scholarly journals The grain size(s) of Black Hills Quartzite deformed in the dislocation creep regime

Solid Earth ◽  
2017 ◽  
Vol 8 (5) ◽  
pp. 1071-1093 ◽  
Author(s):  
Renée Heilbronner ◽  
Rüdiger Kilian
Keyword(s):  
Grain Size ◽  
Black Hills ◽  
Dislocation Creep ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Axis Orientation ◽  
Grain Sizes ◽  
Deformation Intensity ◽  
Recrystallized Grain Size ◽  
Creep Regime

Abstract. General shear experiments on Black Hills Quartzite (BHQ) deformed in the dislocation creep regimes 1 to 3 have been previously analyzed using the CIP method (Heilbronner and Tullis, 2002, 2006). They are reexamined using the higher spatial and orientational resolution of EBSD. Criteria for coherent segmentations based on c-axis orientation and on full crystallographic orientations are determined. Texture domains of preferred c-axis orientation (Y and B domains) are extracted and analyzed separately. Subdomains are recognized, and their shape and size are related to the kinematic framework and the original grains in the BHQ. Grain size analysis is carried out for all samples, high- and low-strain samples, and separately for a number of texture domains. When comparing the results to the recrystallized quartz piezometer of Stipp and Tullis (2003), it is found that grain sizes are consistently larger for a given flow stress. It is therefore suggested that the recrystallized grain size also depends on texture, grain-scale deformation intensity, and the kinematic framework (of axial vs. general shear experiments).

scholarly journals The grain size(s) of Black Hills Quartzite deformed in the dislocation creep regime

2017 ◽  
Author(s):  
Renée Heilbronner ◽  
Rüdiger Kilian
Keyword(s):  
Grain Size ◽  
Black Hills ◽  
Dislocation Creep ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Cip Method ◽  
Axis Orientation ◽  
Creep Regime ◽  
Crystallographic Orientations ◽  
Shape And Size

Abstract. A number of general shear experiments on Black Hills Quartzite (BHQ) in the dislocation creep regime, 5 of which have been analyzed previously using the CIP method (Heilbronner & Tullis, 2002 and 2006), are (re-)examined using the higher spatial and orientational resolution of EBSD. Segmentations based on c-axis orientation and on full crystallographic orientations are compared. Texture domains of preferred c-axis orientation are extracted and analyzed separately. Subdomains are recognized and their shape and size is related the kinematic framework and the original grains in the BHQ. Grain size analysis using a segmentation based on c-axis orientations is carried out for all, high and low strain samples of all regimes, and for a number of texture domains. The results are compared to the recrystallized quartz piezometer of Stipp & Tullis (2003), returning consistently higher values for stress or grain size. Possible causes for the discrepancy are texture dependence, grain scale strain, and dependence on the kinematic framework (in axial versus general shear experiments).

scholarly journals Grain Size and Heavy Minerals Analysis of Maastrichtian Sandstone, Anambra Basin, Nigeria: Implication for Aquifer Properties

2020 ◽  
Vol 24 (11) ◽  
pp. 1881-1888
Author(s):  
M Ilevbare ◽  
OI Imasuen
Keyword(s):  
Grain Size ◽  
Drinking Water ◽  
Hydraulic Conductivity ◽  
Heavy Minerals ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Grain Sizes ◽  
Anambra Basin ◽  
Aquifer Geometry ◽  
Aquifer Properties

The Maastrichtian sediments of Anambra Basin, south western Nigeria was studied for grain characteristics and maturity of the sediments, so that by combining sedimentological characteristics, maturity and its paleoenvironment of deposition of the Ajali sandstone, in order to ascertain the aquifer properties of the groundwater within the study area and by extension the availability of drinking water for both the urban and rural settlers. Grain size analysis (51 samples) and heavy mineral analysis (15 samples each) were analyzed. The textural parameters show that the Sandstone are medium sand, poorly to moderately sorted, coarse to strongly coarse skewed with mesokurtic to leptokurtic grains. The heavy minerals present in lithologic sand and sandstone units of Ajali Formation are mainly zircon, rutile, tourmaline, apatite, staurolite, and opaque minerals (Goethite, hematite, ilmenite), these heavy minerals found in the sandstone are associated with igneous and metamorphic source which indicates that these maastritchian sediments are from basement complex rock The ZTR index of 67.96% and the values of the kurtosis indicates a sub-mature sandstone to mature sandstone, which gives an excellent aquifer properties. Also, the paleoenvironment of deposition of the Maastrichtian sediments is Fluvial. The sand and sandstone bodies deposited in a fluvial system have sheet-like geometries and due to the differences in the extent of aquifer compartmentalization, Sandstone deposited in fluvial environment normally has better hydraulic conductivity which again reveals a good aquifer property. The sedimentological characteristics for the Sandstone exposed at Fugar and environs, is a coarsening upward sequence (increasing grain sizes) with a progressive increase in sorting. since hydraulic conductivity increases with increasing grain sizes and sorting, hence, excellent aquifer characteristics for the groundwater within the study area. The foregoing revealed that the aquifer geometry and properties of the study areas is favourable for the availability of drinking water for both the Urban and rural dwellers within these communities. Keywords: Aquifer geometry, groundwater, hydraulic conductivity, Anambra Basin

