基于数字图像处理的矿物颗粒形态定量分析

矿物颗粒形态的评价一般采用目估法在显微镜下观测岩石薄片,其评价结果受主观影响.本文利用岩石薄片显微照片,基于图像处理技术提出了矿物颗粒形态定量分析方法.矿物颗粒形态参数主要包括球度、凸度、长宽比、磨圆度等.该方法利用图像分割技术将显微照片中的矿物颗粒区分开,提取颗粒的像素轮廓坐标进行离散几何分析,计算矿物颗粒形态参数....     

扫描仪在岩矿鉴定与岩相学研究中的应用——薄片扫描法

利用偏光显微镜进行岩矿鉴定和岩相学分析是矿物学、岩石学研究的一项基本工作。常用偏光显微镜的观察视域范围狭小,视域大小不能随意变动,这对大视域观察与识别镜下岩石的结构、构造、显微地质现象和粗大矿物等造成困难。基于上述问题,本文在偏光显微镜成像原理基础上,开发出利用扫描仪和偏振光片获取岩石薄片大视域图像的方法,即薄片扫描法。该方法能获得大视域的单偏光和正交偏光图像,为科学研究提供精确的、全面的图像证据资料。薄片扫描法所需设备简单、操作简易、能获得全域精美的数字化图像、能清晰的反映矿物结构构造和地质现象,为识别矿物学和岩石学信息提供了科学方法。薄片扫描法适用于矿物颗粒粗大、形态复杂的显微地质现象,常规偏光显微镜下不能反映结构、构造的样品。薄片扫描法的成功开发,对岩相学、构造岩相学等方面的研究具有现实意义。     

基于深度学习的鲕粒智能检测与特征统计

鲕粒是一类特殊的沉积颗粒,其分布的疏密程度、粒径大小等信息可以直观地反映形成环境的水深以及水动力条件,具有重要的地质意义。在地质学中,通常将鲕粒岩石标本磨制成岩石薄片,并依靠专业人员在显微镜下观察来获取鲕粒含量、圆度、径粒大小等数据的估计值,存在着计算量大、成本高、周期长、人力投入大等缺点,而且该方法受主观因素影响较大,不同专家得出的结果也不尽相同。针对上述问题,本文提出了基于深度学习的鲕粒智能检测与特征统计方法,主要采用YOLOv5检测模型对鲕粒岩石薄片显微图像进行检测,并在YOLOv5网络主干部分添加轻量级的SE-Net通道注意力机制模块来提升检测性能;其次,本次使用DIoU-NMS替换NMS方法,改善图像中鲕粒分布拥挤时的漏检问题。实验证明改进后的算法最终精确率达到了98.8%,比原算法提升了1.3%。最后利用图像处理技术,对检测结果进行量化统计和分析,得到图像中鲕粒含量、圆度信息、粒径大小的统计结果直方图,为地质工作人员进行相关工作提供了极大的便利。     

岩石颗粒度测量

岩石颗粒度是岩石学研究的一个重要内容,矿物颗粒大小及其分布特征与岩石形成的环境有密切的关系,也是岩石的结晶作用、重结晶作用、沉积作用乃至变形过程的物理化学条件的一种标志。本文介绍了三种岩石颗粒度测量的方法:直线截距法、单位面积/颗粒数法和标准圆量板法。测量结果的对比研究表明,三种方法之间存在系统的差别,其中单位面积/颗粒数法相对最好,能比较客观地反映实际的颗粒大小。     

单轴压缩条件下花岗岩中不同矿物的形状变化

岩石中不同矿物的形状变化反映了岩石的变形破坏过程。在分析花岗岩试样表面图像不同矿物纹理特征基础上,使用室内单轴压缩试验视频图像和灰度分界阈值分割法,研究了单帧图像中不同矿物的分布特征,使用形状参数描述了岩石变形过程中不同成分的形状特征,探讨了不同成分区域形状变化与裂隙扩展过程的关系。结果表明,花岗岩变形过程中圆形度的大小顺序为长石黑云母石英,内切圆半径的大小顺序为黑云母长石石英;离散指数的大小顺序为长石石英黑云母;长石承受了轴向力的主要部分,形状变化与所处位置关系较大;破坏过程中裂隙面积出现大小顺序为长石、石.英、黑云母,裂隙扩展较快时裂隙大多出现在长石和石英区域。     

岩石有限应变测量反向轮法的计算机CSD软件设计

用计算机实现反向轮法测岩石有限应变的过程, 可提高有限应变测量的准确性和效率.开发出了用Visual Basic 5.0编写的CSD软件, 利用岩石薄片图像或者矿物颗粒轮廓图测出岩石有限应变的大小及应变椭圆长轴方向, 同时测出矿物颗粒分布的优选方位.其操作相当简便, 首先统计出图像中0°~180°各方向上矿物颗粒的边界数目; 然后在方位-边界坐标系中投点, 并利用最小二乘法进行数据点的多项式曲线拟合; 最后求出曲线的极值点坐标, 并根据坐标绘制相应的应变椭圆.软件运行中, 统计出的边界数据和拟合曲线以及应变椭圆图形都是可视的, 并能进行相应的保存.      

