Application of backscattered electron microscopy in shale petrology

1983 ◽  
Vol 120 (2) ◽  
pp. 109-114 ◽  
Author(s):  
D. H. Krinsley ◽  
K. Pye ◽  
A. T. Kearsley
Keyword(s):  
Electron Microscopy ◽  
Upper Ordovician ◽  
Thin Sections ◽  
Backscattered Electrons ◽  
Particle Form ◽  
History Of ◽  
Backscattered Electron ◽  
Electron Microscopical ◽  
Diagenetic History ◽  
Z Contrast

SummaryA grey pyritic mudstone from Central Wales (Red Vein unit of the Dicellograptus anceps zone, Upper Ordovician Ashgill) has been examined in thin section by scanning electron microscopy using backscattered electrons. Using backscatter it is possible to identify individual mineral constituents of the mudstone by virtue of their atomic number (Z) contrast and differential hardness (relief). The amount of detail observable is far greater than that possible with optical microscopy. Valuable information can be obtained relating to particle form, orientation, texture and internal structure which aids in interpretation of the deformational and diagenetic history of the rock. The adoption of electron microscopical methods in the study of thin sections and polished rock chip surfaces promises to revolutionize the field of shale petrology.

Some early history of replica techniques for electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1076-1077
Author(s):  
Robert M. Fisher
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Optical Microscope ◽  
Early History ◽  
Bulk Materials ◽  
Thin Sections ◽  
Transmission Electron ◽  
Reflected Light ◽  
History Of ◽  
Electron Microscopes

By 1940, a half dozen or so commercial or home-built transmission electron microscopes were in use for studies of the ultrastructure of matter. These operated at 30-60 kV and most pioneering microscopists were preoccupied with their search for electron transparent substrates to support dispersions of particulates or bacteria for TEM examination and did not contemplate studies of bulk materials. Metallurgist H. Mahl and other physical scientists, accustomed to examining etched, deformed or machined specimens by reflected light in the optical microscope, were also highly motivated to capitalize on the superior resolution of the electron microscope. Mahl originated several methods of preparing thin oxide or lacquer impressions of surfaces that were transparent in his 50 kV TEM. The utility of replication was recognized immediately and many variations on the theme, including two-step negative-positive replicas, soon appeared. Intense development of replica techniques slowed after 1955 but important advances still occur. The availability of 100 kV instruments, advent of thin film methods for metals and ceramics and microtoming of thin sections for biological specimens largely eliminated any need to resort to replicas.

scholarly journals Catatropis pakistanensis n. sp. (Trematoda: Notocotylidae) from Northern shovelers, Anas clypeata (Anatidae: Aves) from Pakistan with some remarks on the history of Catatropis species

2012 ◽  
Vol 49 (1) ◽  
pp. 43-48 ◽  
Author(s):  
R. Schuster ◽  
G. Wibbelt
Keyword(s):  
Electron Microscopy ◽  
Histological Evaluation ◽  
Thin Sections ◽  
Genital Opening ◽  
Morphological Studies ◽  
Anas Clypeata ◽  
History Of ◽  
Free Ranging ◽  
A New Species ◽  
Scanning Electron

AbstractFive out of 15 free-ranging Northern shovelers (Anas clypeata Linneus) caught in Pakistan were infected with notocotylid trematodes. Out of the 31 flukes, 10 specimens were used morphological studies, 4 others were also examined by scanning electron microscopy and one remaining trematode was cut in serial semi-thin sections for histological evaluation in order to describe a new species. Like all species of this genus, Catatropis pakistanensis n. sp has a median ridge starting posterior to the basis of the cirrus sac and extends posterior to the ovary. Bilateral to this ridge there are two rows of 9–10 ventral papillae each. Metraterm and cirrus sac are equally in length. In contrast to most other Catatropis spp. the genital opening in C. pakistanensis is situated between the oral sucker and bifurcation of the caeca.

Multi-purpose backscattered electron detector

1978 ◽  
Vol 36 (1) ◽  
pp. 82-83
Author(s):  
M. Kikuchi ◽  
S. Takashima
Keyword(s):  
Solid State ◽  
Magnetic Domain ◽  
High Sensitivity ◽  
Solid State Detector ◽  
Response Characteristics ◽  
Backscattered Electrons ◽  
Backscattered Electron ◽  
Takeoff Angle ◽  
Z Contrast ◽  
State Detector

Backscattered electrons (BSE) permit a variety of information regarding the specimen, e.g., composition, topography, magnetic domain structure, crystalline states, etc., to be obtained. However, since conventional BSE detectors are all single-purpose designed, several different detectors are required to obtain the required variety of information.In order to circumvent this inconvenience, we have developed a multi-purpose BSE detector system. As shown in Fig. 1, the detector can be freely rotated around the specimen surface. In addition to which, the distance between the detector and the specimen can be varied. The newly developed solid state detector used in this system possesses high sensitivity and high response characteristics. Some advantages and applications of the system are given below.1. By setting the detector at the low and high takeoff angle positions, topographic contrast and composite contrast (Z-contrast) can be respectively enhanced.2. By using the rotation and distance varing mechanisms in combination, the optimum detecting condition for ensuring a good magnetic domain image can be selected.

