scholarly journals Microstructural constraints on magmatic mushes under Kīlauea Volcano, Hawaiʻi

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Penny E. Wieser ◽  
Marie Edmonds ◽  
John Maclennan ◽  
John Wheeler
Keyword(s):  
Spatial Distribution ◽  
Dendritic Growth ◽  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Kilauea Volcano ◽  
Kīlauea Volcano ◽  
Mantle Peridotites ◽  
Wide Range ◽  
Electron Backscatter ◽  
Backscatter Diffraction

AbstractDistorted olivines of enigmatic origin are ubiquitous in erupted products from a wide range of volcanic systems (e.g., Hawaiʻi, Iceland, Andes). Investigation of these features at Kīlauea Volcano, Hawaiʻi, using an integrative crystallographic and chemical approach places quantitative constraints on mush pile thicknesses. Electron backscatter diffraction (EBSD) reveals that the microstructural features of distorted olivines, whose chemical composition is distinct from undistorted olivines, are remarkably similar to olivines within deformed mantle peridotites, but inconsistent with an origin from dendritic growth. This, alongside the spatial distribution of distorted grains and the absence of adcumulate textures, suggests that olivines were deformed within melt-rich mush piles accumulating within the summit reservoir. Quantitative analysis of subgrain geometry reveals that olivines experienced differential stresses of ∼3–12 MPa, consistent with their storage in mush piles with thicknesses of a few hundred metres. Overall, our microstructural analysis of erupted crystals provides novel insights into mush-rich magmatic systems.

scholarly journals Application of Electron Backscatter Diffraction (EBSD) for Crystallographic Characterization of Aluminum-Doped Zinc Oxide Sputtered Films

2013 ◽  
Vol 19 (S4) ◽  
pp. 103-104
Author(s):  
C.B. Garcia ◽  
E. Ariza ◽  
C.J. Tavares
Keyword(s):  
Electron Microscopy ◽  
Grain Size ◽  
Zinc Oxide ◽  
Electron Backscatter Diffraction ◽  
Wide Range ◽  
Electron Backscatter ◽  
Aluminum Doped Zinc Oxide ◽  
Ebsd Technique ◽  
Backscatter Diffraction

Zinc Oxide is a wide band-gap compound semiconductor that has been used in optoelectronic and photovoltaic applications due to its good electrical and optical properties. Aluminium has been an efficient n-type dopant for ZnO to produce low resistivity films and high transparency to visible light. In addition, the improvement of these properties also depends on the morphology, crystalline structure and deposition parameters. In this work, ZnO:Al films were produced by d.c. pulsed magnetron sputtering deposition from a ZnO ceramic target (2.0 wt% Al2O3) on glass substrates, at a temperature of 250 ºC.The crystallographic orientation of aluminum doped zinc oxide (ZnO:Al) thin films has been studied by Electron Backscatter Diffraction (EBSD) technique. EBSD coupled with Scanning Electron Microscopy (SEM) is a powerful tool for the microstructural and crystallographic characterization of a wide range of materials.The investigation by EBSD technique of such films presents some challenges since this analysis requires a flat and smooth surface. This is a necessary condition to avoid any shadow effects during the experiments performed with high tilting conditions (70º). This is also essential to ensure a good control of the three dimensional projection of the crystalline axes on the geometrical references related to the sample.Crystalline texture is described by the inverse pole figure (IPF) maps (Figure 1). Through EBSD analysis it was observed that the external surface of the film presents a strong texture on the basal plane orientation (grains highlighted in red colour). Furthermore it was possible to verify that the grain size strongly depends on the deposition time (Figure 1 (a) and (b)). The electrical and optical film properties improve with increasing of the grain size, which can be mainly, attributed to the decrease in scattering grain boundaries which leads to an increasing in carrier mobility (Figure 2).The authors kindly acknowledge the financial support from the Portuguese Foundation for Science and Technology (FCT) scientific program for the National Network of Electron Microscopy (RNME) EDE/1511/RME/2005.

scholarly journals To sink, swim, twin, or nucleate: A critical appraisal of crystal aggregation processes

Geology ◽  
2019 ◽  
Vol 47 (10) ◽  
pp. 948-952 ◽  
Author(s):  
Penny E. Wieser ◽  
Zoja Vukmanovic ◽  
Rüdiger Kilian ◽  
Emilie Ringe ◽  
Marian B. Holness ◽  
...  
Keyword(s):  
Dendritic Growth ◽  
Critical Appraisal ◽  
Bushveld Complex ◽  
Electron Backscatter Diffraction ◽  
Relative Orientation ◽  
Igneous Rocks ◽  
Growth Processes ◽  
Aggregation Processes ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Abstract Crystal aggregates in igneous rocks have been variously ascribed to growth processes (e.g., twinning, heterogeneous nucleation, epitaxial growth, dendritic growth), or dynamical processes (e.g., synneusis, accumulation during settling). We tested these hypotheses by quantifying the relative orientation of adjacent crystals using electron backscatter diffraction. Both olivine aggregates from Kīlauea volcano (Hawaiʻi, USA) and chromite aggregates from the Bushveld Complex (South Africa) show diverse attachment geometries inconsistent with growth processes. Near-random attachments in chromite aggregates are consistent with accumulation by settling of individual crystals. Attachment geometries and prominent geochemical differences across grain boundaries in olivine aggregates are indicative of synneusis.

