Quantification and assessment of quartz-particle 2D size and shape using digital image analysis.

2021 ◽  
Author(s):  
Edgar Berrezueta ◽  
José Cuervas-Mons ◽  
Cynthia Gallego-Ruiz ◽  
Berta Ordóñez-Casado ◽  
Manuel Ignacio de Paz-Álvarez ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Qualitative Evaluation ◽  
Shape Parameters ◽  
Thrust Sheet ◽  
Chemical Corrosion ◽  
Size And Shape ◽  
Geological Processes ◽  
Natural Rock ◽  
Quartz Grains ◽  
Rock Specimens

<p>The size and shape of rock constituent particles can provide substantial information about the environment in which rocks are formed and also about their evolution during their geological history. There are several geological processes that generate specific particle shapes. We focus on three processes and their effects on particles as end members: sediment transport in water producing sub-rounded particles, tectonic fracturing producing angular fragments and chemical corrosion at grain boundaries increasing their rugosity. In this work we test several shape morphological parameters in natural rock specimens with the ultimate goal of quantifying the proportion of different typologies of particles in a rock, all of which can be related to specific geological processes. The main aim of this work is to distinguish different typologies of quartz particles according to the quantitative and qualitative evaluation of shape parameters by using several shape parameters in grains and/or particles.</p><p>The procedure followed includes: i) the petrographic characterization of rock specimens in thin section, visually establishing the different typologies of quartz grains present, ii) the acquisition and segmentation of outlines of quartz particles and iii) the quantification of size and shape parameters such as area (A), perimeter (P), fractal dimension (FD), solidity (So), normalized perimeter-area (PoA), Wadell roundness (Rw), Drevin roundness (RD), Pg/Pe roundness (RP), sphericity (S) and a regularity indicator (RBC). A total of 293 particles were studied by means of ImagePro-Plus, ImageJ and Roussillon Toolbox software.</p><p>We have used two rock specimens from the base of the Esla nappe, a thrust sheet emplaced in the foreland fold and thrust belt of the Variscan orogen in NW Iberia (Cantabrian Zone). The first phase of this work was to identify the petrographic characteristics of the samples. One specimen was sampled from a quartz sand injection at the base of the thrust sheet. The other is from a sandstone in the footwall, the likely source for the quartz grains injected in the hanging wall. There are some evidence of fracturing and corrosion of the injected quartz grains during the injection process at the base of the Esla nappe. In summary, the first sample contains quartz grains with distinctive shapes that can be directly related to very specific geological processes affecting particle shape in a rock.</p><p>The result of the analysis completed allowed the definition of: i) the parameters that best represent the grain shape variations and ii) the range of values for each parameter that are characteristic of each process, thus allowing the classification of the grain shapes. Furthermore, the analysis allowed distinguishing sub-rounded quartz grains of detrital sedimentary origin from grains that have been partially or totally fractured. However, the used shape parameters do not allow a univocal identification of grains corroded by fluids.</p><p>Acknowledgments: The Spanish National Plan (CGL2017-86487-P PETROCANTABRICA Project) funded this research.</p>

scholarly journals Synchrotron FTIR imaging of OH in quartz mylonites

Solid Earth ◽  
2017 ◽  
Vol 8 (5) ◽  
pp. 1025-1045 ◽  
Author(s):  
Andreas K. Kronenberg ◽  
Hasnor F. B. Hasnan ◽  
Caleb W. Holyoke III ◽  
Richard D. Law ◽  
Zhenxian Liu ◽  
...  
Keyword(s):  
Water Content ◽  
Point Defects ◽  
Fluid Inclusions ◽  
Hanging Wall ◽  
Molecular Water ◽  
Main Central Thrust ◽  
Absorption Bands ◽  
Uniform Equilibrium ◽  
Quartz Grains ◽  
Water Contents

