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1.
根据衍射峰具有的不同分布特点推导出了14个伊利石结晶度Kbler指数,Weaver指数和Weber指数关系式中常数项C1-C14的数值,提出了PearsonVII分布中形态参数μ与C5,C6,C11,C12的4个定量方程。由此,14个伊利石结晶度指数关系式可直接用于实际计算。根据阿尔卑斯复理石伊利石形态特征Sc=0.731,由这些关系式进行近变质带上下界线的转换得出与Kbler指数0.42~0.25。△2θ界线对应的Weaver指数和Weber指数的界线值分别为5.8~17.6和300~179。讨论了在自然干燥状态下直接进行伊蒙混层鉴定的基本原理。  相似文献   

2.
根据衍射峰具有的不同分布特点推导出了14个伊利石结晶度Kübler指数,Weaver指数和Weber指数关系式中常数项C1-C14的数值,提出了PearsonⅦ分布中形态参数μ与C5,C6,C11,C12的4个定量方程.由此,14个伊利石结晶度指数关系式可直接用于实际计算.根据阿尔卑斯复理石伊利石形态特征Sc=0.731,由这些关系式进行近变质带上下界线的转换得出与Kübler指数0.42~0.25°△2θ界线对应的Weaver指数和Weber指数的界线值分别为5.8~17.6和300~179.讨论了在自然干燥状态下直接进行伊蒙混层鉴定的基本原理.  相似文献   

3.
伊利石结晶度及其在低温变质研究中若干问题的讨论   总被引:4,自引:0,他引:4  
王河锦  陶晓风  M.Rahn 《地学前缘》2007,14(1):151-156
文中介绍与伊利石结晶度相关的伊利石矿物新的定名方案;讨论了伊利石结晶度的结晶学基础与Scherrer方程式的关系;讨论了三个重要的伊利石结晶度指数Weaver、K櫣bler和Weber指数的关系,并介绍推导的Weaver、K櫣bler和Weber指数的理论关系式;评价了衍射仪测量条件对结晶度数值的影响和三套伊利石结晶度标样的作用以及成岩带、变质带与葡萄石-绿纤石相、沸石相、绿纤石-阳起石亚相对比的依据。建议(1)停用绢云母一词;(2)建立可供各实验室使用的具有晶体结构和晶体化学参数和多型参数的伊利石结晶度标样;(3)建议多开展规范的可进行国际对比的低温变质研究,划分出与国际上一致的成岩带和近变质带,不仅利于低温变质作用理论的研究,而且由于成岩带到近变质转变带是重要的煤气油的生成带,也利于中国煤气油资源的勘探与开发,利于国民经济的长远持续发展。  相似文献   

4.
由伊利石结晶度研究桂西右江地区区域极低级变质作用   总被引:10,自引:0,他引:10  
运用伊利石结晶度Kübler指数将桂西右江地区下三叠统罗楼群和中三叠统百逢组下段划归为浅层变质带(K.I△2θ°为0.22~0.25);将中三叠统百逢组上段和河口组划归为近变质带,中三叠统百逢组上段为高级近变质带(K.I△2θ°为0.26~0.33);中三叠统上部河口组为低级近变质带(K.I△2θ°为0.38~0.40),不排除局部为成岩带的可能.地层柱自下向上,伊利石结晶度Kübler指数由小变大,变质程度由高变低,而且,变质作用级别与岩层在地层柱中位置协调以及变质带边界与地层界线趋于一致,证明为区域埋藏极低级变质作用.凌云明山金矿区剖面矿体和百逢组各层段伊利石结晶度Kübler指数为0.42~0.50,属成岩带,且没有明显时空变化规律.  相似文献   

5.
王河锦 《地质学报》2022,96(5):1711-1723
本文集中讨论了甚低级变质作用研究中涉及到的几个问题,包括:① 近变质带的创立及其在解决划分成岩作用与变质作用界线这一国际难题中所取得的进步;② 伊利石结晶度对碎屑岩甚低级变质作用研究起到的作用与贡献;③ 仪器校正、粒度大小及其与Kübler指数的经验关系式;④ 泥质碎屑岩中的成岩指示矿物与变质指示矿物;⑤ 松潘 甘孜、巴颜喀拉造山带的甚低级变质作用的模式与新的成因解释;⑥ 讨论了涉及到的科学研究的相关规则。提出了运用指示矿物结合伊利石结晶度划分成岩作用/变质作用界线的方案和建立喜马拉雅伊利石结晶度标样的重要性与必要性;提出碎屑岩甚低级变质作用的新成因模式。  相似文献   

