resolution SEM and TEM studies of clay minerals in mudstone show that there occur a mixed layer assemblage of bertherine and illite/chlorite and transformation from bertherine to chlorite. On that basis coupled by the X-ray diffraction analysis the author suggests the following transformation of clay minerals during burial metamorphism: the earliest smectite-kaolinite assemblage changes into the bertherine-illite mixture with increasing depth, then into the illite/chlorite mixed layer assemblage and finally into dispersed individual illite and chlorite. The reaction of the transformation is:smectite+kaolinite+K~+=illite+chlorite+quartz According to the study of the oxygen isotope thermometry of the coexisting illitequartz pair, the temperature of the above transformation is lower than 180℃. 相似文献