Abstract. Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR) instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.Synchrotron infrared (IR) radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR) plates can be prepared with thicknesses down to 4–8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples < 25 µm thick, precluding measurements of water within individual, finely recrystallized grains. By translating specimens under the 10 µm IR beam by steps of 10 to 50 µm, using a software-controlled x − y stage, spectra have been collected over specimen areas of nearly 4.5 mm2. This technique allowed us to separate and quantify broad OH bands due to fluid inclusions in quartz and OH bands due to micas and map their distributions in quartzites from the Moine Thrust (Scotland) and Main Central Thrust (Himalayas).Mylonitic quartzites deformed under greenschist facies conditions in the footwall to the Moine Thrust (MT) exhibit a large and variable 3400 cm−1 OH absorption band due to molecular water, and maps of water content corresponding to fluid inclusions show that inclusion densities correlate with deformation and recrystallization microstructures. Quartz grains of mylonitic orthogneisses and paragneisses deformed under amphibolite conditions in the hanging wall to the Main Central Thrust (MCT) exhibit smaller broad OH bands, and spectra are dominated by sharp bands at 3595 to 3379 cm−1 due to hydrogen point defects that appear to have uniform, equilibrium concentrations in the driest samples. The broad OH band at 3400 cm−1 in these rocks is much less common. The variable water concentrations of MT quartzites and lack of detectable water in highly sheared MCT mylonites challenge our understanding of quartz rheology. However, where water absorption bands can be detected and compared with deformation microstructures, OH concentration maps provide information on the histories of deformation and recovery, evidence for the introduction and loss of fluid inclusions, and water weakening processes.

Shape difference of mud clasts depending on depositional facies: application of newly modified elliptic Fourier analysis to hybrid event beds

2020 ◽  
Vol 90 (10) ◽  
pp. 1410-1435
Author(s):  
Sojiro Fukuda ◽  
Hajime Naruse
Keyword(s):  
Fourier Analysis ◽  
Shape Analysis ◽  
Transport Processes ◽  
Transport Systems ◽  
Shape Parameters ◽  
Elliptic Fourier Analysis ◽  
Depositional Facies ◽  
Size And Shape ◽  
Muddy Sediments ◽  
Hybrid Event

ABSTRACT Hybrid event beds are the deposits from sediment gravity flows that change their rheological behavior through their passage, entraining muddy sediments and damping turbulence. Muddy facies of hybrid event beds are often associated with abundant mud clasts which show a wide variety of size and shape. The variation of clast occurrence in hybrid event beds is expected to preserve the information of entrainment and transport processes of muddy sediments in submarine density currents. However, previous analyses of hybrid event beds have focused on describing the overall clast occurrence rather than the statistical size and shape analyses because traditional shape parameters are incapable of characterizing the complex shape of mud clasts. Here, a new quantitative grain-shape analysis of mud clasts is conducted and allows visualization of the spatial variation of clast size and shape, which suggests the wide variety of origin and transport systems of entrained mud clasts. This new method revises the traditional elliptic Fourier analysis, substituting Fourier power spectra (FPS) for traditional elliptic Fourier descriptors to overcome the mirror-wise shape problem. Further, principal-component analysis is shown to capture significant shape attributes more effectively than traditional shape parameters. The proposed method is applied to mud clasts in sediment-gravity-flow deposits in the lower Pleistocene Otadai Formation, central Japan. Results imply that there are distinctive shape and size differences of mud clasts that are strongly associated with depositional facies rather than the distance from the source. The clasts have a higher angularity than other facies in the debrite intervals in hybrid event beds. It is also shown that clasts in sandy, structureless facies have different characteristics in shapes based on elongation and convexity compared to laminated facies. Comparison between different shape-analysis methods demonstrates that none of the traditional methods are able to visualize these trends as effectively as the method presented herein. These results highlight the importance of the quantitative shape analysis of sediment grains and the effectiveness of FPS-based elliptic Fourier analysis.

scholarly journals Descriptive text to the Geological map of Greenland, 1:100 000, Kilen 81 Ø.1 Syd

2018 ◽  
pp. 1-29
Author(s):  
Kristian Svennevig ◽  
Peter Alsen ◽  
Pierpaolo Guarnieri ◽  
Jussi Hovikoski ◽  
Bodil Wesenberg Lauridsen ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Field Work ◽  
Normal Faults ◽  
The South ◽  
Thrust Sheet ◽  
Basin Inversion ◽  
North East ◽  
The North ◽  
Geological Map ◽  
Surrounding Areas