一种岩石薄片智能分类识别方法

<正>在偏光显微镜下观察岩石薄片,对岩石结构和矿物成分进行分析和鉴定,是地质工作者进行岩石命名、研究岩石成因、进行地质勘探等任务最常用的工具和方法之一~([1])。岩石薄片显微图像全面真实地反映了岩石微观的结构构造、矿物成分、粒度大小、蚀变程度等特征。目前在显微镜下观察岩石薄片主要是专业人员凭借多年积累的知识、经验来确定岩石薄片中的矿物,受主观因素影响较大且费时费力,不同专家对分析结果也存在一定的差异。研究人员借助计算机技术分析岩石薄片图像并自动识别岩石种类,提高岩石薄片显微图像分类效率,节约时间和成本~([2])。     

基于花岗闪长岩矿物成分的热导率预测模型

岩石矿物成分的种类及相应体积分数是影响岩石热导率的主要因素,通过室内实验测定花岗闪长岩的热导率及矿物成分的含量,研究矿物成分对岩石热导率的影响规律。将岩样各矿物成分体积分数转化为相同平板面积的壁面厚度,建立了花岗闪长岩矿物成分对其热导率影响规律的预测模型,预测值与实测值误差在0.2～0.6 W/(m·K)之间,通过修正系数调整模型使误差控制在5%范围,同时分析模型得到花岗闪长岩热导率随石英体积分数与长石体积分数比值的增加而变大,为开发利用干热岩地热能和岩石热物性研究提供理论参考。     

花岗岩矿物正交偏光镜下图像人工智能识别研究

人工智能在地球科学领域中的应用是近年来研究的热点,对地球科学的发展有着重要意义,其应用之一就是使用计算机视觉技术实现岩石或矿物的自动化识别分类。然而,目前大多研究直接对岩石薄片图像进行分类,不能够精细定位并识别薄片中多且复杂的矿物目标。虽然现已有许多学者将目标检测技术应用于岩石矿物的图像识别分类中,但这些方法识别的对象大多是岩石手标本图像,只能对图像中的单一对象检测。在识别分类研究领域中,缺少对岩石薄片镜下图像识别的算法及质量较好的相关数据集。为了解决这些问题,本文首先采集了3000张正交偏光镜下花岗岩薄片图像,标注矿物样本10000余个,并通过数据增广方式对数据集进行增强,建立了一个质量较好、具有多样性的数据集。其次本文提出基于Yolov5x的改进算法RDB-Yolov5x。这种方法在特征提取过程中添加了密集连接方式,使用密集连接残差模块（RDB）替代传统的残差结构,有效地保留了图像的语义和位置信息细节。实验结果表明该方法泛化能力较好,在对图像中小尺寸、特征模糊的矿物颗粒的识别中表现出优秀的性能,可以准确有效地对花岗岩中的五类目标矿物（石英、黑云母、白云母、斜长石、钾长石）进行识别,...     

花岗质超糜棱岩的微观构造与变形机制

花岗质岩石的变形方式和过程决定大陆地壳的流变学特性。本文聚焦藏南拆离系超糜棱岩化的花岗质岩石，借助传统显微构造分析方法和扫描电镜、阴极发光、矿相自动分析系统和电子背散射衍射等新技术手段，开展微观组分、结构、组构定量化观测和分析。超糜棱岩主要造岩矿物为钾长石、斜长石、石英、黑云母等，显微构造呈现为单矿物相域与多相矿物混合域交织结构。相平衡模拟与斜长石钙含量等值线变形温度估算结果为390～410℃。单相域的矿物集合体条带主要分为钾长石条带与石英条带，其中钾长石条带内变形颗粒呈现典型的核 幔构造。组构分析表明钾长石颗粒具有强烈的晶格优选定向，残斑与动态重结晶的钾长石颗粒具有相似的晶格优选方位(CPOs)特征。施密特因子法分析揭示钾长石残斑变形过程中主要活动的滑移系为(100)\[010\]、(010)\[001\]和(001)\[100\]，基质钾长石颗粒形成机制主要为位错蠕变驱动的亚颗粒旋转重结晶。在混合相域，矿物颗粒发生强烈细粒化而只含有少量残斑，基质颗粒主要为斜长石，斜长石颗粒间广泛分布微米级黑云母颗粒。斜长石无组构或弱组构，主导变形机制为颗粒边界滑动。在单相域条带与混合相域基质内，石英颗粒均发生强烈细粒化，颗粒表面发育溶蚀结构以及细小的新晶晶核，石英＜c＞轴晶格优选定向及形态学长轴优选定向皆平行于线理X方向，变形机制为溶解 沉淀蠕变。这显示在由单相域向混合相域的演化过程中，流体作用至关重要，流体与单相域钾长石进行交代使其分解为细粒的斜长石与石英，并导致花岗质岩石变形机制由位错蠕变向非位错蠕变转换，并诱发岩石的流变弱化。     