scholarly journals Resolving pseudosymmetry in tetragonal ZrO2 using electron backscatter diffraction with a modified dictionary indexing approach

2020 ◽  
Vol 53 (4) ◽  
pp. 1060-1072 ◽  
Author(s):  
Edward L. Pang ◽  
Peter M. Larsen ◽  
Christopher A. Schuh
Keyword(s):  
Present Method ◽  
Electron Backscatter Diffraction ◽  
Source Code ◽  
Tetragonal Zro2 ◽  
Data Set ◽  
Orientation Space ◽  
Indexing Method ◽  
Wide Range ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Resolving pseudosymmetry has long presented a challenge for electron backscatter diffraction and has been notoriously challenging in the case of tetragonal ZrO2 in particular. In this work, a method is proposed to resolve pseudosymmetry by building upon the dictionary indexing method and augmenting it with the application of global optimization to fit accurate pattern centers, clustering of the Hough-indexed orientations to focus the dictionary in orientation space and interpolation to improve the accuracy of the indexed solution. The proposed method is demonstrated to resolve pseudosymmetry with 100% accuracy in simulated patterns of tetragonal ZrO2, even with high degrees of binning and noise. The method is then used to index an experimental data set, which confirms its ability to efficiently and accurately resolve pseudosymmetry in these materials. The present method can be applied to resolve pseudosymmetry in a wide range of materials, possibly even some more challenging than tetragonal ZrO2. Source code for this implementation is available online.

Microstructural Constraints on Magmatic Mushes under Kīlauea Volcano, Hawai'i

2020 ◽  
Author(s):  
Penny Wieser ◽  
Marie Edmonds ◽  
John Maclennan ◽  
John Wheeler
Keyword(s):  
Dendritic Growth ◽  
Melt Inclusion ◽  
Electron Backscatter Diffraction ◽  
Southern Volcanic Zone ◽  
Mantle Peridotites ◽  
Wide Range ◽  
Plumbing Systems ◽  
Lattice Distortions ◽  
Rift Zones ◽  
Andean Southern Volcanic Zone

<p>Distorted olivines of enigmatic origin are ubiquitous in erupted products from a wide range of volcanic systems (e.g., Hawai'i, Iceland, Andean Southern Volcanic Zone). At Kīlauea volcano, distorted olivines are commonly attributed to ductile creep within dunitic bodies located around the central conduit, or within the deep rift zones (~5–9 km depth). However, a recent suggestion that lattice distortions are produced by an early phase of branching dendritic growth, followed by textural ripening and the merging of misoriented crystal buds, has gained considerable traction.</p><p>A quantitative examination of the microstructures in distorted olivines by electron backscatter diffraction (EBSD) reveals striking similarities to microstructures observed in deformed mantle peridotites, but significant differences to the crystallographic signatures of dendritic growth. This suggests that lattice distortions record the application of differential stresses at high temperatures within the magmatic plumbing system, rather than rapid crystal growth. Previous petrological work has suggested that differential stresses are produced by ductile creep within Kīlauea’s deep rift zones. Crucially, this has fuelled suggestions that significant quantities of magma must travel along these rift zones in order to acquire distorted olivines, despite the paucity of geophysical evidence for these magma transport paths. In contrast, we show that the spatial distribution of eruptions containing distorted olivines is consistent with their derivation from the main magma storage reservoir. This model not only aligns petrological and geophysical observations at Kīlauea, but also accounts for the occurrence of distorted olivines in a wide variety of basaltic systems worldwide (which lack deep rift zones).</p><p>Application of piezometers developed for mantle peridotites reveals that distorted olivines have experienced differential stresses of ~3–12 MPa. Assuming that mush piles behave as granular materials, and form force chains, these stresses can be generated within cumulate piles of ~180–720 m. Based on available constraints on the magma supply rate and the geometry of Kīlauea’s summit reservoir, these thicknesses accumulate in a few centuries (consistent with residence times inferred from melt inclusion records).</p><p>Overall, we demonstrate that microstructural investigations of erupted olivine crystals by EBSD generates rich datasets which provide quantitative insights into crystal storage within mush piles. Under the increasingly prevalent view that crustal magmatic systems are mush-dominated, constraining the geometry and dynamics of crystal storage regions is crucial to further our understanding of magmatic plumbing systems. The presence of distorted olivines in many different volcanic settings highlights the global applicability of the methods developed in this study. Furthermore, assessments of deformation conditions using EBSD need not be restricted to olivine-bearing lavas. Microstructural fabrics types in natural and experimental samples have been established for a wide variety of igneous phases (e.g. diopside, plagioclase, hornblende), so similar approaches may be utilized in more evolved volcanic systems.</p>

scholarly journals Dislocation Creep of Olivine and Amphibole in Amphibole Peridotites from Åheim, Norway

