Quantitative analysis on volcanic ash surfaces: Application of extended depth-of-field (focus) algorithm for light and scanning electron microscopy and 3D reconstruction

Ersoy, Orkun; Aydar, Erkan; Gourgaud, Alain; Bayhan, Hasan Alı

doi:10.1016/j.micron.2006.11.010

Cited by 34 publications

(15 citation statements)

References 26 publications

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“…The fractal dimension measurements were computed with the Map Fractal Count 1.36 plugin (Campos et al,2009), developed by Per Christian Henden and Jens Bache‐Wiig (http://www.pvv.org/~perchrh/imagej/mapfractalcount.html). For instance, both plugins have also successfully used by Ersoy et al (2008), for the quantitative description of volcanic ash surfaces, and by Meager et al (2011) to study the topographic complexity and heterogeneity of habitat structure on a rocky intertidal shore.…”

Section: Methodsmentioning

confidence: 99%

Electronic and vibrational optical activity of several peptides related to neurohypophyseal hormones: Disulfide group conformation

et al. 2012

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Electronic and vibrational optical activity of the set of neurohypophyseal hormones and their analogs was investigated to clarify the S-S bond solution conformation. The selected compounds include oxytocin (I), lysine vasopressin (II), arginine vasopressin (III), and their analogs (IV-IX), differing widely in their pharmacological properties. We have extended the already known electronic circular dichroism data by new information provided by vibrational circular dichroism (VCD) and Raman optical activity (ROA). The use of VCD brought additional details on three-dimensional structure of the chain reversal in the ring moiety and on its left handedness. Furthermore, Raman scattering and ROA allowed us to deduce the sense of the disulfide bond torsion.

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Section: Methodsmentioning

confidence: 99%

Electronic and vibrational optical activity of several peptides related to neurohypophyseal hormones: Disulfide group conformation

et al. 2012

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“…From a microscopic perspective, the relation between particle morphology and eruptive and transport mechanisms has been abundantly explored (e.g., Dellino and Liotino 2002;Ersoy et al 2006Ersoy et al , 2008Heiken and Wohletz 1985;Leibrandt and Le Pennec 2015;Liu et al 2015;Rausch et al 2015;Riley et al 2003;Sheridan and Kortemeier 1987;Sheridan and Marshall 1983;Vonlanthen et al 2015). Heiken (1972) considered that the shape of particles in the ash size range is mostly dependent on the shape of magmatic gas bubbles at the moment of fragmentation: flat and platy shards arise from broken vesicle walls, and droplet shapes are produced from low viscosity magma where the effect of surface tension is likely to become more important.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of formation of volcanic bombs: insights from a pilot study of anisotropy of magnetic susceptibility and preliminary assessment of analytical models

Cañón‐Tapia

2017

Bull Volcanol

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Volcanic bombs and achneliths are a special type of pyroclastic fragments formed by mildly explosive volcanic eruptions. Models explaining the general shapes of those particles can be divided in two broad categories. The most popular envisages the acquisition of shapes of volcanic bombs as the result of the rush of air acting on a fluid clot during flight, and it includes many variants. The less commonly quoted model envisages their shapes as the result of forces acting at the moment of ejection of liquid from the magma pool in the conduit, experiencing an almost negligible modification through its travel through air. Quantitative evidence supporting either of those two models is limited. In this work, I explore the extent to which the anisotropy of magnetic susceptibility (AMS) might be useful in the study of mechanisms of formation of volcanic bombs by comparing measurements made on two spindle and two bread-crusted bombs. The results of this pilot study reveal that the degree of anisotropy of spindle bombs is larger, and their principal susceptibility axes are better clustered than on bread-crusted bombs. Also, the orientation of the principal susceptibility axes is consistent with two specific models (one of the in-flight variants and the general ejection model). Consequently, the reported AMS measurements, albeit limited in number, indicate that it is reasonable to focus attention on only two specific models to explain the acquisition of the shapes of volcanic bombs. Based on a parallel theoretical assessment of analytical models, a third alternative is outlined, envisaging volcanic bomb formation as a two-stage process that involves the bursting of large (~m) gas bubbles on the surface of a magma pond. The new model advanced here is also consistent with the reported AMS results, and constitutes a working hypothesis that should be tested by future studies richer in data. Fortunately, since this work also establishes that AMS can be used to determine magnetic fabric in small size samples, the possibility to expand this study to a larger collection of bombs is granted.

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“…Such material easily disaggregates allowing for individual ash particles to be picked and analyzed independently using 3D scanning electron microscopy (SEM) methods [9]. The analysis of 2D particle images involves the use of particleshape descriptors [13,15,[28][29][30][31][32][33][34]. While numerous studies have utilized data derived from individual ash particles, few have attempted to apply this method to lithified pyroclastic rocks.…”

Section: Introductionmentioning

confidence: 99%

Volcanic glass textures, shape characteristics and compositions of phreatomagmatic rock units from the Western Hungarian monogenetic volcanic fields and their implications for magma fragmentation

Németh

2010

Open Geosciences

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Abstract:The majority of the Mio-Pleistocene monogenetic volcanoes in Western Hungary had, at least in their initial eruptive phase, phreatomagmatic eruptions that produced pyroclastic deposits rich in volcanic glass shards. Electron microprobe studies on fresh samples of volcanic glass from the pyroclastic deposits revealed a primarily tephritic composition. A shape analysis of the volcanic glass shards indicated that the fine-ash fractions of the phreatomagmatic material fragmented in a brittle fashion. In general, the glass shards are blocky in shape, low in vesicularity, and have a low-to-moderate microlite content. The glass-shape analysis was supplemented by fractal dimension calculations of the glassy pyroclasts. The fractal dimensions of the glass shards range from 1.06802 to 1.50088, with an average value of 1.237072876, based on fractal dimension tests of 157 individual glass shards. The average and mean fractal-dimension values are similar to the theoretical Kochflake (snowflake) value of 1.262, suggesting that the majority of the glass shards are bulky with complex boundaries. Light-microscopy and backscattered-electron-microscopy images confirm that the glass shards are typically bulky with fractured and complex particle outlines and low vesicularity; features that are observed in glass shards generated in either a laboratory setting or naturally through the interaction of hot melt and external water. Textural features identified in fine-and coarse-ash particles suggest that they were formed by brittle fragmentation both at the hot melt-water interface (forming active particles) as well as in the vicinity of the interaction interface. Brittle fragmentation may have occurred when hot melt rapidly penetrated abundant water-rich zones causing the melt to cool rapidly and rupture explosively.

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Quantitative analysis on volcanic ash surfaces: Application of extended depth-of-field (focus) algorithm for light and scanning electron microscopy and 3D reconstruction

Cited by 34 publications

References 26 publications

Electronic and vibrational optical activity of several peptides related to neurohypophyseal hormones: Disulfide group conformation

Electronic and vibrational optical activity of several peptides related to neurohypophyseal hormones: Disulfide group conformation

Mechanism of formation of volcanic bombs: insights from a pilot study of anisotropy of magnetic susceptibility and preliminary assessment of analytical models

Volcanic glass textures, shape characteristics and compositions of phreatomagmatic rock units from the Western Hungarian monogenetic volcanic fields and their implications for magma fragmentation

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