6.
自1967年Kübler用X射线衍射(XRD)法测量伊利石结晶度以划分极低级变质带以来,伊利石结晶度一直是划分极低级变质带的主要指标。但是不同的人用伊利石结晶度Kübler指数划分变质级的方案不同。因此,尚需要结合岩石学分析方法判定变质级。作为一种尝试,对川西北松潘—阿坝地区红参1井5975m深度内的变泥质岩进行了矿物共生分析。结果表明,钻遇地层遭受了高级近变质作用,只是由于岩石化学成分原因,未能出现泥质岩近变质指示矿物黑硬绿泥石,并未达到浅变质级别,不至于破坏油气的保存。Kisch(1990)提出的变质级划分方案比较符合研究区的实际情况。在极低级变质研究中应用矿物共生分析,一方面可以解决类似的结晶度研究的分歧,另一方面对于指导薄片观察以及X衍射物相分析十分有益。  相似文献   

7.
关于伊利石结晶度诸指数的评价   总被引:14,自引:1,他引:13  
王河锦  周健 《岩石学报》1998,14(3):395-405
本文根据结晶学原理、Scherrer定律、Warren-Averbach理论和X射线衍射峰形态学原理提出任何衍射峰都是由五个基本要素组成的,即:衍射峰位置;最大衍射强度;半高宽;衍射峰形态和对称性。各衍射峰要素都具有其自身的物理学意义,其中,只有半高宽和衍射峰形态是与晶体内部结构和大小即结晶度相联系的。据此,分析评价了与X射线衍射相关的Kübler指数、Weber-DunoyerdeSegonzac-Economou指数、Weaver指数、Miliers指数、Weber指数、分解HW及纯C轴厚度等伊利石结晶度指数的理论基础、使用前提和条件、特点及误差源。指出Kübler指数、Weber-DunoyerdeSegonzac-Economou指数和分解HW为非条件性单一结晶度指数;Weaver指数、Weber指数和高宽比为条件性单一结晶度指数;消除晶体内部微应变影响的c轴厚度为全面描述伊利石结晶度指数;而Miliers指数不可描述伊利石结晶度。  相似文献   

8.
就像用"砝码"标定"称"来测量物质质量一样,伊利石结晶度的测量也需要这样的"砝码"标定它的测量工具——衍射仪,从而能够进行伊利石结晶度的测量和对比。这个砝码就是伊利石结晶度标样或称伊利石结晶度国际标样。第2届Kübler-Frey国际研讨会伊利石结晶度圆桌会议就伊利石结晶度标样和近变质带的确定的问题进行了深入的讨论。会议一致认为,用伊利石结晶度标样校正X射线衍射仪是极为重要和必要的,没有进行标样校正的伊利石结晶度数据将被拒绝发表,经过伊利石结晶度国际标样校正后的伊利石结晶度数据才可用于近变质带的划分和国际对比。本文就伊利石结晶度测量的有关衍射仪类型与差别,衍射仪系统,测量条件,样品的影响和国际标样对仪器的校正等问题进行了分析研究。结果表明不同型号仪器,同型号仪器不同测量条件与状态,样品的不同制备方法都将影响伊利石结晶度Kübler指数的测量。指出只有使用国际标样才可校正测量的伊利石结晶度Kübler指数,从而达到消除偏差准确划分近变质带的标准和进行国际对比的目的。  相似文献   