The geological map sheet of Kilen in 1:100 000 scale covers the south-eastern part of the Carboniferous– Palaeogene Wandel Sea Basin in eastern North Greenland. The map area is dominated by the Flade Isblink ice cap, which separates several minor isolated landmasses. On the semi-nunatak of Kilen, the map is mainly based on oblique photogrammetry and stratigraphical field work while in Erik S. Henius Land, Nordostrundingen and northern Amdrup Land the map is based on field data collected during previous, 1:500 000 scale regional mapping. Twenty-one Palaeozoic–Mesozoic mappable units were identified on Kilen, while the surrounding areas comprise the Late Cretaceous Nakkehoved Formation to the north-east and the Late Carboniferous Foldedal Formation to the south-west. On Kilen, the description of Jurassic–Cretaceous units follows a recently published lithostratigraphy. The Upper Palaeozoic–lowermost Cretaceous strata comprise seven formations and an informal mélange unit. The overlying Lower–Upper Cretaceous succession comprises the Galadriel Fjeld and Sølverbæk Formations, which are subdivided into six and five units, respectively. In addition, the Quaternary Ymer Formation was mapped on south-east Kilen. The Upper Palaeozoic to Mesozoic strata of Kilen are faulted and folded. Several post-Coniacian NNW–SSE-trending normal faults are identified and found to be passively folded by a later N–S compressional event. A prominent subhorizontal fault, the Central Detachment, separates two thrust sheets, the Kilen Thrust Sheet in the footwall and the Hondal Elv Thrust Sheet in the hanging wall. The style of deformation and the structures found on Kilen are caused by compressional tectonics resulting in post-extensional, presumably Early Eocene, folding and thrusting and basin inversion. The structural history of the surrounding areas and their relation to Kilen await further studies.

Structure and genesis of the Boulder-Weld allochthon, Denver Basin, Colorado - Gravity slide or Laramide thrust sheet?

2020 ◽  
Vol 57 (3) ◽  
pp. 271-304
Author(s):  
Edward J. Sterne
Keyword(s):  
Hanging Wall ◽  
Normal Fault ◽  
Normal Faults ◽  
Front Range ◽  
Denver Basin ◽  
Thrust Sheet ◽  
Pierre Shale ◽  
Transport Direction ◽  
Tear Fault ◽  
Gravity Slide

This study was undertaken to determine the structure and genesis of the Boulder-Weld allochthon (BWA), the 216 mi2 (559 km2) remnant of a once larger feature, that moved east from the flank of the Front Range into the western part of the Denver Basin. This review of surface and subsurface data revealed new aspects of the BWA, especially in its western part. There, the decollement of the BWA ramps 900 feet up-section to the east from a near bedding-parallel detachment low in the upper transition member of the Pierre Shale to a bedding-parallel detachment near the base of the Fox Hills Formation. Repeated sections found in wells east of the decollement ramp demonstrate up to two miles of translation in the system. Secondary faults in the hanging wall of the allochthon include antithetic thrusts bounding pop-up structures and occasional normal faults that almost exclusively overprint the decollement ramp. The hanging wall is also cut by a postulated tear fault separating areas exhibiting different amounts of translation. The western, trailing edge of the decollement shows attenuation in its hanging wall that increases to the west. This part of the decollement either represents a very low-angle breakaway normal fault or a thrust fault cutting slightly down-section in the direction of transport. Past studies perceived a southeast transport direction for the BWA in contrast to the northeast slip directions on nearby Laramide thrusts, a difference used to interpret the allochthon as a gravity slide. However, similar east-west oriented slickenlines on thrusts across the western part of the allochthon and into the neighboring Front Range leave open the possibility the BWA originated as a Laramide thrust sheet. Furthermore, both the BWA and Laramide thrusts in the neighboring Front Range utilized detachments near the top of the Pierre Shale, suggesting a possible common genesis. Given the available data, both the gravity slide and Laramide thrust models provide viable explanations for the BWA.