scholarly journals Deconvolution of Laboratory IR Spectral Reflectance Measurements of Olivine-Pyroxene Mineral Mixtures.

2020 ◽  
Author(s):  
Karin E. Bauch ◽  
Iris Weber ◽  
Maximilian P. Reitze ◽  
Andreas Morlok ◽  
Harald Hiesinger ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Channel ◽  
Signal To Noise Ratio ◽  
Analytical Techniques ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
High Signal ◽  
Grain Sizes ◽  
Mineral Mixtures ◽  
Rich Mixtures

<p>The imaging spectrometer MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) is part of the payload of ESA/JAXA’s BepiColombo mission, launched in 2018 [1,2]. The instrument consists of an IR-spectrometer and radiometer, which will observe the surface in the wavelength range of 7–14µm and 7–40μm, respectively. In preparation of the mission, we are investigating Mercury analog minerals at the IRIS (Infrared and Raman for Interplanetary Spectroscopy) laboratory of the Institut für Planetologie at the Westfälische Wilhelms-Universität Münster. We study typical rock-forming minerals, e.g., pyroxenes, olivines, and feldspars, as well as mineral mixtures.</p><p>Here we present results of a deconvolution model used to quantify mineral specific abundances of mineral mixtures [4,5]. Planetary surfaces are composed of a variety of different minerals, therefore the obtained spectral data reflects a mixture of these minerals. In order to quantify the mineral abundances a non-linear unmixing model is necessary. Our model is based on the Hapke reflectance theory [6-8] and is applied to data obtained at the IRIS laboratory [9]. Results of olivine and pyroxene mixtures, as well as grain size mixtures, will be presented at the meeting.</p><p>We used olivine (Fo<sub>91</sub>) from Dreiser Weiher, Germany, and pyroxene (En<sub>87</sub>) from Bamble, Norway and a range of mineral mixtures for IR measurements. Samples are sieved in grain size fractions of <25µm, 25-63µm, 63-125µm, and 125-250µm. For the mineral mixing analysis presented here, we focus on the 63-125µm fraction, which was also used by [10,11] for further investigations. Samples are analyzed by a Bruker Vertex 70v spectrometer with an A513 variable mirror reflectance stage for various incidence/emergence angles. A total of 512 single channel scans of the sample and the background (diffuse gold standard INFRAGOLD™) were accumulated to ensure a high signal-to-noise ratio.</p><p>The pure pyroxene and olivine spectra clearly show characteristic Christiansen features and Reststrahlen bands for all applied geometries and increasing phase angles result in decreased intensities. The reflectance increases from pyroxene and pyroxene-rich mixtures to olivine and olivine-rich mixtures. Moreover, the olivine-rich mixtures exhibit more olivine reflectance features, compared to pyroxene-rich mixtures [11].</p><p>Our studies of pyroxene grain size analysis focus on pyroxene mixtures of 50%fine/50%coarse and 30%fine/70%coarse material. Generally, the intensities increase with increasing grain sizes. The transparency feature is evident for small grain sizes and the 50%fine/50%coarse mixture.</p><p>At IRIS laboratory, we will further investigate planetary analog material and their mineral mixtures applying various analytical techniques. With these data we are establishing a database that will enable the correct interpretation of MERTIS results.</p><p><strong> </strong></p><p>This work has been funded by DLR grant 50 QW 1701 in the framework of the BepiColombo mission.</p><p> </p><p>[1] Hiesinger H. et al. (2010) <em>PSS58</em>, 144-165. [2] Benkhoff J. et al. (2010) <em>PSS58</em>, 2-20. [3] Grumpe A. et al (2017) <em>Icarus299</em>, 1-14. [4] Rommel D. et al. (2017) <em>Icarus284</em>, 126-149. [5] Hapke B. (1981), <em>JGR86</em><em>(B4)</em>, 3039-3054. [6] Hapke B. (2002), <em>Icarus157</em>, 523-534. [7] Hapke B. (2012), <em>2<sup>nd</sup>Cambr. Univ. Press., NY.</em> [8] Bauch, K.E. et al. (2019) <em>LPSC L</em>, Abstract#2521. [9] Weber I. et al. (2019) <em>LPSC L</em>, Abstract#2326. [10] Weber, I. et al. (2020) <em>LPSC LI</em>, Abstract#1889.</p>

scholarly journals Geochemical and Mineralogical Characterisation of Historic Zn–Pb Mine Waste, Plombières, East Belgium