9.
应用国际标样对伊利石结晶度测定值的校正及其意义   总被引:1,自引:0,他引:1  
伊利石的结晶度(IC),又称Kbler指数(K.I.),是指粘土矿物伊利石10×10-8cmXRD峰的半高宽。作为一个变质程度的指标,结晶度广泛用于研究高级成岩—极低级变质—低级变质作用的演变过程,随着变质程度的提高,伊利石结晶度逐渐增大。根据Kbler的建议,近变质带(极低级变质带)上、下边界的伊利石结晶度分别为0.42(°Δ2θ)和0.25(°Δ2θ)。然而,测定伊利石结晶度时,由于缺少国际标样,且各实验室间的样品制备、仪器条件、测试方法也不相同,因而导致获得的数据有较大差别,缺少可比性;因此,使用国际标样对数据进行校正,使各实验室获得的数据都能直接地进行对比,是非常必要的。利用X射线衍射方法测定了由L.N.Warr提供的5个伊利石结晶度的国际标样(其中,4个为岩石碎屑样品,采自英格兰西南部的极低级变质带;1个为单矿物样品,采自印度的花岗岩),获得了校正方程,ICCIS=0.977IC测定值+0.0336(°Δ2θ),R2=0.9835。在实验室内对213件采自国内的样品进行测定,测试条件与国际标样的测试条件相同,利用此方程对测得的伊利石结晶度数值进行校正,证实本实验室对伊利石结晶度的测定具有较高的可信度和国际可比性。  相似文献   

10.
本文运用伊利石结晶度、绿泥石结晶度、云母b0值和绿泥石地质温度计研究了梵净山前寒武系甚低级变质作用。结果表明经Kisch伊利石结晶度标样校正的伊利石结晶度Kübler指数为0.20~0.99°Δ2θ,绿泥石结晶度árkai指数为0.22~0.63°Δ2θ。由此阐明梵净山前寒武系经历了成岩作用到浅变质作用的影响,迄今依然保留了成岩带、近变质带和浅变质带的岩石记录。成岩岩石具有伊蒙混层特征成岩指示矿物,浅变质带具有钠云母特征变质指示矿物。钾云母(伊利石)b0值范围为:0.9000~0.9045nm;平均0.9018nm,b0值累积频率曲线分布介于典型中压—中低压系列之间,估算的压力为366MPa。峰期变质温度为293~364℃,平均342℃,古变质温压梯度为27℃/km。近变质带界线穿越地层和梵净山背斜轴线,表明甚低级变质作用为成岩-构造运动同期或后期构造增厚引起下部和底部岩石随温压的升高而产生的。  相似文献   

11.
Definition of low-grade metamorphic zones using illite crystallinity   总被引:4,自引:0,他引:4  
Abstract Two major problems which exist in the use of illite crystallinity to define low-grade metamorphic zones are the variety of values chosen for the zone boundaries and the persistent use of three different indices of crystallinity. Although measurement techniques, which cause much of the interlaboratory variation, can be standardized, it is shown that there is, nevertheless, significant additional variation which demands calibration on standards. The greatest variations are due to choices of different absolute values of crystallinity to define zone boundaries. The problem of relating measurements between different indices is approached by fitting mathematical relationships to pairs of measurements from the same sample. A power–law relationship is a satisfactory fit to the Kubler–Weaver and Weaver–Weber pairs, while the Kubler–Weber indices are linearly related. These relationships are used to transform definitions of the diagenetic zone, anchizone and epizone from one index to the others, although they apply strictly only to the data set from which they are derived. This results in compatibility between the three zones and shows that previous definitions to the anchizone in different indices have been chosen at incompatible values. The boundaries of Kubler's anchizone (0.42 and 0.25 Δ2θ) are 0.4 and 0.215 Δ2θ in this study, which become 5.1 and 14.6 in the Weaver index and 278 and 149 in the Weber index. An error analysis shows that percentage errors in both Kubler and Weaver indices increase with crystallinity; the Kubler measurements are marginally preferred at all grades.  相似文献   