Descriptive text to the Geological map of Greenland, 1:100 000, Kilen 81 Ø.1 Syd

2018 ◽  
pp. 1-29
Author(s):  
Kristian Svennevig ◽  
Peter Alsen ◽  
Pierpaolo Guarnieri ◽  
Jussi Hovikoski ◽  
Bodil Wesenberg Lauridsen ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Field Work ◽  
Normal Faults ◽  
The South ◽  
Thrust Sheet ◽  
Basin Inversion ◽  
North East ◽  
The North ◽  
Geological Map ◽  
Surrounding Areas

NOTE: This Map Description was published in a former series of GEUS Bulletin. Please use the original series name when citing this series, for example: Svennevig, K., Alsen, P., Guarnieri, P., Hovikoski, J., Wesenberg Lauridsen, B., Krarup Pedersen, G., Nøhr-Hansen, H., & Sheldon, E. (2018). Descriptive text to the Geological map of Greenland, 1:100 000, Kilen 81 Ø.1 Syd. Geological Survey of Denmark and Greenland Map Series 8, 1-29. https://doi.org/10.34194/geusm.v8.4526 _______________ The geological map sheet of Kilen in 1:100 000 scale covers the south-eastern part of the Carboniferous–Palaeogene Wandel Sea Basin in eastern North Greenland. The map area is dominated by the Flade Isblink ice cap, which separates several minor isolated landmasses. On the semi-nunatak of Kilen, the map is mainly based on oblique photogrammetry and stratigraphical field work while in Erik S. Henius Land, Nordostrundingen and northern Amdrup Land the map is based on field data collected during previous, 1:500 000 scale regional mapping. Twenty-one Palaeozoic–Mesozoic mappable units were identified on Kilen, while the surrounding areas comprise the Late Cretaceous Nakkehoved Formation to the north-east and the Late Carboniferous Foldedal Formation to the south-west. On Kilen, the description of Jurassic–Cretaceous units follows a recently published lithostratigraphy. The Upper Palaeozoic–lowermost Cretaceous strata comprise seven formations and an informal mélange unit. The overlying Lower–Upper Cretaceous succession comprises the Galadriel Fjeld and Sølverbæk Formations, which are subdivided into six and five units, respectively. In addition, the Quaternary Ymer Formation was mapped on south-east Kilen. The Upper Palaeozoic to Mesozoic strata of Kilen are faulted and folded. Several post-Coniacian NNW–SSE-trending normal faults are identified and found to be passively folded by a later N–S compressional event. A prominent subhorizontal fault, the Central Detachment, separates two thrust sheets, the Kilen Thrust Sheet in the footwall and the Hondal Elv Thrust Sheet in the hanging wall. The style of deformation and the structures found on Kilen are caused by compressional tectonics resulting in post-extensional, presumably Early Eocene, folding and thrusting and basin inversion. The structural history of the surrounding areas and their relation to Kilen await further studies.

Dextran-induced modifications of calcium carbonate particles precipitated during carbonatation

2019 ◽  
pp. 382-391
Author(s):  
Karin Abraham ◽  
Liza Splett ◽  
Eckhard Flöter
Keyword(s):  
Particle Size ◽  
Image Analysis ◽  
Calcium Carbonate ◽  
Filter Cake ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Shape Parameters ◽  
Size And Shape ◽  
Static Image ◽  
Particle Size And Shape

The effects of high and low molecular mass dextran (T2000 and T40) on the size and shape of particles precipitated during carbonatation and their correlation with filtration performances were key to this study. Varying contents of T2000 and T40 dextran in sugar solutions corresponding to DS contents of thin juice were investigated. For particle size and shape analysis, static image analysis and laser particle size analysis were used. Both methods, static image analysis and laser diffraction, revealed that the presence of T2000 and T40 dextran leads to a higher amount of large-sized particles at the expense of small-sized particles, indicating pronounced agglomeration. The additional evaluation of shape parameters (circularity, roundness, solidity) obtained from static image analysis indicates that the agglomeration is oriented in the absence and in the presence of lower T40 dextran levels. Besides, non-oriented agglomeration, resulting in more round agglomerates with smoother surfaces, was found for samples loaded with T2000 dextran and high T40 dextran levels. Only the latter samples have shown to negatively affect the filtration performance. Thus, in the presence of T2000 dextran and high T40 dextran levels, the filtration was hampered. This appears to be mainly caused by a tighter packing of more round calcium carbonate agglomerates in the porous structure of the filter cake.