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 28
Author(s):  
Srećko Bevandić ◽  
Rosie Blannin ◽  
Jacqueline Vander Auwera ◽  
Nicolas Delmelle ◽  
David Caterina ◽  
...  
Keyword(s):  
Grain Size ◽  
Mine Waste ◽  
Geophysical Methods ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Mine Wastes ◽  
Metallurgical Waste ◽  
High Concentration ◽  
Geochemical Properties ◽  
Potential Applications

Mine wastes and tailings derived from historical processing may contain significant contents of valuable metals due to processing being less efficient in the past. The Plombières tailings pond in eastern Belgium was selected as a case study to determine mineralogical and geochemical characteristics of the different mine waste materials found at the site. Four types of material were classified: soil, metallurgical waste, brown tailings and yellow tailings. The distribution of the mine wastes was investigated with drill holes, pit-holes and geophysical methods. Samples of the materials were assessed with grain size analysis, and mineralogical and geochemical techniques. The mine wastes dominantly consist of SiO2, Al2O3 and Fe2O3. The cover material, comprising soil and metallurgical waste is highly heterogeneous in terms of mineralogy, geochemistry and grain size. The metallurgical waste has a high concentration of metals (Zn: 0.1 to 24 wt.% and Pb: 0.1 to 10.1 wt.%). In the tailings materials, Pb and Zn vary from 10 ppm to 8.5 wt.% and from 51 ppm to 4 wt.%, respectively. The mining wastes comprises mainly quartz, amorphous phases and phyllosilicates, with minor contents of Fe-oxide and Pb- and Zn-bearing minerals. Based on the mineralogical and geochemical properties, the different potential applications of the four waste material types were determined. Additionally, the theoretical economic potential of Pb and Zn in the mine wastes was estimated.

scholarly journals Centennial Impacts of the East Asian Summer Monsoon on Holocene Deltaic Evolution of the Huanghe River, China

2021 ◽  
Vol 11 (6) ◽  
pp. 2799
Author(s):  
Yanping Chen ◽  
Wenzhe Lyu ◽  
Tengfei Fu ◽  
Yan Li ◽  
Liang Yi
Keyword(s):  
Grain Size ◽  
Yellow River ◽  
Asian Summer Monsoon ◽  
River Delta ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Sediment Grain Size ◽  
Huanghe River ◽  
Huanghe River Delta ◽  
The Huanghe River

The Huanghe River (Yellow River) is the most sediment laden river system in the world, and many efforts have been conducted to understand modern deltaic evolution in response to anthropological impacts. However, the natural background and its linkage to climatic changes are less documented in previous studies. In this work, we studied the sediments of core YDZ–3 and marine surface samples by grain-size analysis to retrieve Holocene dynamics of the Huanghe River delta in detail. The main findings are as follows: The mean value of sediment grain size of the studied core is 5.5 ± 0.9 Φ, and silt and sand contents are 5.2 ± 2.3% and 8.2 ± 5.3%, respectively, while the variance of clay particles is relatively large with an average value of 86.4 ± 8.5%. All grain-size data can be mathematically partitioned by a Weibull-based function formula, and three subgroups were identified with modal sizes of 61.1 ± 28.9 μm, 30.0 ± 23.9 μm, and 2.8 ± 1.6 μm, respectively. There are eight intervals with abrupt changes in modal size of core YDZ–3, which can be correlated to paleo-superlobe migration of the Huanghe River in the Holocene. Based on these observations, the presence of seven superlobes in the history are confirmed for the first time and their ages are well constrained in this study, including Paleo-Superlobes Lijin (6400–5280 yr BP), Huanghua (4480–4190 yr BP), Jugezhuang (3880–3660 yr BP), Shajinzi (3070–2870 yr BP), Nigu (2780–2360 yr BP), Qikou (2140–2000 yr BP), and Kenli (1940–1780 and 1700–1650 yr BP). By tuning geomorphological events to a sedimentary proxy derived from core YDZ–3 and comparing to various paleoenvironmental changes, we proposed that winter climate dominated Holocene shifts of the Huanghe River delta on millennial timescales, while summer monsoons controlled deltaic evolution on centennial timescales.

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