12.
This study collected the early Oligocene to middle Miocene sediments from the Gerze Basin of Tibet, and used X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM) to discuss their clay mineralolgy, clay indices, better understand the clay mineralogy and its paleoclimatic significance. The results show that clay minerals of the Gerze Basin sediments are mainly composed of iilite and chlorite, with minor amounts of smectite and kaolinite, and their relative content varies along the section. Variations of relative contents and clay indices suggest that the Gerze Basin has experienced three-stage evolution of paleoclimate: I ) high ilUte and chlorite contents, with fluctuant smectite and low (I+Ch)/(K+S) ratio, indicative of a dominant seasonal arid climate from the early Oligoeene to late Oligocene; Ⅱ) higher illite and chlorite contents and larger (I+Ch)/(K+S) ratio but absence of kaolinite, indicating a colder and drier climate from the late Oligocene to early Miocene; Ⅲ) high iilite and chlorite contents with fluctuant (I+Ch)/(K+S) ratios and occasional occurrence of kaolinite, suggesting that the climate became warmer and more humid compared with that of stage Ⅱ in the mid-Miocene. These conclusions were also reinforced by the clay morphology, which suggests that physical weathering dominated in stage Ⅱ, while relatively strong chemical weathering was dominant in stages Ⅰ and Ⅲ Clay minerals of the sediments mainly consist of illite and chlorite, indicating that the source rock played a significant role in clay origin. It is inferred that global cooling and the enhancement of denudation and obstruction of northward moisture due to the uplift of the Qinghai-Tibet Plateau were responsible for the provenance of iUite and chlorite under weak chemical weathering. Though the Qinghai-Tibet Plateau reached a certain elevation by the mid-Miocene, yet the mid-Miocene widespread warming might have largely impacted the Gerze climate.  相似文献   

13.
为揭示循化盆地沉积物对古气候及青藏高原隆升过程的指示作用, 采用X射线衍射(XRD)、扫描电子显微镜(SEM)方法对循化盆地中新世沉积物中粘土矿物组成、微观形貌进行了深入研究.结果表明, 沉积物中粘土矿物以伊利石、蒙脱石为主, 绿泥石、高岭石和坡缕石含量较低; 粘土矿物相对含量及伊利石结晶度变化特征指示, 在23.1~21.2 Ma期间, 古气候以温暖潮湿为主; 21.2~14.3 Ma期间古气候以冷干为主, 出现短暂的相对暖湿时段; 14.3~10.6 Ma期间, 古气候以相对暖湿为主; 10.6~9.3 Ma时期, 气候以冷干为主; 9.3~5.2 Ma期间, 气候虽有冷干与暖湿波动, 但总体上以暖湿为主.在21.2 Ma和5.8 Ma时期发生的明显强降温事件, 可能与青藏高原的阶段性隆升有关.   相似文献   

14.
The dispersed carbonaceous matter (kerogen), illite, and magnetic response of the Tindelpina Shale Member in the lower part of the thick, extensive Tapley Hill Formation provide three complementary methods for zoning the incipient metamorphic character of rocks comprising the late Precambrian Adelaide System where they crop out between Adelaide, Olary, and Marree in the Adelaide Geosyncline. The methods are based on the following parameters: kerogen structure (as determined by X-ray diffraction) and composition (percentage carbon, hydrogen to carbon atomic ratio, δ 13CPDB); illite crystallinity; and amplitude and type of aeromagnetic anomalies.Kerogen is the most definitive indicator of metamorphic change in the Tindelpina Shale. It has been used to delineate a western subgraphitic zone (85–91%C, H/C > 0.10) which is separated from an eastern graphitic zone (91–98%C, H/C < 0.10) by a north-trending line through Adelaide, Mintaro, Orroroo, and Baratta. A similar two-fold zonation appears to exist in the Mouth Painter—Copley—Marree area. Metamorphic adjustment of the stable carbon isotopic composition of the kerogen is also evident. Kerogen rank correlates well with illite crystallinity. Illites in the western zone have Weaver indices of less than six. Crystallinity increases to the east where 2M illite becomes the dominant illite polymorph. The eastern graphitic zone largely coincides in location and extent with a zone of linear aeromagnetic anomalies of amplitude exceeding 100 gammas. In the lower Tapley Hill Formation the anomaly is attributed to remanent magnetism, probably associted with metamorphic growth of magnetite.All three indicators suggest an increase in metamorphic grade from west to east across the geosyncline, in agreement with published observations based on conventional petrographic analysis of pelitic (and to a lesser extent, carbonate) rocks. Illite and chlorite, characteristic of the anchizone of burial diagenesis, are the dominant sheet silicates in the shales studied, although incipient metamorphic alteration of chlorite to biotite has occurred in some specimens from the graphitic zone. The subgraphitic and graphitic facies of the Tindelpina Shale correspond with the chlorite and biotite (and higher) zones, respectively, of low-pressure intermediate-type metamorphism previously established for the Mount Lofty and Flinders Ranges.Greater depth of burial of the lower Tapley Hill Formation in the eastern half of the geosyncline would account for the metamorphic trend observed in its organic matter and clay mineral content. Differential burial does not, however, adequately explain the magnetics, nor the absence of biotite-grade rocks in the central Flinders Ranges. Other magnetically anomalous beds are found throughout the Adelaide System and in overlying Cambrian strata. For the magnetism in these different stratigraphic intervals to be of metamorphic derivation, a regional thermal event, perhaps related to the Cambro-Ordovician Delamerian Orogeny, must be postulated.  相似文献   