Petrographic analysis using cathodoluminescence microscopy with simultaneous energy-dispersive X-ray spectroscopy

Summary ¶Mineral grains unidentifiable by means of cathodoluminescence (CL) and/or polarizing microscopy (including non-luminescent or opaque minerals) can be readily identified with energy dispersive X-ray spectrometry, attached to the CL equipment. Chemical identification is possible of mineral grains (ten to a few tens of microns) that are even smaller than the electron beam area, by using index elements if the unknown mineral analyzed is surrounded by grains of simple or known chemical composition (e.g. minute areas of carbonate cement surrounded by quartz or clay minerals; clay cements surrounded by quartz or carbonate) and simultaneous with CL microscopy.Results are presented of Cambrian, Carboniferous and Jurassic sandstones from Sweden and Germany. Transparent and opaque minerals, i.a. feldspars, luminescent and non-luminescent carbonate minerals as well as luminescent and non-luminescent clay minerals were identified in thin sections. The analytical procedure described here is especially helpful when rapid petrographic analysis has to be carried out of samples with complex composition, of which the petrographer had no previous experience.     

P-A分形模型定量度量糜棱岩变形过程中石英微结构的变化

定量度量动力变质作用下组成糜棱岩矿物颗粒的不规则变化是一项挑战性的研究.以基于GIS的PA(周长-面积)模型定量地描述糜棱岩中具自相似性石英形态的不规则变化.研究实例是苏格兰西北地区Moine逆冲断裂带前缘变质程度不同的5种类型的糜棱岩.石英是糜棱岩的主要矿物成分,其镜下的显微图片经扫描转换成数字图像,再通过GIS技术转换成矢量图,并计算出每颗石英的周长和面积.研究结果表明,随变质程度的增加,其PA分形维数分别从1.20、1.28、1.38、1.46,逐步增加到1.60.这表明,随变质程度的增加,变形程度与动态重结晶作用加强,石英颗粒从规则到不规则.     

Petrological features of a Numidian section in the Lucanian Apennine (southern Italy)

A continuous section of Numidian sandstones cropping out along the eastern margin of the Lucanian Apennine (southern Italy) has been studied in relation to its petrographic and geochemical aspects. Owing to their simple mineralogy, both chemical and petrographic classifications indicate that the sandstones are subarkoses. They are characterized by high mineralogical maturity, poor sorting, abundant siliciclastic matrix and subangular quartz grains. The principal composition is Q_80–94 F_6–20 L_0–1 corresponding to SiO₂/Al₂O₃ and Fe₂O₃/K₂O ratios ranging from 37·216 to 17·124 and from 1·182 to 0·514 respectively. Two quartz grain types were distinguished: deformed and undeformed quartz grains, the former generally subangular in shape and the latter rounded. Two distinct origins of detritus can be suggested; (i) the undeformed and rounded quartz grains derive from arenaceous continental sequences; (ii) the siliciclastic matrix, the deformed subangular quartz grains, the heavy minerals and the large crystals of K-feldspar probably derive from a crystalline basement formed by low–medium–high grade metamorphic rocks and granitoids. The Numidian subarkoses represent the mixing of these two components. Both kinds of detritus can be referred to the African Craton where crystalline basement is extensively overlain by Palaeozoic and Mesozoic sandstones. The different proportions of the two components in the mixture account for the variability of the sandstone composition and might explain the mixed Numidian successions cropping out in various sectors of the Mediterranean area. Copyright © 1998 John Wiley & Sons, Ltd.     

High Temperature Mylonitization of Quartzofeldspathic Gneisses: Example from the Schirmacher Hills, East Antarctica

In the Schirmacher Hills, most of the ductile shearing took place under high to medium grade amphibolite facies metamorphism. The microstructure of the mylonites shows characteristic features of high temperature deformation and thus gives us an idea of deformation mechanisms of the constituent minerals at great crustal depth. The variation in microstructure of the sheared rock is partly due to heterogeneity of the intensity of strain from domain to domain, producing protomylonites, orthomylonites and ultramylonites. However, a large part of the microstructural variation has resulted from syn- to post-tectonic recrystallization and grain growth of constituent minerals. Both quartz and feldspar have deformed by crystal plastic processes with dominant grain boundary migration. The present aspect ratio of the feldspar grains is a result of various degrees of dynamic recrystallization along the grain boundary. The ratio varies between 1.5 and 2. Presence of exsolution lamellae in perthites and formation of myrmekite at the strained grains of K-feldspar suggest diffusion assisted dislocation creep. These mylonites are characterized by the presence of weakly strained or unstrained long quartz ribbons. The development of quartz ribbons with the absence of significant strain suggests grain recovery and grain growth during high temperature mylonitization. The growth of quartz ribbons took place by coalescing neighbouring grains both along and across the ribbon length. At the ultramylonite stage the fine-grained matrix of quartz and feldspar mostly accommodates the bulk strain.     

