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 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 Boom boom pow: Shock-facilitated aqueous alteration and evidence for two shock events in the Martian nakhlite meteorites

2019 ◽  
Vol 5 (9) ◽  
pp. eaaw5549 ◽  
Author(s):  
L. Daly ◽  
M. R. Lee ◽  
S. Piazolo ◽  
S. Griffin ◽  
M. Bazargan ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Mechanical Twinning ◽  
Igneous Rocks ◽  
Aqueous Alteration ◽  
Rock Interaction ◽  
Spatially Correlated ◽  
Electron Backscatter ◽  
Parent Rocks ◽  
Backscatter Diffraction ◽  
Water Rock Interaction

Nakhlite meteorites are ~1.4 to 1.3 Ga old igneous rocks, aqueously altered on Mars ~630 Ma ago. We test the theory that water-rock interaction was impact driven. Electron backscatter diffraction demonstrates that the meteorites Miller Range 03346 and Lafayette were heterogeneously deformed, leading to localized regions of brecciation, plastic deformation, and mechanical twinning of augite. Numerical modeling shows that the pattern of deformation is consistent with shock-generated compressive and tensile stresses. Mesostasis within shocked areas was aqueously altered to phyllosilicates, carbonates, and oxides, suggesting a genetic link between the two processes. We propose that an impact ~630 Ma ago simultaneously deformed the nakhlite parent rocks and generated liquid water by melting of permafrost. Ensuing water-rock interaction focused on shocked mesostasis with a high density of reactive sites. The nakhlite source location must have two spatially correlated craters, one ~630 Ma old and another, ejecting the meteorites, ~11 Ma ago.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

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