15.
Average crystallite size and mean-square strain of illite in rock specimens and clay separates were measured independently in TEM images and by single-line Fourier (Voigt method) profile analysis of the c. 1 nm peak of XRD patterns for a prograde sequence of pelitic rocks (illite crystallinity indices=0.17–0.58°Δ2θ) from the Gaspé Peninsula, Quebec. The TEM-determined crystallite sizes in clay separates approximate those determined by Fourier profile analyses and those calculated from illite crystallinity indices by the Scherrer equation, with the exception of the diagenetic sample. The crystallite sizes and mean-square strains of illite in rock samples exhibit a trend similar to that determined by profile analyses, but the average crystallite sizes are up to five times larger than those measured for clay separates. TEM images show that all rock samples have a wide range of crystallite sizes, and the proportions of larger crystallites increase with metamorphic grade. The diagenetic illite is defect-rich, fine-grained (mean thickness by volume=c. 70 nm), 1Md material. Anchizonal illite tends to occur as separate aggregates of small 1Md and larger 2M1 crystals (c. 200 nm), comprising arrays of subparallel coalescing packets. The epizone sample has thick (c. 400 nm), defect-free crystals of muscovite occurring in stacks of parallel layers, or subhedral crystals intergrown with large-angle boundaries. Cleaved crystals that are free of intracrystalline layer terminations are dominant in clay separates of all samples, having ranges of smaller sizes with volume-average thicknesses of c. 43, 43, and 81 nm (c. 14, 28, 67 nm by the Voigt method), respectively, for the three zones. The results suggest that illite crystallinity indices do not provide a direct measure of a single microstructural state of illite in rocks, although they yield consistent limits for average crystallite sizes for the anchizone (23 & 48 nm here). Therefore, they serve as a general parameter of the degree of recrystallization on a relative basis, in part because the contributions of all peak-broadening variables (mixed layering, size and strain) decrease regularly with prograde regional metamorphism of pelites. The microstructural changes caused by rock disaggregation are probably a function of those variables as well. The data collectively demonstrate a trend from metastable, defect-rich, small crystals towards a stable assemblage of larger, defect-free crystals, through dissolution of strained crystals and neocrystallization, consistent with the Ostwald step rule.  相似文献   

16.
Abstract Fairly strong (r= 0.75–0.85) positive linear correlations were found between crystallinity indices (peak widths) measured on the first two basal reflections of chlorite and those of illite–muscovite in <2-μm fractions of a representative shale–slate–phyllite series from Palaeozoic and Mesozoic formations of northeast Hungary. The metamorphic grade ranges from late or deep diagenesis through anchizone to epizone conditions. Chlorite crystallinity values measured on air-dried and ethylene-glycol-solvated samples suggest that the effects of expandable interlayers are negligable, especially in the higher grade (~temperature) part of the series. However, the greater scattering of crystallinity values for the chlorite 001 reflection compared to those of the 002 reflection may be related to the effects of minor amounts of interlayered and/or discrete smectite and/or vermiculite. With increasing metamorphic grade and advancing equilibrium recrystallization, the chlorite compositions in different samples become more homogenous. No correlation exists between crystallinity and changes in chlorite composition as estimated from the intensity ratios of basal reflections. Hence an increase of domain size and a decrease of lattice distortion with increasing grade (~temperature) may be decisive factors affecting chlorite crystallinity. Chlorite crystallinity can be applied as a reliable regional, statistical technique complementary with, or instead of, the illite crystallinity method. The illite and chlorite crystallinity scales used here are related to Kübler's epi-, anchi- and diagenetic zones and correlated with coal rank, conodont colour alteration and mineral facies data. As the effects of the detrital white mica can be observed even in the <2-μm fractions of anchizonal metapelites, the anchizone boundaries determined solely on the base of ‘fixed’illite crystallinity values may vary with amounts of detrital and newly formed muscovite–illite. Hence a complex approach utilizing more than one method for determination of grade is preferred for petrogenetic purposes, even if relationships between crystallinity scales, coal rank and mineral facies also vary strongly in different tectonic settings and lithologies.  相似文献   