闽南-台湾浅滩陆架沉积砂中石英颗粒表面的微结构

石英颗粒表面微结构的研究是随着电子显微镜应用到地质学上而发展起来的。近年来利用扫描电镜观察石英颗粒表面形态特征及差异来研究沉积物物质来源、搬运方式和沉积环境已在我国开展起来。本文是在对闽南-台湾浅滩陆架的地形、沉积物粒度研究基础上,用JSM-50A扫描电镜观察、研究石英颗粒表面微结构时,发现调查海区的(中砂)沉积物中的石英颗粒具有各种微结构,反映特有的沉积环境。     

Fractal Modelling of the Microstructure Property of Quartz Mylonite During Deformation Process

Mylonite is the result of the dynamic metamorphism and minerals in mylonite are deformed gradually with an increase in the degree of metamorphism. Quantifying the degree of deformation including the irregularities of shapes and the frequency distribution of the minerals becomes one of the most challenging efforts in mylonite analysis. Fractal modelling has been demonstrated in this paper to be an effective mean to achieve the above goal. Perimeter-Area fractal model was used to quantify the irregularities in the geometries and Cumulative Number-Area model is used to characterize the irregularities of distribution of quartzs in mylonites, respectively. Examples of quartz from five types of mylonites with different degree of deformation within the foreland of the Moine Thrust Zone in NW Scotland are chosen to study the evolution processes of deformation. As the main mineral component of quartzite mylonite, patterns are extracted from digital photomicrographics of the multiscale-grey image grid data to show quartz grains with different degree of deformation, The areas and perimeters of the quartz grains were calculated by GIS-based image processing technologies. From type one to type five, with an increase in degree of deformation, the corresponding Perimeter-Area exponent increases from 1.20, 1.28, 1.38, 1.46, to 1.60, respectively, the fractal dimension of the perimeter from 1.07, 1.08, 1.17, 1.23, to 1.44, as well as the exponent of Cumulative Number- Area from 0.50, 0.51, 0.58, 0.82, to 0.85, respectively. The result has shown that as increase of the intensity of deformation, the shape of quartz grains tends to be more irregular, grain size tends to be smaller, and the number of grains increases. The results obtained using GSI model has indicated that as an increase in the intensity of deformation, the patterns of quartz grains tends to be more stratified and randomness increases.     

基于多分辨率图像融合的多尺度多组分数字岩心构建

针对单一分辨率的数字岩心模型无法完整描述岩心不同尺度结构信息的问题,以砂岩样品为例,通过对岩心多分辨率CT成像,采用基于特征的图像配准方法实现了不同分辨率岩心图像的精确匹配。通过融合不同分辨率岩心扫描图像进行孔隙分割和矿物分割,构建多尺度、多组分的数字岩心模型。结果表明:多尺度多组分数字岩心模型可以表征跨尺度的岩心孔隙结构,孔隙分布与核磁测量结果有较好的一致性;与Qemscan相比,数字岩心矿物体积分数同X衍射测定结果更吻合,真实地还原了岩心不同组分的结构信息。     

Cathodoluminescence characterization of quartz particles in mature arenites

A combination of cathodoluminescence (CL) microscopy with digital image analysis and spectroscopic analysis allows the detailed investigation of the commonly occurring colour shift from initial to final CL‐colours in detrital quartz with increasing irradiation. A method for the quantification of the colour shift is presented and applied to different quartz sands: unlithified sands of the Lower Cretaceous Kuhfeld Formation from Ottenstein (W Germany) and Holocene sands from the barrier island of Wangerooge (N Germany). The colour shift depends on the defect structure of the quartz grains. The defect structure is determined by the physico‐chemical conditions during crystallization and therefore can help trace the source of quartz grains. A total of 25 different types of quartz grains in the Ottenstein‐sands indicates a highly variable southern provenance. Many of the grains have recycled quartz cement overgrowths indicating an at least second cycle origin. In contrast, only 16 different quartz types have been observed in the Wangerooge‐sands reflecting a less varied plutonic to metamorphic Scandinavian provenance. The study demonstrates the potential of quantified CL initial colour and colour shift in assessing the provenance of quartz‐rich sands and sandstones.