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1018
Author(s):  
Sejin Jung ◽  
Takafumi Yamamoto ◽  
Jun-ichi Ando ◽  
Haemyeong Jung
Keyword(s):  
Electron Microscopy ◽  
Slip System ◽  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Dislocation Creep ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Different Types ◽  
Localized Shear Deformation ◽  
Backscatter Diffraction

Amphibole peridotite samples from Åheim, Norway, were analyzed to understand the deformation mechanism and microstructural evolution of olivine and amphibole through the Scandian Orogeny and subsequent exhumation process. Three Åheim amphibole peridotite samples were selected for detailed microstructural analysis. The Åheim amphibole peridotites exhibit porphyroclastic texture, abundant subgrain boundaries in olivine, and the evidence of localized shear deformation in the tremolite-rich layer. Two different types of olivine lattice preferred orientations (LPOs) were observed: B- and A-type LPOs. Electron backscatter diffraction (EBSD) mapping and transmission electron microscopy (TEM) observations revealed that most subgrain boundaries in olivine consist of dislocations with a (001)[100] slip system. The subgrain boundaries in olivine may have resulted from the deformation of olivine with moderate water content. In addition, TEM observations using a thickness-fringe method showed that the free dislocations of olivine with the (010)[100] slip system were dominant in the peridotites. Our data suggest that the subgrain boundaries and free dislocations in olivine represent a product of later-stage deformation associated with the exhumation process. EBSD mapping of the tremolite-rich layer revealed intracrystalline plasticity in amphibole, which can be interpreted as the activation of the (100)[001] slip system.

scholarly journals Evolution Of Precipitate Morphology During Extrusion In Mg ZK60A Alloy

2015 ◽  
Vol 60 (2) ◽  
pp. 1423-1426 ◽  
Author(s):  
J. Park ◽  
K.H. Jung ◽  
G.A. Lee ◽  
M. Kawasaki ◽  
B. Ahn
Keyword(s):  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Extrusion Process ◽  
Formation Mechanisms ◽  
Precipitate Morphology ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Evolution Of Precipitates

Abstract In this study, a continuously casted ZK60A magnesium alloy (Mg-Zn-Zr) was extruded in two different extrusion ratios, 6:1 and 10:1. The evolution of precipitates was investigated on the two extruded materials and compared with that of as-casted material. The microstructural analysis was performed by electron backscatter diffraction and transmission electron microscopy, and the compositional information was obtained using energy-dispersive X-ray spectroscopy. Several distinct morphologies of precipitates were observed, such as dot, rod, and disk shaped. The formation mechanisms of those precipitates were discussed with respect to the heat and strain during the extrusion process.

scholarly journals Electron Backscatter Diffraction: A Powerful Tool for Phase Identification in the SEM

1999 ◽  
Vol 589 ◽  
Author(s):  
J. R. Michael ◽  
R. P. Goehner
Keyword(s):  
Spatial Resolution ◽  
Electron Backscatter Diffraction ◽  
Unit Cell ◽  
Particle Analysis ◽  
Phase Identification ◽  
Cell Determination ◽  
Wide Range ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Better Than

AbstractEBSD in the SEM has been developed into a tool that can provide identification of unknown crystalline phases with a spatial resolution that is better than one micrometer. This technique has been applied to a wide range of materials. Use of the HOLZ rings in the EBSD patterns has enabled the reduced unit cell to be determined from unindexed EBSD patterns. This paper introduces EBSD for phase identification and illustrates the technique with examples from metal joining and particle analysis. Reduced unit cell determination from EBSD patterns is then discussed.

Scale-bridging Microstructural Analysis – A Correlative Approach to Microstructure Quantification Combining Microscopic Images and EBSD Data

2021 ◽  
Vol 58 (7) ◽  
pp. 408-426
Author(s):  
M. Müller ◽  
D. Britz ◽  
F. Mücklich
Keyword(s):  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Comprehensive Description ◽  
Microscopic Images ◽  
Practical Applications ◽  
Ebsd Data ◽  
Electron Backscatter ◽  
Microstructure Quantification ◽  
Backscatter Diffraction ◽  
Source Of Information

Abstract A comprehensive description of complex material structures may require characterization using different methods and observations across several scales. This work will present a correlative approach including light optical microscopy, scanning electron microscopy and electron backscatter diffraction, enabling microstructure quantification which combines microscopic images and electron backscatter diffraction data. The parameters obtained from electron backscatter diffraction such as misorientation parameters or grain and phase boundary data are an ideal source of information, complementing microscopic images. Two case studies performed on bainitic microstructures will be presented to demonstrate practical applications of this approach.

Sign in / Sign up

Export Citation Format

Share Document