17.
为了探讨伊利石对煤化作用和沉积环境的指示作用,以华北地区京西煤田侏罗纪煤层夹矸为研究对象,采用X射线衍射方法(XRD)和X射线荧光方法(XRF)分别测定煤层夹矸的矿物组成和化学组成,研究夹矸中伊利石矿物学特征及成因。结果表明,京西煤田侏罗纪煤层夹矸主要由伊利石、绿泥石和石英组成,其中,伊利石质量分数平均为62.92%。将XRD数据和XRF数据进行对比分析,计算得到伊利石平均化学式为(K0.37(NH40.03)Al2(Si3.60Al0.40O10)(OH)2。京西煤田煤层夹矸中伊利石主要由高岭石转化而来,伊利石的NH4+占层间阳离子的比例具有随沉积古盐度升高而逐渐升高的趋势,n(Si)/n(Al)Ⅳ具有随煤化程度升高而逐渐降低的趋势,这表明京西煤田侏罗纪煤层夹矸中的伊利石矿物学特征对沉积环境和煤化作用具有一定的指示作用。   相似文献   

18.
萝卜纹是田黄的重要鉴定特征。本文通过岩石薄片、X射线衍射分析和电子探针分析等手段,确定萝卜纹的组成矿物为伊利石;萝卜纹的成因为田黄的原岩受到构造应力作用后产生了显微裂隙,次生的伊利石填充了显微裂隙;显微裂隙中的伊利石与岩石中的主要矿物迪开石光学性质差别较大而呈丝缕状(萝卜纹)。  相似文献   

19.
The Shurijeh Reservoir Formation of Neocomian age is represented by a sandstone sequence, occasionally interbedded with shale, in the Gonbadli gas field, Kopet-Dagh Basin, Northeastern Iran. In this study X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques were used together to characterize the Shuirjeh clay minerals in 76 core samples collected from two deep Gonbadli wells. The results of XRF analysis showed high percentages of silicon and moderate to low percentages of aluminum, sulfur, calcium, potassium, sodium, magnesium, and iron in both wells. The XRD analysis indicated that the above elements were concentrated in the form of quartz, anhydrite, dolomite, calcite, plagioclase, K-feldspar, hematite, and clay minerals. Further XRD examination of the clay fraction revealed that illite, chlorite, and kaolinite were the major types of clay minerals. Unlike, glauconite, smectite, and a mixed layer clays of both the illite–smectite and chlorite–smectite types were observed only in very few samples. The percentages of individual clay minerals were determined using external standard calibration curves and successfully validated by a system of simultaneous linear equations acquired from detailed elemental information based on the XRF analysis. The error reached ± 5% for the main mineral constituent and ± 15% for minor minerals. A local regression relationship was also derived, based on the XRF elemental information, which can be used to estimate the clay contents of other Shurijeh drilled wells with data of pulsed-neutron spectroscopy tools. According to the proposed quantitative approach, the amount of illite varied considerably, reaching 18.3%. In contrast, the amounts of kaolinite and chlorite were generally small, i.e., less than 8.4%. The amount of total clay minerals changed greatly from a minimum of 5% to a maximum of 32.5%. An increase in illite with increasing burial depth and temperature was an obvious indication of deep burial diagenesis in this formation.  相似文献   

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