Atomic number and crystallographic contrast images with the SEM: a review of backscattered electron techniques

1987 ◽  
Vol 51 (359) ◽  
pp. 3-19 ◽  
Author(s):  
Geoffrey E. Lloyd
Keyword(s):  
Crystal Structure ◽  
Atomic Number ◽  
Image Contrast ◽  
Specimen Preparation ◽  
Backscattered Electrons ◽  
Orientation Contrast ◽  
Electron Channelling ◽  
Backscattered Electron ◽  
Geological Sciences ◽  
Z Contrast

AbstractBackscattered electrons (BSE) are incident electrons reflected back from a target specimen and imaged with the scanning electron microscope (SEM). Three distinct BSE signals exist: atomic number or Z-contrast, in which composition determines image contrast; orientation contrast, in which specimen crystal structure determines image contrast; and electron channelling patterns (ECP), which are unique for a particular crystal orientation. The origins of these three signals are described, with particular attention being given to the necessary SEM operational and specimen preparation requirements. Z-contrast images are relatively simple to obtain and also have a familiar appearance such that their usage should become commonplace. ECP in comparison require subsequent interpretation which depends on the crystal structure and the relationship between crystal and specimen coordinate systems. A general solution to ECP interpretation is therefore presented, involving the construction of reference ‘ECP-maps’ over the surface of a sphere. A brief summary of the applications and potential use of the three BSE signals in the geological sciences is also given.

scholarly journals Petrography And Diagenetic History Of The Kometan Formation (Upper Cretaceous) In The Imbricated Zone, Iraqi Kurdistan Region

2020 ◽  
Vol 70 (1) ◽  
pp. 195-208
Author(s):  
Irfan Sh. Asaad ◽  
◽  
Sardar M. Balaky ◽  
Keyword(s):  
Upper Cretaceous ◽  
Planktonic Foraminifera ◽  
Kurdistan Region ◽  
Thin Sections ◽  
Iraqi Kurdistan ◽  
Diagenetic Processes ◽  
History Of ◽  
Diagenetic History ◽  
Petrographic Study ◽  
Late Stages

The petrography and diagenetic history of Upper Cretaceous Kometan Formation is investigated from its type locality in Kometan Village, Imbricated Zone, Kurdistan Region, Northeastern Iraq. The formation comprised 44 m of white weathered, light grey, thin to medium bedded fractured limestones with chert nodules and lenses in the upper part. The petrographic study of the formation is based on 50 thin sections and showed that the majority of limestones microfacies are carbonate mud (micrite). The skeletal grains include planktonic foraminifera, oligostegina, calcisphers, ostracods, pelecypods, larvae ammonoids and echinoderms. Non-skeletal grains include peloids only. The Kometan Formation has been subjected to several diagenetic processes such as: micritization, dolomitization, cementation, neomorphism, compaction, silicification, solution, phosphatization, glauconitization and fracturing. All these occurred during marine phreatic shallow burial stage and activated during intermediate to deep burial and uplifting in the late stages. The paragenetic history of the Kometan Formation has passed through four diagenetic environments including; marine, meteoric, burial and uplifting.

Correlative LM, SEM and TEM of argentaffin cells

1978 ◽  
Vol 36 (2) ◽  
pp. 84-85
Author(s):  
R.G. Frederickson ◽  
D.B. Spagnoli ◽  
P.B. DeNee
Keyword(s):  
Electron Microscopy ◽  
Secondary Electron ◽  
Thin Sections ◽  
Backscattered Electron Imaging ◽  
Selective Staining ◽  
Transmission Electron ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Different Levels ◽  
Tem Grid

The identification of small numbers of cells containing specific materials or having a particular location in a tissue can be observed cften in light microscopic (IM) sections by selective staining. In contrast, the same cells are often difficult to identify in alternate thin sections on grids by transmission electron microscopy (TEM). Grid bars produce periodic obstructions and consequently prevent the visualization of tissue continuity, making it difficult to identify landmarks. Also, the TEM image of a thin section of tissue does not correlate well with the thicker IM image. This is a matter of interpretation based on the different principles of image formation and the different levels of resolution.The purpose of this paper is to demonstrate a method which allows the same cells identified by IM to be more easily located in thin sections for TEM. This method combines the principles of backscattered electron imaging (BSI), secondary electron imaging (SEI) and heavy metal staining with scanning electron microscopy (SEM).