scholarly journals Tracing the Mahabharat Thrust (MT) on the basis of lithology and microstructures around Bhainse-Manahari area, central Nepal

2016 ◽  
Vol 51 ◽  
pp. 39-48
Author(s):  
Laxman Subedi ◽  
Kamala Kant Acharya
Keyword(s):  
Hanging Wall ◽  
Strain Analysis ◽  
Metamorphic Rocks ◽  
Foot Wall ◽  
Low Grade ◽  
The North ◽  
Central Nepal ◽  
Complex Shear ◽  
Thrust Zone ◽  
Quartz Grains

Lithological and microstructural study carried out in Bhainse –Manahari area, central Nepal reveals that the rock sequences of the Bhainse–Manahari area can be divided into two successions: the Nawakot Complex and the Kathmandu Complex. These two Complexes are separated by a distinct thrust boundary, the Mahabharat Thrust (MT). The Nawakot Complex consists of low-grade metamorphic rocks like slate, phyllite, quartzite and limestone while the Kathmandu Complex comprises medium grade (up to garnet grade) metamorphic rocks like garnet-schist, marble and mica-schist. The Mahabharat Thrust (MT) and the Manahari Thrust (MnT) are the two major thrusts in the study area. The MT separates the rocks of the Nawakot Complex (foot wall) in the south from the rocks of the Kathmandu Complex (hanging wall) in the north. The Manahari Thrust in the western part of the study area separates the Dunga Quartzite and the older Benighat Slates lying above it. The microstructure analysis reveals that the rocks in the thrust zone show higher deformation than in the neighboring rocks, and this gradually decreases away from the MT zone. The strain analysis of quartz grains reveals that the rock sequences of the hanging wall of the MT showed pure, simple and complex shear senses and the rocks of the footwall also showed the same pattern indicating MT as a stretching fault.

Kinematic analysis of rock flow and deformation temperature of the Sirjan thrust sheet, Zagros Orogen, Iran

2016 ◽  
Vol 154 (1) ◽  
pp. 147-165 ◽  
Author(s):  
KHALIL SARKARINEJAD ◽  
SAEEDE KESHAVARZ ◽  
ALI FAGHIH ◽  
BABAK SAMANI
Keyword(s):  
Deformation Temperature ◽  
Structural Characteristics ◽  
Pure Shear ◽  
Hanging Wall ◽  
Arabian Plate ◽  
Metamorphic Belt ◽  
Thrust Sheet ◽  
Shear Sense ◽  
Zagros Orogen ◽  
Shear Sense Indicators

AbstractMicrostructural, finite strain and vorticity analyses of quartz-rich mylonites were used in order to investigate kinematics of rock flow and deformation temperature in the Sirjan thrust sheet exposed in a structural window within the Sanandaj–Sirjan High Pressure – Low Temperature (HP–LT) metamorphic belt that forms part of the hinterland of the Zagros orogenic belt of Iran. A dominant top-to-the-SW sense of shear in the study area is indicated by several shear sense indicators such as asymmetric boudins, rotated porphyroclasts, mica fish and S/C fabrics. Quantitative analyses reveal approximately plane strain deformation conditions with Rxz values ranging from 2.5 to 4.3 and increasing towards the Sirjan thrust. Opening angles of quartz c-axis fabrics and recrystallization regimes suggest deformation temperatures vary from 430 to 625 ± 50°C in the hanging wall rocks. Oblique grain shape and quartz c-axis fabrics were used to estimate the degree of non-coaxiality during deformation. The obtained vorticity profile indicates a down-section increase in kinematic vorticity number (Wm) from 0.6 to 0.89. This range of vorticity numbers confirms contributions of both simple (41–68 %) and pure shear (32–59 %) deformation components. The structural characteristics of the study area ultimately were controlled by oblique motion of the Afro-Arabian plate relative to the Iranian plate.

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