Zoning in granitoid accessory minerals as revealed by backscattered electron imagery

1989 ◽  
Vol 53 (369) ◽  
pp. 55-61 ◽  
Author(s):  
B. A. Paterson ◽  
W. E. Stephens ◽  
D. A. Herd
Keyword(s):  
Source Region ◽  
Magma Source ◽  
Thin Sections ◽  
Accessory Minerals ◽  
Sector Zoning ◽  
Backscattered Electron ◽  
Z Contrast ◽  
First Time ◽  
Zonation Patterns ◽  
Compositional Zonation

AbstractAccessory minerals are often difficult to investigate with light optics as the mineral grains tend to be small and the refractive indices high. Textural features due to variations in composition are well displayed in such minerals by backscattered electron imagery under circumstances designed to select only the composition contribution to electron backscattering and displayed as atomic number (Z)-contrast imagery (ZCI). It is shown by this technique that compositional zonation patterns are very common and sector zoning in titanite is described for the first time. The compositional basis for zonation of titanites in this study is shown to be controlled by coupled substitutions involving the REE. The technique is particularly good at revealing rounded cores to zircon grains which are normally taken to be refractory grains from the magma source region, and ZCI studies may improve targeting of grains for U-Pb geochronological investigations. Several examples are presented of applications of the technique to accessory minerals encountered in polished thin sections of granitoids in the Caledonian of Scotland. The consequences of ZCI studies for trace element modelling of REE in granitoid petrogenesis are discussed.

scholarly journals Diagenetic history of the upper Tanglewood Member (upper Ordovician) of the Lexington Limestone, central Kentucky, U.S.A. with special emphasis on petrographic differences between deformed and undeformed beds

2017 ◽  
Vol 53 ◽  
pp. 9-16
Author(s):  
Dibya Raj Koirala ◽  
Frank R. Ettensohn
Keyword(s):  
Upper Ordovician ◽  
Diagenetic Processes ◽  
Lexington Limestone ◽  
History Of ◽  
Sediment Deformation ◽  
Diagenetic History ◽  
Petrographic Study

Petrographic study was carried out for the upper Tanglewood Member (upper Ordovician) of the Lexington Limestone in order to understand its diagenetic history and predict whether the cementation is pre-deformational or post-deformational by comparing the deformed and undeformed beds of the same horizon. This study shows that the diagenetic processes, which have modified the sequence of the upper Tanglewood Member of the Lexington Limestone, consist of micritization, cementation, compaction, dolomitization and internal filling. Moreover, it indicates that the main episode of cementation took place after the sediment deformation.

scholarly journals Bone microstructure and diagenesis of saurischian dinosaurs from the Upper Cretaceous (Neuquén Group), Argentina

2017 ◽  
Vol 44 (1) ◽  
pp. 39 ◽  
Author(s):  
Elena Previtera
Keyword(s):  
Upper Cretaceous ◽  
Bone Microstructure ◽  
Depositional Environments ◽  
Integral Approach ◽  
Burial History ◽  
Thin Sections ◽  
Diagenetic Processes ◽  
History Of ◽  
Diagenetic History ◽  
Fluvial Environments

The Neuquén Basin in northwestern Patagonia, Argentina, holds the most important record of Cretaceous dinosaurs in South America.The Neuquén Group (Upper Cretaceous) is the richest dinosaur-bearing unit of the basin. It comprises the Río Limay, the Río Neuquén and the Río Colorado subgroups. In this study, dinosaur remains from the Río Neuquén and the Río Colorado subgroups outcropping in Mendoza are examined. In this group, isolated, disarticulated or partially articulated sauropods and theropods are abundant. However, little is known about the diagenetic history of fossil assemblages. In southern Mendoza, three fossiliferous sites were found in the areas of Paso de las Bardas (Quebrada Norte) and Cerro Guillermo (CG1, CG2). This study aims to add to the knowledge of diagenetic processes involving dinosaur remains from the Neuquén Group, as well as their relation to the depositional environment. Histologic features and diagenetic processes of dinosaur bones were analyzed through thin sections in order to interpret the degree of taphonomic alteration. The fossil-diagenetic processes inferred include substitution, fracturing, plastic deformation and different permineralization events. Combined analyses through X-ray diffractometry (XRD) and petrographic studies reveal the substitution of hydroxyapatite by francolite. The presence of fluorine -in one of the cases- suggests a link between the elemental composition and depositional environments: floodplain and fluvial channel. Permineralization stages include infilling of vascular canals, trabeculae and fractures with iron oxides and iron carbonate minerals during the burial history. This contribution represents an integral approach to the study of Cretaceous dinosaurs for assessing the diagenetic changes in the bone microstructure and the differential preservation of fossil remains in fluvial environments.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

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